JVM 心得分享(加载 链接 初始化)

 package com.chong.studyparalell.clazz.loader;public class ClassLoaderDemo {public static void main(String []args){Test test2 = new Test();System.out.println("Test2实例化结束"+test2.toString());}}

package com.chong.studyparalell.clazz.loader;public class Test{private static Test test1 = new Test();private static int a = 2;private static int b = 2;static {System.out.println("【Test类静态块】a=" + a);}public Test(){System.out.println("【Test类构造方法】a=" + a);System.out.println("【Test类构造方法】b=" + b);System.out.println("【Test类实例】" + this.toString());}public static Test newInstance(){return test1;}}

package com.chong.studyparalell.clazz.loader;public class TestBase {private static int base_a = 2;private static int base_b = 2;static {System.out.println("【父类静态块】 base_a="+base_a);}public TestBase(){System.out.println("【父类 构造方法】base_a=" + base_a);System.out.println("【父类 构造方法】base_b=" + base_b);System.out.println("【父类 实例】"+ this.toString());}}

package com.chong.studyparalell.clazz.loader;public class Test extends TestBase{内容同第一步；}

 package com.chong.studyparalell.clazz.loader;public class MyClassLoaderPilot {public static void main(String[] args) {try {MyClassLoader classLoader = new MyClassLoader();String filename = "com.chong.studyparalell.demon.DemonThreadDemo";Object clazz = classLoader.loadCustomizeClass(filename);System.out.println(clazz);} catch (Exception e) {e.printStackTrace();}}}

package com.chong.studyparalell.clazz.loader;import java.io.ByteArrayOutputStream;import java.io.FileInputStream;import java.io.IOException;public class MyClassLoader extends ClassLoader {private String demoPath = "D://work//temp//";public Class<?> loadCustomizeClass(String filename) throws ClassNotFoundException {FileInputStream fis = null;ByteArrayOutputStream baos = new ByteArrayOutputStream();try {// 1.获取class文件的字节码（二进制数据）String[] fileNames = filename.split("//.");fis = new FileInputStream(demoPath + fileNames[fileNames.length-1] +".class");byte[] bytes = new byte[1024];int len = 0;while ((len = fis.read(bytes)) != -1) {baos.write(bytes, 0, len);}} catch (Exception e) {throw new ClassNotFoundException();} finally {try {fis.close();} catch (IOException e) {throw new ClassNotFoundException();}}byte[] paramArrayOfByte = baos.toByteArray();// 2。把二进制文件定义为class对象返回return defineClass(filename, paramArrayOfByte, 0, paramArrayOfByte.length);}}

class com.chong.studyparalell.demon.DemonThreadDemo