Java多线程你知道有几种实现方式？

Posted 2021-09-25 JunMain

多线程的四种实现

1. 继承Thread

​ 1.创建一个MyThread 类继承Thread

​ 2. 并且重写run()方法

pakage com.lzj;

public class MyThread extends Thread{
    @Override
    public void run(){
        for (int i = 1; i < 20; i++){
            System.out.println("我是 "+Thread.currentThread().getName()+"线程 "+i);
        }
    }

}

​ 3.创建MyThread实例

​ 4.调用start()方法启动线程

pakage com.lzj;
public class ThreadTest {
    
 	//Thread.currentThread()可以获取当前正在运行的线程 getName()获取线程名
     @Test
    public void testThread(){

        MyThread myThread = new MyThread();
        myThread.start();
        for (int i = 0; i < 20; i++){
            System.out.println("我是 "+Thread.currentThread().getName()+"线程 "+i);
        }
    }
}

2. 实现Runnable接口

1. 创建类实现Runnable接口

2. 实现run()方法

package com.lzj;

public class MyRunnable implements Runnable{
    
    public void run(){
        for (int  i = 0; i < 40; i++){
            System.out.println("我是 " + Thread.currentThread().getName()+"线程 "+i);
        }
    }
}

3. 创建MyRunnable实例

4. MyRunnable实例作为创建Thread类实例的参入传入

5. 调用start()

pakage com.lzj;
public class ThreadTest {
    
 	 @Test
    public void testRunnable(){
        MyRunnable myRunnable = new MyRunnable();
        Thread thread = new Thread(myRunnable,"通过实现Runnable接口的");
        thread.start();

        for (int i = 0; i < 20; i++){
            System.out.println("我是 "+Thread.currentThread().getName()+"线程 "+i);
        }

    }
}

3. 实现Callable接口

1.创建MyCallable实现Callable接口 传入泛型的类型作为call的返回值类型

2.实现call()方法

package com.lzj;

import java.util.concurrent.Callable;

public class MyCallable implements Callable<String> {
    
    public String call() {

        for(int i = 1; i < 30; i++){
            System.out.println("我是"+Thread.currentThread().getName()+"线程"+i);
        }
        return "实现Callable接口的线程运行结束";
    }
}

3.创建MyCallable实例 MyCallable myCallable = new MyCallable();

4.创建FutureTask的实例 myCallable 作为参数 泛型的类型与Callable泛型的类型一致

5.创建Thread的实例 futureTask作为参数传入

6.调用start()方法

7.可以futureTask.get()获取call()的返回值 捕获异常

pakage com.lzj;
import java.util.concurrent.ExecutionException;
import java.util.concurrent.FutureTask;

public class ThreadTest {
    
 	
    @Test
    public void testCallable(){

        MyCallable myCallable = new MyCallable();
        FutureTask<String> futureTask = new FutureTask<String>(myCallable);
        Thread thread = new Thread(futureTask,"通过实现Callable接口的");
        thread.start();

        for (int i = 1; i < 30; i ++){
            System.out.println("我是 "+Thread.currentThread().getName()+"线程 "+i);
        }

        String result = null;
        try {
            result = futureTask.get();
        } catch (InterruptedException e) {
            e.printStackTrace();
        } catch (ExecutionException e) {
            e.printStackTrace();
        }
        System.out.println(result);
    }
}

4. 通过线程池创建

1.通过Executors这个包中提供的newFixedThreadPool()创建定长线程池

2.execute()执行线程 MyRunnable实体类作为参数

package com.lzj;

public class MyRunnable implements Runnable{
    
    public void run(){
        for (int  i = 0; i < 40; i++){
            System.out.println("我是 " + Thread.currentThread().getName()+"线程 "+i);
        }
    }
}

package com.lzj;
import java.util.concurrent.ExecutorService;
import java.util.concurrent.Executors;

public class MyThreadPoolTest {
    @Test
 
    public void testPool(){
        ExecutorService executorService = Executors.newFixedThreadPool(10);
        executorService.execute(new MyRunnable());

        for (int i = 0; i < 20; i++){
            System.out.println(Thread.currentThread().getName()+i);
        }
    }