詳見：http://blog.yemou.net/article/query/info/tytfjhfascvhzxcyt125

毫無疑問 Runnable會進(jìn)行異步執(zhí)行，此處不多說，主要說明Callable的使用，看實例：

1、

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public?class?ThreadTest?{ ????public?static?void?main(String[]?args)?throws?InterruptedException,?ExecutionException?{ ????????ExecutorService?executor?=?Executors.newFixedThreadPool(4); ????????MyTread?m1?=?new?MyTread(); ????????Future?f?=?executor.submit(m1); ????????//?System.out.println(f.get()); ????????executor.shutdown(); ????????System.out.println("主線程執(zhí)行完了"); ????} ?? }

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?? class?MyTread?implements?Callable<String>?{ ????@Override ????public?String?call()?{ ????????try?{ ????????????System.out.println("線程調(diào)度："?+?Thread.currentThread()); ????????????TimeUnit.SECONDS.sleep(3); ????????}?catch?(InterruptedException?e)?{ ????????????e.printStackTrace(); ????????} ????????return?"123"; ????} }

此程序雖然獲取了call方法的返回值，但是沒有做處理，所以主線程main和m1同時執(zhí)行，執(zhí)行結(jié)果如下：

主線程執(zhí)行完了

線程調(diào)度：Thread[pool-1-thread-1,5,main]

?

2、

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public?class?ThreadTest?{ ????public?static?void?main(String[]?args)?throws?InterruptedException,?ExecutionException?{ ????????ExecutorService?executor?=?Executors.newFixedThreadPool(4); ????????MyTread?m1?=?new?MyTread(); ????????Future?f?=?executor.submit(m1); ????????System.out.println(f.get());?//?進(jìn)行了輸出 ????????executor.shutdown(); ????????System.out.println("主線程執(zhí)行完了"); ????} ?? }

?

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class?MyTread?implements?Callable<String>?{ ????@Override ????public?String?call()?{ ????????try?{ ????????????System.out.println("線程調(diào)度："?+?Thread.currentThread()); ????????????TimeUnit.SECONDS.sleep(3); ????????}?catch?(InterruptedException?e)?{ ????????????e.printStackTrace(); ????????} ????????return?"123"; ????} }

?

在2中，對m1中call方法的返回值在main中進(jìn)行了處理（輸出），所以在此種情況下，main需要等待m1執(zhí)行完，再繼續(xù)執(zhí)行，執(zhí)行結(jié)果如下

線程調(diào)度：Thread[pool-1-thread-1,5,main]

123

主線程執(zhí)行完了

?

3、再看當(dāng)主線程中同時啟動兩個由Callable生成的線程時

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public?class?ThreadTest?{ ????public?static?void?main(String[]?args)?throws?InterruptedException,?ExecutionException?{ ????????ExecutorService?executor?=?Executors.newFixedThreadPool(4); ????????MyTread?m1?=?new?MyTread(); ????????MyTread2?m2?=?new?MyTread2(); ????????Long?time1?=?TimeUnit.MILLISECONDS.toSeconds(System.currentTimeMillis()); ????????Future?f?=?executor.submit(m1); ????????Future?f2?=?executor.submit(m2); ????????System.out.println(f.get());?//?進(jìn)行了輸出m1 ????????System.out.println(f2.get());?//?進(jìn)行了輸出m2 ????????executor.shutdown(); ????????System.out.println("主線程執(zhí)行完了"); ????????Long?time2?=?TimeUnit.MILLISECONDS.toSeconds(System.currentTimeMillis()); ????????System.out.println("主線程等待了"?+?(time2?-?time1)?+?"秒"); ????} ?? }

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class?MyTread?implements?Callable<String>?{ ????@Override ????public?String?call()?{ ????????try?{ ????????????System.out.println("線程調(diào)度："?+?Thread.currentThread()); ????????????TimeUnit.SECONDS.sleep(3); ????????}?catch?(InterruptedException?e)?{ ????????????e.printStackTrace(); ????????} ????????return?"123"; ????} } ?? class?MyTread2?implements?Callable<String>?{ ????@Override ????public?String?call()?{ ????????try?{ ????????????System.out.println("線程調(diào)度2："?+?Thread.currentThread()); ????????????TimeUnit.SECONDS.sleep(3); ????????}?catch?(InterruptedException?e)?{ ????????????e.printStackTrace(); ????????} ????????return?"abc"; ????} }

當(dāng)不對m1和m2做輸出時，main和m1、m2并發(fā)執(zhí)行，當(dāng)對m1和m2中任意一個的返回值進(jìn)行處理的時候，main需要等待，但是m1和m2之前仍然是并發(fā)執(zhí)行，執(zhí)行結(jié)果如下：

線程調(diào)度2：Thread[pool-1-thread-2,5,main]

線程調(diào)度：Thread[pool-1-thread-1,5,main]

123

abc

主線程執(zhí)行完了

主線程等待了3秒

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