ModelAttribute注解的方法会在controller每个方法执行前自动执行
User.java
public class User {
private int id;
private String name;
public void setId(int id) {
this.id = id;
}
public void setName(String name) {
this.name = name;
}
public int getId() {
return id;
}
public String getName() {
return name;
}
}
用法1.void返回值的方法
HelloController.java
@Controller
public class HelloController {
@ModelAttribute
public void before(@RequestParam String name, Model model) {
model.addAttribute("myname", name);
}
@RequestMapping(value = "/sayhello")
public String sayhello() {
return "hello";
}
}
hello.jsp
<%@ page contentType="text/html;charset=UTF-8" language="java" %>
<%@ taglib uri="http://java.sun.com/jsp/jstl/core" prefix="c" %>
<html>
<head>
<title>hello</title>
</head>
<body>
hello,My name is ${myname}
</body>
</html>
浏览器运行http://localhost:8080/sayhello?name=xiaoming
显示 hello,My name is xiaoming
===
用法2.返回具体类的方法
HelloController.java
@Controller
public class HelloController {
@ModelAttribute
public User before() {
User user=new User();
user.setName("xiaoming");
return user;
}
@RequestMapping(value = "/sayhello2")
public String sayhello() {
return "hello2";
}
}
hello2.jsp
<%@ page contentType="text/html;charset=UTF-8" language="java" %>
<%@ taglib uri="http://java.sun.com/jsp/jstl/core" prefix="c" %>
<html>
<head>
<title>hello2</title>
</head>
<body>
hello,My name is ${user.name}
</body>
</html>
浏览器运行http://localhost:8080/sayhello2
显示 hello,My name is xiaoming
修改对象
@RequestMapping(value = "/sayhello2")
public String sayhello(User user) {//参数为User
user.setName("zhangsan");//修改
return "hello2";
}
浏览器运行http://localhost:8080/sayhello2
显示 hello,My name is zhangsan
指定对象名称
@RequestMapping(value = "/sayhello2")
public String sayhello(@ModelAttribute("myUser") User user) {//类为User,对象名称为myUser
user.setName("zhangsan");//修改
return "hello2";
}
hello2.jsp
<%@ page contentType="text/html;charset=UTF-8" language="java" %>
<%@ taglib uri="http://java.sun.com/jsp/jstl/core" prefix="c" %>
<html>
<head>
<title>hello2</title>
</head>
<body>
hello,My name is ${myUser.name}
</body>
</html>