DuplicateAwareJarOutputStream.java

/*
 * Copyright 2008 Toni Menzel.
 *
 * Licensed  under the  Apache License,  Version 2.0  (the "License");
 * you may not use  this file  except in  compliance with the License.
 * You may obtain a copy of the License at
 *
 *   http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed  under the  License is distributed on an "AS IS" BASIS,
 * WITHOUT  WARRANTIES OR CONDITIONS  OF ANY KIND, either  express  or
 * implied.
 *
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
package org.ops4j.pax.exam.spi.intern;

import java.io.IOException;
import java.io.OutputStream;
import java.util.HashSet;
import java.util.Set;
import java.util.jar.JarOutputStream;
import java.util.jar.Manifest;
import java.util.zip.ZipEntry;

/**
 * This is a more convenient JarOutputStream that imits any writing of duplicate entries. If someone
 * tries to do so, it just does not write anything. Be aware that this could be a source of trouble
 * - but it simplifies merging jars with first come first serve policy.
 * <p>
 * Implementation note: some silly class init starvation prevents constructor initialization of
 * entrynames..
 * 
 * @author Toni Menzel (tonit)
 * @since May 29, 2008
 */
public class DuplicateAwareJarOutputStream extends JarOutputStream {

    private Set<String> entrynames;
    private boolean writable;

    public DuplicateAwareJarOutputStream(OutputStream outputStream, Manifest manifest)
        throws IOException {
        super(outputStream, manifest);
    }

    public DuplicateAwareJarOutputStream(OutputStream outputStream) throws IOException {
        super(outputStream);
    }

    public void write(int i) throws IOException {
        if (writable) {
            super.write(i);
        }
    }

    public synchronized void write(byte[] bytes, int i, int i1) throws IOException {
        if (writable) {
            super.write(bytes, i, i1);
        }
    }

    public void write(byte[] bytes) throws IOException {
        if (writable) {
            super.write(bytes);
        }
    }

    public void putNextEntry(ZipEntry zipEntry) throws IOException {
        if (entrynames == null) {
            entrynames = new HashSet<String>();
        }

        if (entrynames.add(zipEntry.getName())) {
            super.putNextEntry(zipEntry);
            writable = true;
        }
        else {
            writable = false;
        }
    }
}