classpath.java

Java Bytecode Editor 是一个 JAVA 的字节码反汇编和修改器。它可以很方便的修改已经编译成 Class 文件的 JAVA 文件。

package org.apache.bcel.util;

/* ====================================================================
 * The Apache Software License, Version 1.1
 *
 * Copyright (c) 2001 The Apache Software Foundation.  All rights
 * reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 *
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 *
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in
 *    the documentation and/or other materials provided with the
 *    distribution.
 *
 * 3. The end-user documentation included with the redistribution,
 *    if any, must include the following acknowledgment:
 *       "This product includes software developed by the
 *        Apache Software Foundation (http://www.apache.org/)."
 *    Alternately, this acknowledgment may appear in the software itself,
 *    if and wherever such third-party acknowledgments normally appear.
 *
 * 4. The names "Apache" and "Apache Software Foundation" and
 *    "Apache BCEL" must not be used to endorse or promote products
 *    derived from this software without prior written permission. For
 *    written permission, please contact [e-mail].
 *
 * 5. Products derived from this software may not be called "Apache",
 *    "Apache BCEL", nor may "Apache" appear in their name, without
 *    prior written permission of the Apache Software Foundation.
 *
 * THIS SOFTWARE IS PROVIDED ``AS IS'' AND ANY EXPRESSED OR IMPLIED
 * WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
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 * ITS CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
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 * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF
 * USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
 * ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
 * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
 * OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 * ====================================================================
 *
 * This software consists of voluntary contributions made by many
 * individuals on behalf of the Apache Software Foundation.  For more
 * information on the Apache Software Foundation, please see
 * <http://www.apache.org/>.
 */

import java.util.*;
import java.util.zip.*;
import java.io.*;

/**
 * Responsible for loading (class) files from the CLASSPATH. Inspired by
 * sun.tools.ClassPath.
 * 
 * @version $Id: ClassPath.java,v 1.2 2006/08/23 13:48:30 andos Exp $
 * @author <A HREF="mailto:[e-mail]">M. Dahm</A>
 */
public class ClassPath implements Serializable {
	/**
	 * 
	 */
	private static final long serialVersionUID = 8708518440751729976L;

	public static final ClassPath SYSTEM_CLASS_PATH = new ClassPath();

	private PathEntry[] paths;

	private String class_path;

	/**
	 * Search for classes in given path.
	 */
	public ClassPath(String class_path) {
		this.class_path = class_path;

		ArrayList<PathEntry> vec = new ArrayList<PathEntry>();

		for (StringTokenizer tok = new StringTokenizer(class_path, System
				.getProperty("path.separator")); tok.hasMoreTokens();) {
			String path = tok.nextToken();

			if (!path.equals("")) {
				File file = new File(path);

				try {
					if (file.exists()) {
						if (file.isDirectory())
							vec.add(new Dir(path));
						else
							vec.add(new Zip(new ZipFile(file)));
					}
				} catch (IOException e) {
					System.err
							.println("CLASSPATH component " + file + ": " + e);
				}
			}
		}

		paths = new PathEntry[vec.size()];
		vec.toArray(paths);
	}

	/**
	 * Search for classes in CLASSPATH.
	 * 
	 * @deprecated Use SYSTEM_CLASS_PATH constant
	 */
	public ClassPath() {
		this(getClassPath());
	}

	/**
	 * @return used class path string
	 */
	public String toString() {
		return class_path;
	}

	public int hashCode() {
		return class_path.hashCode();
	}

	public boolean equals(Object o) {
		if (o instanceof ClassPath) {
			return class_path.equals(((ClassPath) o).class_path);
		}

		return false;
	}

	private static final void getPathComponents(String path,
			ArrayList<String> list) {
		if (path != null) {
			StringTokenizer tok = new StringTokenizer(path, File.pathSeparator);

			while (tok.hasMoreTokens()) {
				String name = tok.nextToken();
				File file = new File(name);

				if (file.exists())
					list.add(name);
			}
		}
	}

	/**
	 * Checks for class path components in the following properties:
	 * "java.class.path", "sun.boot.class.path", "java.ext.dirs"
	 * 
	 * @return class path as used by default by BCEL
	 */
	public static final String getClassPath() {
		String class_path = System.getProperty("java.class.path");
		String boot_path = System.getProperty("sun.boot.class.path");
		String ext_path = System.getProperty("java.ext.dirs");

		ArrayList<String> list = new ArrayList<String>();

		getPathComponents(class_path, list);
		getPathComponents(boot_path, list);

		ArrayList<String> dirs = new ArrayList<String>();
		getPathComponents(ext_path, dirs);

		for (Iterator e = dirs.iterator(); e.hasNext();) {
			File ext_dir = new File((String) e.next());
			String[] extensions = ext_dir.list(new FilenameFilter() {
				public boolean accept(File dir, String name) {
					name = name.toLowerCase();
					return name.endsWith(".zip") || name.endsWith(".jar");
				}
			});

			if (extensions != null)
				for (int i = 0; i < extensions.length; i++)
					list.add(ext_path + File.separatorChar + extensions[i]);
		}

		StringBuffer buf = new StringBuffer();

		for (Iterator e = list.iterator(); e.hasNext();) {
			buf.append((String) e.next());

			if (e.hasNext())
				buf.append(File.pathSeparatorChar);
		}

		return buf.toString().intern();
	}

	/**
	 * @param name
	 *            fully qualified class name, e.g. java.lang.String
	 * @return input stream for class
	 */
	public InputStream getInputStream(String name) throws IOException {
		String suffix;
		if (name.endsWith(".class")) {
			suffix = "";
		} else {
			suffix = ".class";
		}
		return getInputStream(name, suffix);
	}

	/**
	 * Return stream for class or resource on CLASSPATH.
	 * 
	 * @param name
	 *            fully qualified file name, e.g. java/lang/String
	 * @param suffix
	 *            file name ends with suff, e.g. .java
	 * @return input stream for file on class path
	 */
	public InputStream getInputStream(String name, String suffix)
			throws IOException {
		InputStream is = null;

		try {
			is = getClass().getClassLoader().getResourceAsStream(name + suffix);
		} catch (Exception e) {
		}

		if (is != null)
			return is;

		return getClassFile(name, suffix).getInputStream();
	}

	/**
	 * @param name
	 *            fully qualified file name, e.g. java/lang/String
	 * @param suffix
	 *            file name ends with suff, e.g. .java
	 * @return class file for the java class
	 */
	public ClassFile getClassFile(String name, String suffix)
			throws IOException {
		for (int i = 0; i < paths.length; i++) {
			ClassFile cf;

			if ((cf = paths[i].getClassFile(name, suffix)) != null)
				return cf;
		}

		throw new IOException("Couldn't find: " + name + suffix);
	}

	/**
	 * @param name
	 *            fully qualified class name, e.g. java.lang.String
	 * @return input stream for class
	 */
	public ClassFile getClassFile(String name) throws IOException {
		return getClassFile(name, ".class");
	}

	/**
	 * @param name
	 *            fully qualified file name, e.g. java/lang/String
	 * @param suffix
	 *            file name ends with suffix, e.g. .java
	 * @return byte array for file on class path
	 */
	public byte[] getBytes(String name, String suffix) throws IOException {
		InputStream is = getInputStream(name, suffix);

		if (is == null)
			throw new IOException("Couldn't find: " + name + suffix);

		DataInputStream dis = new DataInputStream(is);
		byte[] bytes = new byte[is.available()];
		dis.readFully(bytes);
		dis.close();
		is.close();

		return bytes;
	}

	/**
	 * @return byte array for class
	 */
	public byte[] getBytes(String name) throws IOException {
		return getBytes(name, ".class");
	}

	/**
	 * @param name
	 *            name of file to search for, e.g. java/lang/String.java
	 * @return full (canonical) path for file
	 */
	public String getPath(String name) throws IOException {
		int index = name.lastIndexOf('.');
		String suffix = "";

		if (index > 0) {
			suffix = name.substring(index);
			name = name.substring(0, index);
		}

		return getPath(name, suffix);
	}

	/**
	 * @param name
	 *            name of file to search for, e.g. java/lang/String
	 * @param suffix
	 *            file name suffix, e.g. .java
	 * @return full (canonical) path for file, if it exists
	 */
	public String getPath(String name, String suffix) throws IOException {
		return getClassFile(name, suffix).getPath();
	}

	private static abstract class PathEntry implements Serializable {
		abstract ClassFile getClassFile(String name, String suffix)
				throws IOException;
	}

	/**
	 * Contains information about file/ZIP entry of the Java class.
	 */
	public interface ClassFile {
		/**
		 * @return input stream for class file.
		 */
		public abstract InputStream getInputStream() throws IOException;

		/**
		 * @return canonical path to class file.
		 */
		public abstract String getPath();

		/**
		 * @return base path of found class, i.e. class is contained relative to
		 *         that path, which may either denote a directory, or zip file
		 */
		public abstract String getBase();

		/**
		 * @return modification time of class file.
		 */
		public abstract long getTime();

		/**
		 * @return size of class file.
		 */
		public abstract long getSize();
	}

	private static class Dir extends PathEntry {
		/**
		 * 
		 */
		private static final long serialVersionUID = -1016179728689833015L;

		private String dir;

		Dir(String d) {
			dir = d;
		}

		ClassFile getClassFile(String name, String suffix) throws IOException {
			final File file = new File(dir + File.separatorChar
					+ name.replace('.', File.separatorChar) + suffix);

			return file.exists() ? new ClassFile() {
				public InputStream getInputStream() throws IOException {
					return new FileInputStream(file);
				}

				public String getPath() {
					try {
						return file.getCanonicalPath();
					} catch (IOException e) {
						return null;
					}

				}

				public long getTime() {
					return file.lastModified();
				}

				public long getSize() {
					return file.length();
				}

				public String getBase() {
					return dir;
				}

			} : null;
		}

		public String toString() {
			return dir;
		}
	}

	private static class Zip extends PathEntry {
		private ZipFile zip;

		Zip(ZipFile z) {
			zip = z;
		}

		ClassFile getClassFile(String name, String suffix) throws IOException {
			final ZipEntry entry = zip
					.getEntry(name.replace('.', '/') + suffix);

			return (entry != null) ? new ClassFile() {
				public InputStream getInputStream() throws IOException {
					return zip.getInputStream(entry);
				}

				public String getPath() {
					return entry.toString();
				}

				public long getTime() {
					return entry.getTime();
				}

				public long getSize() {
					return entry.getSize();
				}

				public String getBase() {
					return zip.getName();
				}
			} : null;
		}
	}
}