spring整合mybatis的异常，求解决。。。
运行tomcat是，总是报错：查找了很多资料，没找到原因：

2012-08-28 14:33:49,531 >> ERROR >> main >> >> [org.springframework.web.context.ContextLoader] : Context initialization failed
org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'sqlSessionFactory' defined in class path resource [applicationContext.xml]: Invocation of init method failed; nested exception is org.springframework.core.NestedIOException: Failed to parse mapping resource: 'class path resource [SqlMapConfig.xml]'; nested exception is java.lang.RuntimeException: Error parsing Mapper XML. Cause: java.lang.NullPointerException
  at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.initializeBean(AbstractAutowireCapableBeanFactory.java:1455)
  at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.doCreateBean(AbstractAutowireCapableBeanFactory.java:519)
  at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.createBean(AbstractAutowireCapableBeanFactory.java:456)
  at org.springframework.beans.factory.support.AbstractBeanFactory$1.getObject(AbstractBeanFactory.java:294)
  at org.springframework.beans.factory.support.DefaultSingletonBeanRegistry.getSingleton(DefaultSingletonBeanRegistry.java:225)
  at org.springframework.beans.factory.support.AbstractBeanFactory.doGetBean(AbstractBeanFactory.java:291)
  at org.springframework.beans.factory.support.AbstractBeanFactory.getBean(AbstractBeanFactory.java:193)
  at org.springframework.beans.factory.support.DefaultListableBeanFactory.preInstantiateSingletons(DefaultListableBeanFactory.java:591)
  at org.springframework.context.support.AbstractApplicationContext.finishBeanFactoryInitialization(AbstractApplicationContext.java:918)
  at org.springframework.context.support.AbstractApplicationContext.refresh(AbstractApplicationContext.java:469)
  at org.springframework.web.context.ContextLoader.configureAndRefreshWebApplicationContext(ContextLoader.java:383)
  at org.springframework.web.context.ContextLoader.initWebApplicationContext(ContextLoader.java:283)
  at org.springframework.web.context.ContextLoaderListener.contextInitialized(ContextLoaderListener.java:111)
  at org.apache.catalina.core.StandardContext.listenerStart(StandardContext.java:4206)
  at org.apache.catalina.core.StandardContext.start(StandardContext.java:4705)
  at org.apache.catalina.core.ContainerBase.addChildInternal(ContainerBase.java:799)
  at org.apache.catalina.core.ContainerBase.addChild(ContainerBase.java:779)
  at org.apache.catalina.core.StandardHost.addChild(StandardHost.java:601)
  at org.apache.catalina.startup.HostConfig.deployDirectory(HostConfig.java:1079)
  at org.apache.catalina.startup.HostConfig.deployDirectories(HostConfig.java:1002)
  at org.apache.catalina.startup.HostConfig.deployApps(HostConfig.java:506)
  at org.apache.catalina.startup.HostConfig.start(HostConfig.java:1317)
  at org.apache.catalina.startup.HostConfig.lifecycleEvent(HostConfig.java:324)
  at org.apache.catalina.util.LifecycleSupport.fireLifec