我們在開發過程中可能會遇到這樣的場景:在執行一個耗時操作的時候,如果在規定的時間內處理完成了,則返回正確的結果,否則視爲超時任務,這個時候我們將不再等待(不再執行)該耗時操作,直接告訴調用者:這個任務由於耗時過多,被取消了。
import java.util.Random;
import java.util.concurrent.Callable;
import java.util.concurrent.ExecutionException;
import java.util.concurrent.ExecutorService;
import java.util.concurrent.Executors;
import java.util.concurrent.FutureTask;
import java.util.concurrent.TimeUnit;
import java.util.concurrent.TimeoutException;
public class TimeoutTest {
private static ExecutorService executorService = Executors.newSingleThreadExecutor();
/**
* @param args
*/
public static void main(String[] args) {
// TODO Auto-generated method stub
long start = System.currentTimeMillis();
String result = timeoutMethod(5000);
System.out.println("方法實際耗時:" + (System.currentTimeMillis() - start) + "毫秒");
System.out.println("結果:" + result);
try {
Thread.sleep(8000);
long start1 = System.currentTimeMillis();
String result1 = timeoutMethod(5000);
System.out.println("方法實際耗時:" + (System.currentTimeMillis() - start1) + "毫秒");
System.out.println("結果:" + result1);
} catch (Exception e) {
// TODO: handle exception
}
}
/**
* 有超時時間的方法
* @param timeout
* @return
*/
private static String timeoutMethod(int timeout) {
String result = "默認";
FutureTask<String> futureTask = new FutureTask<>(new Callable<String>() {
@Override
public String call() throws Exception {
return unknowMethod();
}
});
executorService.execute(futureTask);
try {
result = futureTask.get(timeout, TimeUnit.MILLISECONDS);
} catch (InterruptedException | ExecutionException | TimeoutException e) {
//e.printStackTrace();
futureTask.cancel(true);
result = "默認";
}
return result;
}
/**
* 這個方法的耗時不確定
* @return
*/
private static String unknowMethod() {
Random random = new Random();
int time = (random.nextInt(10) + 1) * 1000;
System.out.println("任務將耗時: " + time + "毫秒");
try {
Thread.sleep(time);
} catch (Exception e) {
// TODO: handle exception
}
return "獲得方法執行後的返回值";
}
}
文章轉發,原文參考:https://blog.csdn.net/ithouse/article/details/78257418