深入研究Java类加载机制

public  class HelloWorld { 
         public  static  void main(String[] args) { 
                HelloWorld hello =  new HelloWorld(); 
                Class c = hello.getClass(); 
                ClassLoader loader = c.getClassLoader(); 
                System.out.println(loader); 
                System.out.println(loader.getParent()); 
                System.out.println(loader.getParent().getParent()); 
        } 
}

sun.misc.Launcher$AppClassLoader@19821f 
sun.misc.Launcher$ExtClassLoader@addbf1 
null 

Process finished with exit code 0

public  class HelloWorld { 
         public  static  void main(String[] args)  throws ClassNotFoundException { 
                ClassLoader loader = HelloWorld. class.getClassLoader(); 
                System.out.println(loader); 
                 //使用ClassLoader.loadClass()来加载类，不会执行初始化块 
                loader.loadClass( "Test2"); 
                 //使用Class.forName()来加载类，默认会执行初始化块 
//                Class.forName("Test2"); 
                 //使用Class.forName()来加载类，并指定ClassLoader，初始化时不执行静态块 
//                Class.forName("Test2", false, loader); 
        } 
}

public  class Test2 { 
         static { 
                System.out.println( "静态初始化块执行了！"); 
        } 
}

package test; 

import java.net.MalformedURLException; 
import java.net.URL; 
import java.net.URLClassLoader; 

/** 
* 自定义ClassLoader 
* 
* @author leizhimin 2009-7-29 22:05:48 
*/ 
public  class MyClassLoader { 
         public  static  void main(String[] args)  throws MalformedURLException, ClassNotFoundException, IllegalAccessException, InstantiationException { 
                URL url =  new URL( "file:/E:\\projects\\testScanner\\out\\production\\testScanner"); 
                ClassLoader myloader =  new URLClassLoader( new URL[]{url}); 
                Class c = myloader.loadClass( "test.Test3"); 
                System.out.println( "----------"); 
                Test3 t3 = (Test3) c.newInstance(); 
        } 
}

public  class Test3 { 
         static { 
                System.out.println( "Test3的静态初始化块执行了！"); 
        } 
}