day14 tomcat 综合小案例中遇到的java.lang.classnotfoundexception问题
HTTP Status 500 – Internal Server Error
Type Exception Report
Message Servlet execution threw an exception
Description The server encountered an unexpected condition that prevented it from fulfilling the request.
Exception
javax.servlet.ServletException: Servlet execution threw an exception
org.apache.tomcat.websocket.server.WsFilter.doFilter(WsFilter.java:52)
Root Cause
java.lang.NoClassDefFoundError: org/springframework/dao/DataAccessException
com.cixa.web.servlet.LoginServlet.doPost(LoginServlet.java:27)
javax.servlet.http.HttpServlet.service(HttpServlet.java:661)
javax.servlet.http.HttpServlet.service(HttpServlet.java:742)
org.apache.tomcat.websocket.server.WsFilter.doFilter(WsFilter.java:52)
Root Cause
java.lang.ClassNotFoundException: org.springframework.dao.DataAccessException
org.apache.catalina.loader.WebappClassLoaderBase.loadClass(WebappClassLoaderBase.java:1308)
org.apache.catalina.loader.WebappClassLoaderBase.loadClass(WebappClassLoaderBase.java:1136)
com.cixa.web.servlet.LoginServlet.doPost(LoginServlet.java:27)
javax.servlet.http.HttpServlet.service(HttpServlet.java:661)
javax.servlet.http.HttpServlet.service(HttpServlet.java:742)
org.apache.tomcat.websocket.server.WsFilter.doFilter(WsFilter.java:52)
Note The full stack trace of the root cause is available in the server logs.
Apache Tomcat/8.5.31
解决：清除idea缓存
File-->Invalidate Cashes
检查jar包所在的lib是不是在web-inf下，多一个s或者-变成_都不行
感觉将来还会遇到很多lang问题，会慢慢记下来
