CompletableFuture 類詳解

1.runAsync、supplyAsync、get、join：開啟異步任務(wù)，獲取結(jié)果。

// runAsync：沒有返回值
CompletableFuture<Void> future = CompletableFuture.runAsync(() -> {
    System.out.println("Hello");
});

// supplyAsync：有返回值
CompletableFuture<String> future2 = CompletableFuture.supplyAsync(() -> {
    return "World";
});

// join：不強(qiáng)制 try，不能設(shè)置超時(shí)時(shí)間，不能響應(yīng)線程中斷
System.out.println(future2.join());// World

// get：必須 try 或 添加異常簽名，可以設(shè)置超時(shí)時(shí)間，可以響應(yīng)線程中斷
try {
    System.out.println(future2.get());// World
} catch (Exception ignored) {
}

2.thenApply、thenAccept、thenRun：處理任務(wù)的結(jié)果。

CompletableFuture<String> future = CompletableFuture.supplyAsync(() -> "Hello");

// thenRun：在任務(wù)完成后執(zhí)行
CompletableFuture<Void> future2 = future.thenRun(() -> System.out.println("完成了"));

// thenAccept：接收任務(wù)的結(jié)果
CompletableFuture<Void> future3 = future.thenAccept(s -> System.out.println(s + " World"));// Hello World

// thenApply：接收任務(wù)的結(jié)果，返回一個(gè)新值
CompletableFuture<String> future4 = future.thenApply(s -> s + " World");

System.out.println("------");
System.out.println(future2.join());// null
System.out.println(future3.join());// null
System.out.println(future4.join());// Hello World

3.thenCombine、thenAcceptBoth、runAfterBoth：處理兩個(gè)任務(wù)的結(jié)果。

CompletableFuture<String> future1 = CompletableFuture.supplyAsync(() -> "Hello");
CompletableFuture<String> future2 = CompletableFuture.supplyAsync(() -> "World");

// runAfterBoth：在兩個(gè)任務(wù)完成后執(zhí)行
CompletableFuture<Void> combinedFuture = future1.runAfterBoth(future2, () -> System.out.println("完成了"));

// thenAcceptBoth：接收兩個(gè)任務(wù)的結(jié)果
CompletableFuture<Void> combinedFuture2 = future1.thenAcceptBoth(future2, (s1, s2) -> System.out.println(s1 + " " + s2));// Hello World

// thenCombine：接收兩個(gè)任務(wù)的結(jié)果，返回一個(gè)新值
CompletableFuture<String> combinedFuture3 = future1.thenCombine(future2, (s1, s2) -> s1 + " " + s2);

System.out.println("------");
System.out.println(combinedFuture.join());// null
System.out.println(combinedFuture2.join());// null
System.out.println(combinedFuture3.join());// Hello World

4.applyToEither、acceptEither、runAfterEither：處理兩個(gè)任務(wù)任一的結(jié)果。

CompletableFuture<String> future1 = CompletableFuture.supplyAsync(() -> "Hello");
CompletableFuture<String> future2 = CompletableFuture.supplyAsync(() -> "World");

// runAfterBoth：在兩個(gè)任務(wù)任一完成后執(zhí)行
CompletableFuture<Void> combinedFuture = future1.runAfterEither(future2, () -> System.out.println("完成了"));

// thenAcceptBoth：接收兩個(gè)任務(wù)的任一結(jié)果
CompletableFuture<Void> combinedFuture2 = future1.acceptEither(future2, (s) -> System.out.println(s));// Hello 或 World

// thenCombine：接收兩個(gè)任務(wù)的任一結(jié)果，返回一個(gè)新值
CompletableFuture<String> combinedFuture3 = future1.applyToEither(future2, (s) -> s);

System.out.println("------");
System.out.println(combinedFuture.join());// null
System.out.println(combinedFuture2.join());// null
System.out.println(combinedFuture3.join());// Hello 或 World

5.exceptionally、whenComplete、handle：處理異常。

CompletableFuture<String> future = CompletableFuture.supplyAsync(() -> {
    if(Math.random() > 0.5){
        throw new RuntimeException();
    }
    return "Hello";
});

// exceptionally：處理異常
CompletableFuture<String> future2 = future.exceptionally(e -> {
    System.out.println("異常信息: " + e.getMessage());// 異常信息: java.lang.RuntimeException
    return null;
});

// whenComplete：處理異常和結(jié)果
CompletableFuture<String> future3 = future.whenComplete((s, e) -> {
    if (e != null) {
        System.out.println("異常信息: " + e.getMessage());
    } else {
        System.out.println(s);
    }
});

// handle：處理異常和結(jié)果，返回新結(jié)果
CompletableFuture<String> future4 = future.handle((s, e) -> {
    if (s != null) {
        return s + " World";
    } else {
        return "異常信息: " + e.getMessage();
    }
});

System.out.println("------");
System.out.println(future2.join());// Hello 或 null
System.out.println(future4.join());// Hello World 或 異常信息: java.lang.RuntimeException
System.out.println(future3.join());// Hello World 或 直接報(bào)錯(cuò)退出

6.allOf、anyOf：等待多個(gè) 或任一任務(wù)的完成。

String[] arr = new String[2];
CompletableFuture<String> future1 = CompletableFuture.supplyAsync(() -> {
    arr[0] = "Hello";
    return "Hello";
});
CompletableFuture<String> future2 = CompletableFuture.supplyAsync(() -> {
    arr[1] = "World";
    return "World";
});

// anyOf：等待任一任務(wù)完成
CompletableFuture<Object> future3 = CompletableFuture.anyOf(future1, future2);
System.out.println(arr[0] + " " + arr[1]);// Hello World 或 Hello null 或 null World

// allOf：等待所有任務(wù)全部完成
CompletableFuture<Void> future4 = CompletableFuture.allOf(future1, future2);
System.out.println(arr[0] + " " + arr[1]);// Hello World

System.out.println("------");
System.out.println(future3.join());// Hello 或 World
System.out.println(future4.join());// null

posted @ 2024-04-28 20:07 Yfeil 閱讀(140) 評(píng)論(0) 收藏舉報(bào)

刷新頁(yè)面返回頂部