java多线程-GuardedSuspension保护暂停模式

写在前面的话：假设一种情景，假设你在家里换衣服，这个时候有顺风快递员在门外敲门，你会说等一下，换完衣服你去开门。假设你换衣服是一个线程，顺风快递员把东西送到你的手机是另一个线程，很明显后者线程要目的达到需要前者线程的执行完的条件，这个“保护暂停模式”就是应这样的需求而生。

下面是实例程序：
涉及类及作用介绍：
1，Request：用来表示请求的类。
2，RequestQueue：依次存放请求以待使用的类。
3，ClientRequest：送出请求的类。
4，ServerThread：接收请求的类。
5，Main：操作测试类。

类Request：

package GuardedSuspensionPattern;
/*
 *该类用来表示请求
 */
public class Request {
	private final String name;
	public Request(String name){
		this.name = name;
	}
	public String getName(){
		return name;
	}
	public String toString(){
		return "[Request:" + name + "]";
	}
}

类RequestQueue：

package GuardedSuspensionPattern;
import java.util.LinkedList;
/*
 *请求队列类，有放入请求方法，拿出请求方法，注意都是synchronized的。
 *放入的方法没有限制，取出的方法就要先判断有没有请求了，如果没有请求就一直等到有请求。
 */
public class RequestQueue {
	private final LinkedList queue = new LinkedList();
	//取出请求的方法
	public synchronized Request getRequest(){
	   while(queue.size() <= 0){
		   try {
			wait();//一旦请求队列中没有请求，持有RequestQueue实例的线程放入到RequestQueue实例的线程等待区（一旦进入到该区就释放了之前的锁）
		} catch (InterruptedException e) {
			// TODO Auto-generated catch block
			e.printStackTrace();
		}
	   }
	   return queue.removeFirst();//拿出队列的第一个请求并返回该请求
	}
	//放入请求的方法，一旦放入请求，就唤醒所有RequestQueue实例线程等待区的所有等待线程
	public synchronized void putRequest(Request request){
		queue.addLast(request);//请新的请求放入到队列的最后
		notifyAll();//唤醒所有等待的线程
	}
}

类：ClientThread

package GuardedSuspensionPattern;
import java.util.Random;
/*
 * 该线程类主要负责生产一千个请求放进请求队列中，供处理线程处理
 */
public class ClientThread extends Thread{
	private Random random;
	private RequestQueue requestQueue;
	public ClientThread(RequestQueue requestQueue,String name,long seed){
		this.requestQueue = requestQueue;
		this.random = new Random(seed);
	}
	public void run(){
		for(int i=0; i<10000; i++){
			Request request = new Request("NO:" + i);
			System.out.println(Thread.currentThread().getName() + "requests: " + request);
			requestQueue.putRequest(request);
			try {
				Thread.sleep(random.nextInt(1000));
			} catch (InterruptedException e) {
				// TODO Auto-generated catch block
				e.printStackTrace();
			}
		}
	}
}

类ServerThread：

package GuardedSuspensionPattern;
import java.util.Random;
/*&
 * 该线程主要带请求队列中拿出一千个请求来处理，如果请求队列中没有请求，就一直等到
 * 有请求为止。
 */
public class ServerThread extends Thread{
	private Random random;
	private RequestQueue requestQueue;
	public ServerThread(RequestQueue requestQueue,String name,long seed){
      this.requestQueue = requestQueue;
      this.random = new Random(seed);
	}
	public void run(){
		for(int i = 0; i < 10000; i++){
			Request request = requestQueue.getRequest();
			System.out.println(Thread.currentThread().getName() + "handles:" + request);
		    try {
				Thread.sleep(random.nextInt(1000));
			} catch (InterruptedException e) {
				// TODO Auto-generated catch block
				e.printStackTrace();
			}
		}
	}
}

类Main

package GuardedSuspensionPattern;
public class Main {

	public static void main(String[] args) {
		//定义请求队列实例，注意该实例就是共享资源
		RequestQueue requestQueue = new RequestQueue();
		//开启“产生1000个请求的实例”线程
		new ClientThread(requestQueue,"Supan1",3141592L).start();
		//开始“处理1000个请求的实例“线程
		new ServerThread(requestQueue, "Supan2", 6535897L).start();
	}
}

运行结果：
Thread-0requests: [Request:NO:0]
Thread-1handles:[Request:NO:0]
Thread-0requests: [Request:NO:1]
Thread-0requests: [Request:NO:2]
Thread-1handles:[Request:NO:1]
Thread-1handles:[Request:NO:2]
Thread-0requests: [Request:NO:3]
Thread-1handles:[Request:NO:3]
Thread-0requests: [Request:NO:4]
Thread-1handles:[Request:NO:4]
Thread-0requests: [Request:NO:5]
Thread-0requests: [Request:NO:6]
Thread-1handles:[Request:NO:5]
Thread-1handles:[Request:NO:6]
Thread-0requests: [Request:NO:7]
Thread-1handles:[Request:NO:7]
Thread-0requests: [Request:NO:8]
Thread-1handles:[Request:NO:8]
Thread-0requests: [Request:NO:9]
Thread-1handles:[Request:NO:9]
Thread-0requests: [Request:NO:10]
Thread-0requests: [Request:NO:11]
Thread-1handles:[Request:NO:10]
Thread-1handles:[Request:NO:11]
Thread-0requests: [Request:NO:12]
Thread-1handles:[Request:NO:12]
Thread-0requests: [Request:NO:13]
Thread-1handles:[Request:NO:13]
Thread-0requests: [Request:NO:14]
Thread-1handles:[Request:NO:14]
Thread-0requests: [Request:NO:15]
Thread-1handles:[Request:NO:15]
Thread-0requests: [Request:NO:16]
Thread-1handles:[Request:NO:16]
Thread-0requests: [Request:NO:17]
Thread-1handles:[Request:NO:17]
Thread-0requests: [Request:NO:18]
Thread-1handles:[Request:NO:18]
Thread-0requests: [Request:NO:19]
Thread-1handles:[Request:NO:19]