Jakarta Commons Cookbook

10.11. Splitting an OutputStream

Problem

You need to send the same output to two OutputStreams.

Solution

Use Commons IO TeeOutputStream to send the same data to two instances of OutputStream. When data is written to a TeeOutputStream , that data is sent to the two instances of OutputStream passed to its constructor. The following example demonstrates the use of TeeOutputStream to write the same String to two instances of FileOutputStream :

import org.apache.commons.io.IOUtils;
import org.apache.commons.io.output.TeeOutputStream;

File test1 = new File("split1.txt");
File test2 = new File("split2.txt");
OutputStream outStream = null;
        
try {
    FileOutputStream fos1 = new FileOutputStream( test1 );
    FileOutputStream fos2 = new FileOutputStream( test2 );
    outStream = new TeeOutputStream( fos1, fos2 );
            
    outStream.write( "One Two Three, Test".getBytes( ) );
    outStream.flush( );
} catch( IOException ioe ) {
    System.out.println( "Error writing to split output stream" );
} finally {
    IOUtils.closeQuietly( outStream );
}

Flushing or closing a TeeOutputStream will flush or close both of the OutputStream instances it contains. After this example is executed, two files, split1.txt and split2.txt, will contain the same text.