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。

public String read(InputStream in) throws IOException {
    try (BufferedReader buffer = new BufferedReader(new InputStreamReader(in))) {
        return buffer.lines().collect(Collectors.joining("\n"));
    }
}

Use:

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();
}

在Groovy中

inputStream.getText()

此代码适用于新的Java学习者：

private String textDataFromFile;

public String getFromFile(InputStream myInputStream) throws FileNotFoundException, IOException {

    BufferedReader bufferReader = new BufferedReader(new InputStreamReader(myInputStream));

    StringBuilder stringBuilder = new StringBuilder();

    String eachStringLine;

    while ((eachStringLine = bufferReader.readLine()) != null) {
        stringBuilder.append(eachStringLine).append("\n");
    }
    textDataFromFile = stringBuilder.toString();

    return textDataFromFile;
}

使用Streams的纯Java解决方案，从Java8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()));
    }
}

正如Christoffer Hammarström在其他答案中提到的那样，明确指定Charset更安全。即InputStreamReader构造函数可以按如下方式更改：

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