0

我正在使用 EJB、JPA 和 JSF 制作一个简单的登录 Web 应用程序。我有一个login.xhtml带有传递 aUserName和Passwordinto的表单的页面LoginJSFBean，它调用我的 EJB 方法LoginBean.validate来查找 MySQL 数据库。如果凭据有效，它会设置customerIdin的值LoginJSFBean并加载欢迎页面。我正在尝试将其注入LoginJSFBean到我的CustomerJSFBeanvia@ManagedProperty中，这样我就可以保留 的值，customerId以便创建具有Customer该 的对象id。但是，我不断收到以下错误：

javax.servlet.ServletException: Cannot invoke "bean.LoginJSFBean.getCustomerId()" because "this.loginJSFBean" is null

这是我的代码：

登录.xhtml：

<html lang="en" xmlns="http://www.w3.org/1999/xhtml"
    xmlns:f="http://xmlns.jcp.org/jsf/core"
    xmlns:ui="http://xmlns.jcp.org/jsf/facelets"
    xmlns:h="http://xmlns.jcp.org/jsf/html">
<head>
<title>Login</title>
</head>
<body>
    <h2>Login</h2>
    <h:outputText value="#{LoginBean.login.errorMsg}"
        rendered="#{LoginBean.login.errorMsg != null}" style="color:red;" />
    <h:form> 
        User Name: <h:inputText id="userName" value="#{LoginBean.login.userName}"/><br /> 
        Password: <h:inputSecret id="password" value="#{LoginBean.login.password}"/><br />
        <h:commandButton value="Submit" action="#{LoginBean.validate}" />
    </h:form>
</body>
</html>

欢迎.xhtml：

<!DOCTYPE html>
<html xmlns="http://www.w3.org/1999/xhtml"
    xmlns:f="http://java.sun.com/jsf/core"
    xmlns:h="http://java.sun.com/jsf/html">
<head>
<title>Insert title here</title>
</head>
<body>
    <h2>Welcome <h:outputLabel class="successText" value="#{CustomerBean.customer.id}"/> !</h2>
    You are successfully logged in
</body>
</html>

登录JSFBean.java：

package bean;

import javax.ejb.EJB;
import javax.faces.bean.ManagedBean;
import javax.faces.bean.SessionScoped;

import dto.LoginDTO;
import ejb.LoginBeanRemote;

@ManagedBean(name = "LoginBean", eager = true)
@SessionScoped
public class LoginJSFBean {
    
    private LoginDTO login = new LoginDTO();
    
    private int customerId;
    
    @EJB
    LoginBeanRemote loginBean;
        
    public LoginDTO getLogin() {
        return login;
    }

    public void setLogin(LoginDTO login) {
        this.login = login;
    }

    public int getCustomerId() {
        return customerId;
    }

    public void setCustomerId(int customerId) {
        this.customerId = customerId;
    }
    
    public String validate() {
        if (loginBean.validate(login.getUserName(), login.getPassword())) {
            login.setErrorMsg(null);
            setCustomerId(loginBean.getCustomerId(login.getUserName()));
            return "welcome";
        } else {
            login.setErrorMsg("Invalid user id or password. Please try again");
            return null;
        }
    }
}

客户JSFBean.java：

package bean;

import java.util.List;

import javax.ejb.EJB;
import javax.faces.bean.ManagedBean;
import javax.faces.bean.ManagedProperty;
import javax.faces.bean.SessionScoped;
import dto.CustomerDTO;
import ejb.CustomerBeanRemote;

@ManagedBean(name = "CustomerBean", eager = true)
@SessionScoped
public class CustomerJSFBean {
    
    @ManagedProperty(value = "#{LoginBean}")
    private LoginJSFBean loginJSFBean;

    private CustomerDTO customer = new CustomerDTO(loginJSFBean.getCustomerId());
    
    @EJB
    CustomerBeanRemote customerBean;

    public CustomerDTO getCustomer() {
        return customer;
    }

    public void setCustomer(CustomerDTO customer) {
        this.customer = customer;
    }
    
    public LoginJSFBean getLoginJSFBean() {
        return loginJSFBean;
    }

    public void setLoginJSFBean(LoginJSFBean loginJSFBean) {
        this.loginJSFBean = loginJSFBean;
    }
    
    public List<CustomerDTO> getCustomers() {
        return customerBean.getCustomers();
    }
}

我觉得这很奇怪，因为如果我CustomerJSFBean.loginJSFBean.customerId从我的welcome.xhtml页面中引用它，它会正确显示customerId并且不会抛出任何错误，这表明注入loginJSFBean的不是null. 但是当我尝试从CustomerJSFBean它声称的内部进行相同的引用loginJSFBean时null。这与 JSF 各个部分的执行顺序有关吗？你可能会说，我对这一切都很陌生！

4

0 回答 0