这里或多或少有sampath的答案，清理了一点并表示为函数：

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();
}

这是最适合Android和任何其他JVM的纯Java解决方案。

这个解决方案非常好。。。它简单、快速，适用于大小河流！！（见上文第8号基准）

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;
}

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apache实现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();
}

另一个，对于所有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中类似，但它们在完成后会使流保持打开状态。

嗯，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();
    }

与Okio一起：

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