Tomcat releases the WEB Project JSP page and returns a null pointer exception.

When you access the JSP page, the following message is displayed:

HTTP status 500-
 
TypeException report
Message
Description The server encountered an internal error () that prevented it from fulfilling this request.
Exception
org.apache.jasper.JasperException: java.lang.NullPointerExceptionorg.apache.jasper.servlet.JspServletWrapper.handleJspException(JspServletWrapper.java:538)org.apache.jasper.servlet.JspServletWrapper.service(JspServletWrapper.java:370)org.apache.jasper.servlet.JspServlet.serviceJspFile(JspServlet.java:313)org.apache.jasper.servlet.JspServlet.service(JspServlet.java:260)javax.servlet.http.HttpServlet.service(HttpServlet.java:717)org.springframework.web.servlet.view.InternalResourceView.renderMergedOutputModel(InternalResourceView.java:238)org.springframework.web.servlet.view.AbstractView.render(AbstractView.java:250)org.springframework.web.servlet.DispatcherServlet.render(DispatcherServlet.java:1047)org.springframework.web.servlet.DispatcherServlet.doDispatch(DispatcherServlet.java:817)org.springframework.web.servlet.DispatcherServlet.doService(DispatcherServlet.java:719)org.springframework.web.servlet.FrameworkServlet.processRequest(FrameworkServlet.java:669)org.springframework.web.servlet.FrameworkServlet.doGet(FrameworkServlet.java:574)javax.servlet.http.HttpServlet.service(HttpServlet.java:617)javax.servlet.http.HttpServlet.service(HttpServlet.java:717)org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:70)org.springframework.web.filter.CharacterEncodingFilter.doFilterInternal(CharacterEncodingFilter.java:88)org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:76)
Root Cause
java.lang.NullPointerExceptionorg.apache.jsp.WEB_002dINF.pages.imagecheck.test_jsp._jspInit(test_jsp.java:22)org.apache.jasper.runtime.HttpJspBase.init(HttpJspBase.java:52)org.apache.jasper.servlet.JspServletWrapper.getServlet(JspServletWrapper.java:164)org.apache.jasper.servlet.JspServletWrapper.service(JspServletWrapper.java:340)org.apache.jasper.servlet.JspServlet.serviceJspFile(JspServlet.java:313)org.apache.jasper.servlet.JspServlet.service(JspServlet.java:260)javax.servlet.http.HttpServlet.service(HttpServlet.java:717)org.springframework.web.servlet.view.InternalResourceView.renderMergedOutputModel(InternalResourceView.java:238)org.springframework.web.servlet.view.AbstractView.render(AbstractView.java:250)org.springframework.web.servlet.DispatcherServlet.render(DispatcherServlet.java:1047)org.springframework.web.servlet.DispatcherServlet.doDispatch(DispatcherServlet.java:817)org.springframework.web.servlet.DispatcherServlet.doService(DispatcherServlet.java:719)org.springframework.web.servlet.FrameworkServlet.processRequest(FrameworkServlet.java:669)org.springframework.web.servlet.FrameworkServlet.doGet(FrameworkServlet.java:574)javax.servlet.http.HttpServlet.service(HttpServlet.java:617)javax.servlet.http.HttpServlet.service(HttpServlet.java:717)org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:70)org.springframework.web.filter.CharacterEncodingFilter.doFilterInternal(CharacterEncodingFilter.java:88)org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:76)
Note The full stack trace of the root cause is available in the Apache Tomcat/6.0.35 logs.
 
After Baidu checked the cause, is the project lib under the jsp-api.jar and tomcat under the jsp-api.jar conflict caused. Because I used a user library in my project that contains two packages: jsp-api.jar and servlet-api.jar, and then copied the two packages to webroot/lib at myeclips release, the two packages under Tomcat lib are already in conflict, which is the main cause of this error.
The solution is to edit the Custom User library and set the user library to system library, so that the two jar packages will not be automatically copied when published through myeclips.
You can also add a configuration file under tomcat_home/CONF/Catalina/to specify webroot to release the project to avoid unnecessary automatic copying.
Previously, the project was released in the latter way. Today, I suddenly tested a code, and then I was lazy to use the release button on myeclipse to publish it to the webapps directory of Tomcat. The result is that today's problem occurs, and it is strange that the Code is not easy to use. After several hours, all sorts of things cannot be understood. It turns out to be caused by jar package conflicts throughout the whole day.
Spring MVC is ready for use. You can access JSP. Code---#
 Apache Tomcat/6.0.35