Java 类加载器（三）-自定义加载器源代码

来源：互联网发布：淘宝onlyanna罗晓颖编辑：程序博客网时间：2024/06/06 20:42

下午刚写的自定义的加载器，附上源代码

HelloWord.java

package com.goodtion.sweetop;

public class HelloWord {
public String getInfo(){
return "This is a HelloWorld!";
}
}

FileClassLoader.java

package com.goodtion.sweetop;

import java.io.ByteArrayOutputStream;
import java.io.File;
import java.io.FileInputStream;
import java.io.FileNotFoundException;
import java.io.IOException;

public class FileClassLoader extends ClassLoader {
public static final String drive="D://sweetop//搜索引擎//TomcatTest//bin//com//goodtion//sweetop//";
public static final String fileType=".class";

public Class findClass(String name){
byte[] data=loadClassData(name);
return defineClass(name,data,0,data.length);
}

private byte[] loadClassData(String name) {
  FileInputStream fis=null;
  byte[] data = null;
  try {
   fis = new FileInputStream(new File(drive+name+fileType));
   ByteArrayOutputStream baos=new ByteArrayOutputStream();
   int ch=0;
   while((ch=fis.read())!=-1){
    baos.write(ch);
   }
   data=baos.toByteArray();
  } catch (IOException e) {
   // TODO Auto-generated catch block
   e.printStackTrace();
  }
  return data;
}

public static void main(String[] args) throws ClassNotFoundException, InstantiationException, IllegalAccessException{
  FileClassLoader loader = new FileClassLoader();
  Class objClass=loader.loadClass("com.goodtion.sweetop.HelloWord",true);
  Object obj=objClass.newInstance();
  System.out.println(objClass.getName());
  System.out.println(objClass.getClassLoader().getClass().getName());
  System.out.println(((HelloWord)obj).getInfo());
}
}