org.apache.jasper.JasperException: Unable to compile class for JSP

Posted 2020-10-31 zeroingToOne

在controller中跳转到.jsp文件时报错：Unable to compile class for JSP

严重: Servlet.service() for servlet jsp threw exception
org.apache.jasper.JasperException: Unable to compile class for JSP: 

An error occurred at line: [14] in the generated java file: [C:\\Users\\Admin\\workspace\\.metadata\\.plugins\\org.eclipse.wst.server.core\\tmp0\\work\\Catalina\\localhost\\SpringDemo\\org\\apache\\jsp\\WEB_002dINF\\contents\\front\\news_jsp.java]
Only a type can be imported. view.News resolves to a package

Stacktrace:
    at org.apache.jasper.compiler.DefaultErrorHandler.javacError(DefaultErrorHandler.java:103)
    at org.apache.jasper.compiler.ErrorDispatcher.javacError(ErrorDispatcher.java:366)
    at org.apache.jasper.compiler.JDTCompiler.generateClass(JDTCompiler.java:490)
    at org.apache.jasper.compiler.Compiler.compile(Compiler.java:379)
    at org.apache.jasper.compiler.Compiler.compile(Compiler.java:354)
    at org.apache.jasper.compiler.Compiler.compile(Compiler.java:341)
    org.apache.jasper.JspCompilationContext.compile(JspCompilationContext.java:662)
    org.apache.jasper.servlet.JspServletWrapper.service(JspServletWrapper.java:364)
    org.apache.jasper.servlet.JspServlet.serviceJspFile(JspServlet.java:395)
    org.apache.jasper.servlet.JspServlet.service(JspServlet.java:339)
    javax.servlet.http.HttpServlet.service(HttpServlet.java:731)
    org.apache.tomcat.websocket.server.WsFilter.doFilter(WsFilter.java:52)
    org.springframework.web.servlet.view.InternalResourceView.renderMergedOutputModel(InternalResourceView.java:168)
    org.springframework.web.servlet.view.AbstractView.render(AbstractView.java:303)
    org.springframework.web.servlet.DispatcherServlet.render(DispatcherServlet.java:1282)
    org.springframework.web.servlet.DispatcherServlet.processDispatchResult(DispatcherServlet.java:1037)
    org.springframework.web.servlet.DispatcherServlet.doDispatch(DispatcherServlet.java:980)
    org.springframework.web.servlet.DispatcherServlet.doService(DispatcherServlet.java:897)
    org.springframework.web.servlet.FrameworkServlet.processRequest(FrameworkServlet.java:970)
    org.springframework.web.servlet.FrameworkServlet.doGet(FrameworkServlet.java:861)
    javax.servlet.http.HttpServlet.service(HttpServlet.java:624)
    org.springframework.web.servlet.FrameworkServlet.service(FrameworkServlet.java:846)
    javax.servlet.http.HttpServlet.service(HttpServlet.java:731)
    org.apache.tomcat.websocket.server.WsFilter.doFilter(WsFilter.java:52)
    org.springframework.web.filter.CharacterEncodingFilter.doFilterInternal(CharacterEncodingFilter.java:197)
    org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:107)
note The full stack trace of the root cause is available in the Apache Tomcat/7.0.78 logs.

网上找的原因大多是
1. jdk和Tomcat版本不对应
2. javax.servlet.jar 和 javax.servlet.jsp.jar 等包重复
但之前的页面都能正常运行，只有这一个界面不能请求，猜想应该不是上述问题。然后发现.jsp文件没有被编译，如图，因此应该是jsp页面中有什么问题导致.jsp页面没有被编译。

后来受Stack Overflow的启发，这里说jsp中导入的.java文件时的格式问题，想到是不是自己.jsp引入了什么错误的文件，发现引入了一个不存在的.java文件：Domain.News.java，直接删了这个引用就好了。因为直接复制的之前的代码，忘了删除引用的文件

因为jsp本质是一个servlet。在第一次请求jsp时，jsp会被容器转译为Servlet源代码、自动编译为.class文件、载入.class文件，然后生成Servlet对象。