ClassLoader

Class-->ClassLoader

 

Class 文件有来源：
1）Bootstrap ClassLoader ：
2）Extension ClassLoader
3）App ClassLoader ：开发者在项目中编写的类
4）Custom ClassLoader

 

 

 

package project03;

/*
代码执行顺序
Java源代码（.java文件）->编译->java字节码（.class文件）->类加载器->java.lang.Class->虚拟机 newInstance-->实例对象

Class-->ClassLoader 



Class 文件有来源：
1）Bootstrap ClassLoader ：
2）Extension ClassLoader 
3）App ClassLoader ：开发者在项目中编写的类
4）Custom ClassLoader 

*/

import org.junit.Test;

public class test02 {
    
    @Test
    public void test03() throws ClassNotFoundException {
        //1.获取Class对象
        Class <?> c = Class.forName("AtStudent.Student");
        
        //2.获取ClassLoader对象
        ClassLoader loader = c.getClassLoader();
        System.out.println(loader);//sun.misc.Launcher$AppClassLoader@7852e922
        
        
    }
    
    
    @Test
    public void test02() {
        //1.获取Class对象
        Class<?> c = MyClass.class;
        
        //2.获取ClassLoader对象
        ClassLoader loader = c.getClassLoader();
        System.out.println(loader);//sun.misc.Launcher$AppClassLoader@7852e922
        
        ClassLoader parent= loader.getParent();
        System.out.println(parent);//sun.misc.Launcher$ExtClassLoader@330bedb4
        
        ClassLoader grandparent = parent.getParent();
        System.out.println(grandparent);//null
        
        
    }
    @Test
    public void test01() {
        //1.获取Class对象
        Class<?> c = String.class;
        
        //2.获取ClassLoader对象
        ClassLoader loader = c.getClassLoader();
        System.out.println(loader);//null
        
    }

}

class MyClass{    
    public void test03() throws ClassNotFoundException {
        //1.获取Class对象
        Class <?> c = Class.forName("AtStudent1.Student");
        
        //2.获取ClassLoader对象
        ClassLoader loader = c.getClassLoader();
        System.out.println(loader);//jdk.internal.loader.ClassLoaders$AppClassLoader@7907ec20
        
        
    }
}