java 第59节 同步问题Java的解决方案

2016-07-02

1 同步问题Java的解决方案
同步方法：当线程进入同步方法的时候，会获得同步方法所属对象的锁，
一旦获得对象锁，则其他线程不能再执行被锁对象的其他任何同步方法。
只有在同步方法执行完毕之后释放了锁，其他线程才能继续执行。

synchronized 方法声明{

}

同步块：
synchronized(资源对象){
//需要进行同步的方法
}

package com.java1995;

/**
 * 打印机类
 *
 * @author Administrator
 *
 */
public class Print {

    /**
     *
     * @param name
     *            学生姓名
     * @param eScore
     *            英语成绩
     * @param mScore
     *            数学成绩
     * @param yScore
     *            语文成绩
     */
    public void printScore(String name, int eScore, int mScore, int yScore) {
        System.out.println(name + "的英语成绩:" + eScore);
        try {
            Thread.sleep(2000);
        } catch (InterruptedException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        }
        System.out.println(name + "的数学成绩:" + mScore);
        System.out.println(name + "的语文成绩:" + yScore);

    }

}

package com.java1995;
/**
 * 老师类
 * @author Administrator
 *
 */
public class Teacher implements Runnable{
    //封装
    private Print p;
    private String name;
    private int eScore,mScore,yScore;

    public Teacher(Print p,String name,int eScore,int mScore,int yScore){
        this.p=p;
        this.name=name;
        this.eScore=eScore;
        this.mScore=mScore;
        this.yScore=yScore;
    }

    //封装的实现
    public Print getP() {
        return p;
    }

    public void setP(Print p) {
        this.p = p;
    }

    public String getName() {
        return name;
    }

    public void setName(String name) {
        this.name = name;
    }

    public int geteScore() {
        return eScore;
    }

    public void seteScore(int eScore) {
        this.eScore = eScore;
    }

    public int getmScore() {
        return mScore;
    }

    public void setmScore(int mScore) {
        this.mScore = mScore;
    }

    public int getyScore() {
        return yScore;
    }

    public void setyScore(int yScore) {
        this.yScore = yScore;
    }

    //重写run()方法
    @Override
    public void run() {
        // TODO Auto-generated method stub
        synchronized (p) {

            p.printScore(name, eScore, mScore, yScore);
        }
    }

}

package com.java1995;

public class Test {

    public static void main(String[] args) {

        Print p = new Print();
        Teacher t1 = new Teacher(p, "博尔特", 10, 11, 12);
        Teacher t2 = new Teacher(p, "加特林", 23, 56, 1);
        Teacher t3 = new Teacher(p, "苏炳添", 34, 55, 90);

        Thread th1 = new Thread(t1);
        Thread th2 = new Thread(t2);
        Thread th3 = new Thread(t3);
        th1.start();
        th2.start();
        th3.start();

    }

}

package com.java1995;

public class Source {

    synchronized void method1(){
        System.out.println("进入method1方法，获得锁");
        try {
            Thread.sleep(3000);
        } catch (InterruptedException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        }
        System.out.println("method1执行完毕，释放锁");
    }

    synchronized void method2(){
        System.out.println("进入method2方法，获得锁");
        try {
            Thread.sleep(3000);
        } catch (InterruptedException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        }
        System.out.println("method2执行完毕，释放锁");
    }

}

package com.java1995;

public class MyThread extends Thread{

    String name;
    Source s;

    MyThread(String name,Source s){
        this.name=name;
        this.s=s;
    }

    @Override
    public void run() {
        // TODO Auto-generated method stub
        if("method1".equals(name)){
            s.method1();
        }else{
            s.method2();
        }
    }

    public static void main(String[] args) {
        Source s=new Source();
        MyThread t1=new MyThread("method1",s);
        MyThread t2=new MyThread("method2",s);
        t1.start();
        t2.start();
    }

}

【参考资料】

[1] Java轻松入门经典教程【完整版】