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转载地址：https://blog.csdn.net/weixin_42245930/article/details/88761176
Guarded Suspension
Guarded 是被守护，被保护的意思，Suspension 是暂停的意思。如果执行现在的处理会造成问题，就让执行处理的线程进行等待。**当现在并不适合马上执行某个操作时，就要求想要执行该操作的线程等待，**这就是Guarded Suspension Pattern。Guarded Suspension Pattern 会要求线程等候，以保障实例的安全性。 其实和生产者和消费者模式有点类似。
Request
public class Request {
private final String name;
public Request(String name) {
this.name = name;
}
public String getName() {
return name;
}
@Override
public String toString() {
return "Request{" + "name='" + name + '\'' + '}';
}
}
RequestQueue
public class RequestQueue {
private final Queue<Request> queue = new LinkedList<>();
// 取出最先放在RequestQueue的中的一个请求，作为返回值，
// 如果一个请求也没有就一直等待，直到其他线程执行putRequest.
public synchronized Request getRequest() {
while (queue.peek() == null) {
try {
wait();
} catch (InterruptedException e) {
e.printStackTrace();
}
}
return queue.remove();
}
// 添加一个请求
public synchronized void putRequest(Request request) {
queue.offer(request);
notifyAll();
}
}
ClientThread
public class ClientThread extends Thread {
private final Random random;
private final RequestQueue requestQueue;
public ClientThread(RequestQueue requestQueue, String name, long seed) {
super(name);
this.requestQueue = requestQueue;
this.random = new Random(seed);
}
@Override
public void run() {
for (int i = 0; i < 10; i++) {
Request request = new Request("No." + i);
System.out.println(Thread.currentThread().getName() + " requests " + request+"/n");
requestQueue.putRequest(request);
try {
// 为了错开发送请求的执行点，使用java.util.Random类随机生成0-1000之间的数
Thread.sleep(random.nextInt(1000));
} catch (InterruptedException e) {
e.printStackTrace();
}
}
}
}
ServerThread
/**
* 用于表示接收请求的线程，该类也持有RuquestQueue的实例，ServerThread使用该实例的getRequst方法来接受请求。
*/
public class ServerThread extends Thread {
private final Random random;
private final RequestQueue requestQueue;
public ServerThread(RequestQueue requestQueue, String name, long seed) {
super(name);
this.requestQueue = requestQueue;
this.random = new Random(seed);
}
@Override
public void run() {
for (int i = 0; i < 10; i++) {
Request request = requestQueue.getRequest();
System.out.println(Thread.currentThread().getName() + " handles " + request);
try {
Thread.sleep(random.nextInt(1000));
} catch (InterruptedException e) {
e.printStackTrace();
}
}
}
}
Main
public class Main {
public static void main(String[] args) {
RequestQueue requestQueue = new RequestQueue();
new ClientThread(requestQueue, "发送请求-->", 3141592L).start();
new ServerThread(requestQueue, "处理请求-->", 6535897L).start();
}
}
运行结果
送请求--> requests Request{name='No.0'}
处理请求--> handles Request{name='No.0'}
发送请求--> requests Request{name='No.1'}
发送请求--> requests Request{name='No.2'}
处理请求--> handles Request{name='No.1'}
处理请求--> handles Request{name='No.2'}
发送请求--> requests Request{name='No.3'}
处理请求--> handles Request{name='No.3'}
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