Question

我需要有关Java中简单servlet的帮助。我在HTML文件中有一个登录表单（电子邮件和密码字段），一个Java servlet和一个用于登录女巫的实用程序，如果数据库中存在一对使用相同电子邮件和密码的夫妇，则将对其进行检查。运行该程序，查询中出现语法错误，错误提示“用户未映射”。我认为这是一个虚拟错误，有人可以帮我吗？

这里是模型。用户类

import javax.persistence.Column;
import javax.persistence.Entity;
import javax.persistence.GeneratedValue;
import javax.persistence.GenerationType;
import javax.persistence.Id;
import javax.persistence.Table;
import javax.persistence.UniqueConstraint;

@Entity
@Table( name = "USERS",
        uniqueConstraints = {@UniqueConstraint(columnNames = {"email"})})

public class User {
    @Id
    @GeneratedValue(strategy = GenerationType.IDENTITY)
    @Column(name="user_id", nullable=false, unique=true)
    private int id;

    @Column(name="firstName", length=40, nullable=false)
    private String firstName;

    @Column(name="lastname", length=40, nullable=false)
    private String lastName;

    @Column(name="email", length=40, nullable=false)
    private String email;

    @Column(name="password", length=40, nullable=false)
    private String password;

    public User(String firstName, String lastName, String email, String password){
        this.firstName = firstName;
        this.lastName = lastName;
        this.email = email;
        this.password = password;
    }

    public int getId(){
        return this.id;
    }

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

    public String getFirstName(){
        return this.firstName;
    }

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

    public String getLastName(){
        return this.lastName;
    }

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

    public String getEmail(){
        return this.email;
    }

    public void setEmail(String email){
        this.email = email;
    }

    public String getPassword(){
        return this.password;
    }

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

这里是实用程序。LoginDao类

public static boolean validateCredentials(String email, String password){
        Session session = DbService.getSession();

        session.beginTransaction();

        Query query = session.createQuery
                ("from Users u where u.email=:email and u.password=:password");

        query.setParameter("email", email);
        query.setParameter("password", password);

        List list=query.list();
                ...

这是我的LoginServlet doPost（）方法：

protected void doPost(HttpServletRequest request, HttpServletResponse response) 
            throws ServletException, IOException {  
        String email = request.getParameter("email");  
        String password = request.getParameter("password");

        if(LoginDao.validateCredentials(email, password)){
            RequestDispatcher view = request.getRequestDispatcher("SigninSuccess.jsp");
            view.forward(request, response);
        }
        else{  
            RequestDispatcher rd=request.getRequestDispatcher("index.html");  
            rd.include(request,response);  
        }  
    }

在这里signin.html表单文件

<form method="POST" action="LoginServlet">
            <p>
                <label for="fname">E-mail</label>
                <input type="text" name="email" placeholder="e-mail">
            </p>
            <p>
                <label for="lname">Password</label>
                <input type="password" name="password" placeholder="password">
            </p>        
            <input type="submit" value="Login">
            <p class="message">Not registered? <a href="./signup.html">Create an account</a></p>
        </form>

这是错误：

未映射用户[从用户u，其中u.email =：email和p.password =：password] 在org.hibernate.internal.ExceptionConverterImpl.convert（ExceptionConverterImpl.java:133）在org.hibernate.internal.ExceptionConverterImpl.convert（ExceptionConverterImpl.java:157） ...

Answer 1

这里您正在使用数据库中的表名（用户）创建Query-

Query query = session.createQuery
                ("from Users u where u.email=:email and u.password=:password");

这就是为什么您得到此错误。您需要使用实体名称-User-

Query query = session.createQuery
                ("from User u where u.email=:email and u.password=:password");

HQL期望您正在使用Java类名和Java属性名。您还必须注意使用的是javax.persistence.Entity而不是org.hibernate.annotations.Entity

Answer 2

Razib为您提供了正确的答案，告诉您在查询中使用User而不是Users。如果仍然遇到相同的错误，则可能仅是因为Hibernate尚未找到@Entity类。

请运行以下代码并响应输出。

sessionFactory.getConfiguration()
                .getClassMappings()
                .forEachRemaining(pc -> System.out.println(pc.getEntityName() + "\t" + pc.getTable().getName()));

提示：要获取sessionFactory，只需将其自动连接到服务或dAO中即可：

@Autowired
private LocalSessionFactoryBean sessionFactory;

Answer 3

终于我解决了我的问题。我忘记在LoginDao类的配置中添加config.addAnnotatedClass(model.User.class);。谢谢大家。

表未映射

3 个答案: