Java多线程与线程池

说明：本文主要是线程的四种启动方法，第四种是线程池，如若想查找线程池相关资料，可以忽略前面三种。

区别：方法一二不能得到返回值，方法三四可以获取返回值，方法一二三都不能控制资源，方法四可以控制资源且性能稳定。

方法一：继承extends类，没有返回结果

public class ThreadTestOne {

    public static void main(String args[]){
        System.out.println("main...........start");
        Thread01 thread01 = new Thread01();
        thread01.run();
        System.out.println("main...........end");
    }

    public static class Thread01 extends Thread{
        public void run(){
            System.out.println("当前线程名称..........."+ Thread.currentThread().getId());
            int i = 10/2;
            System.out.println("当前线程运行结果..........."+i);
        }
    }
}

方法二：实现Runnable接口，没有返回结果

public class ThreadTestTwo {

    public static void main(String args[]){
        System.out.println("main..........start");
        Runable01 runable01 = new Runable01();
        runable01.run();
        System.out.println("main..........end");
    }

    public static class Runable01 implements Runnable{
        @Override
        public void run() {
            System.out.println("当前线程名称..........." + Thread.currentThread().getId());
            int i = 10/2;
            System.out.println("当前线程运行结果..........." + i);
        }
    }

}

方法三：实现Callable接口，有返回结果

import java.util.concurrent.Callable;
import java.util.concurrent.ExecutionException;
import java.util.concurrent.FutureTask;

public class ThreadTestThr {

    public static void main(String args[]) throws ExecutionException, InterruptedException {
        System.out.println("main...........start");

        FutureTask<Integer> futureTask = new FutureTask<Integer>(new Callable01());
        new Thread(futureTask).start();
        Integer i = futureTask.get();

        System.out.println("main...........end   "+ i);
    }

    public static class Callable01 implements Callable<Integer> {
        @Override
        public Integer call() throws Exception {
            System.out.println("当前线程名称..........." + Thread.currentThread().getId());
            int i = 10/2;
            System.out.println("当前线程运行结果..........." + i);
            return i;
        }
    }

}

方法四：使用线程池，该方法中存在着多种方式

方式A://能获取到上一步的结果 //这里可以处理上面方法完成返回的结果 //不能返回结果

import java.util.concurrent.CompletableFuture;
import java.util.concurrent.ExecutionException;
import java.util.concurrent.ExecutorService;
import java.util.concurrent.Executors;

/**
 * @author 李庆伟
 * @date 2020/12/30 15:12
 */
public class ThreadFour {
    public static ExecutorService executor = Executors.newFixedThreadPool(10);

    public static void main(String args[]) throws ExecutionException, InterruptedException {
        System.out.println("main...........start");

        CompletableFuture<Integer> future = CompletableFuture.supplyAsync(()->{
            System.out.println("当前线程名称..........." + Thread.currentThread().getId());
            int i = 10/5;
            //int i = 10/0;
            System.out.println("当前线程运行结果..........." + i);
            return i;
        },executor).whenComplete((res,exception)->{
            //能获取到上一步的结果
            //这里可以处理上面方法完成返回的结果
            //不能返回结果
            System.out.println("完成异步任务......res为" + res + ", 异常是 "+ exception);
        });
        Integer i = future.get();//得到的是原来的结果
        System.out.println("main...........end......" + i);
    }
}

方式B://能获取到上一步的结果 //这里可以处理上面方法完成返回的结果 //返回结果

import java.util.concurrent.CompletableFuture;
import java.util.concurrent.ExecutionException;
import java.util.concurrent.ExecutorService;
import java.util.concurrent.Executors;

/**
 * @author 李庆伟
 * @date 2020/12/30 15:12
 */
public class ThreadFive {
    public static ExecutorService executor = Executors.newFixedThreadPool(10);

    public static void main(String args[]) throws ExecutionException, InterruptedException {
        System.out.println("main...........start");

        CompletableFuture<Integer> future = CompletableFuture.supplyAsync(()->{
            System.out.println("当前线程名称..........." + Thread.currentThread().getId());
            int i = 10/10;
            //int i = 10/0;
            System.out.println("当前线程运行结果..........." + i);
            return i;
        },executor).handle((res,exception)->{
            //能获取到上一步的结果
            //这里可以处理上面方法完成返回的结果
            //有返回结果
            System.out.println("完成异步任务......res为" + res + ", 异常是 "+ exception);
            if(res == 1){
                return 10;
            } else {
                return res;
            }
        });
        Integer i = future.get();//得到的是处理后的结果
        System.out.println("main...........end......" + i);
    }
}

方式C://不能获取到上一步的结果

import java.util.concurrent.CompletableFuture;
import java.util.concurrent.ExecutorService;
import java.util.concurrent.Executors;

/**
 * @author 李庆伟
 * @date 2020/12/30 15:12
 */
public class ThreadSix {
    public static ExecutorService executor = Executors.newFixedThreadPool(10);

    public static void main(String args[]) {
        System.out.println("main...........start");
        CompletableFuture<Void> future = CompletableFuture.supplyAsync(()->{
            System.out.println("当前线程名称..........." + Thread.currentThread().getId());
            int i = 10/4;
            System.out.println("当前线程运行结果..........." + i);
            return i;
        },executor).thenRunAsync(()->{
            //不能获取到上一步的结果
            System.out.println("完成异步任务......");
        },executor);
        System.out.println("main...........end......");
    }
}

方式D://能获取到上一步的结果//没有返回值

 

import java.util.concurrent.CompletableFuture;
import java.util.concurrent.ExecutorService;
import java.util.concurrent.Executors;

/**
 * @author 李庆伟
 * @date 2020/12/30 15:12
 */
public class ThreadSeven {
    public static ExecutorService executor = Executors.newFixedThreadPool(10);

    public static void main(String args[]) {
        System.out.println("main...........start");
        CompletableFuture<Void> future = CompletableFuture.supplyAsync(()->{
            System.out.println("当前线程名称..........." + Thread.currentThread().getId());
            int i = 10/3;
            System.out.println("当前线程运行结果..........." + i);
            return i;
        },executor).thenAcceptAsync((res)->{
            //能获取到上一步的结果//没有返回值
            System.out.println("完成异步任务......" + res);
        },executor);
        System.out.println("main...........end......");
    }

}

方式E://能获取到上一步的结果//有返回值

import java.util.concurrent.CompletableFuture;
import java.util.concurrent.ExecutionException;
import java.util.concurrent.ExecutorService;
import java.util.concurrent.Executors;

/**
 * @author 李庆伟
 * @date 2020/12/30 15:12
 */
public class ThreadEight {
    public static ExecutorService executor = Executors.newFixedThreadPool(10);

    public static void main(String args[]) throws ExecutionException, InterruptedException {
        System.out.println("main...........start");
        CompletableFuture<String> future = CompletableFuture.supplyAsync(()->{
            System.out.println("当前线程名称..........." + Thread.currentThread().getId());
            int i = 10/3;
            System.out.println("当前线程运行结果..........." + i);
            return i+"";
        },executor).thenApplyAsync((res)->{
            //能获取到上一步的结果//有返回值
            System.out.println("完成异步任务......" + res);
            return res + " hello";
        },executor);
        String str = future.get();
        System.out.println("main...........end......" + str);
    }

}

方式F://综合Demo

import java.util.concurrent.CompletableFuture;
import java.util.concurrent.ExecutionException;
import java.util.concurrent.ExecutorService;
import java.util.concurrent.Executors;

/**
 * @author 李庆伟
 * @date 2020/12/30 15:12
 */
public class ThreadDemo {
    public static ExecutorService executor = Executors.newFixedThreadPool(10);

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

        String str = "hello";

        //异步1，  2和3需要依赖1  4独立
        CompletableFuture<String> futureOne = CompletableFuture.supplyAsync(()->{
            String one = str + " world + futureOne";
            return one;
        },executor);

        CompletableFuture<String> futureTwo = futureOne.thenApplyAsync((res)->{
            String two = res + " + futureTwo";
            return two;
        },executor);

        CompletableFuture<String> futureThr = futureOne.thenApplyAsync((res)->{
            String thr = res + " + futureThr";
            return thr;
        },executor);

        CompletableFuture<String> futureFou = CompletableFuture.supplyAsync(()->{
            String fou = str + " + futureFou";
            return fou;
        },executor);


        // 等到所有任务都完成
        CompletableFuture.allOf(futureOne, futureTwo, futureThr, futureFou).get();

        System.out.println(futureOne.get());
        System.out.println(futureTwo.get());
        System.out.println(futureThr.get());
        System.out.println(futureFou.get());
    }

}

记录一点。。。。。。。。。。

 

 

 

 

本文地址：https://blog.csdn.net/liqingwei168/article/details/111981159