【发布时间】：2016-01-13 11:21:06
【问题描述】：
此时代码出现错误
org.apache.catalina.core.StandardWrapperValve invoke SEVERE:
Servlet.service() for servlet [jsp] in context with path [/Work] threw exception [An exception occurred processing JSP page /Display.jsp at line 49
46:<td>
47: <%
48: String sql="select * from Patient ";
49: pstmt=con.prepareStatement(sql);
50: rs=pstmt.executeQuery();
51: while(rs.next()){
52: %>
Stacktrace:] 根本原因是 java.lang.NullPointerException
<!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=ISO-8859-1"> <title>Insert title here</title> </head>
<%@page import="java.sql.DriverManager"%>
<%@page import="java.sql.ResultSet"%>
<%@page import="java.sql.PreparedStatement"%>
<%@page import="java.sql.Connection"%>
<%@page import="com.connection.*"%> <body>
<%! Connection con=null;
PreparedStatement pstmt=null;
ResultSet rs=null;
public void init() {
try{
Connection con = ConnectionImplementation.wantConnection();
// Statement stmt= con.createStatement();
} catch (Exception e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
}
%>
<table>
<tr> <td>
<select name="PERSON_TYPE" id="PERSON_TYPE">
<option value="">SELECT</option>
<option value="Doctor">Doctor</option>
<option value="Nurse">Nurse</option>
<option value="Patient">Patient</option>
</select> </td>
</tr>
<tr> <td>
<% String sql="select * from Patient ";
pstmt=con.prepareStatement(sql);
rs=pstmt.executeQuery();
while(rs.next()){ %>
<tr><td> <%= rs.getInt(1)%></td>
<td><%= rs.getString(2) %></td>
<td><%= rs.getString(3) %></td>
<td><%= rs.getInt(4) %></td>
<td><%= rs.getString(5) %></td>
<td><%= rs.getString(6) %></td>
<td><%= rs.getString(7) %></td></tr>
<% } %> </table> </body> </html>
【问题讨论】：