jsp 后台报错日志； - Java / Web 开发

看不出到底是什么原因，请高手帮忙分析一下，报错日志和源文件如下：


HTTP Status 500 - 

--------------------------------------------------------------------------------

type Exception report

message 

description The server encountered an internal error () that prevented it from fulfilling this request.

exception 

org.apache.jasper.JasperException: javax.el.PropertyNotFoundException: Property 'id' not found on type java.lang.String
org.apache.jasper.servlet.JspServletWrapper.handleJspException(JspServletWrapper.java:522)
org.apache.jasper.servlet.JspServletWrapper.service(JspServletWrapper.java:416)
org.apache.jasper.servlet.JspServlet.serviceJspFile(JspServlet.java:337)
org.apache.jasper.servlet.JspServlet.service(JspServlet.java:266)
javax.servlet.http.HttpServlet.service(HttpServlet.java:803)
dao.UserM.doPost(UserM.java:30)
dao.UserM.doGet(UserM.java:22)
javax.servlet.http.HttpServlet.service(HttpServlet.java:690)
javax.servlet.http.HttpServlet.service(HttpServlet.java:803)


root cause 

javax.el.PropertyNotFoundException: Property 'id' not found on type java.lang.String
javax.el.BeanELResolver$BeanProperties.get(BeanELResolver.java:193)
javax.el.BeanELResolver$BeanProperties.access$400(BeanELResolver.java:170)
javax.el.BeanELResolver.property(BeanELResolver.java:279)
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