Quartz之QuartzInitializerListener

问题:我想在WEB容器启动时就执行任务怎么办呢 
Quartz:使用QuartzInitializerListener就可办到了 
请注意它的优先级别比QuartzInitializerServlet要高 
在web.xml中可配置的参数如下: 
如： 

<context-param>
         <param-name>quartz:config-file</param-name>
         <param-value>/quartz.properties</param-value>
</context-param>

以下二者参数可代表都是同一个意思 
quartz:config-file                                                       或者 config-file 
quartz:shutdown-on-unload                                       或者  shutdown-on-unload 
quartz:wait-on-shutdown 
quartz:start-on-load                                                  或者   start-scheduler-on-load 
quartz:start-delay-seconds                                        或者   start-delay-seconds 
quartz:servlet-context-factory-key                              或者   servlet-context-factory-key 
默认值为:org.quartz.impl.StdSchedulerFactory.KEY 
quartz:scheduler-context-servlet-context-key              或者 scheduler-context-servlet-context-key 
以上参数都是根据QuartzInitializerListener源码得来的 
QuartzInitializerListener源码如下： 

package org.quartz.ee.servlet;

import javax.servlet.ServletContext;
import javax.servlet.ServletContextEvent;
import javax.servlet.ServletContextListener;
import org.quartz.Scheduler;
import org.quartz.impl.StdSchedulerFactory;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

public class QuartzInitializerListener implements ServletContextListener {

    public static final String QUARTZ_FACTORY_KEY = "org.quartz.impl.StdSchedulerFactory.KEY";
    private boolean performShutdown;
    private boolean waitOnShutdown;
    private Scheduler scheduler;
    private final Logger log;

    public QuartzInitializerListener() {
        this.performShutdown = true;
        this.waitOnShutdown = false;

        this.scheduler = null;

        this.log = LoggerFactory.getLogger(super.getClass());
    }

    public void contextInitialized(ServletContextEvent sce) {
        this.log
                .info("Quartz Initializer Servlet loaded, initializing Scheduler...");

        ServletContext servletContext = sce.getServletContext();
        try {
            String configFile = servletContext
                    .getInitParameter("quartz:config-file");
            if (configFile == null)
                configFile = servletContext.getInitParameter("config-file");
            String shutdownPref = servletContext
                    .getInitParameter("quartz:shutdown-on-unload");
            if (shutdownPref == null)
                shutdownPref = servletContext
                        .getInitParameter("shutdown-on-unload");
            if (shutdownPref != null) {
                this.performShutdown = Boolean.valueOf(shutdownPref)
                        .booleanValue();
            }
            String shutdownWaitPref = servletContext
                    .getInitParameter("quartz:wait-on-shutdown");
            if (shutdownPref != null)
                this.waitOnShutdown = Boolean.valueOf(shutdownWaitPref)
                        .booleanValue();

            StdSchedulerFactory factory;

            if (configFile != null)
                factory = new StdSchedulerFactory(configFile);
            else {
                factory = new StdSchedulerFactory();
            }

            this.scheduler = factory.getScheduler();

            String startOnLoad = servletContext
                    .getInitParameter("quartz:start-on-load");
            if (startOnLoad == null) {
                startOnLoad = servletContext
                        .getInitParameter("start-scheduler-on-load");
            }
            int startDelay = 0;
            String startDelayS = servletContext
                    .getInitParameter("quartz:start-delay-seconds");
            if (startDelayS == null)
                startDelayS = servletContext
                        .getInitParameter("start-delay-seconds");
            try {
                if ((startDelayS != null) && (startDelayS.trim().length() > 0))
                    startDelay = Integer.parseInt(startDelayS);
            } catch (Exception e) {
                this.log
                        .error("Cannot parse value of 'start-delay-seconds' to an integer: "
                                + startDelayS + ", defaulting to 5 seconds.");
                startDelay = 5;
            }

            if ((startOnLoad == null)
                    || (Boolean.valueOf(startOnLoad).booleanValue()))
                if (startDelay <= 0) {
                    this.scheduler.start();
                    this.log.info("Scheduler has been started...");
                } else {
                    this.scheduler.startDelayed(startDelay);
                    this.log.info("Scheduler will start in " + startDelay
                            + " seconds.");
                }
            else {
                this.log
                        .info("Scheduler has not been started. Use scheduler.start()");
            }

            String factoryKey = servletContext
                    .getInitParameter("quartz:servlet-context-factory-key");
            if (factoryKey == null)
                factoryKey = servletContext
                        .getInitParameter("servlet-context-factory-key");
            if (factoryKey == null) {
                factoryKey = "org.quartz.impl.StdSchedulerFactory.KEY";
            }

            this.log
                    .info("Storing the Quartz Scheduler Factory in the servlet context at key: "
                            + factoryKey);

            servletContext.setAttribute(factoryKey, factory);

            String servletCtxtKey = servletContext
                    .getInitParameter("quartz:scheduler-context-servlet-context-key");
            if (servletCtxtKey == null)
                servletCtxtKey = servletContext
                        .getInitParameter("scheduler-context-servlet-context-key");
            if (servletCtxtKey != null) {
                this.log
                        .info("Storing the ServletContext in the scheduler context at key: "
                                + servletCtxtKey);

                this.scheduler.getContext().put(servletCtxtKey, servletContext);
            }
        } catch (Exception e) {
            this.log.error("Quartz Scheduler failed to initialize: "
                    + e.toString());
            e.printStackTrace();
        }
    }

    public void contextDestroyed(ServletContextEvent sce) {
        if (!this.performShutdown) {
            return;
        }
        try {
            if (this.scheduler != null)
                this.scheduler.shutdown(this.waitOnShutdown);
        } catch (Exception e) {
            this.log.error("Quartz Scheduler failed to shutdown cleanly: "
                    + e.toString());
            e.printStackTrace();
        }

        this.log.info("Quartz Scheduler successful shutdown.");
    }
}