多线程

Posted 2020-10-29 bigstrawberrywakaka

java多线程经典的生产者 / 消费者实例，线程的协调。

 1 package java语言程序设计进阶篇;
 2 
 3 import java.util.concurrent.ExecutorService;
 4 import java.util.concurrent.Executors;
 5 import java.util.concurrent.locks.Condition;
 6 import java.util.concurrent.locks.Lock;
 7 import java.util.concurrent.locks.ReentrantLock;
 8 
 9 public class Chapter30_7 {
10     private static Buffer buffer = new Buffer();
11     public static void main(String[] args){
12         ExecutorService executor = Executors.newFixedThreadPool(2);
13         executor.execute(new ProducerTask());
14         executor.execute(new ConsumerTask());
15         executor.shutdown();
16     }
17 
18     public static class ProducerTask implements Runnable{
19         public void run(){
20             try{
21                 int i = 1;
22                 while(true){
23                     System.out.println("Producer writes " + i);
24                     buffer.write(i++);
25                     Thread.sleep((int)(Math.random() * 10000));
26                 }
27             }
28             catch (InterruptedException ex){
29                 ex.printStackTrace();
30             }
31         }
32     }
33 
34     public static class ConsumerTask implements Runnable{
35         public void run(){
36             try{
37                 while(true){
38                     System.out.println("\t\tConsumer reads " + buffer.read());
39                     Thread.sleep((int)(Math.random() * 10000));
40                 }
41             }
42             catch(InterruptedException ex){
43                 ex.printStackTrace();
44             }
45         }
46     }
47 
48     public static class Buffer{
49         private static final int CAPACITY = 1;   //缓冲区的大小
50         private java.util.LinkedList<Integer> queue = new java.util.LinkedList<>();
51         private static Lock lock = new ReentrantLock();
52         private static Condition notFull = lock.newCondition();
53         private static Condition notEmpty = lock.newCondition();
54 
55         public void write(int value){
56             lock.lock();
57             try{
58                 while(queue.size() == CAPACITY){
59                     System.out.println("Wait for notFull condition");
60                     notFull.await();
61                 }
62                 queue.offer(value);
63                 notEmpty.signal();
64             }
65             catch(InterruptedException ex){
66                 ex.printStackTrace();
67             }
68             finally {
69                 lock.unlock();
70             }
71         }
72 
73         public int read(){
74             int value = 0;//存放被删除数
75             lock.lock();
76             try{
77                 while(queue.isEmpty()){
78                     System.out.println("\t\tWait for notEmpty condition");
79                     notEmpty.await();
80                 }
81                 value = queue.remove();
82                 notFull.signal();
83             }
84             catch (InterruptedException ex){
85                 ex.printStackTrace();
86             }
87             finally {
88                 lock.unlock();
89                 return value;
90             }
91         }
92     }
93 }