有关于JSTL中org.apache.jasper.JasperException与javax.el.PropertyNotFoundException的错误解决方法
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org.apache.jasper.JasperException错误的解决方案
大家首先看一下我这个错误提示：
严重: Servlet.service() for servlet [jsp] in context with path [/AboutJSP] threw exception [The absolute uri: http://java.sun.com/jsp/jstl/core cannot be resolved in either web.xml or the jar files deployed with this application] with root cause
org.apache.jasper.JasperException: The absolute uri: http://java.sun.com/jsp/jstl/core cannot be resolved in either web.xml or the jar files deployed with this application
at org.apache.jasper.compiler.DefaultErrorHandler.jspError(DefaultErrorHandler.java:55)
at org.apache.jasper.compiler.ErrorDispatcher.dispatch(ErrorDispatcher.java:277)
at org.apache.jasper.compiler.ErrorDispatcher.jspError(ErrorDispatcher.java:75)
at org.apache.jasper.compiler.TagLibraryInfoImpl.generateTldResourcePath(TagLibraryInfoImpl.java:250)
at org.apache.jasper.compiler.TagLibraryInfoImpl.(TagLibraryInfoImpl.java:125)
at org.apache.jasper.compiler.Parser.parseTaglibDirective(Parser.java:421)
at org.apache.jasper.compiler.Parser.parseDirective(Parser.java:479)
at org.apache.jasper.compiler.Parser.parseElements(Parser.java:1435)
at org.apache.jasper.compiler.Parser.parse(Parser.java:139)
at org.apache.jasper.compiler.ParserController.doParse(ParserController.java:227)
at org.apache.jasper.compiler.ParserController.parse(ParserController.java:100)
at org.apache.jasper.compiler.Compiler.generateJava(Compiler.java:201)
at org.apache.jasper.compiler.Compiler.compile(Compiler.java:358)
at org.apache.jasper.compiler.Compiler.compile(Compiler.java:338)
at org.apache.jasper.compiler.Compiler.compile(Compiler.java:325)
at org.apache.jasper.JspCompilationContext.compile(JspCompilationContext.java:580)
at org.apache.jasper.servlet.JspServletWrapper.service(JspServletWrapper.java:363)
at org.apache.jasper.servlet.JspServlet.serviceJspFile(JspServlet.java:396)
at org.apache.jasper.servlet.JspServlet.service(JspServlet.java:340)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:729)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:292)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:207)
at org.apache.tomcat.websocket.server.WsFilter.doFilter(WsFilter.java:52)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:240)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:207)
at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:212)
at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:94)
at org.apache.catalina.authenticator.AuthenticatorBase.invoke(AuthenticatorBase.java:492)
at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:141)
at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:80)
at org.apache.catalina.valves.AbstractAccessLogValve.invoke(AbstractAccessLogValve.java:620)
at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:88)
at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:502)
at org.apache.coyote.http11.AbstractHttp11Processor.process(AbstractHttp11Processor.java:1152)
at org.apache.coyote.AbstractProtocol$AbstractConnectionHandler.process(AbstractProtocol.java:684)
at org.apache.tomcat.util.net.NioEndpoint$SocketProcessor.doRun(NioEndpoint.java:1539)
at org.apache.tomcat.util.net.NioEndpoint$SocketProcessor.run(NioEndpoint.java:1495)
at java.util.concurrent.ThreadPoolExecutor.runWorker(Unknown Source)
at java.util.concurrent.ThreadPoolExecutor$Worker.run(Unknown Source)
at org.apache.tomcat.util.threads.TaskThread$WrappingRunnable.run(TaskThread.java:61)
at java.lang.Thread.run(Unknown Source)
如果你能翻到这篇文章的话，说明你也遇到了这个问题。心里先不要着急，因为大家遇到的问题都异曲同工，但是Eclipse会报同一个错误。再看一下我的jsp文件,如下截图：
大家请看我画出的箭头，总有三个，这是对比在taglib标签中的uri字符串中空格问题。箭头一与箭头三的性质是相同的（此处指位置的性质，都是靠近结束的双引号），而箭头二是结束时的空格，那么这个问题的解决方案之一就是空格。
解决方法：
1. 首先查看一下箭头一所指的位置是否有空格，如果有空格就会报这种错误，而箭头二的位置有没有空格没什么关系，但是为了保险起见，还是不要的这个标签里面肆意留空格；
2. 可能是tomcat服务器版本的问题：详细请点击关于tomcat服务器版本问题导致报此错误的详解
3. 也有可能是没有导入jstl.jar包，在这里也要注意包的版本，jstl1.0以下版本不支持EL表达式，而1.1版本支持，我们要导的包有jsp这个关键字：详细请点击：有关于没有导入jstl.jar包的详细解释；这里也有一篇：https://blog.csdn.net/liu_yuan_kai/article/details/80268323
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javax.el.PropertyNotFoundException错误的解决方案
首先，我们来看一下我出现的这个错误，错误代码如下：
javax.el.PropertyNotFoundException: Property 'Id' not found on type com.itheima.stuManager.StuDao.Student
at javax.el.BeanELResolver$BeanProperties.get(BeanELResolver.java:269)
at javax.el.BeanELResolver$BeanProperties.access$300(BeanELResolver.java:221)
at javax.el.BeanELResolver.property(BeanELResolver.java:356)
at javax.el.BeanELResolver.getValue(BeanELResolver.java:95)
at org.apache.jasper.el.JasperELResolver.getValue(JasperELResolver.java:110)
at org.apache.el.parser.AstValue.getValue(AstValue.java:169)
at org.apache.el.ValueExpressionImpl.getValue(ValueExpressionImpl.java:190)
at org.apache.jasper.runtime.PageContextImpl.proprietaryEvaluate(PageContextImpl.java:943)
at org.apache.jsp.stu_005finfo_jsp._jspx_meth_c_005fforEach_005f0(stu_005finfo_jsp.java:189)
at org.apache.jsp.stu_005finfo_jsp._jspService(stu_005finfo_jsp.java:142)
at org.apache.jasper.runtime.HttpJspBase.service(HttpJspBase.java:70)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:729)
at org.apache.jasper.servlet.JspServletWrapper.service(JspServletWrapper.java:438)
at org.apache.jasper.servlet.JspServlet.serviceJspFile(JspServlet.java:396)
at org.apache.jasper.servlet.JspServlet.service(JspServlet.java:340)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:729)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:292)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:207)
at org.apache.tomcat.websocket.server.WsFilter.doFilter(WsFilter.java:52)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:240)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:207)
at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:212)
at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:94)
at org.apache.catalina.authenticator.AuthenticatorBase.invoke(AuthenticatorBase.java:492)
at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:141)
at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:80)
at org.apache.catalina.valves.AbstractAccessLogValve.invoke(AbstractAccessLogValve.java:620)
at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:88)
at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:502)
at org.apache.coyote.http11.AbstractHttp11Processor.process(AbstractHttp11Processor.java:1152)
at org.apache.coyote.AbstractProtocol$AbstractConnectionHandler.process(AbstractProtocol.java:684)
at org.apache.tomcat.util.net.NioEndpoint$SocketProcessor.doRun(NioEndpoint.java:1539)
at org.apache.tomcat.util.net.NioEndpoint$SocketProcessor.run(NioEndpoint.java:1495)
at java.util.concurrent.ThreadPoolExecutor.runWorker(Unknown Source)
at java.util.concurrent.ThreadPoolExecutor$Worker.run(Unknown Source)
at org.apache.tomcat.util.threads.TaskThread$WrappingRunnable.run(TaskThread.java:61)
at java.lang.Thread.run(Unknown Source)
根据提示信息，大家可能可以看出是Id这个属性在这个类中没有找到，那该怎么办呢？当然是检查属性名称与此处的名称是否一模一样，当然，也有例外，如果你在类中的属性名称是大写的，那在EL表达式中属性值要小写哦！
此错误的解决方案：
1.首先检测你所写的属性值是否与你此时在EL表达式中的名称一致，如果你的属性名称为首字母大写，例如我定义一个变量private int Id;但是在写EL表达式的时候必须写为${XXX.id}；一定不能写大写；还有，必须要有属性的set()和get()方法。EL实际使用的是反射机制，它会在电泳表达式时自己在前面加上"get" + 属性名称的首字母大写；关于更多具体的内部实现请点击这里
2.可能会涉及一些类型的转换；不过这个不会经常涉及。
写在最后，昨天晚上遇到第一个错误，找到了半夜两点多，心里还挺难受的。当知道错误竟然是一个空格时（是在结束的双英引号前面有个空格），真的好生气，毕竟找了这么久，但是最后还是解决了。这还是在编程的道路上第一次这么努力的找bug，加油吧！少年！共勉~