Java中应用Executors来建立Thread pool
有时候您需要建立一堆Thread来执行一些小任务,然而频繁的建立Thread有时会是个开销,因为Thread的建立必须与作业系统互动,如果能建立一个Thread pool来管理这些小的Thread并加以重复使用,对于系统效能会是个改善的方式。
您可以使用Executors来建立Thread pool,Executors有几个static方法,列出如下:?
newSingleThreadExecutor
只有一个Thread,循序的执行指定给它的每个任务newScheduledThreadPool可排程的ThreadnewSingleThreadScheduledExecutor单一可排程的Threadpackage onlyfun.caterpillar;import java.util.concurrent.ExecutorService;import java.util.concurrent.Executors;public class ExecutorDemo {public static void main(String[] args) {ExecutorService service = Executors.newFixedThreadPool(5);for(int i = 0; i < 10; i++) {final int count = i;service.submit(new Runnable() {public void run() {System.out.println(count);try {Thread.sleep(2000);} catch (InterruptedException e) {e.printStackTrace();}}});}service.shutdown(); // 最后记得关闭Thread pool}}
submit()方法也接受实作Callable介面的物件,最后传回Future物件,可以取得Callable执行过后的传回结果。
如果想利用Executors进行排程,例如排定某个工作30秒后执行:
??? ??? ScheduledExecutorService scheduler = Executors.newSingleThreadScheduledExecutor( );
??? ??? scheduler.schedule(new Runnable( ) {
??? ??? ?????????????????????? public void run() {
??? ??? ?????????????????????????? // 排程工作
??? ??? ?????????????????????? }
??? ??? ?????????????????? },?
??? ??? ?????????????????? 30, TimeUnit.SECONDS);
或排定某个工作5秒后执行,之后每30秒执行一次:
??? ??? ScheduledExecutorService scheduler = Executors.newSingleThreadScheduledExecutor( );
??? ??? final ScheduledFuture future = scheduler.scheduleAtFixedRate(new Runnable( ) {
??? ??? ?????????????????????? public void run() {
??? ??? ?????????????????????????? // 排程工作
??? ??? ??????????????????? ??? ?? System.out.println("t");
??? ??? ?????????????????????? }
??? ??? ?????????????????? },?
??? ??? ?????????????????? 0, 5, TimeUnit.SECONDS);
??? ????
??? ??? // 排定 60 秒后取消future
??? ??? scheduler.schedule(new Runnable( ) {
??? ??????? public void run( ) {
??? ????????? future.cancel(false);
??? ??????? }
??? ????? }, 60, TimeUnit.SECONDS);
如上所示,想要取消排程任务,可以呼叫ScheduledFuture的cancel()方法。
来源:http://blog.csdn.net/HuDon/article/details/1922563