浅谈java多线程回调的三种方式适用于实际工程项目_java多线程for循环回调

前言

掌握同步操作，实现资源最大程度利用

---

目标

掌握三种回电方式
1 while循环等待
2 join
3 implements Callable

关键字

Executors，Future，get，Callable，Runnable

一、定义

以空间换时间的方式解决问题。

二、使用及场景

import java.util.ArrayList;
import java.util.concurrent.*;

/**
 * 多线程返回值的三种方式
 * 1 while循环等待
 * 2 join
 * 3  implements Callable
 * Created by xiaojinlu1990@163.com on 2020/11/29 0029.
 */
public class ExecutorDemo {

    public static void main(String[] args) throws InterruptedException, ExecutionException {

        //第一种 循环主线程等待法
        TestTreadFrist testTreadFrist = new TestTreadFrist();
        testTreadFrist.setNum("test1");
        Thread thread1 = new Thread();
        thread1.start();
        while (testTreadFrist.getNum()==null){
          Thread.sleep(1000);
        }
        System.out.println(testTreadFrist.getNum());
        //第二种  join等待法
        TestTreadTwe testTreadTwe = new TestTreadTwe();
        testTreadTwe.setNum("test2");
        Thread thread2 = new Thread();
        thread2.start();
        thread2.join();//join等待法
        System.out.println(testTreadTwe.getNum());
        //第三种1 实现Callable  获取返回值
        ExecutorService service = Executors.newCachedThreadPool();
        TestTreadThree testTreadThree = new TestTreadThree();
        Future<String> str = service.submit(testTreadThree);
        System.out.println(str.get());

        //第三种2 多回调返回 + 超时时间版本
        ExecutorDemo executorDemo = new ExecutorDemo();
        executorDemo.getThread();
    }

    public void  getThread() {
       ExecutorService service = Executors.newCachedThreadPool();
        ArrayList<Future<String>> results = new ArrayList<Future<String>>();
        for (int i = 0; i < 10; i++) {
           TestTread testTread = new TestTread();
           testTread.setNum(String.valueOf(i));
            results.add(service.submit(testTread));
        }
        for(Future<String> fs : results){
            try {
                System.out.println("");
                long timeOut =2;
                System.out.println(fs.get(timeOut, TimeUnit.SECONDS));
            } catch (InterruptedException e) {
                e.printStackTrace();
                return ;
            } catch (ExecutionException e) {
                e.printStackTrace();
            } catch (TimeoutException e) {
                //打印超时
                e.printStackTrace();
            } finally{
                service.shutdown();
            }
        }
    }
}

class TestTread implements Callable{
    private String num;

    public void setNum(String num) {
        this.num = num;
    }

    public String getNum() {
        return num;
    }

    @Override
    public Object call() throws Exception {
        if(num.equals("3")){

            Thread.sleep(10000);
        }else {
            Thread.sleep(1900);
        }
        System.out.printf(num);
        return getNum();
    }
}

//第一种
class TestTreadFrist implements Runnable{

    private String num;

    public void setNum(String num) {
        this.num = num;
    }

    public String getNum() {
        return num;
    }

    @Override
    public void run() {
        try {
            Thread.sleep(1000);
        } catch (InterruptedException e) {
            e.printStackTrace();
        }
        setNum("------");

    }
}
//第二种
class TestTreadTwe implements Runnable{
    private String num;

    public void setNum(String num) {
        this.num = num;
    }

    public String getNum() {
        return num;
    }

    @Override
    public void run() {

    }
}
//第三种 实现Callable
class TestTreadThree implements Callable{
    private String num;

    public void setNum(String num) {
        this.num = num;
    }

    public String getNum() {
        return num;
    }

    @Override
    public Object call() throws Exception {
        setNum("test3");
        return getNum();
    }
}


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总结

根据场景对用适应才最好，最适宜的就是最好的。

参考

java API
https://tool.oschina.net/apidocs/apidoc?api=jdk-zh
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