大家好，我为用户创建了一个 jsp 页面，他们可以在其中更新其现有详细信息，并且提交时记录会在数据库中更新。
1.> 帐户详细信息.java
//Java Servlet program responsible for obtaining the user data and updating into database
package roseindia.net;
import java.io.*;
import java.sql.*;
import javax.servlet.RequestDispatcher;
import javax.servlet.ServletConfig;
import javax.servlet.ServletException;
import javax.servlet.annotation.WebServlet;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
/**
* Servlet implementation class Accountdetails
*/
@WebServlet("/Accountdetails")
public class Accountdetails extends HttpServlet {
private static final long serialVersionUID = 1L;
/**
* @see HttpServlet#HttpServlet()
*/
public Accountdetails() {
super();
// TODO Auto-generated constructor stub
}
/**
* @see HttpServlet#doGet(HttpServletRequest request, HttpServletResponse response)
*/
protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
// TODO Auto-generated method stub
System.out.println("Servlet is in the doGet method of account details");
}
/**
* @see HttpServlet#doPost(HttpServletRequest request, HttpServletResponse response)
*/
protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
// TODO Auto-generated method stub
System.out.println("Servlet is in the doPost method of account details");
response.setContentType("text/html");
PrintWriter pw = response.getWriter();
pw.println("<html>");
pw.println("<body>");
pw.println("<h1>Hello Servlet Post</h1>");
pw.println("</body>");
pw.println("</html>");
Connection conn=null;
String url="jdbc:mysql://localhost:3306/";
String dbName="userlogindb";
String driver="com.mysql.jdbc.Driver";
try{
String Fname = request.getParameter("fname");
String Mname = request.getParameter("mname");
String Lname = request.getParameter("lname");
String Uname = request.getParameter("username");
String Emailid = request.getParameter("emailid");
String Mobno = request.getParameter("mobno");
String Address = request.getParameter("address");
String Password1 = request.getParameter("password1");
String Password2 = request.getParameter("password2");
String ID = request.getParameter("id");
Class.forName(driver);
conn = DriverManager.getConnection(url+dbName,"root", "root");
String update="update registerutable set fname='"+Fname+"', mname='"+Mname+"', lname='"+Lname+"', username='"+Uname+"', emailid='"+Emailid+"', mobno='"+Mobno+"', address='"+Address+"', password1='"+Password1+"', password2='"+Password2+"' where id='"+ID+"' ";
System.out.println("The sql is " +update);
PreparedStatement pst = (PreparedStatement) conn.prepareStatement(update);
pst.setString(1,Fname);
pst.setString(2,Mname);
pst.setString(3,Lname);
pst.setString(4,Uname);
pst.setString(5,Emailid);
pst.setString(6,Mobno);
pst.setString(7,Address);
pst.setString(8,Password1);
pst.setString(9,Password2);
pst.setString(11,ID);
int i = pst.executeUpdate();
String msg=" ";
if(i!=0){
msg="User Updated";
pw.print(i);
pw.print("<font size='6' color=blue>" + msg + "</font>");
pw.print(" '"+Fname+"'");
}
else{
msg="failed to update the data";
pw.print("<font size='6' color=blue>" + msg + "</font>");
}
pw.close();
pst.close();
conn.close();
}
catch (Exception e){
e.printStackTrace();
}
}
}
2.> 成功.jsp
//JSP page which shows existing value and new value to be entered by user.
<form name="myaccountform" action="Accountdetails" method="post">
<table border="1">
<tr>
<td>First name:</td>
<%Object value11 = request.getAttribute("fname");%>
<td><%=value11%></td>
</tr>
<tr>
<td>Enter the new first name:</td>
<td><input type="text" name="fname" value=""></td>
</tr>
<tr>
<td>Middle name:</td>
<%Object value12 = request.getAttribute("mname");%>
<td><%=value12%></td>
</tr>
<tr>
<td>Enter the new middle name:</td>
<td><input type="text" name="mname" value=""></td>
</tr>
<tr>
<td>Last name:</td>
<%Object value13 = request.getAttribute("lname");%>
<td><%=value13%></td>
</tr>
<tr>
<td>Enter the new last name:</td>
<td><input type="text" name="lname" value=""></td>
</tr>
<tr>
<td>Username:</td>
<%Object value14 = request.getAttribute("uname");%>
<td><%=value14%></td>
</tr>
<tr>
<td>Enter new username:</td>
<td><input type="text" name="username" value=""></td>
</tr>
<tr>
<td>Email id:</td>
<%Object value15 = request.getAttribute("emailid");%>
<td><%=value15%></td>
</tr>
<tr>
<td>Enter new email id:</td>
<td><input type="text" name="emailid" value=""></td>
</tr>
<tr>
<td>Mobile number:</td>
<%Object value16 = request.getAttribute("mobno");%>
<td><%=value16%></td>
</tr>
<tr>
<td>Enter new mobile number:</td>
<td><input type="text" name="mobno" value=""></td>
</tr>
<tr>
<td>Address:</td>
<%Object value17 = request.getAttribute("address");%>
<td><%=value17%></td>
</tr>
<tr>
<td>Enter new address:</td>
<td><textarea rows="5" cols="15" name="address"></textarea></td>
</tr>
<tr>
<td>Old password:</td>
<%Object value18 = request.getAttribute("password1");%>
<td><%=value18%></td>
</tr>
<tr>
<td>Enter the new password:</td>
<td><input type="password" name="password1" value=""></td>
</tr>
<tr>
<td>Reenter the new password:</td>
<td><input type="password" name="password2" value=""></td>
</tr>
</table>
<input type="submit">
</form>
3.> web.xml
//mapping between servlet and jsp
<?xml version="1.0" encoding="UTF-8"?>
<web-app xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns="http://java.sun.com/xml/ns/javaee" xsi:schemaLocation="http://java.sun.com/xml/ns/javaee http://java.sun.com/xml/ns/javaee/web- app_3_0.xsd" id="WebApp_ID" version="3.0">
<display-name>LoginExample</display-name>
<welcome-file-list>
<welcome-file>index.html</welcome-file>
<welcome-file>index.htm</welcome-file>
<welcome-file>index.jsp</welcome-file>
<welcome-file>default.html</welcome-file>
<welcome-file>default.htm</welcome-file>
<welcome-file>default.jsp</welcome-file>
</welcome-file-list>
<servlet>
<description>Login Servlet</description>
<display-name>Login</display-name>
<servlet-name>Login</servlet-name>
<servlet-class>roseindia.net.Login</servlet-class>
</servlet>
<servlet-mapping>
<servlet-name>Login</servlet-name>
<url-pattern>/login</url-pattern>
</servlet-mapping>
<servlet>
<description>Servlet Example</description>
<display-name>ServletExample</display-name>
<servlet-name>ServletExample</servlet-name>
<servlet-class>servletexample.com.ServletExample</servlet-class>
</servlet>
<servlet-mapping>
<servlet-name>ServletExample</servlet-name>
<url-pattern>/register</url-pattern>
</servlet-mapping>
<servlet>
<description>Account Details</description>
<display-name>Accountdetails</display-name>
<servlet-name>Accountdetails</servlet-name>
<servlet-class>roseindia.net.Accountdetails</servlet-class>
</servlet>
<servlet-mapping>
<servlet-name>Accountdetails</servlet-name>
<url-pattern>/Accountdetails</url-pattern>
</servlet-mapping>
</web-app>
这里的问题是，当填写所有字段并单击提交时，它无法更新。
它进入其他部分显示未能更新数据。
当我 sys 输出时，它显示 sql 是
update registerutable set
fname='admin11', mname='admin11', lname='admin11', username='admin11',
emailid='admin', mobno='1111', address='admin', password1='admin',
password2='admin'
where id='null'
我也尝试过
String ID = request.getParameter("id");
to
int ID = Integer.parseInt(request.getParameter("id"));
但仍然无法更新。
请帮助我纠正，因为我现在不知道我错在哪里。
