写在前面：分享技术，共同进步，把之前写的笔记搬运至博客，*有不足请见谅，相关意见可评论告知 (≧∇≦)ﾉ
编程路漫漫，学习无止尽！
目录
线程同步
三大线程不安全案例
一、多人同时抢票问题
二、银行存款问题
package ThreadProcessStudy.ThreeSync;
public class UnsafeBank {
public static void main(String[] args) {
Account account = new Account(100,"结婚基金");
Drawing you1 = new Drawing(account,50,"you1");
Drawing you2 = new Drawing(account,100,"you2");
you1.start();
you2.start();
}
}
class Drawing extends Thread{
Account account ;
int drawingMoney ;
int nowMoney;
public Drawing( Account account ,int drawingMoney,String name){
super(name);
this.account = account;
this.drawingMoney = drawingMoney;
}
@Override
public void run(){
if(account.money-drawingMoney<0){
System.out.println(Thread.currentThread().getName()+"钱不够");
return;
}
// sleep可以放大问题
try {
Thread.sleep(1000);
} catch (InterruptedException e) {
e.printStackTrace();
}
account.money = account.money - drawingMoney;
nowMoney = nowMoney + drawingMoney;
System.out.println(account.name+"余额为"+account.money);
System.out.println(this.getName()+"手里得钱"+nowMoney);
}
}
// 账户
class Account {
int money ; // 余额
String name ;
public Account(int money, String name) {
this.money = money;
this.name = name;
}
}
三、同时添加集合问题
同步方法
同步块
银行取钱举例
死锁
package ThreadProcessStudy;
public class DeadLock {
public static void main(String[] args) {
Makeup g1 = new Makeup(0,"灰姑娘");
Makeup g2 = new Makeup(0,"白雪公主");
g1.start();
g2.start();
}
}
class Lipstick{
}
class Mirror{
}
class Makeup extends Thread{
static Lipstick lipstick= new Lipstick();
static Mirror mirror = new Mirror();
int choice ;
String girl ;
public Makeup( int choice, String girl) {
this.choice = choice;
this.girl = girl;
}
@Override
public void run(){
// 化妆
try {
makeuo();
} catch (InterruptedException e) {
e.printStackTrace();
}
}
// 化妆，互相持有对方的锁，级需要拿到对方的资源
private void makeuo() throws InterruptedException {
if(choice ==0){
synchronized (lipstick){ // 获得口红的锁
System.out.println(this.girl+"获得口红的锁");
Thread.sleep(1000);
// synchronized (mirror){ // 一秒后想获得镜子的锁
// System.out.println(this.girl+"获得镜子的锁");
// ****注意这样放在代码块里面就形成死锁
// }
}
synchronized (mirror){ // 一秒后想获得镜子的锁
System.out.println(this.girl+"获得镜子的锁");
}
}else{
synchronized (mirror){ // 一秒后想获得镜子的锁
System.out.println(this.girl+"获得镜子的锁");
Thread.sleep(2000);
}
synchronized (lipstick){
System.out.println(this.girl+"获得口红的锁");
}
}
}
}
输出结果：
死锁的避免方法
Lock(锁)
加锁前代码：
package ThreadProcessStudy;
public class TestLock {
public static void main(String[] args) {
TestLock2 testLock2 = new TestLock2();
// 模拟三个线程同时操作一个对象
new Thread(testLock2).start();
new Thread(testLock2).start();
new Thread(testLock2).start();
}
}
class TestLock2 implements Runnable{
int ticketNums = 10;
@Override
public void run() {
while(true){
if(ticketNums >= 0) {
try {
Thread.sleep(1000);
} catch (InterruptedException e) {
e.printStackTrace();
}
System.out.println(Thread.currentThread().getName()+"拿到"+ticketNums--); //注意分割符的位置
}else{
break ;
}
}
}
}
输出结果：
加锁后：
synchronized 与Lock的对比
生产者消费者问题
通信问题
方法一：
方法二：
线程池
代码实列
写在最后：全栈方向，前端已经大部分学完，将会以复习的形式出现在博客，大家敬请期待哈~