JVM

JVM Structure

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JVM Architecture

Life of JVM

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Loading

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ClassLoader

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public class ClassLoaderTest{
    public static void main(String[] args){
        // 系统类加载器
        ClassLoader systemClassLoader =  ClassLoader.getSystemClassLoader();
        System.out.println(systemClassLoader); // sun.misc.Launcher$AppClassLoader@2a139a55 
        //获取系统类加载器的上级：扩展类加载器
        ClassLoader extClassLoader = systemClassLoader.getParent();
        System.out.println(extClassLoader); // sun.misc.Launcher$ExtClassLoader@7852e922

        // 获取本类的加载器
        ClassLoader selfClassLoader = ClassLoaderTest.class.getClassLoader();
        System.out.println(selfClassLoader);  // sun.misc.Launcher$AppClassLoader@2a139a55
    }
}

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双亲委派机制

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What makes it all the same:

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PC register

VM Stack

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操作数栈（表达式栈）

动态链接

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Native Method Interface

Native Method Stack

Default Garbage Collector : G1