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分享JSP页面在if条件语句中出现空指针异常，求大神解决！
原始代码：
userLogin.jsp
<%@ page language="java" contentType="text/html; charset=utf-8"
pageEncoding="utf-8"%>
<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=utf-8">
<title>蓝梦集团CRM系统的登录界面</title>
</head>
<body>
<form method = "post" action = "${pageContext.request.contextPath }/sessionTracking/responseUserLoginSession.jsp">
输入右边的认证码：<input type="text" name = "verifyCodeDigit" /> <br/>
用户类型：<select name = "type_User_Admin">
<option value = "1">前台用户</option>
<option value = "2">后台管理员</option>
</select><br/>
你的名称：<input type="text" name = "userName"/> <br />
你的密码：<input type="password" name = "userPassWord" /> <br />
<input type = "submit" value = "提交" name = "submitButton" onclick = "this.value = '正在提交请求，请等候'" />
<input type = "reset" value = "取消" />
</form>
</body>
</html>
跳转页面：
responsrUserLoginSession.jsp
<%@ page language="java" contentType="text/html; charset=utf-8"
pageEncoding="utf-8"%>
<%---@ page errorPage = "/errorDealAll/showSystemError.jsp" --%>
<jsp:useBean id="oneUserInfo" scope = "page" class = "com.J2EE_CH2.vo.UserInfoBaseVO"/>
<jsp:setProperty property="userName" name="oneUserInfo" param = "userName"/>
<jsp:setProperty property="userPassWord" name="oneUserInfo" param = "userPsaaWord"/>
<jsp:setProperty property="type_User_Admin" name="oneUserInfo" param = "type_User_Admin"/>
<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=utf-8">
<title>响应用户登陆界面Session</title>
</head>
<body>
<%!
String targetPage = null;
RequestDispatcher oneRequestDispatcher = null;
%>
<%
request.setCharacterEncoding("utf-8");
if(oneUserInfo.getUserName().equals("yang")&&oneUserInfo.getUserPassWord().equals("1234")){
targetPage = "/sessionTracking/userManage/showOneOnlineUserInfoS.jsp";
request.setAttribute("userNameString", oneUserInfo.getUserName());
session.setAttribute("oneUserInfoVO", oneUserInfo);
}else{
targetPage = "/sessionTracking/errorDeal/showWebAppErrorS.jsp";
request.setAttribute("errorText", "登陆失败！并且你的用户名是： " + oneUserInfo.getUserName());
session.setAttribute("oneUserInfoVO", null);
}
oneRequestDispatcher = request.getRequestDispatcher(targetPage);
oneRequestDispatcher.forward(request, response);
%>
</body>
</html>
出现错误如下：
您的JSP页面发生了异常错误。 错误信息如下：
null
Stack Track is: java.lang.NullPointerException
at org.apache.jsp.sessionTracking.responseUserLoginSession_jsp._jspService(responseUserLoginSession_jsp.java:149) at org.apache.jasper.runtime.HttpJspBase.service(HttpJspBase.java:70) at javax.servlet.http.HttpServlet.service(HttpServlet.java:742) at org.apache.jasper.servlet.JspServletWrapper.service(JspServletWrapper.java:443) at org.apache.jasper.servlet.JspServlet.serviceJspFile(JspServlet.java:385) at org.apache.jasper.servlet.JspServlet.service(JspServlet.java:329) at javax.servlet.http.HttpServlet.service(HttpServlet.java:742) at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:231) at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:166) at org.apache.tomcat.websocket.server.WsFilter.doFilter(WsFilter.java:52) at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:193) at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:166) at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:198) at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:96) at org.apache.catalina.authenticator.AuthenticatorBase.invoke(AuthenticatorBase.java:478) at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:140) at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:80) at org.apache.catalina.valves.AbstractAccessLogValve.invoke(AbstractAccessLogValve.java:624) at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:87) at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:342) at org.apache.coyote.http11.Http11Processor.service(Http11Processor.java:799) at org.apache.coyote.AbstractProcessorLight.process(AbstractProcessorLight.java:66) at org.apache.coyote.AbstractProtocol$ConnectionHandler.process(AbstractProtocol.java:868) at org.apache.tomcat.util.net.NioEndpoint$SocketProcessor.doRun(NioEndpoint.java:1455) at org.apache.tomcat.util.net.SocketProcessorBase.run(SocketProcessorBase.java:49) at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1149) at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:624) at org.apache.tomcat.util.threads.TaskThread$WrappingRunnable.run(TaskThread.java:61) at java.lang.Thread.run(Thread.java:748)
userLogin.jsp
<%@ page language="java" contentType="text/html; charset=utf-8"
pageEncoding="utf-8"%>
<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=utf-8">
<title>蓝梦集团CRM系统的登录界面</title>
</head>
<body>
<form method = "post" action = "${pageContext.request.contextPath }/sessionTracking/responseUserLoginSession.jsp">
输入右边的认证码：<input type="text" name = "verifyCodeDigit" /> <br/>
用户类型：<select name = "type_User_Admin">
<option value = "1">前台用户</option>
<option value = "2">后台管理员</option>
</select><br/>
你的名称：<input type="text" name = "userName"/> <br />
你的密码：<input type="password" name = "userPassWord" /> <br />
<input type = "submit" value = "提交" name = "submitButton" onclick = "this.value = '正在提交请求，请等候'" />
<input type = "reset" value = "取消" />
</form>
</body>
</html>
跳转页面：
responsrUserLoginSession.jsp
<%@ page language="java" contentType="text/html; charset=utf-8"
pageEncoding="utf-8"%>
<%---@ page errorPage = "/errorDealAll/showSystemError.jsp" --%>
<jsp:useBean id="oneUserInfo" scope = "page" class = "com.J2EE_CH2.vo.UserInfoBaseVO"/>
<jsp:setProperty property="userName" name="oneUserInfo" param = "userName"/>
<jsp:setProperty property="userPassWord" name="oneUserInfo" param = "userPsaaWord"/>
<jsp:setProperty property="type_User_Admin" name="oneUserInfo" param = "type_User_Admin"/>
<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=utf-8">
<title>响应用户登陆界面Session</title>
</head>
<body>
<%!
String targetPage = null;
RequestDispatcher oneRequestDispatcher = null;
%>
<%
request.setCharacterEncoding("utf-8");
if(oneUserInfo.getUserName().equals("yang")&&oneUserInfo.getUserPassWord().equals("1234")){
targetPage = "/sessionTracking/userManage/showOneOnlineUserInfoS.jsp";
request.setAttribute("userNameString", oneUserInfo.getUserName());
session.setAttribute("oneUserInfoVO", oneUserInfo);
}else{
targetPage = "/sessionTracking/errorDeal/showWebAppErrorS.jsp";
request.setAttribute("errorText", "登陆失败！并且你的用户名是： " + oneUserInfo.getUserName());
session.setAttribute("oneUserInfoVO", null);
}
oneRequestDispatcher = request.getRequestDispatcher(targetPage);
oneRequestDispatcher.forward(request, response);
%>
</body>
</html>
出现错误如下：
您的JSP页面发生了异常错误。 错误信息如下：
null
Stack Track is: java.lang.NullPointerException
at org.apache.jsp.sessionTracking.responseUserLoginSession_jsp._jspService(responseUserLoginSession_jsp.java:149) at org.apache.jasper.runtime.HttpJspBase.service(HttpJspBase.java:70) at javax.servlet.http.HttpServlet.service(HttpServlet.java:742) at org.apache.jasper.servlet.JspServletWrapper.service(JspServletWrapper.java:443) at org.apache.jasper.servlet.JspServlet.serviceJspFile(JspServlet.java:385) at org.apache.jasper.servlet.JspServlet.service(JspServlet.java:329) at javax.servlet.http.HttpServlet.service(HttpServlet.java:742) at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:231) at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:166) at org.apache.tomcat.websocket.server.WsFilter.doFilter(WsFilter.java:52) at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:193) at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:166) at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:198) at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:96) at org.apache.catalina.authenticator.AuthenticatorBase.invoke(AuthenticatorBase.java:478) at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:140) at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:80) at org.apache.catalina.valves.AbstractAccessLogValve.invoke(AbstractAccessLogValve.java:624) at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:87) at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:342) at org.apache.coyote.http11.Http11Processor.service(Http11Processor.java:799) at org.apache.coyote.AbstractProcessorLight.process(AbstractProcessorLight.java:66) at org.apache.coyote.AbstractProtocol$ConnectionHandler.process(AbstractProtocol.java:868) at org.apache.tomcat.util.net.NioEndpoint$SocketProcessor.doRun(NioEndpoint.java:1455) at org.apache.tomcat.util.net.SocketProcessorBase.run(SocketProcessorBase.java:49) at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1149) at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:624) at org.apache.tomcat.util.threads.TaskThread$WrappingRunnable.run(TaskThread.java:61) at java.lang.Thread.run(Thread.java:748)
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