如何将数据写入两个java。木卫一。一次输出流对象？

Question

我正在寻找神奇的Java类，它可以让我做如下事情：

ByteArrayOutputStream byteStream = new ByteArrayOutputStream();
FileOutputStream fileStream = new FileOutputStream(new File("/tmp/somefile"));

MultiOutputStream outStream = new MultiOutputStream(byteStream, fileStream);

outStream.write("Hello world".getBytes());

基本上，我希望Java中的OutputStream使用tee。有什么想法吗

谢谢

Answer 1

我刚找到这条线，因为我必须面对同样的问题。 如果有人想查看我的解决方案（java7代码）：

package Core;
import java.io.IOException;
import java.io.OutputStream;
import java.util.Iterator;
import java.util.LinkedList;
import java.util.List;

public class MultiOutputStream extends OutputStream {

private List<OutputStream> out;

public MultiOutputStream(List<OutputStream> outStreams) {

    this.out = new LinkedList<OutputStream>();

    for (Iterator<OutputStream> i = outStreams.iterator(); i.hasNext();) {
        OutputStream outputStream = (OutputStream) i.next();

        if(outputStream == null){
            throw new NullPointerException();
        }
        this.out.add(outputStream);
    }
}

@Override
public void write(int arg0) throws IOException {

    for (Iterator<OutputStream> i = out.iterator(); i.hasNext();) {
        OutputStream var = (OutputStream) i.next();

        var.write(arg0);
    }
}

@Override
public void write(byte[] b) throws IOException{

    for (Iterator<OutputStream> i = out.iterator(); i.hasNext();) {
        OutputStream var = (OutputStream) i.next();

        var.write(b);
    }
}

@Override
public void write(byte[] b, int off, int len) throws IOException{

    for (Iterator<OutputStream> i = out.iterator(); i.hasNext();) {
        OutputStream var = (OutputStream) i.next();

        var.write(b, off, len);
    }
}

@Override
public void close() throws IOException{

    for (Iterator<OutputStream> i = out.iterator(); i.hasNext();) {
        OutputStream var = (OutputStream) i.next();

        var.close();
    }
}

@Override
public void flush() throws IOException{

    for (Iterator<OutputStream> i = out.iterator(); i.hasNext();) {
        OutputStream var = (OutputStream) i.next();

        var.flush();
    }
}

}

到目前为止工作正常，只是测试了一些基本操作，例如从系统设置多输出流。out Stream和2个PrintStreams各写入一个单独的日志。 我曾经

System.setOut(multiOutputStream);

写入我的终端屏幕和两个工作正常的日志

Answer 2

试试Apache Commons TeeOutputStream

Answer 3

你自己滚吧，基本上没什么大不了的。使用ArrayList<OutputStream>或当今流行的任何方法来存储您想要的所有流，并编写write方法来循环所有流，并对每个流进行写入

Answer 4

你自己滚吧。根本就没有什么魔力。使用Apache's TeeOutputStream基本上可以使用下面的代码。当然，使用ApacheCommons I/O库，您可以利用其他类，但有时为自己编写一些东西是很好的

public final class TeeOutputStream extends OutputStream {

  private final OutputStream out;
  private final OutputStream tee;

  public TeeOutputStream(OutputStream out, OutputStream tee) {
    if (out == null)
      throw new NullPointerException();
    else if (tee == null)
      throw new NullPointerException();

    this.out = out;
    this.tee = tee;
  }

  @Override
  public void write(int b) throws IOException {
    out.write(b);
    tee.write(b);
  }

  @Override
  public void write(byte[] b) throws IOException {
    out.write(b);
    tee.write(b);
  }

  @Override
  public void write(byte[] b, int off, int len) throws IOException {
    out.write(b, off, len);
    tee.write(b, off, len);
  }

  @Override
  public void flush() throws IOException {
    out.flush();
    tee.flush();
  }

  @Override
  public void close() throws IOException {
    try {
      out.close();
    } finally {
      tee.close();
    }
  }
}

使用上述类进行测试，并执行以下操作

public static void main(String[] args) throws IOException {
  TeeOutputStream out = new TeeOutputStream(System.out, System.out);
  out.write("Hello world!".getBytes());
  out.flush();
  out.close();
}

将打印Hello World!Hello World!

（注意：被重写的close()可能需要一些注意：

Answer 5

final ByteArrayOutputStream byteStream = new ByteArrayOutputStream();
final FileOutputStream fileStream = new FileOutputStream(new File("/tmp/somefile"));
OutputStream outStream = new OutputStream() {

    public void write(int b) throws IOException {
        byteStream.write(b);
        fileStream.write(b);
    }
};
outStream.write("Hello world".getBytes());