多线程的并发与协作

  多线程可以提高一个项目的运行效率， 多线程之间的协作也不可避免，先举一个简单的例子：先介绍第一个类

package HelloWorld;

public class ThradStudy {
	private String response  ; 
	
	private Object synObj = new Object();
	
	public void start(){
		System.out.println("AAAAAAAAA");
		try{
			synchronized (synObj) {
				synObj.wait(10000);
			}
		}
		catch(Exception e ){
		}
		System.out.println(response);
	}
	
	public void notify(String a ){
		response = a ;
		synchronized(synObj){
			synObj.notifyAll();
		}
	}
}

 这个类有两个私有字段，一个是字符串str ， 一个是锁synObj对象，在另一个类中，我们先声明一个ThradStudy对象，在main方法中，启动两个线程，一个线程负责执行start，一个线程负责3秒后唤醒另一个线程代码如下

package HelloWorld;

public class notyFyClass {
	public static ThradStudy test = new ThradStudy() ;
	public static void main(String[] args) {
		new Thread(new Runnable(){

			@Override
			public void run() {
				test.start();
			}
			
		}).start();
		
		new Thread(new Runnable(){
			@Override
			public void run() {
				try {
					Thread.sleep(3000) ;
				} catch (InterruptedException e) {
					e.printStackTrace();
				}
				String str = "唤醒" ;
				test.notify(str);
			}
			
		}).start();
	}
}

 执行结果可以看到，先输出AAAAAAA，而后输出“唤醒”；

这个例子可能不太容易理解，下面分别通过synchronized和Lock来实现生产者和消费者

一、Lock

package HelloWorld;

import java.util.concurrent.locks.Condition;
import java.util.concurrent.locks.Lock;
import java.util.concurrent.locks.ReentrantLock;

public class ProduceCustomer {

	public static void main(String[] args) {
		Resouse sss = new Resouse();
		Thread pro = new Thread(new Producer(sss));
		Thread cus = new Thread(new Customer(sss));
		pro.start();
		cus.start();
	}
}
	class Resouse{
		private Lock lock = new ReentrantLock();
		private Condition conditionPro = lock.newCondition() ;
		private Condition conditionCus = lock.newCondition() ;
		private String name ; 
		private int count  = 0 ;
		private boolean flag = false ;  //false 表示没有商品需要生产
		public void set(String name) throws Exception{
			lock.lock();
			try{
			if(flag){
					conditionPro.await();
			}
			count++ ;
			this.name = name+count ;
			conditionCus.signal();
			flag = true ;
			System.out.println("生产   "+this.name);
			}
			finally{
				lock.unlock();
			}
			
			
			
		}
		public void pro() throws Exception{
			lock.lock() ;
			try{
			if(!flag){
				conditionCus.await() ;
			}
			flag = false ;
			System.out.println("消费"+this.name);
			conditionPro.signal();
			}
			finally{
				lock.unlock();
			}
			
		}
		
		
	}
	class Producer extends Resouse implements Runnable{
		private Resouse r ; 
		public Producer(Resouse re){
			super();
			r = re ;
		}
		@Override
		public void run() {
			// TODO Auto-generated method stub
			while(true){
				try {
					r.set("篮球") ;
				} catch (Exception e) {
					// TODO Auto-generated catch block
					e.printStackTrace();
				}
				
			}
		}
		
	}
	class Customer extends Resouse implements Runnable{
		private Resouse r ;
		public Customer(Resouse re ){
			super();
			r = re ;
		}
		@Override
		public void run() {
			// TODO Auto-generated method stub
			while(true){
				try {
					r.pro() ;
				} catch (Exception e) {
					// TODO Auto-generated catch block
					e.printStackTrace();
				}
			}
		}
		
	}

 

里面有一个resource类，他里面有一个set和pro方法，set方法负责生产部件，pro方法负责消费部件，如果没有部件就不能消费只能生产，在这里set方法中，如果有部件需要生产则生产一个部件并唤醒消费，如果不需要生产则睡眠，等待消费线程消费完部件后唤醒，Producer类和Customer则是实现线程不断的执行生产和消费

二、synchronized

package HelloWorld;

import java.util.concurrent.locks.Condition;
import java.util.concurrent.locks.Lock;
import java.util.concurrent.locks.ReentrantLock;

public class ProduceCustomer {

	public static void main(String[] args) {
		Resouse sss = new Resouse();
		Thread pro = new Thread(new Producer(sss));
		Thread cus = new Thread(new Customer(sss));
		pro.start();
		cus.start();
	}
}
	class Resouse{
		private Object synObj = new Object();
		private String name ; 
		private int count  = 0 ;
		private boolean flag = false ;  //false 表示没有商品需要生产
		public  void set(String name) throws Exception{
			synchronized(synObj){
				if(flag){
					synObj.wait();
			}
			count++ ;
			this.name = name+count ;
			synObj.notify();
			flag = true ;
			System.out.println("生产   "+this.name);
			}
			
			
			
		}
		public void pro() throws Exception{
			synchronized(synObj){
				if(!flag){
					synObj.wait() ;
				}
				flag = false ;
				System.out.println("消费"+this.name);
				synObj.notify();
			}
			
		}
		
		
	}
	class Producer extends Resouse implements Runnable{
		private Resouse r ; 
		public Producer(Resouse re){
			super();
			r = re ;
		}
		@Override
		public void run() {
			// TODO Auto-generated method stub
			while(true){
				try {
					r.set("篮球") ;
				} catch (Exception e) {
					// TODO Auto-generated catch block
					e.printStackTrace();
				}
				
			}
		}
		
	}
	class Customer extends Resouse implements Runnable{
		private Resouse r ;
		public Customer(Resouse re ){
			super();
			r = re ;
		}
		@Override
		public void run() {
			// TODO Auto-generated method stub
			while(true){
				try {
					r.pro() ;
				} catch (Exception e) {
					// TODO Auto-generated catch block
					e.printStackTrace();
				}
			}
		}
		
	}

 实现原理和Lock一样