血的教训(错误中成长！！)

1．严重: Servlet.service() for servlet default threw exception
java.lang.NoClassDefFoundError: com_cenqua_clover/CoverageRecorder
原因：clover与Struts2相冲突

2．严重: Exception sending context initialized event to listener instance of class org.springframework.web.context.ContextLoaderListener
org.springframework.beans.factory.BeanDefinitionStoreException: Parser configuration exception parsing XML from ServletContext resource [/WEB-INF/classes/ApplicationContext.xml]; nested exception is javax.xml.parsers.ParserConfigurationException: Unable to validate using XSD: Your JAXP provider [gnu.xml.dom.JAXPFactory@96cf11] does not support XML Schema. Are you running on Java 1.4 with Apache Crimson? Upgrade to Apache Xerces (or Java 1.5) for full XSD support.(这是原因spring与struts2里面的jar与jfreechart里的gnujaxp.jar相冲突.将gnujaxp.jar删除就OK了)
at org.springframework.beans.factory.xml.XmlBeanDefinitionReader.doLoadBeanDefinitions(XmlBeanDefinitionReader.java:412)
at org.springframework.beans.factory.xml.XmlBeanDefinitionReader.loadBeanDefinitions(XmlBeanDefinitionReader.java:342)
at org.springframework.beans.factory.xml.XmlBeanDefinitionReader.loadBeanDefinitions(XmlBeanDefinitionReader.java:310)
at org.springframework.beans.factory.support.AbstractBeanDefinitionReader.loadBeanDefinitions(AbstractBeanDefinitionReader.java:143)
at org.springframework.beans.factory.support.AbstractBeanDefinitionReader.loadBeanDefinitions(AbstractBeanDefinitionReader.java:178)
at org.springframework.beans.factory.support.AbstractBeanDefinitionReader.loadBeanDefinitions(AbstractBeanDefinitionReader.java:149)
at org.springframework.web.context.support.XmlWebApplicationContext.loadBeanDefinitions(XmlWebApplicationContext.java:124)
at org.springframework.web.context.support.XmlWebApplicationContext.loadBeanDefinitions(XmlWebApplicationContext.java:92)
at org.springframework.context.support.AbstractRefreshableApplicationContext.refreshBeanFactory(AbstractRefreshableApplicationContext.java:123)
at org.springframework.context.support.AbstractApplicationContext.obtainFreshBeanFactory(AbstractApplicationContext.java:423)
at org.springframework.context.support.AbstractApplicationContext.refresh(AbstractApplicationContext.java:353)
at org.springframework.web.context.ContextLoader.createWebApplicationContext(ContextLoader.java:255)
at org.springframework.web.context.ContextLoader.initWebApplicationContext(ContextLoader.java:199)
at org.springframework.web.context.ContextLoaderListener.contextInitialized(ContextLoaderListener.java:45)
at org.apache.catalina.core.StandardContext.listenerStart(StandardContext.java:3843)
at org.apache.catalina.core.StandardContext.start(StandardContext.java:4342)
at org.apache.catalina.core.ContainerBase.start(ContainerBase.java:1045)
at org.apache.catalina.core.StandardHost.start(StandardHost.java:719)
at org.apache.catalina.core.ContainerBase.start(ContainerBase.java:1045)
at org.apache.catalina.core.StandardEngine.start(StandardEngine.java:443)
at org.apache.catalina.core.StandardService.start(StandardService.java:516)
at org.apache.catalina.core.StandardServer.start(StandardServer.java:710)
at org.apache.catalina.startup.Catalina.start(Catalina.java:578)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(Unknown Source)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(Unknown Source)
at java.lang.reflect.Method.invoke(Unknown Source)
at org.apache.catalina.startup.Bootstrap.start(Bootstrap.java:288)
at org.apache.catalina.startup.Bootstrap.main(Bootstrap.java:413)
Caused by: javax.xml.parsers.ParserConfigurationException: Unable to validate using XSD: Your JAXP provider [gnu.xml.dom.JAXPFactory@96cf11] does not support XML Schema. Are you running on Java 1.4 with Apache Crimson? Upgrade to Apache Xerces (or Java 1.5) for full XSD support.
at org.springframework.beans.factory.xml.DefaultDocumentLoader.createDocumentBuilderFactory(DefaultDocumentLoader.java:102)
at org.springframework.beans.factory.xml.DefaultDocumentLoader.loadDocument(DefaultDocumentLoader.java:70)
at org.springframework.beans.factory.xml.XmlBeanDefinitionReader.doLoadBeanDefinitions(XmlBeanDefinitionReader.java:396)
... 28 more
Caused by: java.lang.IllegalArgumentException: http://java.sun.com/xml/jaxp/properties/schemaLanguage
at gnu.xml.dom.JAXPFactory.setAttribute(JAXPFactory.java:109)
at org.springframework.beans.factory.xml.DefaultDocumentLoader.createDocumentBuilderFactory(DefaultDocumentLoader.java:99)
... 30 more

3.在web.xml文件里 注: version=”2.5”里或更高版本  你直接将<taglib/>标签贴切到web.xml文件，它会报错.如我加入一段sitemesh标签
<taglib>
      <taglib-uri>sitemesh-page</taglib-uri>
<taglib-location>/WEB-INF/lib/sitemesh-page.tld</taglib-location>
    </taglib>
    <taglib>
      <taglib-uri>sitemesh-decorator</taglib-uri>
<taglib-location>/WEB-INF/lib/sitemesh-decorator.tld</taglib-location>
    </taglib>
须加上标签<jsp-config/>就OK
    <jsp-config>
    <taglib>
      <taglib-uri>sitemesh-page</taglib-uri>
<taglib-location>/WEB-INF/lib/sitemesh-page.tld</taglib-location>
    </taglib>
    <taglib>
      <taglib-uri>sitemesh-decorator</taglib-uri>
<taglib-location>/WEB-INF/lib/sitemesh-decorator.tld</taglib-locatio>
    </taglib>
</jsp-config>

4.在web.xml里，你加入一段<servlet/>标签一定要注意放对位置一段放在<filter-mapping>下面就OK了
5．java.lang.NoClassDefFoundError: com/lxc/dao/user/impl/TestLogBack
Caused by: java.lang.ClassNotFoundException: com.lxc.dao.user.impl.TestLogBack(main（）也不进,说找不到这个类,因为这个项目是maven构建的，maven有一个默认规定，你的java Build Path 必须指到/target/classes)这就OK了

6．严重: Exception sending context initialized event to listener instance of class org.springframework.web.context.ContextLoaderListener
org.springframework.beans.factory.BeanDefinitionStoreException: IOException parsing XML document from ServletContext resource [/WEB-INF/classes/ApplicationContext.xml]; nested exception is java.io.FileNotFoundException: Could not open ServletContext resource [/WEB-INF/classes/ApplicationContext.xml]

7．Exception in thread "main" java.lang.IllegalAccessError: tried to access field org.slf4j.impl.StaticLoggerBinder.SINGLETON from class org.slf4j.LoggerFactory  （导入了二个slf4j-api-1.5.6.jar与slf4j-api-1.5.6.jar不同版本冲突所至,删除一个就OK了）