java 09 06 thread-同步代码块-同步方法

锁

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    任何一个对象都可以是锁。信号灯，同一个参照物。

   同步代码块

       　　 synchronized(lock){...}

   同步方法：非静态同步方法以当前对象作为锁旗标

 　　　　 public synchronized void xxx(){...}

   同步方法：静态同步方法以类作为锁旗标

　　　　　public static synchronized void xxx(){...}

售票

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数据访问：同时卖100张票

线程安全：

class NineThreadDemo4Sale{
public static void main(String[] agrs) {
Saler s1 = new Saler("张");
Saler s2 = new Saler("王");
s1.start();
s2.start();
}
}
class Saler extends Thread{
//静态跟对象无关
static int ticket=100;
private String name;
public Saler( String name){
this.name=name;
}

//run 方法
public void run(){
//循环
while(ticket>0){
//得到当前票号
int currticket =ticket;
//还剩多少张票
ticket=ticket-1;
System.out.println(name +";"+currticket);
}
}
}

锁买票

----------------------------------------------------------

class NineThreadDemo4Sale{
public static void main(String[] agrs) {
Saler s1 = new Saler("张");
Saler s2 = new Saler("王");
s1.start();
s2.start();
}
}

class Saler extends Thread{
//静态跟对象无关
//定义一个对象锁 只要它锁上 别人就要等待
static Object lock = new Object();
static int ticket=100;
private String name;
public Saler( String name){
this.name=name;
}

//run 方法
public void run(){
//循环
while(ticket>0){
//锁的用法，synchronized获得锁定权，同一时刻只能有一个人上锁
synchronized(lock){
//得到当前票号
int currticket =ticket;
//还剩多少张票
ticket=ticket-1;
}
System.out.println(name +";"+currticket);

}
}


}

锁 取票

------------------------------------

class NineThreadDemo4Sale{
public static void main(String[] agrs) {
Saler s1 = new Saler("==>张");
Saler s2 = new Saler("=====>王");
s1.start();
s2.start();
}
}

class Saler extends Thread{
//静态跟对象无关
//定义一个对象锁 只要它锁上 别人就要等待
static Object lock = new Object();
static int ticket=100;
private String name;
public Saler( String name){
this.name=name;
}

//run 方法
public void run(){
while(true){
int tick = getticket();
if(tick >0){
System.out.println( name +":"+tick);
}
else{
return;
}
}

}

//取票动作
public int getticket(){

 //同步代码块
synchronized(lock){
int currticket =ticket;
ticket --;
return currticket;
}
}

}

//同步方法---------------------------------------------------

-----------------------------------------------------------------

class NineThreadDemo4Sale{
public static void main(String[] agrs) {
Saler s1 = new Saler("==>张");
Saler s2 = new Saler("=====>王");
s1.start();
s2.start();
} 
}

class Saler extends Thread{
//静态跟对象无关
//定义一个对象锁 只要它锁上 别人就要等待
//static Object lock = new Object();
static int ticket=100;
private String name;
public Saler( String name){
this.name=name;
}  

//run 方法
public void run(){
while(true){
int tick = getticket();
if(tick >0){
System.out.println( name +":"+tick);
}
else{
return;
}
}
}

 //同步方法（锁为当前对象作为锁 ，三个Saler 每个Saler 都以自己为锁，所以要用static 修饰，静态的方法就以类作为锁）
public static synchronized int getticket(){

int currticket =ticket;
ticket --;
return currticket;
}

}

票池取票-------------------------------------

-------------------------------------------------

class NineThreadDemo6tick{
public static void main(String[] agrs) {
TicketPool pool=new TicketPool();
Saler s1=new Saler("LILI" , pool);
Saler s2=new Saler("MARRY" , pool);
s1.start();
s2.start();
}

}
//票池
class TicketPool{
private int tickets =100;
public synchronized int Getticks(){
//票号
int tick =tickets;
//票数
tickets --;
return tickets;
}
}
//并发线程
class Saler extends Thread{
//所有的售票员从一个票池售票。声明一个变量，传过来票池。
private TicketPool pool ;
private String name;
//构造函数
public Saler(String name, TicketPool pool){
this.name =name;
this.pool =pool;
}

public void run(){
while(true){
////调用取票的方法
int no =pool.Getticks();
if(no>0){
System.out.println(name+":"+no);
}
else{
return;
}
}
}
}