jarclassloader.java

J2me唆哈的代码

package a.a.a.b;
import java.util.jar.*;
import java.util.zip.*;
import java.io.*;

public class JarClassLoader extends ClassLoader {

	JarFile jarFile;
	public JarClassLoader(String jarFileName) throws IOException {
		super();
		jarFile=new JarFile(new File(jarFileName));
	}
	
	public JarClassLoader(JarFile _jarFile){
		jarFile=_jarFile;
	}

	protected Class findClass(String name)throws ClassNotFoundException {
		Class theClass=null;
		theClass=this.findLoadedClass(name);
		if(theClass==null){
			try{
				theClass=this.getParent().loadClass(name);
			}catch(ClassNotFoundException e){
				byte[] bytes = loadClassBytes(name);
				if(bytes!=null){
					theClass = defineClass(name, bytes, 0, bytes.length);
				}
				if (theClass == null){
					throw new ClassFormatError();
				}
			}
		}		
		return theClass;
	}
	
	public InputStream getResourceAsStream(String name){
		InputStream is=null;
		if(is==null){
			String resName=name;
			if(resName.startsWith("/")){
				resName=resName.substring(1);
			}
			try{
				ZipEntry entry=jarFile.getEntry(resName);
				is=jarFile.getInputStream(entry);
			}catch(Exception exp){
				return super.getResourceAsStream(name);
			}
		}
		return is;//new FullReadInputStream(is);
	}
	
	private byte[] loadClassBytes(String className) throws
		ClassNotFoundException {
		byte[] classBytes=null;
		try {
			String clsName=className.replace('.','/')+".class";
			if(clsName.startsWith("/")){
				clsName=clsName.substring(1);
			}
			JarEntry entry=jarFile.getJarEntry(clsName);
			InputStream is=jarFile.getInputStream(entry);
			int len=is.available();
			classBytes=new byte[len];
			int readed=0;
			while(readed<len){
				readed+=is.read(classBytes,readed,len-readed);
			}
			is.close();
		} catch (Exception fnfe) {
			throw new ClassNotFoundException(className);
		}
		return classBytes;	
	}
	
	public void closeLoader(){
		synchronized(jarFile){
			try{
				jarFile.close();
				jarFile=null;
			}catch(IOException e){
				
			}
		}
	}

}