Quartz Job Scheduling Framework［翻译］第十三章. Quartz 和 Web 应用 (第四部分)

2008-05-01 | 阅读(749)

五. 使用 ServletContextListener

很值得一提的是你可以配置和集成 Quartz 到 Web 应用的另一种方式。从 2.3 版本的 Servlet API 开始，你能创建监听器，由容器在其生命周期中的某个特定时间回调。其中的一个监听器接口叫做 java.servlet.ServletContextListener，它包括有两个方法：

public void contextInitialized(ServletContextEvent sce);
public void contextDestroyed(ServeltContextEvent sce);

容器会在启动和关闭的时候相应的调用这两个方法。这就可以在 contextInitialized() 方法中初始化 Quartz Scheduler，并通过 contextDestroyed() 方法关闭它。代码 13.5 描述了这种用法：

代码 13.5. ServletContextListener 也能被用于初始化 Quartz

import javax.servlet.ServletContext;
import javax.servlet.ServletContextEvent;
import javax.servlet.ServletContextListener;

import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;
import org.quartz.SchedulerException;
import org.quartz.impl.StdSchedulerFactory;

public class QuartzServletContextListener implements ServletContextListener {
    private static Log logger = LogFactory
              .getLog(QuartzServletContextListener.class);

    public static final String QUARTZ_FACTORY_KEY =
         "org.quartz.impl.StdSchedulerFactory.KEY";

    private ServletContext ctx = null;

    private StdSchedulerFactory factory = null;

    /**
     * Called when the container is shutting down.
     */
    public void contextDestroyed(ServletContextEvent sce) {
         try {
              factory.getDefaultScheduler().shutdown();
         } catch (SchedulerException ex) {
              logger.error("Error stopping Quartz", ex);
         }

    }

    /**
     * Called when the container is first started.
     */
    public void contextInitialized(ServletContextEvent sce) {

         ctx = sce.getServletContext();

         try {

              factory = new StdSchedulerFactory();

              // Start the scheduler now

              factory.getScheduler().start();

              logger.info("Storing QuartzScheduler Factory at"
                        + QUARTZ_FACTORY_KEY);

              ctx.setAttribute(QUARTZ_FACTORY_KEY, factory);

        } catch (Exception ex) {
              logger.error("Quartz failed to initialize", ex);
         }
    }
}

import javax.servlet.ServletContext;

import javax.servlet.ServletContextEvent;

import javax.servlet.ServletContextListener;

import org.apache.commons.logging.Log;

import org.apache.commons.logging.LogFactory;

import org.quartz.SchedulerException;

import org.quartz.impl.StdSchedulerFactory;

public class QuartzServletContextListener implements ServletContextListener {

private static Log logger = LogFactory

.getLog(QuartzServletContextListener.class);

public static final String QUARTZ_FACTORY_KEY =

"org.quartz.impl.StdSchedulerFactory.KEY";

private ServletContext ctx = null;

private StdSchedulerFactory factory = null;

/**

* Called when the container is shutting down.

public void contextDestroyed(ServletContextEvent sce) {

try {

factory.getDefaultScheduler().shutdown();

} catch (SchedulerException ex) {

logger.error("Error stopping Quartz", ex);

}

/**

* Called when the container is first started.

public void contextInitialized(ServletContextEvent sce) {

ctx = sce.getServletContext();

try {

factory = new StdSchedulerFactory();

// Start the scheduler now

factory.getScheduler().start();

logger.info("Storing QuartzScheduler Factory at"

+ QUARTZ_FACTORY_KEY);

ctx.setAttribute(QUARTZ_FACTORY_KEY, factory);

} catch (Exception ex) {

logger.error("Quartz failed to initialize", ex);

}

正如我们在 QuartzInitializerServlet 中所做的，我们需要为这个监听器加入一些配置信息到 Web 部署描术文件(web.xml) 中。针对我们的监听器，我们需要加一个 <listener> 元素到部署描述中。如下片断中显示：

<web-app>
 <listener>
   <listener-class>
  org.cavaness.jobconsole.web.QuartzServletContextListener
  </listener-class>
 </listener>
 <!--Other deployment descriptor info not shown -->
</web-app>

<web-app>

<listener-class>

org.cavaness.jobconsole.web.QuartzServletContextListener

</listener-class>

</listener>

</web-app>

·新的 QuartzInitializerListener 已加入到 Quartz 中

ServletContextListener 为顺应用户社区而来的呼声被加入到 Quartz 框架中。13.5 中的代码应当认为是一个例子，实际应用时你需要开发你自己的监听器。

本文链接 https://yanbin.blog/quartz-job-scheduling-framework-13-4/, 来自隔叶黄莺 Yanbin Blog

9 Comments

Inline Feedbacks

View all comments

日月雨林@gmail.com

16 years ago

今天我又拜读了你的翻译大作！呵呵！

俞鹏

tomcat运行一段时间后，控制台报以下错误2009-03-06 09:38:21 [org.quartz.core.ErrorLogger]-[ERROR] An error occured while scanning for the next trigger to fire.org.quartz.JobPersistenceException: Couldn't rollback jdbc connection. Io 异常: Connection reset by peer: socket write error [See nested exception: java.sql.SQLException: Io 异常: Connection reset by peer: socket write error] at org.quartz.impl.jdbcjobstore.JobStoreSupport.rollbackConnection(JobStoreSupport.java:2319) at org.quartz.impl.jdbcjobstore.JobStoreTX.acquireNextTrigger(JobStoreTX.java:1222) at org.quartz.core.QuartzSchedulerThread.run(QuartzSchedulerThread.java:233)* Nested Exception (Underlying Cause) ---------------java.sql.SQLException: Io 异常: Connection reset by peer: socket write error at oracle.jdbc.dbaccess.DBError.throwSqlException(DBError.java:134) at oracle.jdbc.dbaccess.DBError.throwSqlException(DBError.java:179) at oracle.jdbc.dbaccess.DBError.throwSqlException(DBError.java:333) at oracle.jdbc.driver.OracleConnection.rollback(OracleConnection.java:1380) at org.apache.commons.dbcp.DelegatingConnection.rollback(DelegatingConnection.java:328) at org.apache.commons.dbcp.PoolingDataSource$PoolGuardConnectionWrapper.rollback(PoolingDataSource.java:312) at org.quartz.impl.jdbcjobstore.JobStoreSupport.rollbackConnection(JobStoreSupport.java:2317) at org.quartz.impl.jdbcjobstore.JobStoreTX.acquireNextTrigger(JobStoreTX.java:1222) at org.quartz.core.QuartzSchedulerThread.run(QuartzSchedulerThread.java:233)2009-03-06 09:38:46 [org.quartz.impl.jdbcjobstore.JobStoreTX]-[ERROR] MisfireHandler: Error handling misfires: Couldn't rollback jdbc connection. Io 异常: Connection reset by peer: socket write errororg.quartz.JobPersistenceException: Couldn't rollback jdbc… Read more »

基本采用就该博文思路制作，根据
at org.quartz.impl.jdbcjobstore.JobStoreSupport.rollbackConnection(JobStoreSupport.java:2319)
查quartz源码，发现connection并不为空，但不知为何不能回滚，以及如何解决该问题，望赐教

隔叶黄莺

必要时用 netstat -na 观察一下连接，异常看起来像连接被断开了。

//JobStoreSupport.java源码段
2315 if (conn != null) {
2316 try {
2317 conn.rollback();
2318 } catch (SQLException e) {
2319 throw new JobPersistenceException(
2320 "Couldn't rollback jdbc connection. "+e.getMessage(), e);
2321 }
2322 }
2324 }

以上信息发现conn并不为空，但不知为何不能回滚，以及如何解决该问题，望赐教

再附:数据库采用是oracle 11g

物理连接断了, conn 也不会为 null 的，用 conn.isClosed() 判断一下看看，必要时观察一下那个特定的连接是不是还通着的。

我故意拔掉客户端网线，重新打开IE，其他页面正常，唯独停止点击执行如下代码
currScheduler.pauseTrigger(trigVO.getTriggerID(),currScheduler.DEFAULT_GROUP);

就会出错，出错信息同上
注：currScheduler不为空,参数也正确

望再赐教，3q

按理说，quartz是tomcat服务器自动运行的东东，不受客户端影响才对呀

那你要检查为什么连接会被断掉

Polo on 想选一种动态语言＋跨平台界面组件的组合，希望大家给点意见Perl + Tkx
best coffee on SciPy 最优化之最小化I wanted to take a moment to commend you on the outstanding quality of...
seetimee on 体验 Python FastAPI 的并发能力及线, 进程模型感谢
Yanbin on Mockito 3.4.0 开始可 Mock 静态方法有一个补救，新写了一篇 https://yanbin.blog/mockito-mock-static-method-in-multiple...
Yanbin on 升级到 Spring Boot 3 后 javax.inject.Named 不可用怎么，被抄袭了！算是被机器翻译引用的？