001    // Copyright 2012 The Apache Software Foundation
002    //
003    // Licensed under the Apache License, Version 2.0 (the "License");
004    // you may not use this file except in compliance with the License.
005    // You may obtain a copy of the License at
006    //
007    //     http://www.apache.org/licenses/LICENSE-2.0
008    //
009    // Unless required by applicable law or agreed to in writing, software
010    // distributed under the License is distributed on an "AS IS" BASIS,
011    // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
012    // See the License for the specific language governing permissions and
013    // limitations under the License.
014    
015    package org.apache.tapestry5.internal.util;
016    
017    import java.io.IOException;
018    import java.io.OutputStream;
019    
020    /**
021     * An output stream that acts like a "tee", copying all provided bytes to two output streams. This is used, for example,
022     * to accumulate a hash of content even as it is being written.
023     *
024     * @since 5.3.5
025     */
026    public class TeeOutputStream extends OutputStream
027    {
028        private final OutputStream left, right;
029    
030        public TeeOutputStream(OutputStream left, OutputStream right)
031        {
032            assert left != null;
033            assert right != null;
034    
035            this.left = left;
036            this.right = right;
037        }
038    
039        @Override
040        public void write(int b) throws IOException
041        {
042            left.write(b);
043            right.write(b);
044        }
045    
046        @Override
047        public void write(byte[] b) throws IOException
048        {
049            left.write(b);
050            right.write(b);
051        }
052    
053        @Override
054        public void write(byte[] b, int off, int len) throws IOException
055        {
056            left.write(b, off, len);
057            right.write(b, off, len);
058        }
059    
060        @Override
061        public void flush() throws IOException
062        {
063            left.flush();
064            right.flush();
065        }
066    
067        @Override
068        public void close() throws IOException
069        {
070            left.close();
071            right.close();
072        }
073    }