[英]Why can't I retrieve an attribute from the Model but I'm able to from JSP?
我正在学习spring mvc,并了解Model和ModelAttribute的用法。 但是,我无法检索Model的属性,因此我求助于使用JSP param值。 我究竟做错了什么? 我使用@ModelAttribute("username") User user / user.username
检查模型是否仍然具有该属性的值,并确保足够。
调节器
package login.user;
import org.springframework.stereotype.Controller;
import org.springframework.ui.Model;
import org.springframework.web.bind.annotation.RequestMapping;
@Controller
public class LoginUser {
@RequestMapping("/")
public String showMenu()
{
return "menu";
}
@RequestMapping("login")
public String loginUser(Model model)
{
User newUser = new User();
model.addAttribute("user", newUser);
return "login-user";
}
@RequestMapping("processUser")
public String processUser(Model model)
{
Option newOption = new Option();
model.addAttribute("option", newOption);
return "process-login";
}
}
用户
package login.user;
public class User {
private String username;
private char password[];
public String getUsername() {
return username;
}
public void setUsername(String username) {
this.username = username;
}
public char[] getPassword() {
return password;
}
public void setPassword(char[] password) {
this.password = password;
}
}
登录-user.jsp
<%@ page language="java" contentType="text/html; charset=ISO-8859-1"
pageEncoding="ISO-8859-1"%>
<%@taglib uri="http://java.sun.com/jsp/jstl/core" prefix="c"%>
<%@ taglib prefix="form" uri="http://www.springframework.org/tags/form"%>
<!DOCTYPE html>
<html>
<head>
<link href="<c:url value="/resources/css/style.css" />" rel="stylesheet" type="text/css" />
<meta http-equiv="Content-Type" content="text/html; charset=ISO-8859-1">
<title>Login User</title>
</head>
<body>
<div>
<form:form action="processUser" modelAttribute="user">
<table>
<tr>
<td>Username:</td>
<td>
<form:input path="username" />
</td>
</tr>
<tr>
<td>Password:</td>
<td>
<form:input type="password" path="password" />
</td>
</tr>
<tr>
<td>
<input type="submit" name="Login" />
</td>
</tr>
</table>
</form:form>
</div>
</body>
</html>
过程的login.jsp
<%@ page language="java" contentType="text/html; charset=ISO-8859-1"
pageEncoding="ISO-8859-1"%>
<%@taglib uri="http://java.sun.com/jsp/jstl/core" prefix="c"%>
<%@ taglib prefix="form" uri="http://www.springframework.org/tags/form"%>
<!DOCTYPE html>
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=ISO-8859-1">
<title>Insert title here</title>
</head>
<body>
<form:form modelAttribute="option">
<h3>Welcome ${param.username}. Please choose an activity below</h3> <---- changed from ${user.username}
<div>
<form:select path="option">
<form:option value="Email" label="Email"></form:option>
<form:option value="Enter Recipe" label="Enter Recipe"></form:option>
<form:option value="Retrieve Recipe" label="Retrieve Recipe"></form:option>
</form:select>
</div>
</form:form>
</body>
</html>
弹簧模型数据存储在标准Java请求范围中。 如果尝试获取用户名,则需要再次将其添加到请求范围中。 因此,您可以编写如下的processUser
方法。
@RequestMapping("processUser")
public String processUser(@ModelAttribute("user") User user,Model model)
{
Option newOption = new Option();
// do stuff with user data
newOption.setUsername(user.getUsername());
model.addAttribute("option", newOption);
return "process-login";
}
因此,您应该能够在jsp中将其作为${option.username}
。
只需更改您的最后一个@RequestMapping
方法,如下所示:
@RequestMapping("processUser")
public String processUser(@ModelAttribute("user") User user, Model model)
{
Option newOption = new Option();
model.addAttribute("user", user);
model.addAttribute("option", newOption);
return "process-login";
}
现在在jsp中使用$ {user.username}。
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