类加载机制(三)

加载机制系列
类加载机制(一)
类加载机制(二)
类加载机制(三)
类加载器这里引用尚学堂的的几张图片

image.png

类加载器的分类：

image.png

类加载器的双亲委托机制

image.png

demo：


public class test {

    public static void  main(String[] agrs) {
        System.out.println(ClassLoader.getSystemClassLoader());

        System.out.println(ClassLoader.getSystemClassLoader().getParent());

        System.out.println(ClassLoader.getSystemClassLoader().getParent().getParent());
        
        
        System.out.println(System.clearProperty("java.class.path"));
        
        String a="gaoga";
        System.out.println(a.getClass().getClassLoader());
            
    }

结果：

sun.misc.Launcher$AppClassLoader@5c647e05
sun.misc.Launcher$ExtClassLoader@3d4eac69
null
/Library/Java/JavaVirtualMachines/jdk1.8.0_161.jdk/Contents/Home/jre/lib/resources.jar:/Library/Java/JavaVirtualMachines/jdk1.8.0_161.jdk/Contents/Home/jre/lib/rt.jar:/Library/Java/JavaVirtualMachines/jdk1.8.0_161.jdk/Contents/Home/jre/lib/jsse.jar:/Library/Java/JavaVirtualMachines/jdk1.8.0_161.jdk/Contents/Home/jre/lib/jce.jar:/Library/Java/JavaVirtualMachines/jdk1.8.0_161.jdk/Contents/Home/jre/lib/charsets.jar:/Library/Java/JavaVirtualMachines/jdk1.8.0_161.jdk/Contents/Home/jre/lib/jfr.jar:/Library/Java/JavaVirtualMachines/jdk1.8.0_161.jdk/Contents/Home/jre/lib/ext/sunec.jar:/Library/Java/JavaVirtualMachines/jdk1.8.0_161.jdk/Contents/Home/jre/lib/ext/nashorn.jar:/Library/Java/JavaVirtualMachines/jdk1.8.0_161.jdk/Contents/Home/jre/lib/ext/cldrdata.jar:/Library/Java/JavaVirtualMachines/jdk1.8.0_161.jdk/Contents/Home/jre/lib/ext/jfxrt.jar:/Library/Java/JavaVirtualMachines/jdk1.8.0_161.jdk/Contents/Home/jre/lib/ext/dnsns.jar:/Library/Java/JavaVirtualMachines/jdk1.8.0_161.jdk/Contents/Home/jre/lib/ext/localedata.jar:/Library/Java/JavaVirtualMachines/jdk1.8.0_161.jdk/Contents/Home/jre/lib/ext/sunjce_provider.jar:/Library/Java/JavaVirtualMachines/jdk1.8.0_161.jdk/Contents/Home/jre/lib/ext/sunpkcs11.jar:/Library/Java/JavaVirtualMachines/jdk1.8.0_161.jdk/Contents/Home/jre/lib/ext/jaccess.jar:/Library/Java/JavaVirtualMachines/jdk1.8.0_161.jdk/Contents/Home/jre/lib/ext/zipfs.jar:/System/Library/Java/Extensions/MRJToolkit.jar:/Users/guozhk/eclipse-workspace/Test/bin
null