从servlet在jsp中填写文本字段数据
我有一个数据库中的数据,我希望一些文本字段来自数据库。我创建了一个从数据库获取数据的方法。我有一个open-account.jsp页面,其中有一个表单,其中的名字、姓氏和电子邮件已经从数据库中预先填充,因此我使用servlet中的get方法。当我尝试将数据从servlet发送到jsp页面时,字段为null。我认为它没有将数据从servlet传递到jsp,我不确定。这是我的密码: 数据库类:从servlet在jsp中填写文本字段数据,jsp,servlets,Jsp,Servlets,我有一个数据库中的数据,我希望一些文本字段来自数据库。我创建了一个从数据库获取数据的方法。我有一个open-account.jsp页面,其中有一个表单,其中的名字、姓氏和电子邮件已经从数据库中预先填充,因此我使用servlet中的get方法。当我尝试将数据从servlet发送到jsp页面时,字段为null。我认为它没有将数据从servlet传递到jsp,我不确定。这是我的密码: 数据库类: public static ArrayList getUsers() { Arr
public static ArrayList getUsers()
{
ArrayList<Users> userList = new ArrayList<>();
try
{
DBConnection.connectToDB();
String query = "SELECT * FROM userlogin";
stmt = DBConnection.conn.prepareStatement(query);
ResultSet rs = stmt.executeQuery();
while(rs.next())
{
Users user = new Users();
user.setFirstName(rs.getString("firstname"));
user.setLastName(rs.getString("lastname"));
user.setEmail(rs.getString("email"));
user.setUsername(rs.getString("username"));
user.setPassword(rs.getString("password"));
userList.add(user);
}
}
catch(Exception e)
{
System.out.println(e);
}
return userList;
}
publicstaticarraylistgetusers()
{
ArrayList userList=新的ArrayList();
尝试
{
DBConnection.connectToDB();
String query=“从用户登录中选择*”;
stmt=DBConnection.conn.prepareStatement(查询);
ResultSet rs=stmt.executeQuery();
while(rs.next())
{
用户=新用户();
user.setFirstName(rs.getString(“firstname”);
user.setLastName(rs.getString(“lastname”);
user.setEmail(rs.getString(“email”);
user.setUsername(rs.getString(“用户名”);
user.setPassword(rs.getString(“password”);
添加(用户);
}
}
捕获(例外e)
{
系统输出打印ln(e);
}
返回用户列表;
}
open-account.jsp
<!DOCTYPE html>
<html>
<head>
<title>Open Account</title>
</head>
<body>
<h3>Please fill in the details</h3>
<form name="openAccount" action="OpenAccount" method="GET">
<!-- in openaccount servlet, we will get the users info and fill some
of the forms below for them -->
First Name: <input type="text" name="firstname" value= <%= request.getAttribute("Users.getFirstName()") %> > <br/><br/>
Last Name: <input type="text" name="lastname"> <br/><br/>
Email: <input type="text" name="email"> <br/><br/>
</form>
<form name="chooseAccount" action="OpenAccount" method="POST">
Select the type of account:
<select name="accounttype">
<option>Checking</option>
<option>Saving</option>
<option>Money Market</option>
<option>Credit Card</option>
</select> <br/><br/>
Please check the box if everything above is complete:
Agree <input type="radio" name="agree" value="Agree">
Disagree <input type="radio" name="agree" value="Disagree">
<br/><br/>
<input type="submit" value="submit" name="Submit">
</form>
</body>
</html>
开户
请填写详细资料
名字:
姓氏:
电子邮件:
选择帐户类型:
检查
节省物
货币市场
信用卡
如果以上所有内容都已完成,请勾选此框:
同意
不同意
开放帐户服务器
@WebServlet("/OpenAccount")
public class OpenAccount extends HttpServlet
{
private static final long serialVersionUID = 1L;
protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException
{
ArrayList<Users> userList = DBConnection.getUsers();
request.setAttribute("Users", userList);
RequestDispatcher dispatcher = request.getRequestDispatcher("open-account.jsp");
dispatcher.forward(request, response);
}
protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException
{
}
}
@WebServlet(“/OpenAccount”)
公共类OpenAccount扩展了HttpServlet
{
私有静态最终长serialVersionUID=1L;
受保护的void doGet(HttpServletRequest请求,HttpServletResponse响应)抛出ServletException,IOException
{
ArrayList userList=DBConnection.getUsers();
setAttribute(“用户”,userList);
RequestDispatcher=request.getRequestDispatcher(“open account.jsp”);
转发(请求、响应);
}
受保护的void doPost(HttpServletRequest请求、HttpServletResponse响应)引发ServletException、IOException
{
}
}
- 为了从
中获取列表,您需要在jsp中执行强制转换请求
- 在jsp中,只需要一个
实例,而您的代码将传递User
的整个User
ArrayList
- 代码片段只是为了理解提取所需信息需要做什么
// make sure to import all required class Object users = request.getAttribute('Users'); if(null != users && users instanceof ArrayList){ ArrayList<User> userList = (ArrayList<User>)request.getAttribute('Users'); for(User user: userList){ out.println(user.getFirstName()); } } else { out.println("No user records found."); }
//确保导入所有必需的类 objectusers=request.getAttribute('users'); if(null!=用户和用户实例ArrayList){ ArrayList userList=(ArrayList)request.getAttribute('Users'); for(用户:userList){ out.println(user.getFirstName()); } }否则{ out.println(“未找到用户记录”); }
另外,使用jsp scriplets是不好的做法,您可以使用JSTL来代替。让我们看看您的jsp页面。似乎您只想显示用户配置文件而不是用户配置文件列表。因此,您应该修改代码,如下所示: 数据库类:
public static Users getUsers(String username)
{
Users user = new Users();
try
{
DBConnection.connectToDB();
String query = "SELECT * FROM userlogin where username=?";
stmt = DBConnection.conn.prepareStatement(query);
stmt.setString(1,username);
ResultSet rs = stmt.executeQuery();
while(rs.next())
{
user.setFirstName(rs.getString("firstname"));
user.setLastName(rs.getString("lastname"));
user.setEmail(rs.getString("email"));
user.setUsername(rs.getString("username"));
user.setPassword(rs.getString("password"));
}
}
catch(Exception e)
{
System.out.println(e);
}
return user;
}
open-account.jsp:
<!DOCTYPE html>
<html>
<head>
<title>Open Account</title>
</head>
<body>
<h3>Please fill in the details</h3>
<form name="chooseAccount" action="OpenAccount" method="POST">
<!-- in openaccount servlet, we will get the users info and fill some
of the forms below for them -->
First Name: <input type="text" name="firstname" value= <%= request.getAttribute("firstname") %> > <br/><br/>
Last Name: <input type="text" name="lastname" value= <%= request.getAttribute("lastname") %>> <br/><br/>
Email: <input type="text" name="email" value= <%= request.getAttribute("email") %>> <br/><br/>
Select the type of account:
<select name="accounttype">
<option>Checking</option>
<option>Saving</option>
<option>Money Market</option>
<option>Credit Card</option>
</select> <br/><br/>
Please check the box if everything above is complete:
Agree <input type="radio" name="agree" value="Agree">
Disagree <input type="radio" name="agree" value="Disagree">
<br/><br/>
<input type="submit" value="submit" name="Submit">
</form>
</body>
</html>
我修改了您的示例,并通过参考
如果你只是一个初学者,我强烈推荐你的系列
希望这有帮助
package com.javabycode;
import java.io.IOException;
import java.util.ArrayList;
import javax.servlet.RequestDispatcher;
import javax.servlet.ServletException;
import javax.servlet.annotation.WebServlet;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
@WebServlet("/OpenAccount")
public class OpenAccount extends HttpServlet
{
private static final long serialVersionUID = 1L;
protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException
{
Users users = DBConnection.getUsers();
request.setAttribute("firstname", users.getFirstName());
request.setAttribute("lastname", users.getLastName());
request.setAttribute("email", users.getEmail());
RequestDispatcher dispatcher = request.getRequestDispatcher("open-account.jsp");
dispatcher.forward(request, response);
}
protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException
{
// do something
//System.out.println(request.getAttribute("firstname"));
}
}