如何正确停止Java中的线程？

发布日期：2018-02-23 16:36
分类：JAVA
浏览次数：123
我需要一个解决方案来正确地停止线程在Java。
我有IndexProcessorclass实现Runnable接口：
public class IndexProcessor implements Runnable {

private static final Logger LOGGER = LoggerFactory.getLogger(IndexProcessor.class);

@Override
    public void run() {
        boolean run = true;
        while (run) {
            try {
                LOGGER.debug("Sleeping...");
                Thread.sleep((long) 15000);

LOGGER.debug("Processing");
            } catch (InterruptedException e) {
                LOGGER.error("Exception", e);
                run = false;
            }
        }

}
}
我有ServletContextListener类启动和停止线程：
private static final Logger LOGGER = LoggerFactory.getLogger(SearchEngineContextListener.class);

private Thread thread = null;

@Override
    public void contextInitialized(ServletContextEvent event) {
        thread = new Thread(new IndexProcessor());
        LOGGER.debug("Starting thread: " + thread);
        thread.start();
        LOGGER.debug("Background process successfully started.");
    }

@Override
    public void contextDestroyed(ServletContextEvent event) {
        LOGGER.debug("Stopping thread: " + thread);
        if (thread != null) {
            thread.interrupt();
            LOGGER.debug("Thread successfully stopped.");
        }
    }
}
但是当我关闭tomcat时，我在我的IndexProcessor类中得到了异常：
2012-06-09 17:04:50,671 [Thread-3] ERROR IndexProcessor Exception
java.lang.InterruptedException: sleep interrupted
at java.lang.Thread.sleep(Native Method)
at lt.ccl.searchengine.processor.IndexProcessor.run(IndexProcessor.java:22)
at java.lang.Thread.run(Unknown Source)
我使用JDK 1.6。所以问题是：
如何停止线程，不抛出任何异常？
P.S。我不想使用.stop（）;方法，因为它已被弃用。
 
回答：
 
在IndexProcessor类中，您需要一种设置标志的方法，通知线程需要终止它，类似于您在类范围中使用的变量运行。
当你想停止线程，你设置这个标志，并调用join()线程，并等待它完成。
通过使用volatile变量或使用与用作标志的变量同步的getter和setter方法，确保该标志是线程安全的。
public class IndexProcessor implements Runnable {

private static final Logger LOGGER = LoggerFactory.getLogger(IndexProcessor.class);
    private volatile boolean running = true;

public void terminate() {
        running = false;
    }

@Override
    public void run() {
        while (running) {
            try {
                LOGGER.debug("Sleeping...");
                Thread.sleep((long) 15000);

LOGGER.debug("Processing");
            } catch (InterruptedException e) {
                LOGGER.error("Exception", e);
                running = false;
            }
        }

}
}
然后在SearchEngineContextListener：
public class SearchEngineContextListener implements ServletContextListener {

private static final Logger LOGGER = LoggerFactory.getLogger(SearchEngineContextListener.class);

private Thread thread = null;
    private IndexProcessor runnable = null;

@Override
    public void contextInitialized(ServletContextEvent event) {
        runnable = new IndexProcessor();
        thread = new Thread(runnable);
        LOGGER.debug("Starting thread: " + thread);
        thread.start();
        LOGGER.debug("Background process successfully started.");
    }

@Override
    public void contextDestroyed(ServletContextEvent event) {
        LOGGER.debug("Stopping thread: " + thread);
        if (thread != null) {
            runnable.terminate();
            thread.join();
            LOGGER.debug("Thread successfully stopped.");
        }
    }
}
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