IT-Swarm.Net

如何在Java中读取/转换InputStream为String?

如果你有一个Java.io.InputStream对象,你应该如何处理该对象并生成一个String


假设我有一个包含文本数据的InputStream,我想将它转换为String,所以例如我可以将它写入日志文件。

采用InputStream并将其转换为String的最简单方法是什么?

public String convertStreamToString(InputStream is) {
    // ???
}
3650
Johnny Maelstrom

一个很好的方法是使用 Apache commonsIOUtilsInputStream复制到StringWriter...类似于

StringWriter writer = new StringWriter();
IOUtils.copy(inputStream, writer, encoding);
String theString = writer.toString();

甚至

// NB: does not close inputStream, you'll have to use try-with-resources for that
String theString = IOUtils.toString(inputStream, encoding); 

或者,如果您不想混合Streams和Writers,可以使用ByteArrayOutputStream

2228
Harry Lime

这是一种仅使用标准Java库的方法(请注意,流未关闭,您的里程可能会有所不同)。

static String convertStreamToString(Java.io.InputStream is) {
    Java.util.Scanner s = new Java.util.Scanner(is).useDelimiter("\\A");
    return s.hasNext() ? s.next() : "";
}

我从 “愚蠢的扫描仪技巧” 文章中学到了这个技巧。它起作用的原因是因为 Scanner 迭代流中的标记,在这种情况下我们使用“输入边界的开头”(\ A)分隔标记,因此只给我们一个标记用于整个内容流。

注意,如果您需要具体了解输入流的编码,可以为Scanner构造函数提供第二个参数,指示要使用的字符集(例如“UTF-8”)。

帽子小贴士也去了 雅各布 ,曾经把我指向上述文章。

2182
Pavel Repin

总结其他答案我找到了11种主要方法(见下文)。我写了一些性能测试(见下面的结果):

将InputStream转换为String的方法:

  1. 使用IOUtils.toString(Apache Utils) 

    String result = IOUtils.toString(inputStream, StandardCharsets.UTF_8);
    
  2. 使用CharStreams(番石榴) 

    String result = CharStreams.toString(new InputStreamReader(
          inputStream, Charsets.UTF_8));
    
  3. 使用Scanner(JDK) 

    Scanner s = new Scanner(inputStream).useDelimiter("\\A");
    String result = s.hasNext() ? s.next() : "";
    
  4. 使用 Stream API (Java 8)。 警告 :此解决方案将不同的换行符(如\r\n)转换为\n

    String result = new BufferedReader(new InputStreamReader(inputStream))
      .lines().collect(Collectors.joining("\n"));
    
  5. 使用 parallel Stream API (Java 8)。 警告 :此解决方案将不同的换行符(如\r\n)转换为\n。 

    String result = new BufferedReader(new InputStreamReader(inputStream)).lines()
       .parallel().collect(Collectors.joining("\n"));
    
  6. 使用InputStreamReaderStringBuilder(JDK) 

    final int bufferSize = 1024;
    final char[] buffer = new char[bufferSize];
    final StringBuilder out = new StringBuilder();
    Reader in = new InputStreamReader(inputStream, "UTF-8");
    for (; ; ) {
        int rsz = in.read(buffer, 0, buffer.length);
        if (rsz < 0)
            break;
        out.append(buffer, 0, rsz);
    }
    return out.toString();
    
  7. 使用StringWriterIOUtils.copy(Apache Commons)

    StringWriter writer = new StringWriter();
    IOUtils.copy(inputStream, writer, "UTF-8");
    return writer.toString();
    
  8. 使用ByteArrayOutputStreaminputStream.read(JDK) 

    ByteArrayOutputStream result = new ByteArrayOutputStream();
    byte[] buffer = new byte[1024];
    int length;
    while ((length = inputStream.read(buffer)) != -1) {
        result.write(buffer, 0, length);
    }
    // StandardCharsets.UTF_8.name() > JDK 7
    return result.toString("UTF-8");
    
  9. 使用BufferedReader(JDK)。 警告: 此解决方案将不同的换行符(如\n\r)转换为line.separator系统属性(例如,在Windows中转换为“\ r\n”)。

    String newLine = System.getProperty("line.separator");
    BufferedReader reader = new BufferedReader(new InputStreamReader(inputStream));
    StringBuilder result = new StringBuilder();
    boolean flag = false;
    for (String line; (line = reader.readLine()) != null; ) {
        result.append(flag? newLine: "").append(line);
        flag = true;
    }
    return result.toString();
    
  10. 使用BufferedInputStreamByteArrayOutputStream(JDK) 

    BufferedInputStream bis = new BufferedInputStream(inputStream);
    ByteArrayOutputStream buf = new ByteArrayOutputStream();
    int result = bis.read();
    while(result != -1) {
        buf.write((byte) result);
        result = bis.read();
    }
    // StandardCharsets.UTF_8.name() > JDK 7
    return buf.toString("UTF-8");
    
  11. 使用inputStream.read()StringBuilder(JDK)。 警告 :此解决方案存在Unicode问题,例如使用俄语文本(仅适用于非Unicode文本)

    int ch;
    StringBuilder sb = new StringBuilder();
    while((ch = inputStream.read()) != -1)
        sb.append((char)ch);
    reset();
    return sb.toString();
    

警告

  1. 解决方案4,5和9将不同的换行符转换为1。

  2. 解决方案11无法与Unicode文本一起正常工作

性能测试

String(长度= 175)的性能测试, github中的url (模式=平均时间,系统= Linux,得分1,343是最好的):

              Benchmark                         Mode  Cnt   Score   Error  Units
 8. ByteArrayOutputStream and read (JDK)        avgt   10   1,343 ± 0,028  us/op
 6. InputStreamReader and StringBuilder (JDK)   avgt   10   6,980 ± 0,404  us/op
10. BufferedInputStream, ByteArrayOutputStream  avgt   10   7,437 ± 0,735  us/op
11. InputStream.read() and StringBuilder (JDK)  avgt   10   8,977 ± 0,328  us/op
 7. StringWriter and IOUtils.copy (Apache)      avgt   10  10,613 ± 0,599  us/op
 1. IOUtils.toString (Apache Utils)             avgt   10  10,605 ± 0,527  us/op
 3. Scanner (JDK)                               avgt   10  12,083 ± 0,293  us/op
 2. CharStreams (guava)                         avgt   10  12,999 ± 0,514  us/op
 4. Stream Api (Java 8)                         avgt   10  15,811 ± 0,605  us/op
 9. BufferedReader (JDK)                        avgt   10  16,038 ± 0,711  us/op
 5. parallel Stream Api (Java 8)                avgt   10  21,544 ± 0,583  us/op

String(长度= 50100)的性能测试, github中的url (模式=平均时间,系统= Linux,得分200,715是最好的):

               Benchmark                        Mode  Cnt   Score        Error  Units
 8. ByteArrayOutputStream and read (JDK)        avgt   10   200,715 ±   18,103  us/op
 1. IOUtils.toString (Apache Utils)             avgt   10   300,019 ±    8,751  us/op
 6. InputStreamReader and StringBuilder (JDK)   avgt   10   347,616 ±  130,348  us/op
 7. StringWriter and IOUtils.copy (Apache)      avgt   10   352,791 ±  105,337  us/op
 2. CharStreams (guava)                         avgt   10   420,137 ±   59,877  us/op
 9. BufferedReader (JDK)                        avgt   10   632,028 ±   17,002  us/op
 5. parallel Stream Api (Java 8)                avgt   10   662,999 ±   46,199  us/op
 4. Stream Api (Java 8)                         avgt   10   701,269 ±   82,296  us/op
10. BufferedInputStream, ByteArrayOutputStream  avgt   10   740,837 ±    5,613  us/op
 3. Scanner (JDK)                               avgt   10   751,417 ±   62,026  us/op
11. InputStream.read() and StringBuilder (JDK)  avgt   10  2919,350 ± 1101,942  us/op

图表(性能测试取决于Windows 7系统中的输入流长度)
enter image description here

性能测试(平均时间)取决于Windows 7系统中的输入流长度:

 length  182    546     1092    3276    9828    29484   58968

 test8  0.38    0.938   1.868   4.448   13.412  36.459  72.708
 test4  2.362   3.609   5.573   12.769  40.74   81.415  159.864
 test5  3.881   5.075   6.904   14.123  50.258  129.937 166.162
 test9  2.237   3.493   5.422   11.977  45.98   89.336  177.39
 test6  1.261   2.12    4.38    10.698  31.821  86.106  186.636
 test7  1.601   2.391   3.646   8.367   38.196  110.221 211.016
 test1  1.529   2.381   3.527   8.411   40.551  105.16  212.573
 test3  3.035   3.934   8.606   20.858  61.571  118.744 235.428
 test2  3.136   6.238   10.508  33.48   43.532  118.044 239.481
 test10 1.593   4.736   7.527   20.557  59.856  162.907 323.147
 test11 3.913   11.506  23.26   68.644  207.591 600.444 1211.545
1964
Viacheslav Vedenin

Apache Commons允许:

String myString = IOUtils.toString(myInputStream, "UTF-8");

当然,您可以选择除UTF-8之外的其他字符编码。

另见:( 文档

810
Chinnery

考虑到文件一应首先获得Java.io.Reader实例。然后可以读取它并将其添加到StringBuilder(如果我们不在多个线程中访问它,我们不需要StringBuffer,并且StringBuilder更快)。这里的诀窍是我们在块中工作,因此不需要其他缓冲流。块大小参数化,用于运行时性能优化。

public static String Slurp(final InputStream is, final int bufferSize) {
    final char[] buffer = new char[bufferSize];
    final StringBuilder out = new StringBuilder();
    try (Reader in = new InputStreamReader(is, "UTF-8")) {
        for (;;) {
            int rsz = in.read(buffer, 0, buffer.length);
            if (rsz < 0)
                break;
            out.append(buffer, 0, rsz);
        }
    }
    catch (UnsupportedEncodingException ex) {
        /* ... */
    }
    catch (IOException ex) {
        /* ... */
    }
    return out.toString();
}
275
Paul de Vrieze

使用:

InputStream in = /* Your InputStream */;
StringBuilder sb = new StringBuilder();
BufferedReader br = new BufferedReader(new InputStreamReader(in));
String read;

while ((read=br.readLine()) != null) {
    //System.out.println(read);
    sb.append(read);
}

br.close();
return sb.toString();
232
sampathpremarathna

如果您使用的是Google-Collections/Guava,则可以执行以下操作:

InputStream stream = ...
String content = CharStreams.toString(new InputStreamReader(stream, Charsets.UTF_8));
Closeables.closeQuietly(stream);

请注意,InputStreamReader的第二个参数(即Charsets.UTF_8)不是必需的,但如果您知道它,通常最好指定编码(您应该这样做!)

163
Sakuraba

这是我的纯Java和Android解决方案,它运行良好......

public String readFullyAsString(InputStream inputStream, String encoding)
        throws IOException {
    return readFully(inputStream).toString(encoding);
}

public byte[] readFullyAsBytes(InputStream inputStream)
        throws IOException {
    return readFully(inputStream).toByteArray();
}

private ByteArrayOutputStream readFully(InputStream inputStream)
        throws IOException {
    ByteArrayOutputStream baos = new ByteArrayOutputStream();
    byte[] buffer = new byte[1024];
    int length = 0;
    while ((length = inputStream.read(buffer)) != -1) {
        baos.write(buffer, 0, length);
    }
    return baos;
}
111
TacB0sS

这是我在经过一些实验后想出的最优雅的纯Java(无库)解决方案:

public static String fromStream(InputStream in) throws IOException
{
    BufferedReader reader = new BufferedReader(new InputStreamReader(in));
    StringBuilder out = new StringBuilder();
    String newLine = System.getProperty("line.separator");
    String line;
    while ((line = reader.readLine()) != null) {
        out.append(line);
        out.append(newLine);
    }
    return out.toString();
}
57
Drew Noakes

使用:

import Java.io.BufferedInputStream;
import Java.io.ByteArrayOutputStream;
import Java.io.InputStream;
import Java.io.IOException;

public static String readInputStreamAsString(InputStream in)
    throws IOException {

    BufferedInputStream bis = new BufferedInputStream(in);
    ByteArrayOutputStream buf = new ByteArrayOutputStream();
    int result = bis.read();
    while(result != -1) {
      byte b = (byte)result;
      buf.write(b);
      result = bis.read();
    }
    return buf.toString();
}
57
Jon Moore

为了完整性,这里是 Java 9 solution:

public static String toString(InputStream input) throws IOException {
    return new String(input.readAllBytes(), StandardCharsets.UTF_8);
}

readAllBytes 目前在JDK 9主代码库中,因此很可能出现在发行版中。您现在可以使用 JDK 9快照构建 来尝试它。

47
Tagir Valeev

我会使用一些Java 8技巧。

public static String streamToString(final InputStream inputStream) throws Exception {
    // buffering optional
    try
    (
        final BufferedReader br
           = new BufferedReader(new InputStreamReader(inputStream))
    ) {
        // parallel optional
        return br.lines().parallel().collect(Collectors.joining("\n"));
    } catch (final IOException e) {
        throw new RuntimeException(e);
        // whatever.
    }
}

基本上与其他一些答案相同,除了更简洁。

35
Simon Kuang

我在这里做了14个不同答案的基准(抱歉没有提供学分,但有太多重复)。

结果非常令人惊讶。事实证明,Apache IOUtils 是最慢的,而ByteArrayOutputStream是最快的解决方案:

所以首先这里是最好的方法:

public String inputStreamToString(InputStream inputStream) throws IOException {
    try(ByteArrayOutputStream result = new ByteArrayOutputStream()) {
        byte[] buffer = new byte[1024];
        int length;
        while ((length = inputStream.read(buffer)) != -1) {
            result.write(buffer, 0, length);
        }

        return result.toString(UTF_8);
    }
}

基准测试结果,20个周期内20 MB随机字节

时间以毫秒为单位

  • ByteArrayOutputStreamTest:194
  • NioStream:198
  • Java9ISTransferTo:201
  • Java9ISReadAllBytes:205
  • BufferedInputStreamVsByteArrayOutputStream:314
  • ApacheStringWriter2:574
  • GuavaCharStreams:589
  • ScannerReaderNoNextTest:614
  • ScannerReader:633
  • ApacheStringWriter:1544
  • StreamApi:错误
  • ParallelStreamApi:错误
  • BufferReaderTest:错误
  • InputStreamAndStringBuilder:错误

基准源代码

import com.google.common.io.CharStreams;
import org.Apache.commons.io.IOUtils;

import Java.io.*;
import Java.nio.ByteBuffer;
import Java.nio.channels.Channels;
import Java.nio.channels.ReadableByteChannel;
import Java.nio.channels.WritableByteChannel;
import Java.util.Arrays;
import Java.util.List;
import Java.util.Random;
import Java.util.stream.Collectors;

/**
 * Created by Ilya Gazman on 2/13/18.
 */
public class InputStreamToString {


    private static final String UTF_8 = "UTF-8";

    public static void main(String... args) {
        log("App started");
        byte[] bytes = new byte[1024 * 1024];
        new Random().nextBytes(bytes);
        log("Stream is ready\n");

        try {
            test(bytes);
        } catch (IOException e) {
            e.printStackTrace();
        }
    }

    private static void test(byte[] bytes) throws IOException {
        List<Stringify> tests = Arrays.asList(
                new ApacheStringWriter(),
                new ApacheStringWriter2(),
                new NioStream(),
                new ScannerReader(),
                new ScannerReaderNoNextTest(),
                new GuavaCharStreams(),
                new StreamApi(),
                new ParallelStreamApi(),
                new ByteArrayOutputStreamTest(),
                new BufferReaderTest(),
                new BufferedInputStreamVsByteArrayOutputStream(),
                new InputStreamAndStringBuilder(),
                new Java9ISTransferTo(),
                new Java9ISReadAllBytes()
        );

        String solution = new String(bytes, "UTF-8");

        for (Stringify test : tests) {
            try (ByteArrayInputStream inputStream = new ByteArrayInputStream(bytes)) {
                String s = test.inputStreamToString(inputStream);
                if (!s.equals(solution)) {
                    log(test.name() + ": Error");
                    continue;
                }
            }
            long startTime = System.currentTimeMillis();
            for (int i = 0; i < 20; i++) {
                try (ByteArrayInputStream inputStream = new ByteArrayInputStream(bytes)) {
                    test.inputStreamToString(inputStream);
                }
            }
            log(test.name() + ": " + (System.currentTimeMillis() - startTime));
        }
    }

    private static void log(String message) {
        System.out.println(message);
    }

    interface Stringify {
        String inputStreamToString(InputStream inputStream) throws IOException;

        default String name() {
            return this.getClass().getSimpleName();
        }
    }

    static class ApacheStringWriter implements Stringify {

        @Override
        public String inputStreamToString(InputStream inputStream) throws IOException {
            StringWriter writer = new StringWriter();
            IOUtils.copy(inputStream, writer, UTF_8);
            return writer.toString();
        }
    }

    static class ApacheStringWriter2 implements Stringify {

        @Override
        public String inputStreamToString(InputStream inputStream) throws IOException {
            return IOUtils.toString(inputStream, UTF_8);
        }
    }

    static class NioStream implements Stringify {

        @Override
        public String inputStreamToString(InputStream in) throws IOException {
            ReadableByteChannel channel = Channels.newChannel(in);
            ByteBuffer byteBuffer = ByteBuffer.allocate(1024 * 16);
            ByteArrayOutputStream bout = new ByteArrayOutputStream();
            WritableByteChannel outChannel = Channels.newChannel(bout);
            while (channel.read(byteBuffer) > 0 || byteBuffer.position() > 0) {
                byteBuffer.flip();  //make buffer ready for write
                outChannel.write(byteBuffer);
                byteBuffer.compact(); //make buffer ready for reading
            }
            channel.close();
            outChannel.close();
            return bout.toString(UTF_8);
        }
    }

    static class ScannerReader implements Stringify {

        @Override
        public String inputStreamToString(InputStream is) throws IOException {
            Java.util.Scanner s = new Java.util.Scanner(is).useDelimiter("\\A");
            return s.hasNext() ? s.next() : "";
        }
    }

    static class ScannerReaderNoNextTest implements Stringify {

        @Override
        public String inputStreamToString(InputStream is) throws IOException {
            Java.util.Scanner s = new Java.util.Scanner(is).useDelimiter("\\A");
            return s.next();
        }
    }

    static class GuavaCharStreams implements Stringify {

        @Override
        public String inputStreamToString(InputStream is) throws IOException {
            return CharStreams.toString(new InputStreamReader(
                    is, UTF_8));
        }
    }

    static class StreamApi implements Stringify {

        @Override
        public String inputStreamToString(InputStream inputStream) throws IOException {
            return new BufferedReader(new InputStreamReader(inputStream))
                    .lines().collect(Collectors.joining("\n"));
        }
    }

    static class ParallelStreamApi implements Stringify {

        @Override
        public String inputStreamToString(InputStream inputStream) throws IOException {
            return new BufferedReader(new InputStreamReader(inputStream)).lines()
                    .parallel().collect(Collectors.joining("\n"));
        }
    }

    static class ByteArrayOutputStreamTest implements Stringify {

        @Override
        public String inputStreamToString(InputStream inputStream) throws IOException {
            try(ByteArrayOutputStream result = new ByteArrayOutputStream()) {
                byte[] buffer = new byte[1024];
                int length;
                while ((length = inputStream.read(buffer)) != -1) {
                    result.write(buffer, 0, length);
                }

                return result.toString(UTF_8);
            }
        }
    }

    static class BufferReaderTest implements Stringify {

        @Override
        public String inputStreamToString(InputStream inputStream) throws IOException {
            String newLine = System.getProperty("line.separator");
            BufferedReader reader = new BufferedReader(new InputStreamReader(inputStream));
            StringBuilder result = new StringBuilder(UTF_8);
            String line;
            boolean flag = false;
            while ((line = reader.readLine()) != null) {
                result.append(flag ? newLine : "").append(line);
                flag = true;
            }
            return result.toString();
        }
    }

    static class BufferedInputStreamVsByteArrayOutputStream implements Stringify {

        @Override
        public String inputStreamToString(InputStream inputStream) throws IOException {
            BufferedInputStream bis = new BufferedInputStream(inputStream);
            ByteArrayOutputStream buf = new ByteArrayOutputStream();
            int result = bis.read();
            while (result != -1) {
                buf.write((byte) result);
                result = bis.read();
            }

            return buf.toString(UTF_8);
        }
    }

    static class InputStreamAndStringBuilder implements Stringify {

        @Override
        public String inputStreamToString(InputStream inputStream) throws IOException {
            int ch;
            StringBuilder sb = new StringBuilder(UTF_8);
            while ((ch = inputStream.read()) != -1)
                sb.append((char) ch);
            return sb.toString();
        }
    }

    static class Java9ISTransferTo implements Stringify {

        @Override
        public String inputStreamToString(InputStream inputStream) throws IOException {
            ByteArrayOutputStream bos = new ByteArrayOutputStream();
            inputStream.transferTo(bos);
            return bos.toString(UTF_8);
        }
    }

    static class Java9ISReadAllBytes implements Stringify {

        @Override
        public String inputStreamToString(InputStream inputStream) throws IOException {
            return new String(inputStream.readAllBytes(), UTF_8);
        }
    }

}
33
Ilya Gazman

我经常进行一些时间测试,因为时间很重要。

我试图以不同的方式将响应变为String 3。 (如下所示)
为了便于阅读,我遗漏了try/catch块。

为了给出上下文,这是所有3种方法的前面的代码:

   String response;
   String url = "www.blah.com/path?key=value";
   GetMethod method = new GetMethod(url);
   int status = client.executeMethod(method);

1)

 response = method.getResponseBodyAsString();

2)

InputStream resp = method.getResponseBodyAsStream();
InputStreamReader is=new InputStreamReader(resp);
BufferedReader br=new BufferedReader(is);
String read = null;
StringBuffer sb = new StringBuffer();
while((read = br.readLine()) != null) {
    sb.append(read);
}
response = sb.toString();

3)

InputStream iStream  = method.getResponseBodyAsStream();
StringWriter writer = new StringWriter();
IOUtils.copy(iStream, writer, "UTF-8");
response = writer.toString();

因此,在使用相同的请求/响应数据对每个方法运行500次测试之后,这里是数字。再一次,这些是我的发现,你的发现可能不完全相同,但我写这篇文章是为了向其他人说明这些方法的效率差异。

排名:
方法#1
方法#3 - 比#1慢2.6%
方法#2 - 比#1慢4.3%

这些方法中的任何一种都是用于获取响应并从中创建String的适当解决方案。

29
Brett Holt

纯Java解决方案使用 Stream s,自Java 8开始工作。

import Java.io.BufferedReader;
import Java.io.IOException;
import Java.io.InputStream;
import Java.io.InputStreamReader;
import Java.util.stream.Collectors;

// ...
public static String inputStreamToString(InputStream is) throws IOException {
    try (BufferedReader br = new BufferedReader(new InputStreamReader(is))) {
        return br.lines().collect(Collectors.joining(System.lineSeparator()));
    }
}

如ChristofferHammarström所述 其他答案 明确指定 Charset 更安全。即InputStreamReader构造函数可以更改如下:

new InputStreamReader(is, Charset.forName("UTF-8"))
27
czerny

这里是或多或少的sampath的答案,清理了一下并表示为一个函数:

String streamToString(InputStream in) throws IOException {
  StringBuilder out = new StringBuilder();
  BufferedReader br = new BufferedReader(new InputStreamReader(in));
  for(String line = br.readLine(); line != null; line = br.readLine()) 
    out.append(line);
  br.close();
  return out.toString();
}
23
TKH

如果您喜欢冒险,可以将Scala和Java混合使用,最后得到:

scala.io.Source.fromInputStream(is).mkString("")

混合Java和Scala代码和库有它的好处。

请在此处查看完整描述: 在Scala中将InputStream转换为String的惯用方法

21
Jack

如果您不能使用Commons IO(FileUtils/IOUtils/CopyUtils),这是一个使用BufferedReader逐行读取文件的示例:

public class StringFromFile {
    public static void main(String[] args) /*throws UnsupportedEncodingException*/ {
        InputStream is = StringFromFile.class.getResourceAsStream("file.txt");
        BufferedReader br = new BufferedReader(new InputStreamReader(is/*, "UTF-8"*/));
        final int CHARS_PER_PAGE = 5000; //counting spaces
        StringBuilder builder = new StringBuilder(CHARS_PER_PAGE);
        try {
            for(String line=br.readLine(); line!=null; line=br.readLine()) {
                builder.append(line);
                builder.append('\n');
            }
        } 
        catch (IOException ignore) { }

        String text = builder.toString();
        System.out.println(text);
    }
}

或者如果你想要原始速度,我会建议Paul de Vrieze建议的变体(这避免使用StringWriter(在内部使用StringBuffer):

public class StringFromFileFast {
    public static void main(String[] args) /*throws UnsupportedEncodingException*/ {
        InputStream is = StringFromFileFast.class.getResourceAsStream("file.txt");
        InputStreamReader input = new InputStreamReader(is/*, "UTF-8"*/);
        final int CHARS_PER_PAGE = 5000; //counting spaces
        final char[] buffer = new char[CHARS_PER_PAGE];
        StringBuilder output = new StringBuilder(CHARS_PER_PAGE);
        try {
            for(int read = input.read(buffer, 0, buffer.length);
                    read != -1;
                    read = input.read(buffer, 0, buffer.length)) {
                output.append(buffer, 0, read);
            }
        } catch (IOException ignore) { }

        String text = output.toString();
        System.out.println(text);
    }
}
18
DJDaveMark

这是一个改编自org.Apache.commons.io.IOUtils源代码 的答案,适用于那些想要实现Apache但不想要整个库的人。

private static final int BUFFER_SIZE = 4 * 1024;

public static String inputStreamToString(InputStream inputStream, String charsetName)
        throws IOException {
    StringBuilder builder = new StringBuilder();
    InputStreamReader reader = new InputStreamReader(inputStream, charsetName);
    char[] buffer = new char[BUFFER_SIZE];
    int length;
    while ((length = reader.read(buffer)) != -1) {
        builder.append(buffer, 0, length);
    }
    return builder.toString();
}
17
Dreaming in Code

如果使用Stream Readers,请务必在结尾处关闭流

private String readStream(InputStream iStream) throws IOException {
    //build a Stream Reader, it can read char by char
    InputStreamReader iStreamReader = new InputStreamReader(iStream);
    //build a buffered Reader, so that i can read whole line at once
    BufferedReader bReader = new BufferedReader(iStreamReader);
    String line = null;
    StringBuilder builder = new StringBuilder();
    while((line = bReader.readLine()) != null) {  //Read till end
        builder.append(line);
        builder.append("\n"); // append new line to preserve lines
    }
    bReader.close();         //close all opened stuff
    iStreamReader.close();
    //iStream.close(); //EDIT: Let the creator of the stream close it!
                       // some readers may auto close the inner stream
    return builder.toString();
}

编辑:在JDK 7+上,您可以使用try-with-resources构造。

/**
 * Reads the stream into a string
 * @param iStream the input stream
 * @return the string read from the stream
 * @throws IOException when an IO error occurs
 */
private String readStream(InputStream iStream) throws IOException {

    //Buffered reader allows us to read line by line
    try (BufferedReader bReader =
                 new BufferedReader(new InputStreamReader(iStream))){
        StringBuilder builder = new StringBuilder();
        String line;
        while((line = bReader.readLine()) != null) {  //Read till end
            builder.append(line);
            builder.append("\n"); // append new line to preserve lines
        }
        return builder.toString();
    }
}
16
Thamme Gowda

这是在不使用任何第三方库的情况下将InputStream转换为String的完整方法。使用StringBuilder表示单线程环境,否则使用StringBuffer。 

public static String getString( InputStream is) throws IOException {
    int ch;
    StringBuilder sb = new StringBuilder();
    while((ch = is.read()) != -1)
        sb.append((char)ch);
    return sb.toString();
}
15
laksys

以下是使用字节数组缓冲区仅使用JDK的方法。这实际上是commons-io IOUtils.copy()方法的工作原理。如果您从Reader而不是InputStream进行复制,则可以将byte[]替换为char[]

import Java.io.ByteArrayOutputStream;
import Java.io.InputStream;

...

InputStream is = ....
ByteArrayOutputStream baos = new ByteArrayOutputStream(8192);
byte[] buffer = new byte[8192];
int count = 0;
try {
  while ((count = is.read(buffer)) != -1) {
    baos.write(buffer, 0, count);
  }
}
finally {
  try {
    is.close();
  }
  catch (Exception ignore) {
  }
}

String charset = "UTF-8";
String inputStreamAsString = baos.toString(charset);
14
Matt Shannon

另一个,适用于所有Spring用户:

import Java.nio.charset.StandardCharsets;
import org.springframework.util.FileCopyUtils;

public String convertStreamToString(InputStream is) throws IOException { 
    return new String(FileCopyUtils.copyToByteArray(is), StandardCharsets.UTF_8);
}

org.springframework.util.StreamUtils中的实用程序方法与FileCopyUtils中的实用程序方法类似,但它们在完成时将流保持打开状态。

12
James

使用 Java.io.InputStream.transferTo(OutputStream) Java 9中支持和 ByteArrayOutputStream.toString(String) 采用charset名称:

public static String gobble(InputStream in, String charsetName) throws IOException {
    ByteArrayOutputStream bos = new ByteArrayOutputStream();
    in.transferTo(bos);
    return bos.toString(charsetName);
}
12
jmehrens

Kotlin用户只需:

println(InputStreamReader(is).readText())

而 

readText()

是Kotlin标准库的内置扩展方法。

11
Alex

这个很好,因为:

  • Charset的手安全。
  • 您可以控制读取缓冲区大小。
  • 您可以设置构建器的长度,但可能不完全相同。
  • 没有库依赖项。
  • 适用于Java 7或更高版本。

为什么?

public static String convertStreamToString(InputStream is) {
   if (is == null) return null;
   StringBuilder sb = new StringBuilder(2048); // Define a size if you have an idea of it.
   char[] read = new char[128]; // Your buffer size.
   try (InputStreamReader ir = new InputStreamReader(is, StandardCharsets.UTF_8)) {
     for (int i; -1 != (i = ir.read(read)); sb.append(read, 0, i));
   } catch (Throwable t) {}
   return sb.toString();
}
9
Daniel De León

JDK中最简单的方法是使用以下代码片段。 

String convertToString(InputStream in){
    String resource = new Scanner(in).useDelimiter("\\Z").next();
    return resource;
}
7
Raghu K Nair

这是我基于Java 8的解决方案,它使用 new Stream API 来收集InputStream中的所有行:

public static String toString(InputStream inputStream) {
    BufferedReader reader = new BufferedReader(
        new InputStreamReader(inputStream));
    return reader.lines().collect(Collectors.joining(
        System.getProperty("line.separator")));
}
6
Christian Rädel

在Groovy中

inputStream.getText()
5
Snekse

reduceconcat而言,它可以在Java 8中表示为:

String fromFile = new BufferedReader(new   
InputStreamReader(inputStream)).lines().reduce(String::concat).get();
5
libnull-dev

我写了一个这样做的课程,所以我想我会和大家分享。有时你不想只为一件事添加Apache Commons,并且想要一些比扫描器更笨的东西不检查内容。

用法如下

// Read from InputStream
String data = new ReaderSink(inputStream, Charset.forName("UTF-8")).drain();

// Read from File
data = new ReaderSink(file, Charset.forName("UTF-8")).drain();

// Drain input stream to console
new ReaderSink(inputStream, Charset.forName("UTF-8")).drainTo(System.out);

以下是ReaderSink的代码:

import Java.io.*;
import Java.nio.charset.Charset;

/**
 * A simple sink class that drains a {@link Reader} to a {@link String} or
 * to a {@link Writer}.
 *
 * @author Ben Barkay
 * @version 2/20/2014
 */
public class ReaderSink {
    /**
     * The default buffer size to use if no buffer size was specified.
     */
    public static final int DEFAULT_BUFFER_SIZE = 1024;

    /**
     * The {@link Reader} that will be drained.
     */
    private final Reader in;

    /**
     * Constructs a new {@code ReaderSink} for the specified file and charset.
     * @param file      The file to read from.
     * @param charset   The charset to use.
     * @throws FileNotFoundException    If the file was not found on the filesystem.
     */
    public ReaderSink(File file, Charset charset) throws FileNotFoundException {
        this(new FileInputStream(file), charset);
    }

    /**
     * Constructs a new {@code ReaderSink} for the specified {@link InputStream}.
     * @param in        The {@link InputStream} to drain.
     * @param charset   The charset to use.
     */
    public ReaderSink(InputStream in, Charset charset) {
        this(new InputStreamReader(in, charset));
    }

    /**
     * Constructs a new {@code ReaderSink} for the specified {@link Reader}.
     * @param in    The reader to drain.
     */
    public ReaderSink(Reader in) {
        this.in = in;
    }

    /**
     * Drains the data from the underlying {@link Reader}, returning a {@link String} containing
     * all of the read information. This method will use {@link #DEFAULT_BUFFER_SIZE} for
     * its buffer size.
     * @return  A {@link String} containing all of the information that was read.
     */
    public String drain() throws IOException {
        return drain(DEFAULT_BUFFER_SIZE);
    }

    /**
     * Drains the data from the underlying {@link Reader}, returning a {@link String} containing
     * all of the read information.
     * @param bufferSize    The size of the buffer to use when reading.
     * @return  A {@link String} containing all of the information that was read.
     */
    public String drain(int bufferSize) throws IOException {
        StringWriter stringWriter = new StringWriter();
        drainTo(stringWriter, bufferSize);
        return stringWriter.toString();
    }

    /**
     * Drains the data from the underlying {@link Reader}, writing it to the
     * specified {@link Writer}. This method will use {@link #DEFAULT_BUFFER_SIZE} for
     * its buffer size.
     * @param out   The {@link Writer} to write to.
     */
    public void drainTo(Writer out) throws IOException {
        drainTo(out, DEFAULT_BUFFER_SIZE);
    }

    /**
     * Drains the data from the underlying {@link Reader}, writing it to the
     * specified {@link Writer}.
     * @param out           The {@link Writer} to write to.
     * @param bufferSize    The size of the buffer to use when reader.
     */
    public void drainTo(Writer out, int bufferSize) throws IOException {
        char[] buffer = new char[bufferSize];
        int read;
        while ((read = in.read(buffer)) > -1) {
            out.write(buffer, 0, read);
        }
    }
}
4
Ben Barkay

基于 接受的Apache Commons回答的第二部分 但是为了总是关闭流来填补小差距:

    String theString;
    try {
        theString = IOUtils.toString(inputStream, encoding);
    } finally {
        IOUtils.closeQuietly(inputStream);
    }
4
Steve Chambers

Raghu K Nair 是唯一使用扫描仪的人。[。_____。]我使用的代码有点不同:

String convertToString(InputStream in){
    Scanner scanner = new Scanner(in)
    scanner.useDelimiter("\\A");

    boolean hasInput = scanner.hasNext();
    if (hasInput) {
        return scanner.next();
    } else {
        return null;
    }

}

关于分隔符: 如何在Java Scanner中使用分隔符?

4
Halfacht

以下代码对我有用。 

URL url = MyClass.class.getResource("/" + configFileName);
BufferedInputStream bi = (BufferedInputStream) url.getContent();
byte[] buffer = new byte[bi.available() ];
int bytesRead = bi.read(buffer);
String out = new String(buffer);

请注意,根据Java文档,available()方法可能不适用于InputStream但总是适用于BufferedInputStream。[。_____。]如果您不想使用available()方法,我们总是可以使用下面的代码

URL url = MyClass.class.getResource("/" + configFileName);
BufferedInputStream bi = (BufferedInputStream) url.getContent();
File f = new File(url.getPath());
byte[] buffer = new byte[ (int) f.length()];
int bytesRead = bi.read(buffer);
String out = new String(buffer);

我不确定是否会出现编码问题。如果代码有任何问题,请发表评论。

4
Anand N

当输入流来自类路径资源(这似乎是流行的任务)时,Guava提供 更短的高效自动闭合解决方案:

byte[] bytes = Resources.toByteArray(classLoader.getResource(path));

要么 

String text = Resources.toString(classLoader.getResource(path), StandardCharsets.UTF_8);

还有 ByteSourceCharSource 的一般概念,它可以轻轻地打开和关闭流。

因此,例如,而不是显式打开一个小文件来读取其内容:

String content = Files.asCharSource(new File("robots.txt"), StandardCharsets.UTF_8).read();
byte[] data = Files.asByteSource(new File("favicon.ico")).read();

要不就

String content = Files.toString(new File("robots.txt"), StandardCharsets.UTF_8);
byte[] data = Files.toByteArray(new File("favicon.ico"));
4
Vadzim
public String read(InputStream in) throws IOException {
    try (BufferedReader buffer = new BufferedReader(new InputStreamReader(in))) {
        return buffer.lines().collect(Collectors.joining("\n"));
    }
}
3
Hao Zheng

有了Okio:

String result = Okio.buffer(Okio.source(inputStream)).readUtf8();
3
drakeet

JDK 7/8回答关闭流并仍然抛出IOException:

StringBuilder build = new StringBuilder();
byte[] buf = new byte[1024];
int length;
try (InputStream is = getInputStream()) {
  while ((length = is.read(buf)) != -1) {
    build.append(new String(buf, 0, length));
  }
}
3
Brian Pontarelli

您可以使用Apache Commons。

在IOUtils中,您可以找到带有三个有用实现的toString方法。

public static String toString(InputStream input) throws IOException {
        return toString(input, Charset.defaultCharset());
}

public static String toString(InputStream input) throws IOException {
        return toString(input, Charset.defaultCharset());
}

public static String toString(InputStream input, String encoding)
            throws IOException {
        return toString(input, Charsets.toCharset(encoding));
}
3
Rys
InputStream is = Context.openFileInput(someFileName); // whatever format you have

ByteArrayOutputStream bos = new ByteArrayOutputStream();

byte[] b = new byte[8192];
for (int bytesRead; (bytesRead = is.read(b)) != -1;) {
    bos.write(b, 0, bytesRead);
}

String output = bos.toString(someEncoding);
3
Vaishali Sutariya
InputStreamReader i = new InputStreamReader(s);
BufferedReader str = new BufferedReader(i);
String msg = str.readLine();
System.out.println(msg);

这是你的InputStream对象,它将被转换为String 

3
Omkar Khot

好吧,你可以自己编程......这并不复杂......

String Inputstream2String (InputStream is) throws IOException
    {
        final int PKG_SIZE = 1024;
        byte[] data = new byte [PKG_SIZE];
        StringBuilder buffer = new StringBuilder(PKG_SIZE * 10);
        int size;

        size = is.read(data, 0, data.length);
        while (size > 0)
        {
            String str = new String(data, 0, size);
            buffer.append(str);
            size = is.read(data, 0, data.length);
        }
        return buffer.toString();
    }
3
Victor

以下内容并未涉及原始问题,而是一些回复。

几个回应表明形式的循环

String line = null;
while((line = reader.readLine()) != null) {
  // ...
}

要么

for(String line = reader.readLine(); line != null; line = reader.readLine()) {
    // ...
}

第一种形式通过在封闭范围内声明变量“read”来污染封闭范围的命名空间,该变量不会用于for循环之外的任何内容。第二种形式重复readline()调用。

这是一种在Java中编写这种循环的更简洁的方法。事实证明,for循环中的第一个子句不需要实际的初始化值。这使变量“line”的范围保持在for循环的主体内。更优雅!我没有看到任何人在任何地方使用这种形式(我在一天前随机发现它),但我一直都在使用它。

for (String line; (line = reader.readLine()) != null; ) {
    //...
}
2
Luke Hutchison

你可以使用 Cactoos

String text = new TextOf(inputStream).asString();

UTF-8编码是默认编码。如果你需要另一个:

String text = new TextOf(inputStream, "UTF-16").asString();
2
yegor256

注意:这可能不是一个好主意。此方法使用递归,因此将非常快速地命中StackOverflowError

public String read (InputStream is) {
    byte next = is.read();
    return next == -1 ? "" : next + read(is); // Recursive part: reads next byte recursively
}

请不要仅仅因为这是一个糟糕的选择而使用;这主要是创意:)

2
HyperNeutrino

ISO-8859-1

如果您知道输入流的编码是ISO-8859-1或ASCII,则这是一种非常高效的方法。它(1)避免了StringWriter的内部StringBuffer中存在的不必要的同步,(2)避免了InputStreamReader的开销,(3)最小化了必须复制StringBuilder的内部char数组的次数。

public static String iso_8859_1(InputStream is) throws IOException {
    StringBuilder chars = new StringBuilder(Math.max(is.available(), 4096));
    byte[] buffer = new byte[4096];
    int n;
    while ((n = is.read(buffer)) != -1) {
        for (int i = 0; i < n; i++) {
            chars.append((char)(buffer[i] & 0xFF));
        }
    }
    return chars.toString();
}

UTF-8

对于使用UTF-8编码的流,可以使用相同的一般策略: 

public static String utf8(InputStream is) throws IOException {
    StringBuilder chars = new StringBuilder(Math.max(is.available(), 4096));
    byte[] buffer = new byte[4096];
    int n;
    int state = 0;
    while ((n = is.read(buffer)) != -1) {
        for (int i = 0; i < n; i++) {
            if ((state = nextStateUtf8(state, buffer[i])) >= 0) {
                chars.appendCodePoint(state);
            } else if (state == -1) { //error
                state = 0;
                chars.append('\uFFFD'); //replacement char
            }
        }
    }
    return chars.toString();
}

其中nextStateUtf8()函数定义如下:

/**
 * Returns the next UTF-8 state given the next byte of input and the current state.
 * If the input byte is the last byte in a valid UTF-8 byte sequence,
 * the returned state will be the corresponding unicode character (in the range of 0 through 0x10FFFF).
 * Otherwise, a negative integer is returned. A state of -1 is returned whenever an
 * invalid UTF-8 byte sequence is detected.
 */
static int nextStateUtf8(int currentState, byte nextByte) {
    switch (currentState & 0xF0000000) {
        case 0:
            if ((nextByte & 0x80) == 0) { //0 trailing bytes (ASCII)
                return nextByte;
            } else if ((nextByte & 0xE0) == 0xC0) { //1 trailing byte
                if (nextByte == (byte) 0xC0 || nextByte == (byte) 0xC1) { //0xCO & 0xC1 are overlong
                    return -1;
                } else {
                    return nextByte & 0xC000001F;
                }
            } else if ((nextByte & 0xF0) == 0xE0) { //2 trailing bytes
                if (nextByte == (byte) 0xE0) { //possibly overlong
                    return nextByte & 0xA000000F;
                } else if (nextByte == (byte) 0xED) { //possibly surrogate
                    return nextByte & 0xB000000F;
                } else {
                    return nextByte & 0x9000000F;
                }
            } else if ((nextByte & 0xFC) == 0xF0) { //3 trailing bytes
                if (nextByte == (byte) 0xF0) { //possibly overlong
                    return nextByte & 0x80000007;
                } else {
                    return nextByte & 0xE0000007;
                }
            } else if (nextByte == (byte) 0xF4) { //3 trailing bytes, possibly undefined
                return nextByte & 0xD0000007;
            } else {
                return -1;
            }
        case 0xE0000000: //3rd-to-last continuation byte
            return (nextByte & 0xC0) == 0x80 ? currentState << 6 | nextByte & 0x9000003F : -1;
        case 0x80000000: //3rd-to-last continuation byte, check overlong
            return (nextByte & 0xE0) == 0xA0 || (nextByte & 0xF0) == 0x90 ? currentState << 6 | nextByte & 0x9000003F : -1;
        case 0xD0000000: //3rd-to-last continuation byte, check undefined
            return (nextByte & 0xF0) == 0x80 ? currentState << 6 | nextByte & 0x9000003F : -1;
        case 0x90000000: //2nd-to-last continuation byte
            return (nextByte & 0xC0) == 0x80 ? currentState << 6 | nextByte & 0xC000003F : -1;
        case 0xA0000000: //2nd-to-last continuation byte, check overlong
            return (nextByte & 0xE0) == 0xA0 ? currentState << 6 | nextByte & 0xC000003F : -1;
        case 0xB0000000: //2nd-to-last continuation byte, check surrogate
            return (nextByte & 0xE0) == 0x80 ? currentState << 6 | nextByte & 0xC000003F : -1;
        case 0xC0000000: //last continuation byte
            return (nextByte & 0xC0) == 0x80 ? currentState << 6 | nextByte & 0x3F : -1;
        default:
            return -1;
    }
}

自动检测编码

如果您的输入流使用ASCII或ISO-8859-1或UTF-8进行编码,但您不确定哪个,我们可以使用与最后一个类似的方法,但使用额外的编码 - 检测组件到 自动检测 返回字符串之前的编码。

public static String autoDetect(InputStream is) throws IOException {
    StringBuilder chars = new StringBuilder(Math.max(is.available(), 4096));
    byte[] buffer = new byte[4096];
    int n;
    int state = 0;
    boolean ascii = true;
    while ((n = is.read(buffer)) != -1) {
        for (int i = 0; i < n; i++) {
            if ((state = nextStateUtf8(state, buffer[i])) > 0x7F)
                ascii = false;
            chars.append((char)(buffer[i] & 0xFF));
        }
    }

    if (ascii || state < 0) { //probably not UTF-8
        return chars.toString();
    }
    //probably UTF-8
    int pos = 0;
    char[] charBuf = new char[2];
    for (int i = 0, len = chars.length(); i < len; i++) {
        if ((state = nextStateUtf8(state, (byte)chars.charAt(i))) >= 0) {
            boolean hi = Character.toChars(state, charBuf, 0) == 2;
            chars.setCharAt(pos++, charBuf[0]);
            if (hi) {
                chars.setCharAt(pos++, charBuf[1]);
            }
        }
    }
    return chars.substring(0, pos);
}

如果您的输入流的编码既不是ISO-8859-1也不是ASCII也不是UTF-8,那么我将遵循已经存在的其他答案。

1
Hans Brende

使用:

String theString = IOUtils.toString(inputStream, encoding);
1
Avinash

这个问题的解决方案并不是最简单的,但由于没有提到NIO流和通道,这里有一个使用NIO通道和ByteBuffer将流转换为字符串的版本。

public static String streamToStringChannel(InputStream in, String encoding, int bufSize) throws IOException {
    ReadableByteChannel channel = Channels.newChannel(in);
    ByteBuffer byteBuffer = ByteBuffer.allocate(bufSize);
    ByteArrayOutputStream bout = new ByteArrayOutputStream();
    WritableByteChannel outChannel = Channels.newChannel(bout);
    while (channel.read(byteBuffer) > 0 || byteBuffer.position() > 0) {
        byteBuffer.flip();  //make buffer ready for write
        outChannel.write(byteBuffer);
        byteBuffer.compact(); //make buffer ready for reading
    }
    channel.close();
    outChannel.close();
    return bout.toString(encoding);
}

以下是如何使用它的示例:

try (InputStream in = new FileInputStream("/tmp/large_file.xml")) {
    String x = streamToStringChannel(in, "UTF-8", 1);
    System.out.println(x);
}

这种方法的性能应该适合大文件。

1
gil.fernandes
InputStream  inputStream = null;
BufferedReader bufferedReader = null;
try {
    BufferedReader bufferedReader = new BufferedReader(new InputStreamReader(inputStream));
    String stringBuilder = new StringBuilder();
    String content;
    while((content = bufferedReader.readLine()) != null){
        stringBuilder.append(content);
    }
    System.out.println("content of file::" + stringBuilder.toString());
}
catch (IOException e) {
            e.printStackTrace();
        }finally{           
            if(bufferedReader != null){
                try{
                    bufferedReader.close();
                }catch(IoException ex){
                   ex.printStackTrace();
            }
1
Harsh

将inputStream转换为String的方法

public static String getStringFromInputStream(InputStream inputStream) {

    BufferedReader bufferedReader = null;
    StringBuilder stringBuilder = new StringBuilder();
    String line;

    try {
        bufferedReader = new BufferedReader(new InputStreamReader(
                inputStream));
        while ((line = bufferedReader.readLine()) != null) {
            stringBuilder.append(line);
        }
    } catch (IOException e) {
        logger.error(e.getMessage());
    } finally {
        if (bufferedReader != null) {
            try {
                bufferedReader.close();
            } catch (IOException e) {
                logger.error(e.getMessage());
            }
        }
    }
    return stringBuilder.toString();
}
1
Jitender Chahar

此代码段位于\ sdk\samples\Android-19\connectivity\NetworkConnect\NetworkConnectSample\src\main\Java\com\example\Android\networkconnect\MainActivity.Java中,该许可在Apache许可2.0版下获得许可,由Google编写。

/** Reads an InputStream and converts it to a String.
 * @param stream InputStream containing HTML from targeted site.
 * @param len Length of string that this method returns.
 * @return String concatenated according to len parameter.
 * @throws Java.io.IOException
 * @throws Java.io.UnsupportedEncodingException
 */
private String readIt(InputStream stream, int len) throws IOException, UnsupportedEncodingException {
    Reader reader = null;
    reader = new InputStreamReader(stream, "UTF-8");
    char[] buffer = new char[len];
    reader.read(buffer);
    return new String(buffer);
}
1
Fred

String resultString = IOUtils.toString(userInputStream,“UTF-8”);

0
Akash

我已经创建了这个代码,它可以工作。没有必需的外部插件。

将String转换为Stream并将Stream转换为String ...

import Java.io.ByteArrayInputStream;
import Java.io.InputStream;

public class STRINGTOSTREAM {

    public static void main(String[] args)
    {
        String text = "Hello Bhola..!\nMy Name Is Kishan ";

        InputStream strm = new ByteArrayInputStream(text.getBytes());    // Convert String to Stream

        String data = streamTostring(strm);

        System.out.println(data);
    }

    static String streamTostring(InputStream stream)
    {
        String data = "";

        try
        {
            StringBuilder stringbuld = new StringBuilder();
            int i;
            while ((i=stream.read())!=-1)
            {
                stringbuld.append((char)i);
            }
            data = stringbuld.toString();
        }
        catch(Exception e)
        {
            data = "No data Streamed.";
        }
        return data;
    }
0
13hola

我建议 StringWriter 类来解决这个问题。

StringWriter wt= new StringWriter();
IOUtils.copy(inputStream, wt, encoding);
String st= wt.toString();
0
Hasee Amarathunga

您还可以从指定的资源路径获取InputStream:

public static InputStream getResourceAsStream(String path)
{
    InputStream myiInputStream = ClassName.class.getResourceAsStream(path);
    if (null == myiInputStream)
    {
        mylogger.info("Can't find path = ", path);
    }

    return myiInputStream;
}

要从特定路径获取InputStream:

public static URL getResource(String path)
{
    URL myURL = ClassName.class.getResource(path);
    if (null == myURL)
    {
        mylogger.info("Can't find resource path = ", path);
    }
    return myURL;
}
0
Ravi