Java 读取InputStream并写入OutputStream的方法及示例代码

1、使用Guava的ByteStreams.copy()方法

文档：ByteStreams.copy()

ByteStreams.copy(inputStream, outputStream);

2、使用read和write实现

private void copyInputStreamToFile( InputStream in, File file ) {
    try {
        OutputStream out = new FileOutputStream(file);
        byte[] buf = new byte[1024];
        int len;
        while((len=in.read(buf))>0){
            out.write(buf,0,len);
        }
        out.close();
        in.close();
    } catch (Exception e) {
        e.printStackTrace();
    }
}

或者

// buffer size used for reading and writing
private static final int BUFFER_SIZE = 8192;
/**
  * Reads all bytes from an input stream and writes them to an output stream.
  */
private static long copy(InputStream source, OutputStream sink) throws IOException {
    long nread = 0L;
    byte[] buf = new byte[BUFFER_SIZE];
    int n;
    while ((n = source.read(buf)) > 0) {
        sink.write(buf, 0, n);
        nread += n;
    }
    return nread;
}

或者

try(InputStream inputStream = new FileInputStream("C:\\mov.mp4");
    OutputStream outputStream = new FileOutputStream("D:\\mov.mp4")) {
    byte[] buffer = new byte[10*1024];
    for (int length; (length = inputStream.read(buffer)) != -1; ) {
        outputStream.write(buffer, 0, length);
    }
} catch (FileNotFoundException exception) {
    exception.printStackTrace();
} catch (IOException ioException) {
    ioException.printStackTrace();
}

或者

byte[] buffer = new byte[2048];
for (int n = in.read(buffer); n >= 0; n = in.read(buffer))
    out.write(buffer, 0, n);

3、使用Spring framework的StreamUtils.copy(in, out)方法

文档：

StreamUtils

FileCopyUtils

StreamUtils.copy(inputStream, outputStream);

或者

FileCopyUtils.copy(inputStream, outputStream);

4、使用Commons Net的 Util类

import org.apache.commons.net.io.Util;
Util.copyStream(inputStream, outputStream);

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