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melin/TestCompletableFuture.java

Created September 24, 2014 13:50
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  1. melin created this gist Sep 24, 2014.
    134 changes: 134 additions & 0 deletions TestCompletableFuture.java
    View file
    Original file line number Diff line number Diff line change
    @@ -0,0 +1,134 @@
    package com.github.melin.concurrnt.future;

    import java.util.concurrent.CompletableFuture;
    import java.util.concurrent.Executor;
    import java.util.concurrent.Executors;
    import java.util.concurrent.TimeUnit;
    import java.util.function.BiFunction;
    import java.util.function.Consumer;
    import java.util.function.Function;
    import java.util.function.Supplier;

    import org.junit.Test;

    public class TestCompletableFuture {

    /**
    * supplyAsync 创建future, 并获取返回返回值，默认使用ForkJoinPool.commonPool() 线程池
    * runAsync 创建future, 无返回值，默认使用ForkJoinPool.commonPool() 线程池
    *
    * get() 获取执行返回值，如果没有执行完成，一直等待执行
    * get(timeout, unit) 获取执行返回值，如果没有执行完成，阻塞等待，直至超时时间。
    * getNow(default) 如果Future没有运行完成返回值，则返回默认值
    * complete(default) 如果没有执行完成，设置get方法的返回值，中断get方法等待。
    * completeExceptionally(throw) 如果没有执行完成，get方法抛出此异常
    */
    //@Test
    public void test0() {
    Executor executor = Executors.newFixedThreadPool(2);
    final CompletableFuture<String> future = CompletableFuture.supplyAsync(
    new Supplier<String>() {
    @Override
    public String get() {
    try {
    TimeUnit.SECONDS.sleep(2);
    } catch (InterruptedException e) {
    e.printStackTrace();
    }
    return "42";
    }
    }, executor);
    /*future.complete("10");
    try {
    System.out.println(future.get(2, TimeUnit.SECONDS));
    } catch (Exception e) {
    e.printStackTrace();
    }*/
    boolean flag = future.completeExceptionally(new RuntimeException("ceshi"));
    System.out.println(flag);
    try {
    System.out.println(future.getNow("12"));
    } catch(RuntimeException e) {
    System.out.println(e.getMessage());
    }
    }

    /**
    * thenApply、thenApplyAsync : 转换叠加处理多个future
    * thenAccept、thenAcceptAsync : future 执行完成以后调用
    * thenRun、thenRunAsync : 与thenAccept类似，只是不能获取future的返回值。
    *
    */
    //@Test
    public void test1() {
    CompletableFuture<String> future = CompletableFuture.supplyAsync(new Supplier<String>() {

    @Override
    public String get() {
    System.out.println(Thread.currentThread().getName());
    return "42";
    }

    });
    CompletableFuture<Integer> future1 = future.thenApply(new Function<String, Integer>() {

    @Override
    public Integer apply(String t) {
    System.out.println(Thread.currentThread().getName());
    return Integer.valueOf(t);
    }
    });

    future1.thenAcceptAsync(new Consumer<Integer>() {

    @Override
    public void accept(Integer t) {
    try {
    TimeUnit.SECONDS.sleep(1);
    } catch (InterruptedException e) {
    e.printStackTrace();
    }
    System.out.println(Thread.currentThread().getName());
    System.out.println(t);
    }
    });
    System.out.println("finished......");
    }

    /**
    * exceptionally : 当future执行出现异常时，被调用
    * handle、handleAsync ： 不管执行成功还是失败，handle都会被执行，如果执行成功，Throwable值为null
    */
    @Test
    public void test2() throws Exception {
    CompletableFuture<String> future = CompletableFuture.supplyAsync(new Supplier<String>() {

    @Override
    public String get() {
    return "10";
    //throw new RuntimeException("test exception");
    }

    })/*.exceptionally(new Function<Throwable, String>() {
    @Override
    public String apply(Throwable t) {
    return "-1";
    }
    })*/.handleAsync(new BiFunction<String, Throwable, String>() {

    @Override
    public String apply(String t, Throwable e) {
    System.out.println(Thread.currentThread().getName());
    if(e == null)
    return "100";
    else {
    System.out.println(e.getMessage());
    return "-1";
    }
    }
    });
    System.out.println(future.get());
    System.out.println("finished......");
    }
    }