CompletableFuture 测试类

package com.example.apidemo.completableFutrue;

import java.util.Random;
import java.util.concurrent.CompletableFuture;
import java.util.concurrent.ExecutionException;
import java.util.concurrent.TimeUnit;
import java.util.function.BiConsumer;
import java.util.function.BiFunction;
import java.util.function.Function;
import java.util.function.Supplier;

/**
 * @Author Tim
 * @Date 2021/10/25 14:18
 */
public class TestComplete {

    //runAsync方法不支持返回值。
    //supplyAsync可以支持返回值。
    public static void main1(String[] args) throws Exception {

        CompletableFuture<String> future = CompletableFuture.supplyAsync(() -> {
            try {
                System.out.println("run end1 ..." + Thread.currentThread().getName());
            } catch (Exception e) {
                e.printStackTrace();
            }
            System.out.println("run end2 ..." + Thread.currentThread().getName());
            return "返回值:" + System.currentTimeMillis();
        });
        System.out.println("run end3 ...:" + future.get() + "/" + Thread.currentThread().getName());
    }


    //当CompletableFuture的计算结果完成的回调方法
    public static void main2(String[] args) throws Exception {

        CompletableFuture<String> future = CompletableFuture.supplyAsync(() -> {
            try {
                System.out.println("run ..." + Thread.currentThread().getName());
            } catch (Exception e) {
            }
            System.out.println("run end ..." + Thread.currentThread().getName());
            return "1234567";
        }).whenComplete((String v, Throwable t) -> {
            System.out.println("run end2 ..." + v + "/" + Thread.currentThread().getName() + "/" + t);
        });
        // v是有返回值的回调的结果，t 是线程... 可省略写法：whenComplete((v, t) -> {});
    }


    //thenApply 方法 : 当一个线程依赖另一个线程时，可以使用 thenApply 方法来把这两个线程串行化。
    //.thenApply(Function<? super T, ? extends U> fn) T是上一个任务返回结果的类型。U：当前任务的返回值类型
    public static void main3(String[] args) throws Exception {
        CompletableFuture<Long> future = CompletableFuture.supplyAsync(new Supplier<Long>() {
            @Override
            public Long get() {
                long result = new Random().nextInt(100);
                System.out.println("result1 ="+result);
                return result;
            }
        }).thenApply(new Function<Long, Long>() {
            @Override
            public Long apply(Long t) {
                long result = t*5;
                System.out.println("result2 ="+result);
                return result;
            }
        });
        long result = future.get();
        System.out.println("result--------:" + result);
    }


    //handle 是执行任务（包括出现异常）完成时对结果的处理。 而thenApply 方法，如果上个任务出现错误，则不会执行 thenApply 方法。
    public static void main4(String[] args) throws Exception {
        CompletableFuture<Integer> future = CompletableFuture.supplyAsync(new Supplier<Integer>() {
            @Override
            public Integer get() {
                return new Random().nextInt(10);
            }
        }).handle(new BiFunction<Integer, Throwable, Integer>() {
            @Override
            public Integer apply(Integer param, Throwable throwable) {
                int result = 1;
                if (throwable == null){
                    result = param * 2;
                    System.out.println("apply: ==== " + param);
                } else {
                    System.out.println("error: ==== " + throwable.getMessage());
                }
                return result;
            }
        });
        System.out.println("result--------:" + future.get());
    }


    //thenAccept 接收任务的处理结果，并消费处理，无返回结果。没有后续的输出操作, 所以future.get() 是null
    public static void main5(String[] args) throws ExecutionException, InterruptedException {
        CompletableFuture<Void> future = CompletableFuture.supplyAsync(new Supplier<Integer>() {
            @Override
            public Integer get() {
                return new Random().nextInt(10);
            }
        }).thenAccept(integer -> {
            System.out.println("integer====" + integer);
        });
        System.out.println("result--------:" + future.get());
    }


    // thenRun: 该方法同 thenAccept 方法类似。不同的是上个任务处理完成后，并不会把计算的结果传给 thenRun 方法。
    // 只是处理玩任务后，执行 thenAccept 的后续操作
    public static void main6(String[] args) throws ExecutionException, InterruptedException {
        CompletableFuture<Void> future = CompletableFuture.supplyAsync(new Supplier<Integer>() {
            @Override
            public Integer get() {
                return new Random().nextInt(10);
            }
        }).thenRun(() -> {
            System.out.println("thenRun ..." + 1);
        });
        System.out.println("result--------:" + future.get());
    }


    //thenCombine 合并任务
    public static void main(String[] args) throws Exception {
        CompletableFuture<String> future1 = CompletableFuture.supplyAsync(new Supplier<String>() {
            @Override
            public String get() {
                return "zhangshan";
            }
        });
        CompletableFuture<String> future2 = CompletableFuture.supplyAsync(new Supplier<String>() {
            @Override
            public String get() {
                return "lisi";
            }
        });
        CompletableFuture<String> result = future1.thenCombine(future2, new BiFunction<String, String, String>() {
            @Override
            public String apply(String t, String u) {
                return t + "===" + u;
            }
        });
        System.out.println("result--------:" + result.get());
    }

}