java中的简单超时
任何人都可以指导我如何在java中使用简单的超时？ 基本上在我的项目中，我正在执行一个语句br.readLine() ，它正在读取调制解调器的响应。 但有时调制解调器没有响应。 为此我想添加一个超时。 我正在寻找像这样的代码：
try { String s= br.readLine(); } catch(TimeoutException e) { System.out.println("Time out has occurred"); }
你在寻找什么可以在这里找到。 它可能存在一种更优雅的方式来实现这一目标，但一种可能的方法是
选项1（首选）：
final Duration timeout = Duration.ofSeconds(30); ExecutorService executor = Executors.newSingleThreadExecutor(); final Future handler = executor.submit(new Callable() { @Override public String call() throws Exception { return requestDataFromModem(); } }); try { handler.get(timeout.toMillis(), TimeUnit.MILLISECONDS); } catch (TimeoutException e) { handler.cancel(true); } executor.shutdownNow();
选项2：
final Duration timeout = Duration.ofSeconds(30); ScheduledExecutorService executor = Executors.newScheduledThreadPool(1); final Future handler = executor.submit(new Callable() { @Override public String call() throws Exception { return requestDataFromModem(); } }); executor.schedule(new Runnable() { @Override public void run(){ handler.cancel(true); } }, timeout.toMillis(), TimeUnit.MILLISECONDS); executor.shutdownNow();
这些只是一个草案，所以你可以得到主要的想法。
示例1将无法编译。 它的这个版本编译并运行。 它使用lambda特征来缩写它。
/* * [RollYourOwnTimeouts.java] * * Summary: How to roll your own timeouts. * * Copyright: (c) 2016 Roedy Green, Canadian Mind Products, http://mindprod.com * * Licence: This software may be copied and used freely for any purpose but military. * http://mindprod.com/contact/nonmil.html * * Requires: JDK 1.8+ * * Created with: JetBrains IntelliJ IDEA IDE http://www.jetbrains.com/idea/ * * Version History: * 1.0 2016-06-28 initial version */ package com.mindprod.example; import java.util.concurrent.ExecutionException; import java.util.concurrent.ExecutorService; import java.util.concurrent.Executors; import java.util.concurrent.Future; import java.util.concurrent.TimeUnit; import java.util.concurrent.TimeoutException; import static java.lang.System.*; /** * How to roll your own timeouts. * Based on code at http://stackoverflow.com/questions/19456313/simple-timeout-in-java * * @author Roedy Green, Canadian Mind Products * @version 1.0 2016-06-28 initial version * @since 2016-06-28 */ public class RollYourOwnTimeout { private static final long MILLIS_TO_WAIT = 10 * 1000L; public static void main( final String[] args ) { final ExecutorService executor = Executors.newSingleThreadExecutor(); // schedule the work final Future future = executor.submit( RollYourOwnTimeout::requestDataFromWebsite ); try { // where we wait for task to complete final String result = future.get( MILLIS_TO_WAIT, TimeUnit.MILLISECONDS ); out.println( "result: " + result ); } catch ( TimeoutException e ) { err.println( "task timed out" ); future.cancel( true /* mayInterruptIfRunning */ ); } catch ( InterruptedException e ) { err.println( "task interrupted" ); } catch ( ExecutionException e ) { err.println( "task aborted" ); } executor.shutdownNow(); } /** * dummy method to read some data from a website */ private static String requestDataFromWebsite() { try { // force timeout to expire Thread.sleep( 14_000L ); } catch ( InterruptedException e ) { } return "dummy"; } }
使用以下代码行：
Thread.sleep(1000);
它会睡1秒钟。