使用 java bean 获取 jsp 页面上的运行时异常

如何解决使用 java bean 获取 jsp 页面上的运行时异常

我正在处理一个 jsp Web 项目，但在浏览器上打开该项目时不断出现运行时错误。它编译和构建成功，我可以在浏览器上很好地查看项目的其他页面。所以我把它缩小到我的 index.jsp 页面。

<%@page contentType="text/html" pageEncoding="UTF-8"%>

<html>
    <head>
        <title>sessions</title>
        <Meta charset="UTF-8">
        <Meta http-equiv="Content-Type" content="text/html; charset=UTF-8">
        
    </head>
    <body>
        <jsp:useBean id = "currentUser" scope = "application" class = "beans.LoggedIn"> 
        </jsp:useBean>
        
    
    <form method="get" action="login.jsp">
    <button type="submit">Login Here!</button>
    </form>
        
        <br>
        
    <form method="get" action="register.jsp">
    <button type="submit">Register Here!</button>
    </form>    
        
    </body>
</html>

这是 beans.LoggedIn 类


package beans;



public class LoggedIn implements java.io.Serializable {
    private String email = null;
    private String name = null;
    private String colour = null;
    private String gender = null;
    
    public LoggedIn() {
    }
    
    public String getEmail(){
       return email;
    }
    public String getName(){
       return name;
    }
    public String getColour(){
       return colour;
    }
    public String getGender() {
        return gender;
    }
    public void setEmail(String email){
       this.email = email;
    }
    public void setName(String name){
       this.name = name;
    }
    public void setColour(String colour) {
        this.colour = colour;
    }
    public void setGender(String gender) {
        this.gender = gender;
    }
}

这是我得到的错误：

StandardWrapperValve[jsp]: Servlet.service() for servlet jsp threw exception
java.lang.RuntimeException: 
    at beans.LoggedIn.<init>(LoggedIn.java:1)
    at org.apache.jsp.index_jsp._jspService(index_jsp.java:77)
    at org.apache.jasper.runtime.HttpJspBase.service(HttpJspBase.java:70)
    at javax.servlet.http.HttpServlet.service(HttpServlet.java:750)
    at org.apache.jasper.servlet.JspServletWrapper.service(JspServletWrapper.java:370)
    at org.apache.jasper.servlet.JspServlet.serviceJspFile(JspServlet.java:432)
    at org.apache.jasper.servlet.JspServlet.service(JspServlet.java:336)
    at javax.servlet.http.HttpServlet.service(HttpServlet.java:750)
    at org.apache.catalina.core.StandardWrapper.service(StandardWrapper.java:1540)
    at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:217)
    at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:119)
    at org.apache.catalina.core.StandardPipeline.doInvoke(StandardPipeline.java:611)
    at org.apache.catalina.core.StandardPipeline.invoke(StandardPipeline.java:550)
    at com.sun.enterprise.web.WebPipeline.invoke(WebPipeline.java:75)
    at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:114)
    at org.apache.catalina.connector.CoyoteAdapter.doService(CoyoteAdapter.java:332)
    at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:199)
    at com.sun.enterprise.v3.services.impl.ContainerMapper$HttpHandlerCallable.call(ContainerMapper.java:439)
    at com.sun.enterprise.v3.services.impl.ContainerMapper.service(ContainerMapper.java:144)
    at org.glassfish.grizzly.http.server.HttpHandler.runService(HttpHandler.java:182)
    at org.glassfish.grizzly.http.server.HttpHandler.doHandle(HttpHandler.java:156)
    at org.glassfish.grizzly.http.server.HttpServerFilter.handleRead(HttpServerFilter.java:218)
    at org.glassfish.grizzly.filterchain.ExecutorResolver$9.execute(ExecutorResolver.java:95)
    at org.glassfish.grizzly.filterchain.DefaultFilterChain.executeFilter(DefaultFilterChain.java:260)
    at org.glassfish.grizzly.filterchain.DefaultFilterChain.executeChainPart(DefaultFilterChain.java:177)
    at org.glassfish.grizzly.filterchain.DefaultFilterChain.execute(DefaultFilterChain.java:109)
    at org.glassfish.grizzly.filterchain.DefaultFilterChain.process(DefaultFilterChain.java:88)
    at org.glassfish.grizzly.ProcessorExecutor.execute(ProcessorExecutor.java:53)
    at org.glassfish.grizzly.nio.transport.TCPNIOTransport.fireIOEvent(TCPNIOTransport.java:515)
    at org.glassfish.grizzly.strategies.AbstractIOStrategy.fireIOEvent(AbstractIOStrategy.java:89)
    at org.glassfish.grizzly.strategies.WorkerThreadioStrategy.run0(WorkerThreadioStrategy.java:94)
    at org.glassfish.grizzly.strategies.WorkerThreadioStrategy.access$100(WorkerThreadioStrategy.java:33)
    at org.glassfish.grizzly.strategies.WorkerThreadioStrategy$WorkerThreadRunnable.run(WorkerThreadioStrategy.java:114)
    at org.glassfish.grizzly.threadpool.AbstractThreadPool$Worker.doWork(AbstractThreadPool.java:569)
    at org.glassfish.grizzly.threadpool.AbstractThreadPool$Worker.run(AbstractThreadPool.java:549)
    at java.lang.Thread.run(Thread.java:748)