Ant example source code file (JarFileIterator.java)

This example Ant source code file (JarFileIterator.java) is included in the DevDaily.com "Java Source Code Warehouse" project. The intent of this project is to help you "Learn Java by Example" ^TM.

Java - Ant tags/keywords

classfile, classfile, classfileiterator, io, ioexception, ioexception, jar, jarfileiterator, problem, runtimeexception, string, string, zip, zipentry, zipinputstream, zipinputstream

The JarFileIterator.java source code

/*
 *  Licensed to the Apache Software Foundation (ASF) under one or more
 *  contributor license agreements.  See the NOTICE file distributed with
 *  this work for additional information regarding copyright ownership.
 *  The ASF licenses this file to You 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.apache.tools.ant.taskdefs.optional.depend;

import java.io.IOException;
import java.io.InputStream;
import java.util.zip.ZipEntry;
import java.util.zip.ZipInputStream;

/**
 * A class file iterator which iterates through the contents of a Java jar
 * file.
 *
 */
public class JarFileIterator implements ClassFileIterator {
    /** The jar stream from the jar file being iterated over*/
    private ZipInputStream jarStream;

    /**
     * Construct an iterator over a jar stream
     *
     * @param stream the basic input stream from which the Jar is received
     * @exception IOException if the jar stream cannot be created
     */
    public JarFileIterator(InputStream stream) throws IOException {
        super();

        jarStream = new ZipInputStream(stream);
    }

    /**
     * Get the next ClassFile object from the jar
     *
     * @return a ClassFile object describing the class from the jar
     */
    public ClassFile getNextClassFile() {
        ZipEntry jarEntry;
        ClassFile nextElement = null;

        try {
            jarEntry = jarStream.getNextEntry();

            while (nextElement == null && jarEntry != null) {
                String entryName = jarEntry.getName();

                if (!jarEntry.isDirectory() && entryName.endsWith(".class")) {

                    // create a data input stream from the jar input stream
                    ClassFile javaClass = new ClassFile();

                    javaClass.read(jarStream);

                    nextElement = javaClass;
                } else {

                    jarEntry = jarStream.getNextEntry();
                }
            }
        } catch (IOException e) {
            String message = e.getMessage();
            String text = e.getClass().getName();

            if (message != null) {
                text += ": " + message;
            }

            throw new RuntimeException("Problem reading JAR file: " + text);
        }

        return nextElement;
    }

}