Quartz的Scheduler初始化源码分析

Quartz的使用： http://donald-draper.iteye.com/admin/blogs/2321886
Quartz的Job存储，触发器、任务删除，源码分析：
http://donald-draper.iteye.com/admin/blogs/2322725

一般获取Scheduler的方式
第一种：

SchedulerFactory schedulerFactory = new StdSchedulerFactory();
Scheduler cronScheduler = schedulerFactory.getScheduler();

第二种：

Scheduler scheduler = StdSchedulerFactory.getDefaultScheduler();

下面先来看看第一种到底做了些什么

public class StdSchedulerFactory
    implements SchedulerFactory
{
        //获取调度器Scheduler
	public Scheduler getScheduler()
		throws SchedulerException
	    {
		if(cfg == null)
		     //初始化Quartz属性，线程池，线程数，线程优先级，job存储容器
		    initialize();
		//获取调度器仓库单例
		SchedulerRepository schedRep = SchedulerRepository.getInstance();
		 //根据调度器name，寻到对应的Scheduler
		Scheduler sched = schedRep.lookup(getSchedulerName());
		if(sched != null)
		    if(sched.isShutdown())
			schedRep.remove(getSchedulerName());
		    else
			return sched;
		//初始化调度器
		sched = instantiate();
		return sched;
	    }
   //从StdSchedulerFactory的getDefaultScheduler方法可以看出
   //与getScheduler相同
   public static Scheduler getDefaultScheduler()
        throws SchedulerException
    {
        StdSchedulerFactory fact = new StdSchedulerFactory();
        return fact.getScheduler();
    }
   //初始化Quartz属性，线程池，线程数，线程优先级，job存储容器配置
   public void initialize()
        throws SchedulerException
    {
        String requestedFile;
        String propFileName;
        File propFile;
        Properties props;
        InputStream in;
        if(cfg != null)
            return;
        if(initException != null)
            throw initException;
        requestedFile = System.getProperty("org.quartz.properties");
        propFileName = requestedFile == null ? "quartz.properties" : requestedFile;
        propFile = new File(propFileName);
        props = new Properties();
        in = null;
	//如果propFile存在，则从文件系统，加载相应的属性文件
        if(propFile.exists())
            try
            {
                if(requestedFile != null)
                    propSrc = (new StringBuilder()).append("specified file: '").append(requestedFile).append("'").toString();
                else
                    propSrc = "default file in current working dir: 'quartz.properties'";
                in = new BufferedInputStream(new FileInputStream(propFileName));
                props.load(in);
            }
            catch(IOException ioe)
            {
                initException = new SchedulerException((new StringBuilder()).append("Properties file: '").append(propFileName).append("' could not be read.").toString(), ioe);
                throw initException;
            }
        else
	//如果org.quartz.propertiess属性文件不为null，则从当前Thread的ClassLoader的Context加载相应的属性文件
        if(requestedFile != null)
        {
            in = Thread.currentThread().getContextClassLoader().getResourceAsStream(requestedFile);
            if(in == null)
            {
                initException = new SchedulerException((new StringBuilder()).append("Properties file: '").append(requestedFile).append("' could not be found.").toString());
                throw initException;
            }
            propSrc = (new StringBuilder()).append("specified file: '").append(requestedFile).append("' in the class resource path.").toString();
            in = new BufferedInputStream(in);
            try
            {
                props.load(in);
            }
            catch(IOException ioe)
            {
                initException = new SchedulerException((new StringBuilder()).append("Properties file: '").append(requestedFile).append("' could not be read.").toString(), ioe);
                throw initException;
            }
        } else
        {
            propSrc = "default resource file in Quartz package: 'quartz.properties'";
            ClassLoader cl = getClass().getClassLoader();
            if(cl == null)
                cl = findClassloader();
            if(cl == null)
                throw new SchedulerConfigException("Unable to find a class loader on the current thread or class.");
            in = cl.getResourceAsStream("quartz.properties");
            if(in == null)
                in = cl.getResourceAsStream("/quartz.properties");
            if(in == null)
                in = cl.getResourceAsStream("org/quartz/quartz.properties");
            if(in == null)
            {
                initException = new SchedulerException("Default quartz.properties not found in class path");
                throw initException;
            }
            try
            {
                props.load(in);
            }
            catch(IOException ioe)
            {
                initException = new SchedulerException("Resource properties file: 'org/quartz/quartz.properties' could not be read from the classpath.", ioe);
                throw initException;
            }
        }
        if(in != null)
            try
            {
                in.close();
            }
            catch(IOException ignore) { }
        break MISSING_BLOCK_LABEL_502;
        Exception exception;
        exception;
        if(in != null)
            try
            {
                in.close();
            }
            catch(IOException ignore) { }
        throw exception;
        initialize(overrideWithSysProps(props));
        return;
    }
  //重载系统属性
  private Properties overrideWithSysProps(Properties props)
    {
        Properties sysProps = null;
        try
        {
            sysProps = System.getProperties();
        }
        catch(AccessControlException e)
        {
            getLog().warn("Skipping overriding quartz properties with System properties during initialization because of an AccessControlException.  This is likely due to not having read/write access for java.util.PropertyPermission as required by java.lang.System.getProperties().  To resolve this warning, either add this permission to your policy file or use a non-default version of initialize().", e);
        }
        if(sysProps != null)
            props.putAll(sysProps);
        return props;
    }
    //初始化PropertiesParser
     public void initialize(Properties props)
        throws SchedulerException
    {
        if(propSrc == null)
            propSrc = "an externally provided properties instance.";
        cfg = new PropertiesParser(props);
    }
     //初始化Quartz属性，线程池，线程数，线程优先级，job存储容器
     private Scheduler instantiate()
        throws SchedulerException
    {   
        JobStore js;//job存储器
        ThreadPool tp;// 线程池
        QuartzScheduler qs;
        DBConnectionManager dbMgr;//数据库连接管理器
        ThreadExecutor threadExecutor;//线程执行器
        SchedulerRepository schedRep;//调度器仓库
        boolean makeSchedulerThreadDaemon;//Scheduler调度线程方式前台，守候
        boolean threadsInheritInitalizersClassLoader;//线程初始化继承属性
        long batchTimeWindow;
        int maxBatchSize;
        if(cfg == null)//initialize(Properties props)已经初始化cfg
            initialize();
        if(initException != null)
            throw initException;
	//初始化相关属性
        schedRep = SchedulerRepository.getInstance();
        schedName = cfg.getStringProperty("org.quartz.scheduler.instanceName", "QuartzScheduler");
        threadName = cfg.getStringProperty("org.quartz.scheduler.threadName", (new StringBuilder()).append(schedName).append("_QuartzSchedulerThread").toString());
        schedInstId = cfg.getStringProperty("org.quartz.scheduler.instanceId", "NON_CLUSTERED")
        String classLoadHelperClass = cfg.getStringProperty("org.quartz.scheduler.classLoadHelper.class", "org.quartz.simpl.CascadingClassLoadHelper");
        String jobFactoryClass = cfg.getStringProperty("org.quartz.scheduler.jobFactory.class", null);
        batchTimeWindow = cfg.getLongProperty("org.quartz.scheduler.batchTriggerAcquisitionFireAheadTimeWindow", 0L);
        maxBatchSize = cfg.getIntProperty("org.quartz.scheduler.batchTriggerAcquisitionMaxCount", 1);
        jmxExport = cfg.getBooleanProperty("org.quartz.scheduler.jmx.export");
        jmxObjectName = cfg.getStringProperty("org.quartz.scheduler.jmx.objectName");
        boolean jmxProxy = cfg.getBooleanProperty("org.quartz.scheduler.jmx.proxy");
        String jmxProxyClass = cfg.getStringProperty("org.quartz.scheduler.jmx.proxy.class");
        loadHelper.initialize();
	//初始化JMX Proxy
        if(jmxProxy)
        {
            if(autoId)
                schedInstId = "NON_CLUSTERED";
            if(jmxProxyClass == null)
                throw new SchedulerConfigException("No JMX Proxy Scheduler class provided");
            RemoteMBeanScheduler jmxScheduler = null;
            try
            {
                jmxScheduler = (RemoteMBeanScheduler)loadHelper.loadClass(jmxProxyClass).newInstance();
            }
            if(jmxObjectName == null)
                jmxObjectName = QuartzSchedulerResources.generateJMXObjectName(schedName, schedInstId);
            jmxScheduler.setSchedulerObjectName(jmxObjectName);
            tProps = cfg.getPropertyGroup("org.quartz.scheduler.jmx.proxy", true);
            try
            {
                setBeanProps(jmxScheduler, tProps);
            }          
            jmxScheduler.initialize();
            schedRep.bind(jmxScheduler);
            return jmxScheduler;
        }
        jobFactory = null;
	//初始化jobFactory
        if(jobFactoryClass != null)
        {
            try
            {
                jobFactory = (jobFactory)loadHelper.loadClass(jobFactoryClass).newInstance();
            }
            tProps = cfg.getPropertyGroup("org.quartz.scheduler.jobFactory", true);
            try
            {
                setBeanProps(jobFactory, tProps);
            }
        }
	//加载JobStore，org.quartz.jobStore.class = org.quartz.simpl.RAMJobStore 
        try
        {
            js = (JobStore)loadHelper.loadClass(jsClass).newInstance();
        }
       //如果org.quartz.jobStore.class = org.quartz.impl.jdbcjobstore.JobStoreTX ，配置数据库信息
        String dsNames[] = cfg.getPropertyGroups("org.quartz.dataSource");
        for(int i = 0; i < dsNames.length; i++)
        {
            PropertiesParser pp = new PropertiesParser(cfg.getPropertyGroup((new StringBuilder()).append("org.quartz.dataSource.").append(dsNames[i]).toString(), true));
            String cpClass = pp.getStringProperty("connectionProvider.class", null);
            if(cpClass != null)
            {
                ConnectionProvider cp = null;
                try
                {
                    cp = (ConnectionProvider)loadHelper.loadClass(cpClass).newInstance();
                }              
                try
                {
                    pp.getUnderlyingProperties().remove("connectionProvider.class");
                    setBeanProps(cp, pp.getUnderlyingProperties());
                    cp.initialize();
                }
                dbMgr = DBConnectionManager.getInstance();
                dbMgr.addConnectionProvider(dsNames[i], cp);
                continue;
            }
            try
            {
                PoolingConnectionProvider cp = new PoolingConnectionProvider(pp.getUnderlyingProperties());
                dbMgr = DBConnectionManager.getInstance();
                dbMgr.addConnectionProvider(dsNames[i], cp);
                continue;
            }
        }
        //初始化插件
        pluginNames = cfg.getPropertyGroups("org.quartz.plugin");
        plugins = new SchedulerPlugin[pluginNames.length];
        for(int i = 0; i < pluginNames.length; i++)
        {
            Properties pp = cfg.getPropertyGroup((new StringBuilder()).append("org.quartz.plugin.").append(pluginNames[i]).toString(), true);
            String plugInClass = pp.getProperty("class", null);
            if(plugInClass == null)
            {
                initException = new SchedulerException((new StringBuilder()).append("SchedulerPlugin class not specified for plugin '").append(pluginNames[i]).append("'").toString());
                throw initException;
            }
            SchedulerPlugin plugin = null;
            try
            {
                plugin = (SchedulerPlugin)loadHelper.loadClass(plugInClass).newInstance();
            }
            try
            {
                setBeanProps(plugin, pp);
            }
            plugins[i] = plugin;
        }
	//job监听器
	String jobListenerNames[] = cfg.getPropertyGroups("org.quartz.jobListener");
        jobListeners = new JobListener[jobListenerNames.length];
        for(int i = 0; i < jobListenerNames.length; i++)
        {
            Properties lp = cfg.getPropertyGroup((new StringBuilder()).append("org.quartz.jobListener.").append(jobListenerNames[i]).toString(), true);
            String listenerClass = lp.getProperty("class", null);
            if(listenerClass == null)
            {
                initException = new SchedulerException((new StringBuilder()).append("JobListener class not specified for listener '").append(jobListenerNames[i]).append("'").toString());
                throw initException;
            }
            JobListener listener = null;
            try
            {
                listener = (JobListener)loadHelper.loadClass(listenerClass).newInstance();
            }
            try
            {
                Method nameSetter = null;
                try
                {
                    nameSetter = listener.getClass().getMethod("setName", strArg);
                }              
                if(nameSetter != null)
                    nameSetter.invoke(listener, new Object[] {
                        jobListenerNames[i]
                    });
                setBeanProps(listener, lp);
            }         
            jobListeners[i] = listener;
        }
	//Trrige监听器
        String triggerListenerNames[] = cfg.getPropertyGroups("org.quartz.triggerListener");
        triggerListeners = new TriggerListener[triggerListenerNames.length];
        for(int i = 0; i < triggerListenerNames.length; i++)
        {
            Properties lp = cfg.getPropertyGroup((new StringBuilder()).append("org.quartz.triggerListener.").append(triggerListenerNames[i]).toString(), true);
            String listenerClass = lp.getProperty("class", null);
            if(listenerClass == null)
            {
                initException = new SchedulerException((new StringBuilder()).append("TriggerListener class not specified for listener '").append(triggerListenerNames[i]).append("'").toString());
                throw initException;
            }
            TriggerListener listener = null;
            try
            {
                listener = (TriggerListener)loadHelper.loadClass(listenerClass).newInstance();
            }
            try
            {
                Method nameSetter = null;
                try
                {
                    nameSetter = listener.getClass().getMethod("setName", strArg);
                }
                if(nameSetter != null)
                    nameSetter.invoke(listener, new Object[] {
                        triggerListenerNames[i]
                    });
                setBeanProps(listener, lp);
            }
            triggerListeners[i] = listener;
        }
        //初始化线程池执行类
        String threadExecutorClass = cfg.getStringProperty("org.quartz.threadExecutor.class");
        if(threadExecutorClass != null)
        {
            tProps = cfg.getPropertyGroup("org.quartz.threadExecutor", true);
            try
            {
                threadExecutor = (ThreadExecutor)loadHelper.loadClass(threadExecutorClass).newInstance();
                log.info((new StringBuilder()).append("Using custom implementation for ThreadExecutor: ").append(threadExecutorClass).toString());
                setBeanProps(threadExecutor, tProps);
            }
        } else
        {
            log.info("Using default implementation for ThreadExecutor");
            threadExecutor = new DefaultThreadExecutor();
        }
        Scheduler scheduler;
	//初始化job执行器
        JobRunShellFactory jrsf = null;
        if(userTXLocation != null)
            UserTransactionHelper.setUserTxLocation(userTXLocation);
        if(wrapJobInTx)
            jrsf = new JTAJobRunShellFactory();
        else
            jrsf = new JTAAnnotationAwareJobRunShellFactory();
        if(autoId)
            try
            {
                schedInstId = "NON_CLUSTERED";
                if(js.isClustered())
                    schedInstId = instanceIdGenerator.generateInstanceId();
            }
            catch(Exception e)
            {
                getLog().error("Couldn't generate instance Id!", e);
                throw new IllegalStateException("Cannot run without an instance id.");
            }
        if(js.getClass().getName().startsWith("org.terracotta.quartz"))
        {
            try
            {
                String uuid = (String)js.getClass().getMethod("getUUID", new Class[0]).invoke(js, new Object[0]);
                if(schedInstId.equals("NON_CLUSTERED"))
                {
                    schedInstId = (new StringBuilder()).append("TERRACOTTA_CLUSTERED,node=").append(uuid).toString();
                    if(jmxObjectName == null)
                        jmxObjectName = QuartzSchedulerResources.generateJMXObjectName(schedName, schedInstId);
                } else
                if(jmxObjectName == null)
                    jmxObjectName = QuartzSchedulerResources.generateJMXObjectName(schedName, (new StringBuilder()).append(schedInstId).append(",node=").append(uuid).toString());
            }
            catch(Exception e)
            {
                throw new RuntimeException("Problem obtaining node id from TerracottaJobStore.", e);
            }
            if(null == cfg.getStringProperty("org.quartz.scheduler.jmx.export"))
                jmxExport = true;
        }
        if(js instanceof JobStoreSupport)
        {
            JobStoreSupport jjs = (JobStoreSupport)js;
            jjs.setDbRetryInterval(dbFailureRetry);
            if(threadsInheritInitalizersClassLoader)
                jjs.setThreadsInheritInitializersClassLoadContext(threadsInheritInitalizersClassLoader);
            jjs.setThreadExecutor(threadExecutor);
        }
       //QuartzScheduler资源管理器
        QuartzSchedulerResources rsrcs = new QuartzSchedulerResources();
        rsrcs.setName(schedName);
        rsrcs.setThreadName(threadName);
        rsrcs.setInstanceId(schedInstId);
        rsrcs.setJobRunShellFactory(jrsf);
        rsrcs.setMakeSchedulerThreadDaemon(makeSchedulerThreadDaemon);
        rsrcs.setThreadsInheritInitializersClassLoadContext(threadsInheritInitalizersClassLoader);
        rsrcs.setRunUpdateCheck(!skipUpdateCheck);
        rsrcs.setBatchTimeWindow(batchTimeWindow);
        rsrcs.setMaxBatchSize(maxBatchSize);
        rsrcs.setInterruptJobsOnShutdown(interruptJobsOnShutdown);
        rsrcs.setInterruptJobsOnShutdownWithWait(interruptJobsOnShutdownWithWait);
        rsrcs.setJMXExport(jmxExport);
        rsrcs.setJMXObjectName(jmxObjectName);
        if(managementRESTServiceEnabled)
        {
            ManagementRESTServiceConfiguration managementRESTServiceConfiguration = new ManagementRESTServiceConfiguration();
            managementRESTServiceConfiguration.setBind(managementRESTServiceHostAndPort);
            managementRESTServiceConfiguration.setEnabled(managementRESTServiceEnabled);
            rsrcs.setManagementRESTServiceConfiguration(managementRESTServiceConfiguration);
        }
        if(rmiExport)
        {
            rsrcs.setRMIRegistryHost(rmiHost);
            rsrcs.setRMIRegistryPort(rmiPort);
            rsrcs.setRMIServerPort(rmiServerPort);
            rsrcs.setRMICreateRegistryStrategy(rmiCreateRegistry);
            rsrcs.setRMIBindName(rmiBindName);
        }
        SchedulerDetailsSetter.setDetails(tp, schedName, schedInstId);
        rsrcs.setThreadExecutor(threadExecutor);
        //线程池初始化
        threadExecutor.initialize();
        rsrcs.setThreadPool(tp);
        if((tp instanceof SimpleThreadPool) && threadsInheritInitalizersClassLoader)
            ((SimpleThreadPool)tp).setThreadsInheritContextClassLoaderOfInitializingThread(threadsInheritInitalizersClassLoader);
        tp.initialize();
        tpInited = true;
        rsrcs.setJobStore(js);
        for(int i = 0; i < plugins.length; i++)
            rsrcs.addSchedulerPlugin(plugins[i]);
        //新建QuartzScheduler
        qs = new QuartzScheduler(rsrcs, idleWaitTime, dbFailureRetry);
        qsInited = true;
	//初始化scheduler
        scheduler = instantiate(rsrcs, qs);
        if(jobFactory != null)
            qs.setJobFactory(jobFactory);
        for(int i = 0; i < plugins.length; i++)
            plugins[i].initialize(pluginNames[i], scheduler, loadHelper);

        for(int i = 0; i < jobListeners.length; i++)
            qs.getListenerManager().addJobListener(jobListeners[i], EverythingMatcher.allJobs());

        for(int i = 0; i < triggerListeners.length; i++)
            qs.getListenerManager().addTriggerListener(triggerListeners[i], EverythingMatcher.allTriggers());

        Object key;
        String val;
        for(Iterator i$ = schedCtxtProps.keySet().iterator(); i$.hasNext(); scheduler.getContext().put((String)key, val))
        {
            key = i$.next();
            val = schedCtxtProps.getProperty((String)key);
        }

        js.setInstanceId(schedInstId);
        js.setInstanceName(schedName);
        js.setThreadPoolSize(tp.getPoolSize());
        js.initialize(loadHelper, qs.getSchedulerSignaler());
        jrsf.initialize(scheduler);
        qs.initialize();
        getLog().info((new StringBuilder()).append("Quartz scheduler '").append(scheduler.getSchedulerName()).append("' initialized from ").append(propSrc).toString());
        getLog().info((new StringBuilder()).append("Quartz scheduler version: ").append(qs.getVersion()).toString());
        qs.addNoGCObject(schedRep);
        if(dbMgr != null)
            qs.addNoGCObject(dbMgr);
	//绑定scheduler到调度器仓库
        schedRep.bind(scheduler);
        return scheduler;//实际为QuartzScheduler
}
//初始化Scheduler
 protected Scheduler instantiate(QuartzSchedulerResources rsrcs, QuartzScheduler qs)
    {
        Scheduler scheduler = new StdScheduler(qs);
        return scheduler;
    }
   //解析quartz.properties配置文件属性
   private PropertiesParser cfg;
}

//调度器仓库

public class SchedulerRepository
{

    private SchedulerRepository()
    {
        schedulers = new HashMap();
    }
    //获取调度器仓库单例
    public static synchronized SchedulerRepository getInstance()
    {
        if(inst == null)
            inst = new SchedulerRepository();
        return inst;
    }
   //添加调度器到仓库
    public synchronized void bind(Scheduler sched)
        throws SchedulerException
    {
        if((Scheduler)schedulers.get(sched.getSchedulerName()) != null)
        {
            throw new SchedulerException((new StringBuilder()).append("Scheduler with name '").append(sched.getSchedulerName()).append("' already exists.").toString());
        } else
        {
            schedulers.put(sched.getSchedulerName(), sched);
            return;
        }
    }

    public synchronized boolean remove(String schedName)
    {
        return schedulers.remove(schedName) != null;
    }
   //根据调度器name，寻到对应的Scheduler
    public synchronized Scheduler lookup(String schedName)
    {
        return (Scheduler)schedulers.get(schedName);
    }

    public synchronized Collection lookupAll()
    {
        return Collections.unmodifiableCollection(schedulers.values());
    }

    private HashMap schedulers;//Hash<String,Scheduler>
    private static SchedulerRepository inst;
}

//标准执行器实际上是包装了QuartzScheduler

public class StdScheduler
    implements Scheduler
{

    public StdScheduler(QuartzScheduler sched)
    {
        this.sched = sched;
    }
        private QuartzScheduler sched;
}

//调度器

public class QuartzScheduler
    implements RemotableQuartzScheduler
{

    public QuartzScheduler(QuartzSchedulerResources resources, long idleWaitTime, long dbRetryInterval)
        throws SchedulerException
    {
    }
     private static String VERSION_MAJOR;
    private static String VERSION_MINOR;
    private static String VERSION_ITERATION;
    private QuartzSchedulerResources resources;
    private QuartzSchedulerThread schedThread;
    private ThreadGroup threadGroup;
    private SchedulerContext context;
    private ListenerManager listenerManager;
    private HashMap internalJobListeners;
    private HashMap internalTriggerListeners;
    private ArrayList internalSchedulerListeners;
    private JobFactory jobFactory;
    ExecutingJobsManager jobMgr;
    ErrorLogger errLogger;
    private SchedulerSignaler signaler;
    private Random random;
    private ArrayList holdToPreventGC;
    private boolean signalOnSchedulingChange;
    private volatile boolean closed;
    private volatile boolean shuttingDown;
    private boolean boundRemotely;
    private QuartzSchedulerMBean jmxBean;
    private Date initialStart;
    private final Timer updateTimer;
    private final Logger log = LoggerFactory.getLogger(getClass());
}

//QuartzScheduler的资源管理器

public class QuartzSchedulerResources
{
 public static final String CREATE_REGISTRY_NEVER = "never";
    public static final String CREATE_REGISTRY_ALWAYS = "always";
    public static final String CREATE_REGISTRY_AS_NEEDED = "as_needed";
    private String name;
    private String instanceId;
    private String threadName;
    private String rmiRegistryHost;
    private int rmiRegistryPort;
    private int rmiServerPort;
    private String rmiCreateRegistryStrategy;
    private ThreadPool threadPool;
    private JobStore jobStore;
    private JobRunShellFactory jobRunShellFactory;
    private List schedulerPlugins;
    private boolean makeSchedulerThreadDaemon;
    private boolean threadsInheritInitializersClassLoadContext;
    private String rmiBindName;
    private boolean jmxExport;
    private String jmxObjectName;
    private ManagementRESTServiceConfiguration managementRESTServiceConfiguration;
    private ThreadExecutor threadExecutor;
    private boolean runUpdateCheck;
    private long batchTimeWindow;
    private int maxBatchSize;
    private boolean interruptJobsOnShutdown;
    private boolean interruptJobsOnShutdownWithWait;
}

从StdSchedulerFactory的getDefaultScheduler方法可以看出与getScheduler相同
总结：
从以上代码分析中，看出StdSchedulerFactory获取执行器，首先从调度器仓库获取调度器，如果为空，则配置属性cfg，如果cfg为空则初始化属性文件，如果没有配置属性文件，则加载默认属性；然后初始化调度器（线程池，存储器，job，trriger监控器，JMX，及调度器仓库，如果存储器为JobStoreTX ，则初始化数据库信息）；从返回的调度器来看实际上就是QuartzScheduler