[b]submit() [/b]
可以接受 Callable 或 Runnable 對象。
返回值是 Future 對象（調用 Future 對象的 get() 方法會導致主線程阻塞）。
[size=medium][b]二、程序[/b][/size]
import java.util.concurrent.Callable;
import java.util.concurrent.ExecutorService;
import java.util.concurrent.Executors;
import java.util.concurrent.TimeUnit;
import org.junit.Test;
public class TestExecutorService {
class Runnabled implements Runnable{
@Override
public void run() {
System.out.println("[Runnable-child] running...");
try {
Thread.sleep(100);
} catch (InterruptedException e) {
e.printStackTrace();
}
}
}
class Callabled implements Callable<String>{
@Override
public String call() throws Exception {
System.out.println("[Callable-child] calling...");
Thread.sleep(100);
return "finished";
}
}
//==========================================================
@Test
public void test() throws Exception{
testExecutorService_Runnable();
testExecutorService_Callable();
testExecutorService_shutdown();
}
//==========================================================
public void testExecutorService_Runnable() throws Exception {
Runnabled runnable = new Runnabled();
ExecutorService es1 = Executors.newCachedThreadPool();
for(int i = 0; i < 10; i++){
System.out.println("[Runnable] main thread : " + i + "[Blocked in Main]");
es1.submit(runnable).get();
}
for(int i = 0; i < 10; i++){
System.out.println("[Runnable] main thread : " + i);
es1.execute(runnable);
//es1.submit(runnable) // same as, if you don't expect a result.
}
}
public void testExecutorService_Callable() throws Exception{
ExecutorService es2 = Executors.newScheduledThreadPool(10);
Callabled callable = new Callabled();
for(int i = 0; i < 10; i++){
System.out.println("[Callable] main thread : " + i + "[Blocked in Main]");
es2.submit(callable).get();
}
for(int i = 0; i < 10; i++){
System.out.println("[Callable] main thread : " + i);
es2.submit(callable);
}
}
public void testExecutorService_shutdown() throws Exception{
ExecutorService es2 = Executors.newScheduledThreadPool(10);
/*
Does not wait for previously submitted tasks to complete execution.
Start an immediately shutdown and no new tasks will be accepted.
The invocation has no additional effect if already shut down.
*/
es2.shutdown();
/*
Blocks, until all tasks have completed execution after
1) a shutdown request,
2) or the timeout occurs,
3) or the current thread is interrupted,
whichever happens first.
*/
es2.awaitTermination(10000, TimeUnit.SECONDS);
System.out.println("----------------------------");
System.out.println("print me immediately after all task completed.");
System.out.println("no need to wait for 10000 seconds.");
}
/**
NOTE: ExecutorService.shutdown()
VS
ExecutorService.awaitTermination()
1.
awaitTermination() will wait for all task to complete.
shutdown() method does not wait.
if shutdown() method comes before awaitTermination(),
Then when all task complete in or less than timeout,
thread will shut down immediately.
2.
If you want to get the task result immediately, you should
use:
result = exec.submit(Callable/Runnable).get();
NOTE:
If you call get(), it will be blocked.
If you just call submit(), it will not be blocked.
3.
If you want to get the task result after all task completed,
you can store the Future object in to a collection.
use:
Future f = exec.submit(Callable/Runnable);
arrayList.add(f);
then after all task completed, you can retrieve the Future
objects stored in arrayList.
*/
/**
* NOTE: Callable VS Runnable
*
* Callable and Runnable are almost same when using
* ExecutorService.submit() method.
*
* They can be both blocked when using Future.get()
* method.
*
* while:
* 1. Callable's call() method can return a result.
* Runnable's run() method is void.
*
* 2. Callable's call() method throws exception.
* Runnable's run() method cannot throw exception.
*/
}
/*
Result:
===============================================================
[Runnable] main thread : 0 [Blocked in Main]
[Runnable-child] running...
[Runnable] main thread : 1 [Blocked in Main]
[Runnable-child] running...
[Runnable] main thread : 2 [Blocked in Main]
[Runnable-child] running...
[Runnable] main thread : 3 [Blocked in Main]
[Runnable-child] running...
[Runnable] main thread : 4 [Blocked in Main]
[Runnable-child] running...
[Runnable] main thread : 5 [Blocked in Main]
[Runnable-child] running...
[Runnable] main thread : 6 [Blocked in Main]
[Runnable-child] running...
[Runnable] main thread : 7 [Blocked in Main]
[Runnable-child] running...
[Runnable] main thread : 8 [Blocked in Main]
[Runnable-child] running...
[Runnable] main thread : 9 [Blocked in Main]
[Runnable-child] running...
[Runnable] main thread : 0
[Runnable] main thread : 1
[Runnable-child] running...
[Runnable-child] running...
[Runnable] main thread : 2
[Runnable] main thread : 3
[Runnable-child] running...
[Runnable] main thread : 4
[Runnable-child] running...
[Runnable] main thread : 5
[Runnable-child] running...
[Runnable] main thread : 6
[Runnable-child] running...
[Runnable] main thread : 7
[Runnable-child] running...
[Runnable] main thread : 8
[Runnable-child] running...
[Runnable] main thread : 9
[Runnable-child] running...
[Runnable-child] running...
[Callable] main thread : 0 [Blocked in Main]
[Callable-child] calling...
[Callable] main thread : 1 [Blocked in Main]
[Callable-child] calling...
[Callable] main thread : 2 [Blocked in Main]
[Callable-child] calling...
[Callable] main thread : 3 [Blocked in Main]
[Callable-child] calling...
[Callable] main thread : 4 [Blocked in Main]
[Callable-child] calling...
[Callable] main thread : 5 [Blocked in Main]
[Callable-child] calling...
[Callable] main thread : 6 [Blocked in Main]
[Callable-child] calling...
[Callable] main thread : 7 [Blocked in Main]
[Callable-child] calling...
[Callable] main thread : 8 [Blocked in Main]
[Callable-child] calling...
[Callable] main thread : 9 [Blocked in Main]
[Callable-child] calling...
[Callable] main thread : 0
[Callable] main thread : 1
[Callable] main thread : 2
[Callable-child] calling...
[Callable] main thread : 3
[Callable-child] calling...
[Callable-child] calling...
[Callable-child] calling...
[Callable] main thread : 4
[Callable] main thread : 5
[Callable-child] calling...
[Callable-child] calling...
[Callable] main thread : 6
[Callable] main thread : 7
[Callable-child] calling...
[Callable-child] calling...
[Callable] main thread : 8
[Callable] main thread : 9
[Callable-child] calling...
[Callable-child] calling...
----------------------------
print me immediately after all task completed.
no need to wait for 10000 seconds.
*/
java.util.concurrent包之Execuotor系列文章
[url=http://lixh1986.iteye.com/blog/2341898]00_Java之 java.util.concurrent 包之概述[/url]
[url=http://lixh1986.iteye.com/blog/2360304]01_Java之java.util.concurrent包之Executor與ExecutorService[/url]
[url=http://lixh1986.iteye.com/blog/2360306]02_Java之 java.util.concurrent 包之ExecutorService之submit () 之 Future[/url]
[url=http://lixh1986.iteye.com/blog/2351367]03_Java之多線程之Callable與Future[/url]
[url=http://lixh1986.iteye.com/blog/2351294]04_Java之多線程之Lock[/url]
轉載請註明，
原文出處：http://lixh1986.iteye.com/blog/2360306
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