本篇文章为你整理了CompletableFuture的入门(completablefuture get)的详细内容,包含有completable future completablefuture get completablefuture allof completablefuture用法 CompletableFuture的入门,希望能帮助你了解 CompletableFuture的入门。
runAsync接受一个Runable的实现,无返回值
CompletableFuture.runAsync(()- System.out.println("无返回结果的运行"));
supplyAsync接受一个Supplier的实现,有返回值
CompletableFuture Integer completableFuture = CompletableFuture.supplyAsync(() - {
System.out.println("有返回结果的运行");
return 1;
获取结果的get和join
都是堵塞,直到返回结果
get方法抛出是经过处理的异常,ExecutionException或**InterruptedException **,需要用户手动捕获
try {
System.out.println(CompletableFuture.supplyAsync(() - {
System.out.println("有返回结果的运行");
return 1;
}).get());
} catch (InterruptedException e) {
e.printStackTrace();
} catch (ExecutionException e) {
e.printStackTrace();
join方法抛出的就不用捕获,是经过包装的**CompletionException **或 CancellationException
System.out.println(CompletableFuture.supplyAsync(() - {
try {
TimeUnit.MILLISECONDS.sleep(1000);
} catch (InterruptedException e) {
e.printStackTrace();
System.out.println("有返回结果的运行");
return 1;
}).join());
获取结果的get\join\getNow
get():一直等待
get(timeout,unit):等待,除非超时
getNow(valueIfAbsent):计算完返回计算的结果,未计算完返回默认的结果
CompletableFuture Integer completableFuture = CompletableFuture.supplyAsync(() - {
try {
TimeUnit.SECONDS.sleep(1);
} catch (InterruptedException e) {
e.printStackTrace();
return 1;
System.out.println("立即获取:"+completableFuture.getNow(9999));
try {
TimeUnit.SECONDS.sleep(2);
System.out.println("doing");
} catch (InterruptedException e) {
e.printStackTrace();
System.out.println("等一会获取:"+completableFuture.getNow(9999));
join() 同get()
thenApply\handle
执行完前面的,前面返回的结果返回,然后传给后面再,执行完后面任务,一步一步来。
CompletableFuture Integer completableFuture = CompletableFuture.supplyAsync(() - {
System.out.println("step 1");
return 1;
}).thenApply(a - {
System.out.println("step 2");
return a + 2;
}).thenApply(a - {
System.out.println("step 3");
return a + 3;
System.out.println(completableFuture.get());
执行结果:
CompletableFuture Integer completableFuture = CompletableFuture.supplyAsync(() - {
System.out.println("step 1");
int a=1/0;
return 1;
}).handle((a,b) - {
System.out.println("step 2");
if (b!=null) {
System.out.println(b.getMessage());
return 0;
return a + 2;
}).handle((a,b) - {
System.out.println("step 3");
if (b!=null) {
System.out.println(b.getMessage());
return 0;
return a + 3;
System.out.println(completableFuture.get());
执行结果:
thenApply和handle的区别:
thenApply执行的时候,有异常的则整个执行链会中断,直接抛出异常。
handle有异常也可以往下一步走,根据带的异常参数可以进一步处理
thenAccept
接收前面任务的返回结果,当前节点处理,并不返回结果。
CompletableFuture.supplyAsync(()- {
System.out.println("step 1");
return 10;
}).thenAccept(a- {
System.out.println("res "+a);
applyToEither
在多个任务段同时执行时,哪个任务段用时最少,就返回哪个
CompletableFuture Integer completableFuture = CompletableFuture.supplyAsync(() - {
System.out.println("step 1");
try {
TimeUnit.SECONDS.sleep(1);
} catch (InterruptedException e) {
e.printStackTrace();
return 1;
}).applyToEither(CompletableFuture.supplyAsync(() - {
System.out.println("step 2");
try {
TimeUnit.SECONDS.sleep(2);
} catch (InterruptedException e) {
e.printStackTrace();
return 2;
}), a - {
return a;
System.out.println(completableFuture.get());
执行结果:
thenCombine
合并多个任务段的返回结果
CompletableFuture Integer completableFuture = CompletableFuture.supplyAsync(() - {
System.out.println("step 1");
return IntStream.range(1, 11).sum();
}).thenCombine(CompletableFuture.supplyAsync(() - {
System.out.println("step 2");
return IntStream.range(11, 21).sum();
}), (a, b) - a + b)
.thenCombine(CompletableFuture.supplyAsync(() - {
System.out.println("step 3");
return IntStream.range(21, 31).sum();
}), (a, b) - a + b);
System.out.println(completableFuture.get());
以上就是CompletableFuture的入门(completablefuture get)的详细内容,想要了解更多 CompletableFuture的入门的内容,请持续关注盛行IT软件开发工作室。
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