Java多線程的生產者與消費者模型，線程間的通訊

java多線程中的生產者與消費者模式：
首先有一個阻塞隊列，生產者將生產的東西放到隊列裏，消費者再從隊列中取。當隊列中的東西數量達到其容量就發生阻塞。

import java.util.Random;
import java.util.concurrent.ArrayBlockingQueue;
import java.util.concurrent.BlockingQueue;
import java.util.concurrent.LinkedBlockingQueue;
import java.util.concurrent.PriorityBlockingQueue;

public class UseBlockingQueue {
    private static BlockingQueue<String> queue = new ArrayBlockingQueue<>(1);//1是隊列容量，超過就會阻塞。
            // new PriorityBlockingQueue<>();
            // new LinkedBlockingQueue<>();
            // new ArrayBlockingQueue<>(10);

    private static class Producer extends Thread {
        @Override
        public void run() {
            Random random = new Random(20191116);
            while (true) {
                try {
                    int message = random.nextInt(100);
                    queue.put(String.valueOf(message));//將消息放入隊列中
                    System.out.println("放入消息: " + message);
                    Thread.sleep(random.nextInt(3) * 100);//睡眠
                } catch (InterruptedException e) {
                    e.printStackTrace();
                }
            }
        }
    }

    private static class Customer extends Thread {
        @Override
        public void run() {
            Random random = new Random(20191116);
            while (true) {
                try {
                    String message = queue.take();//從隊列中取走消息
                    System.out.println("收到消息: " + message);
                    Thread.sleep(random.nextInt(3) * 100);
                } catch (InterruptedException e) {
                    e.printStackTrace();
                }
            }
        }
    }

    public static void main(String[] args) {
        Thread producer = new Producer();
        Thread customer = new Customer();
        producer.start();
        customer.start();
    }
}

synchronized關鍵字修飾：給對象加鎖，保證線程安全，若是CPU發生任意調度，也不會線程不安全。

public class MyQueue2 {
    private int[] array = new int[2];
    private volatile int size;
    private int front;
    private int rear;

    private Object full = new Object();
    private Object empty = new Object();

    public void put(int message) throws InterruptedException {
        while (size == array.length) {
            synchronized (full) {
                full.wait();
            }
        }

        synchronized (this) {
            array[rear] = message;
            rear = (rear + 1) % array.length;
            size++;
        }

        synchronized (empty) {
            empty.notify();
        }
    }

    public synchronized int take() throws InterruptedException {
        while (size == 0) {
            synchronized (empty) {
                empty.wait();
            }
        }

        int message;
        synchronized (this) {
            message = array[front];
            front = (front + 1) % array.length;
            size--;
        }

        synchronized (full) {
            full.notify();
        }

        return message;
    }
}

線程間的通訊
public class ThreadDemo {
public static void main(String[] args){
class Person{
public String name;
private String gender;
public void set(String name,String gender){
this.name =name;
this.gender =gender;
}
public void get(){
System.out.println(this.name+"...."+this.gender);
}
}//Person類 有兩個屬性 兩個方法
final Person p =new Person();//new一個Person類對象p
new Thread(new Runnable(){//匿名線程
public void run(){//覆寫run方法
int x=0;
while(true){
if(x==0){
p.set("張三", "男");
}else{
p.set("lili", "nv");
}
x=(x+1)%2;
}
}
}).start();
new Thread(new Runnable(){
public void run(){
while(true){
p.get();
}
}
}).start();//啓動一個匿名線程
}
}