多线程——(Callable)(Future)(CompletableFuture)

Java使用消息队列还是直接使用线程池ExecutorService异步处理？
AsyncTool框架简介和分析实现

开启线程的方式

JAVA开启线程的三种方式
除了以上三种还可以通过线程池开启

Callable与Future(带返回值的异步线程)

Callable接口详解

CompletableFuture(带返回值升级版)

当几个异步任务相互关联时就要使用到异步任务编排

学习 CompletableFuture 进阶之前先掌握两种线程池
异步编程利器：CompletableFuture详解 ｜Java 开发实战
CompletableFuture异步和线程池讲解
springboot线程池和CompletableFuture配合使用

当几个异步任务相互关联时就要使用到异步任务编排
详情可参考b站视频
CompletableFuture入门

supplyAsync(开启异步任务，带返回值)

package com.example.shiyan.thread;

import java.util.concurrent.CompletableFuture;

public class CompletableFutureDemo1 {
    public static void main(String[] args) throws InterruptedException {
        long l = System.currentTimeMillis();
        System.out.println("小白进入餐厅");
        System.out.println("小白点餐");
        CompletableFuture<String> cf1 = CompletableFuture.supplyAsync(() -> {
            try {
                System.out.println("厨师做饭");
                Thread.sleep(2000);

            } catch (InterruptedException e) {
                e.printStackTrace();
            }
            return "饭做好了";
        });
        System.out.println("小白打游戏");
        System.out.println(String.format("%s ,小白开吃", cf1.join()));
        System.out.println(System.currentTimeMillis() - l);
    }
}

thenCompose(任务A然后紧接着任务B)

package com.example.shiyan.thread;

import java.util.concurrent.CompletableFuture;

public class CompletableFutureDemo2 {
    public static void main(String[] args) throws InterruptedException {
        long l = System.currentTimeMillis();
        System.out.println("小白进入餐厅");
        System.out.println("小白点餐");
        CompletableFuture<String> cf1 = CompletableFuture.supplyAsync(() -> {
            try {
                Thread.sleep(2000);
                System.out.println("厨师炒菜");
            } catch (InterruptedException e) {
                e.printStackTrace();
            }
            return "番茄炒蛋";
        }).thenCompose(dish -> CompletableFuture.supplyAsync(() -> {
                    try {
                        Thread.sleep(2000);
                        System.out.println("服务员打饭");
                    } catch (InterruptedException e) {
                        e.printStackTrace();
                    }
                 return dish+"+米饭";
        }));
        System.out.println("小白打游戏");
        System.out.println(String.format("%s 好了,小白开吃", cf1.join()));
        System.out.println(System.currentTimeMillis() - l);
    }
}

thenCombine(任务a，任务b都完成后接上任务c)

import java.util.concurrent.CompletableFuture;

public class CompletableFutureDemo3 {
    public static void main(String[] args) throws InterruptedException {
        long l = System.currentTimeMillis();
        System.out.println("小白进入餐厅");
        System.out.println("小白点餐");
        CompletableFuture<String> cf1 = CompletableFuture.supplyAsync(() -> {
            try {
                Thread.sleep(2000);
                System.out.println("厨师炒菜");
            } catch (InterruptedException e) {
                e.printStackTrace();
            }
            return "番茄炒蛋";
        }).thenCombine(CompletableFuture.supplyAsync(()->{
            try {
                Thread.sleep(2000);
                System.out.println("服务员煮饭");
            } catch (InterruptedException e) {
                e.printStackTrace();
            }
            return "米饭";
        }),(dish,rice)->{
            try {
                Thread.sleep(2000);
                System.out.println("服务员打饭");
            } catch (InterruptedException e) {
                e.printStackTrace();
            }
            return String.format("%s+%s 好了",dish,rice);
        });
        System.out.println("小白打游戏");
        System.out.println(String.format("%s ,小白开吃", cf1.join()));
        System.out.println(System.currentTimeMillis() - l);
    }
}