How to write data to two java.io.OutputStream objects at once?

Question

I\'m looking for magical Java class that will allow me to do something like this:

ByteArrayOutputStream byteStream = new ByteArrayOutputStream();
FileOutputS         


        

Answer 1

Just found this thread beacause I had to face the same problem. If someone wants to see my solution (java7 code):

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 out;

public MultiOutputStream(List outStreams) {

    this.out = new LinkedList();

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

        var.write(arg0);
    }
}

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

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

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

@Override
public void close() throws IOException{

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

        var.close();
    }
}

@Override
public void flush() throws IOException{

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

        var.flush();
    }
}

}

Works fine so far, just tested some basic operation, e.g. setting up a MultiOutputStream from the System.out Stream and 2 PrintStreams each writing into a seperate log. I used

System.setOut(multiOutputStream);

to write to my terminal screen and two logs which worked without any problems.