@ModelAttribute 註解（8）
- 2020 年 3 月 17 日
- 筆記
@ModelAttribute 注釋方法
@Controller @RequestMapping("/springmvc") public class TestController { /** * 運行流程：@ModelAttribute注釋的方法會在此controller每個方法執行前被執行 * 1. 執行 @ModelAttribute 修飾的方法：模擬資料庫取出行為，將user對象存儲到map中，鍵為 user * 2. 然後在渲染頁面時，模擬回顯數據，將model中的數據取出並顯示在頁面，並把表單的請求參數賦給User對象的對應屬性 * 3. sprinngMVC 最後把上述對象傳入目標方法的參數 * 要注意的是：在存入map時，map的鍵值要和被@RequestMapping("/testModelAttribute")修飾的目標方法入參類型的第一個字元串的字元串一致 * @param user * @return */ @RequestMapping("/testModelAttribute") public String testModelAttribute01(User user){ System.out.println("修改： " + user); return "success"; } /** * @ModelAttribute 標記的方法，會在每個目標方法執行之前被SpringMVC調用 * @param id * @param map */ @ModelAttribute public void testModelAttribute(@RequestParam(value = "id",required = false) Integer id,Map<String,Object> map){ if(id != null){ // 模擬從資料庫中獲取對象 User user = new User(1,"Tom","123456","[email protected]",12); System.out.println("從資料庫中獲取一個對象：" + user); map.put("user",user); } } }
public class User { private Integer id; private String username; private String password; private String email; private int age; private Address address; public void setUsername(String username) { this.username = username; } public String getUsername() { return username; } public void setPassword(String password) { this.password = password; } public String getPassword() { return password; } public void setEmail(String email) { this.email = email; } public String getEmail() { return email; } public void setAge(int age) { this.age = age; } public int getAge() { return age; } public void setAddress(Address address) { this.address = address; } public Address getAddress() { return address; } public void setId(Integer id) { this.id = id; } public Integer getId() { return id; } @Override public String toString() { return "User{" + "id=" + id + ", username='" + username + ''' + ", password='" + password + ''' + ", email='" + email + ''' + ", age=" + age + '}'; } public User(Integer id,String username, String password, String email, int age){ super(); this.username = username; this.password = password; this.email = email; this.age = age; this.id = id; } public User(){} }
<!-- 模擬修改操作 1. 原始數據：1，Tom，[email protected]，12 2. 密碼不能被修改 3. 表單回顯，模擬操作直接填寫對應的屬性值 --> <form action="/springmvc/testModelAttribute" method="post"> <input type="hidden" name="id" value="1"> username:<input type="text" name="username" value="Tom"> email:<input type="text" name="email" value="[email protected]"> age:<input type="text" name="age" value="12"> <input type="submit" name="Submit"> </form>
@ModelAttribute 注釋參數
@ModelAttribute("user") User user注釋方法參數，參數user的值來源於testModelAttribute03()方法中的model屬性。
@ModelAttribute("user") public User testModelAttribute03(){ return new User(1,"aa","123","[email protected]",12); } @RequestMapping("/testModelAttribute01") public String testModelAttribute04(@ModelAttribute("user") User user){ user.setUsername("bb"); return "success"; }
