JavaSE 基础 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】