javassist.ByteArrayClassPath Maven / Gradle / Ivy

Go to download
Show more of this group Show more artifacts with this name
Show all versions of javassist Show documentation
Javassist (JAVA programming ASSISTant) makes Java bytecode manipulation simple. It is a class library for editing bytecodes in Java.
There is a newer version: 3.30.2-GA
Show newest version
/*
 * Javassist, a Java-bytecode translator toolkit.
 * Copyright (C) 1999- Shigeru Chiba. All Rights Reserved.
 *
 * The contents of this file are subject to the Mozilla Public License Version
 * 1.1 (the "License"); you may not use this file except in compliance with
 * the License.  Alternatively, the contents of this file may be used under
 * the terms of the GNU Lesser General Public License Version 2.1 or later,
 * or the Apache License Version 2.0.
 *
 * Software distributed under the License is distributed on an "AS IS" basis,
 * WITHOUT WARRANTY OF ANY KIND, either express or implied. See the License
 * for the specific language governing rights and limitations under the
 * License.
 */

package javassist;

import java.io.ByteArrayInputStream;
import java.io.IOException;
import java.io.InputStream;
import java.net.MalformedURLException;
import java.net.URL;
import java.net.URLConnection;
import java.net.URLStreamHandler;

/**
 * A ByteArrayClassPath contains bytes that is served as
 * a class file to a ClassPool.  It is useful to convert
 * a byte array to a CtClass object.
 *
 * For example, if you want to convert a byte array b
 * into a CtClass object representing the class with a name
 * classname, then do as following:
 *
 * 
 * ClassPool cp = ClassPool.getDefault();
 * cp.insertClassPath(new ByteArrayClassPath(classname, b));
 * CtClass cc = cp.get(classname);
 * 
 *
 * The ClassPool object cp uses the created
 * ByteArrayClassPath object as the source of the class file.
 *
 * A ByteArrayClassPath must be instantiated for every
 * class.  It contains only a single class file.
 *
 * @see javassist.ClassPath
 * @see ClassPool#insertClassPath(ClassPath)
 * @see ClassPool#appendClassPath(ClassPath)
 * @see ClassPool#makeClass(InputStream)
 */
public class ByteArrayClassPath implements ClassPath {
    protected String classname;
    protected byte[] classfile;

    /*
     * Creates a ByteArrayClassPath containing the given
     * bytes.
     *
     * @param name              a fully qualified class name
     * @param classfile         the contents of a class file.
     */
    public ByteArrayClassPath(String name, byte[] classfile) {
        this.classname = name;
        this.classfile = classfile;
    }

    @Override
    public String toString() {
        return "byte[]:" + classname;
    }

    /**
     * Opens the class file.
     */
    @Override
    public InputStream openClassfile(String classname) {
        if(this.classname.equals(classname))
            return new ByteArrayInputStream(classfile);
        return null;
    }

    /**
     * Obtains the URL.
     */
    @Override
    public URL find(String classname) {
        if(this.classname.equals(classname)) {
            String cname = classname.replace('.', '/') + ".class";
            try {
                return new URL(null, "file:/ByteArrayClassPath/" + cname, new BytecodeURLStreamHandler());
            }
            catch (MalformedURLException e) {}
        }

        return null;
    }

    private class BytecodeURLStreamHandler extends URLStreamHandler {
        protected URLConnection openConnection(final URL u) {
            return new BytecodeURLConnection(u);
        }
    }

    private class BytecodeURLConnection extends URLConnection {
        protected BytecodeURLConnection(URL url) {
            super(url);
        }

        public void connect() throws IOException {
        }

        public InputStream getInputStream() throws IOException {
            return new ByteArrayInputStream(classfile);
        }

        public int getContentLength() {
            return classfile.length;
        }
    }
}