今天我們將通過執行緒來談一談生產者消費者的問題
首先我們寫一個小程式生產一個商品並消費一個商品

/**
 * 寫一個商品者生產消費者消費的執行緒小程式
 * @author lover
 *
 */

class goods{
    private int sum=1;
    private String name;
    public void set(String name){
        this.name=name+sum;
        sum++;
        System.out.println(sum);
        System.out.println("....生產...."
 
+this.name);

    }
    public void out(){
        System.out.println(".......消費........"+this.name);
    }

}
class produce implements Runnable{
    goods s;
    public produce(goods s){
        this.s=s;
    }
    public void run(){
        while(true){
            s.set("麵包");
        }
    }
}
class
 
 customer implements Runnable{
    goods s;
    public customer(goods s){
        this.s=s;
    }
    public void run(){
        while(true){
            s.out();
        }
    }
}
public class ShangPin {
public static void main(String[] args) {
    goods s=new goods();
    produce t1=new produce(s);
    customer t2=new
 
 customer(s);
    Thread t11=new Thread(t1);
    Thread t22=new Thread(t2);
    t11.start();
    t22.start();

}
}

執行結果如下

....生產....麵包19312
19314
....生產....麵包19313
19315
....生產....麵包19314
19316
....生產....麵包19315
19317
....生產....麵包19316
19318
....生產....麵包19317
19319
....生產....麵包19318
19320
.......消費........麵包19166
.......消費........麵包19319
.......消費........麵包19319
.......消費........麵包19319

執行之後發現一個很嚴重的問題出現了多生產和消費已經消費的產品，此時我們希望的是能夠生產一個消費一個。之後我們改進程式碼

/**
 * 寫一個商品者生產消費者消費的執行緒小程式
 * @author lover
 *
 */

class goods{
    private int sum=1;
    private String name;
    boolean flag=false;
    public synchronized void set(String name){
        if(!flag){
        this.name=name+sum;
        sum++;
        System.out.println("....生產...."+this.name);
        flag=true;
        notifyAll();
        }else{
            try {
                wait();
            } catch (InterruptedException e) {
                // TODO Auto-generated catch block
                e.printStackTrace();
            }
        }
        }
    public synchronized void out(){
        if(flag){
        System.out.println(".......消費........"+this.name);
        flag=false;
        notifyAll();
        }else{
            try {
                wait();
            } catch (InterruptedException e) {
                // TODO Auto-generated catch block
                e.printStackTrace();
            }
        }
    }
}
class produce implements Runnable{
    goods s;
    public produce(goods s){
        this.s=s;
    }
    public void run(){
            while(true){
                s.set("麵包");
            }


    }
}
class customer implements Runnable{
    goods s;
    public customer(goods s){
        this.s=s;
    }
    public void run(){
        while(true){
            s.out();
        }
    }
}
public class ShangPin {
public static void main(String[] args) {
    goods s=new goods();
    produce t1=new produce(s);
    customer t2=new customer(s);
    Thread t11=new Thread(t1);
    Thread t22=new Thread(t2);
    t11.start();
    t22.start();

}
}
我們來看一下結果
`....生產....麵包45863
.......消費........麵包45863
....生產....麵包45864
.......消費........麵包45864
....生產....麵包45865
.......消費........麵包45865
....生產....麵包45866
.......消費........麵包45866
....生產....麵包45867
.......消費........麵包45867
....生產....麵包45868
.......消費........麵包45868
....生產....麵包45869
.......消費........麵包45869
....生產....麵包45870
.......消費........麵包45870
....生產....麵包45871
`

已經很好的解決了出現的問題
下一節我們將使用jdk1.5的方法來完善這個小程式