（1）传统线程技术回顾

1,java中线程的创建可以有两种方法：1、继承Thread类 2、实现Runnable接口

两者区别：

（1）、继承Thread类创建线程的方法， 在继承了Thread类之后， 不能再继承其他的方法， （在java中支持单继承），这样灵活性就不如实现Runnable接口来创建线程的方法了；

（2）、使用实现Runnable接口来创建线程可以达到资源共享！（继承Thread类创建线程也可以实现资源共享，但是比较的麻烦。）

在我们创建线程的时候都会优先采用实现Runnable接口的方法。

package com.thread;public class TestThread2 {/** * @param args */public static void main(String[] args) {Runner r = new Runner();r.start();for(int i=0; i<100; i++) {System.out.println("Main Thread:------" + i);}}}class Runner extends Thread {public void run() {for(int i=0; i<100; i++) {System.out.println("Runner1 :" + i);}}}

package com.thread;public class TestThread3 {/** 优先考虑的方式。 * @param args */public static void main(String[] args) {Runner2 r = new Runner2();Thread t1 = new Thread(r);Thread t2 = new Thread(r);t1.start();t2.start();}}class Runner2 implements Runnable{@Overridepublic void run() {for(int i=0;i<30;i++){System.out.println("No:" + i);}}}

package com.itm.thread;public class TraditionalThread {/** * @param args */public static void main(String[] args) {Thread thread = new Thread() {@Overridepublic void run() {while(true){try {Thread.sleep(500);} catch (InterruptedException e) {e.printStackTrace();}System.out.println("1  " + Thread.currentThread().getName());System.out.println("2  " + this.getName());}}};thread.start();Thread thread2 = new Thread(new Runnable(){@Overridepublic void run() {while(true){try {Thread.sleep(500);} catch (InterruptedException e) {e.printStackTrace();}System.out.println("1  " + Thread.currentThread().getName());// this 就不代表线程了。因为在 Runnable 对象里面。//System.out.println("2" + this.getName());}}});thread2.start();/******************************************************************************** *  * 注释源码说明：利用了  面向对象的  覆盖技术。 *  *  * 调用 start()方法，start()方法 会找  当前对象的run()方法  * (1) 如果自己没有 就找父类中的run()方法。 * 父类的run()方法 会找 Runnable。 * (2) 如果 自己有 run()方法，就把 父类的覆盖了。 *  *  */new Thread(new Runnable() {@Overridepublic void run() {while(true){try {Thread.sleep(500);} catch (InterruptedException e) {e.printStackTrace();}System.out.println("Runnable :" + Thread.currentThread().getName());}}}){public void run() {while(true){try {Thread.sleep(500);} catch (InterruptedException e) {e.printStackTrace();}System.out.println("Thread :  " + Thread.currentThread().getName());}};}.start();}}

关于 上面注释源码的：

(1):public void run() {if (target != null) { // 如果 target不是为空 就会执行 Runnable的run(); 因为：target是 Runnable的 一个变量。    target.run();}}(2) :  /* What will be run. */    private Runnable target;------------------------------------------------------------------------------------------------------ /**     * Initializes a Thread.     *     * @param g the Thread group     * @param target the object whose run() method gets called     * @param name the name of the new Thread     * @param stackSize the desired stack size for the new thread, or     *        zero to indicate that this parameter is to be ignored.     */    private void init(ThreadGroup g, Runnable target, String name,                      long stackSize) {Thread parent = currentThread();SecurityManager security = System.getSecurityManager();if (g == null) {    /* Determine if it's an applet or not */        /* If there is a security manager, ask the security manager       what to do. */    if (security != null) {g = security.getThreadGroup();    }    /* If the security doesn't have a strong opinion of the matter       use the parent thread group. */    if (g == null) {g = parent.getThreadGroup();    }}/* checkAccess regardless of whether or not threadgroup is           explicitly passed in. */g.checkAccess();/* * Do we have the required permissions? */if (security != null) {    if (isCCLOverridden(getClass())) {        security.checkPermission(SUBCLASS_IMPLEMENTATION_PERMISSION);    }}        g.addUnstarted();this.group = g;this.daemon = parent.isDaemon();this.priority = parent.getPriority();this.name = name.toCharArray();if (security == null || isCCLOverridden(parent.getClass()))    this.contextClassLoader = parent.getContextClassLoader();else    this.contextClassLoader = parent.contextClassLoader;this.inheritedAccessControlContext = AccessController.getContext();this.target = target;setPriority(priority);        if (parent.inheritableThreadLocals != null)    this.inheritableThreadLocals =ThreadLocal.createInheritedMap(parent.inheritableThreadLocals);        /* Stash the specified stack size in case the VM cares */        this.stackSize = stackSize;        /* Set thread ID */        tid = nextThreadID();    }    public void run() {if (target != null) {    target.run();}    }