algorithms/src/test/java/CompletableFutureTest.java at master · verifyCode/algorithms · GitHub

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import java.util.concurrent.CompletableFuture;

import java.util.concurrent.CompletionException;

import java.util.concurrent.ExecutorService;

import java.util.concurrent.Executors;

import java.util.concurrent.ThreadFactory;

import java.util.concurrent.TimeUnit;

/**

* @author xjn

* @since 2020-05-22

public class CompletableFutureTest {

//1.新建一个完成的CompletableFuture

static void completedFutureExample() throws Exception {

CompletableFuture<String> cf = CompletableFuture.completedFuture("message");

if (cf.isDone()) {

System.out.println(cf.get());

}

//2.运行一个简单的异步stage

static void runAsyncExample() {

CompletableFuture<Void> completableFuture = CompletableFuture.runAsync(() -> {

sleep(1000);

});

System.out.println(completableFuture.isDone());

}

//3.将方法作用于前一个Stage

static void thenApplyExample() throws Exception {

CompletableFuture<String> message = CompletableFuture.completedFuture("message").thenApply(s -> s.toUpperCase());

if (message.isDone()) {

System.out.println(message.get());

}

//4.异步的的将方法作用于前一个Stage

static void thenApplyAsyncExample() {

CompletableFuture completableFuture = CompletableFuture.completedFuture("message")

.thenApplyAsync(s -> {

sleep(1000);

return s.toLowerCase();

});

System.out.println(completableFuture.join());

}

static ExecutorService executor = Executors.newFixedThreadPool(3, new ThreadFactory() {

int count = 1;

@Override

public Thread newThread(Runnable runnable) {

return new Thread(runnable, "custom-executor-" + count++);

}

});

//使用一个自定义的Executor来异步执行该方法

static void thenApplyAsyncWithExecutorExample() {

CompletableFuture cf = CompletableFuture.completedFuture("message")

.thenApplyAsync(s -> {

sleep(1000);

return s += "123213";

}, executor);

System.out.println(cf.join());

}

//6.消费(Consume)前一个Stage的结果

static void thenAcceptExample() throws Exception {

StringBuilder result = new StringBuilder();

CompletableFuture<Void> completableFuture = CompletableFuture.completedFuture("thenAccept message")

.thenAccept(s -> result.append(s));

System.out.println(completableFuture.get());

System.out.println(result.toString());

}

//7.异步执行Comsume

static void thenAcceptAsyncExample() {

StringBuilder result = new StringBuilder();

CompletableFuture cf = CompletableFuture.completedFuture("thenAcceptAsync message")

.thenAcceptAsync(s -> result.append(s));

cf.join();

System.out.println(result.toString());

}

//8.计算出现异常时

//TODO

static void completeExceptionallyExample() throws Exception {

// CompletableFuture cf = CompletableFuture.completedFuture("message")

// .thenApplyAsync(String::toUpperCase,

// CompletableFuture.delayedExecutor(1, TimeUnit.SECONDS));

// CompletableFuture exceptionHandler =

// cf.handle((s, th) -> { return (th != null) ? "message upon cancel" : ""; });

}

//9.取消计算

static void cancelExample() {

}

//10.将Function作用于两个已完成Stage的结果之一

static void applyToEitherExample() {

String original = "Message";

CompletableFuture<String> cf1 = CompletableFuture.completedFuture(original)

.thenApplyAsync(s -> {

sleep(100);

return s.toLowerCase() + "1";

});

CompletableFuture cf2 = cf1.applyToEither(

CompletableFuture.completedFuture(original).thenApplyAsync(s -> {

sleep(100);

return s.toUpperCase();

}),

s -> s + " from applyToEither");

System.out.println(cf2.join());

}

//11.消费两个阶段的任意一个结果

static void acceptEitherExample() {

String original = "Message";

StringBuilder result = new StringBuilder();

}

//12.在两个阶段都完成后运行Runnable

static void runAfterBothExample() {

}

public static void main(String[] args) throws Exception {

// completedFutureExample();

// runAsyncExample();

// thenApplyExample();

// thenApplyAsyncExample();

// thenApplyAsyncWithExecutorExample();

// thenAcceptExample();

// completeExceptionallyExample();

// applyToEitherExample();

runAfterBothExample();

}

public static void sleep(int time) {

try {

Thread.sleep(time);

} catch (Exception e) {

}

algorithms/src/test/java/CompletableFutureTest.java at master · verifyCode/algorithms · GitHub

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