JSF EL表達式和Java bean

Question

我有一個JSF項目，我試圖創建一個登錄頁面，我設法從數據庫獲取用戶名和密碼並驗證它們，我的項目有一個Java bean，託管bean和DAO類，當用戶成功登錄時，我想打印您好先生
< h:outputLabel value="#{mBLogin.user.firstName}" />您好先生正在打印，但名稱不是，雖然當測試我的DAO類時，我打印名稱到控制檯沒有任何問題！有人可以建議我做錯了什麼嗎？

我的管理bean類：

@ManagedBean 
    @SessionScoped 
    public class MBLogin { 

     User user = new User(); 
     LoginDAO loginDao = new LoginDAO(); 

     public String validteStudent() { 
      boolean valid = loginDao.validateStudent(user.getUserId(), user.getPassword()); 
      if (valid) { 
       user.getFirstName(); 
       HttpSession session = SessionUtils.getSession(); 
       session.setAttribute("username", user); 
       return "admin"; 
      } else { 
       FacesContext.getCurrentInstance().addMessage(null, new FacesMessage(FacesMessage.SEVERITY_WARN, 
         "Incorrect Username and Passowrd", "Please enter correct username and Password")); 
       return "login"; 
      } 
     } 

     public void setUser(User user) { 
      this.user = user; 
     } 

     public User getUser() { 
      return user; 
     } 
    } 

我的Java Bean類：

@Table(name = "students_info") 
    public class User { 

     @Column(name = "std_record_id") 
     private int id; 

     @Column(name = "std_id") 
     private String userId; 

     @Column(name = "first_name") 
     private String firstName; 

     @Column(name = "last_name") 
     private String lastName; 

     @Column(name = "web_password") 
     private String password; 

     public int getId() { 
      return id; 
     } 

     public void setId(int id) { 
      this.id = id; 
     } 

     public String getFirstName() { 
      return firstName; 
     } 

     public void setFirstName(String firstName) { 
      this.firstName = firstName; 
     } 

     public String getLastName() { 
      return lastName; 
     } 

     public void setLastName(String lastName) { 
      this.lastName = lastName; 
     } 

     public String getUserId() { 
      return userId; 
     } 

     public void setUserId(String userId) { 
      this.userId = userId; 
     } 

     public String getPassword() { 
      return password; 
     } 

     public void setPassword(String password) { 
      this.password = password; 
     } 

    } 

我的DAO類：登錄頁面後

public class LoginDAO { 

     static JKPlainDataAccess dataAccess = JKDataSourceFactory.getPlainDataAccess(); 
     User user; 

     public boolean validateStudent(String userName, String password) { 

      user = dataAccess.executeQueryAsSingleObject(User.class, "id,userId,firstName,lastName,password", 
        "SELECT std_record_id, std_id, first_name, family_name, web_password From students_info WHERE std_id=? and web_password=?", 
        userName, password); 
      JK.print("getAllEmployeeRecords() : ", user); 
      if(user != null) { 
       System.out.println(user.getFirstName()); 
       System.out.println(user.getLastName()); 
       return true; 
      } 
      return false; 
     } 

     public static void main(String[] args) { 
      LoginDAO a = new LoginDAO(); 
      a.validateStudent("200663042001", "1234"); 
     } 

    } 

我XHTML頁面：

<ui:composition template="/WEB-INF/layouts/default.xhtml"> 
    <ui:define name="content"> 
    WELCOME Mr. <h:outputLabel value="#{mBLogin.user.firstName}" /> 
    AND <h:outputLabel value="#{mBLogin.user.lastName}" /> 
    </ui:define> 
</ui:composition> 

Answer 1

驗證時，你似乎把用戶作爲會話屬性，而不把它分配給Managed Bean的領域：

session.setAttribute("username", user); 

因此，無論其分配也與實例用戶變量或簡單地使用：

<ui:composition template="/WEB-INF/layouts/default.xhtml"> 
    <ui:define name="content"> 
    WELCOME Mr. <h:outputLabel value="#{username.firstName}" /> 
    AND <h:outputLabel value="#{username.lastName}" /> 
    </ui:define> 
</ui:composition> 

更新

我建議改變你的服務的方法：

public User validateStudent(..) 

，你實際上將返回，而不是在DAO它設置爲查詢用戶..

就這樣，你會改變ManagedBean方法：

public String validteStudent() { 
    User validatedUser = loginDao.validateStudent(user.getUserId(), user.getPassword()); 
    if (validatedUser != null) { 
      this.user = validatedUser; 
      HttpSession session = SessionUtils.getSession(); 
      session.setAttribute("username", user); 
     ....