Java tutorial
/* * 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.commons.javaflow.utils; import java.io.ByteArrayOutputStream; import java.io.File; import java.io.FileInputStream; import java.io.FileNotFoundException; import java.io.FileOutputStream; import java.io.IOException; import java.io.InputStream; import java.io.OutputStream; import java.util.jar.JarEntry; import java.util.jar.JarInputStream; import java.util.jar.JarOutputStream; import org.apache.commons.javaflow.bytecode.transformation.ResourceTransformer; import org.apache.commons.javaflow.bytecode.transformation.asm.AsmClassTransformer; import org.slf4j.Logger; import org.slf4j.LoggerFactory; public final class RewritingUtils { private final static Logger log = LoggerFactory.getLogger(RewritingUtils.class); public interface Matcher { boolean isMatching(final String name); } private final static Matcher MATCH_ALL = new Matcher() { public boolean isMatching(final String pName) { return true; } }; /* * TODO multiple transformers */ public static void rewriteClassFile(final File pInput, final ResourceTransformer transformer, final File pOutput) throws IOException { final byte[] original = toByteArray(pInput); byte[] transformed = transformer.transform(original); final FileOutputStream os = new FileOutputStream(pOutput); os.write(transformed); os.close(); } public static boolean rewriteJar(final JarInputStream pInput, final ResourceTransformer transformer, final JarOutputStream pOutput) throws IOException { return rewriteJar(pInput, transformer, pOutput, MATCH_ALL); } public static boolean rewriteJar(final JarInputStream pInput, final ResourceTransformer transformer, final JarOutputStream pOutput, final Matcher pMatcher) throws IOException { boolean changed = false; while (true) { final JarEntry entry = pInput.getNextJarEntry(); if (entry == null) { break; } if (entry.isDirectory()) { pOutput.putNextEntry(new JarEntry(entry)); continue; } final String name = entry.getName(); pOutput.putNextEntry(new JarEntry(name)); if (name.endsWith(".class")) { if (pMatcher.isMatching(name)) { if (log.isDebugEnabled()) { log.debug("transforming " + name); } final byte[] original = toByteArray(pInput); byte[] transformed = transformer.transform(original); pOutput.write(transformed); changed |= transformed.length != original.length; continue; } } else if (name.endsWith(".jar") || name.endsWith(".ear") || name.endsWith(".zip") || name.endsWith(".war")) { changed |= rewriteJar(new JarInputStream(pInput), transformer, new JarOutputStream(pOutput), pMatcher); continue; } int length = copy(pInput, pOutput); log.debug("copied " + name + "(" + length + ")"); } pInput.close(); pOutput.close(); return changed; } public static byte[] toByteArray(File f) throws IOException { InputStream in = new FileInputStream(f); try { return toByteArray(in); } finally { in.close(); } } public static byte[] toByteArray(InputStream in) throws IOException { ByteArrayOutputStream baos = new ByteArrayOutputStream(); copy(in, baos); return baos.toByteArray(); } /** * Copies the entire {@link InputStream} to the given {@link OutputStream}. * * @return * the number of bytes copied. */ public static int copy(InputStream in, OutputStream out) throws IOException { byte[] buf = new byte[8192]; int n; int total = 0; while ((n = in.read(buf)) >= 0) { out.write(buf, 0, n); total += n; } return total; } public static void main(final String[] args) throws FileNotFoundException, IOException { ResourceTransformer transformer = new AsmClassTransformer(); for (int i = 0; i < args.length; i += 2) { // System.out.println("rewriting " + args[i]); RewritingUtils.rewriteJar(new JarInputStream(new FileInputStream(args[i])), transformer, new JarOutputStream(new FileOutputStream(args[i + 1]))); } // System.out.println("done"); } }