【异步并行案例】CompletableFuture

 【场景】当一个接口需要调用多个外部接口的时候，自己的接口会随着调用外部接口的耗时增加而增加，如果多个外部接口并行，那么自己接口至少需要多个外部接口的总耗时才能响应，如果多个外部接口异步请求，便可大大节省请求外部接口所耗时。具体请看下图：

 以下简单的写了下代码，类似的实现方式：

//引用类
import java.util.HashMap;
import java.util.Map;
import java.util.concurrent.CompletableFuture;
import java.util.concurrent.ExecutionException;
import java.util.concurrent.ExecutorService;
import java.util.concurrent.Executors;
import java.util.concurrent.TimeUnit;   



//此处忽略class



    private ExecutorService executor = Executors.newFixedThreadPool(3);

    @Test
    void test01() throws ExecutionException, InterruptedException {
        final UserInfo userInfo = new UserInfo();
        CompletableFuture userFuture = CompletableFuture.supplyAsync(() -> {
            userInfo.setUserId(1L);
            try {
                TimeUnit.SECONDS.sleep(5);
                System.out.println("1-"+System.currentTimeMillis());
            } catch (InterruptedException e) {
                e.printStackTrace();
            }
            return Boolean.TRUE;
        }, executor);

        CompletableFuture bonusFuture = CompletableFuture.supplyAsync(() -> {
            userInfo.setHeadImg("sasdasdsa");
            try {
                TimeUnit.SECONDS.sleep(3);
                System.out.println("2-"+System.currentTimeMillis());
            } catch (InterruptedException e) {
                e.printStackTrace();
            }
            return Boolean.TRUE;
        }, executor);

        CompletableFuture growthFuture = CompletableFuture.supplyAsync(() -> {
            userInfo.setBirthday("2022");
            try {
                TimeUnit.SECONDS.sleep(1);
                System.out.println("3-"+System.currentTimeMillis());
            } catch (InterruptedException e) {
                e.printStackTrace();
            }
            return Boolean.TRUE;
        }, executor);

        CompletableFuture.allOf(userFuture, bonusFuture, growthFuture).join();

        System.out.println("4-"+System.currentTimeMillis());
        userFuture.get();
        bonusFuture.get();
        growthFuture.get();
        System.out.println("5-"+System.currentTimeMillis());
        System.out.println(JSONObject.toJSonString(userInfo));
    }