mappedBy引用未知的目标实体属性-hibernate错误

Question

首先，我的课程：

使用者

package com.patpuc.model;

import java.util.List;

import javax.persistence.Column;
import javax.persistence.Entity;
import javax.persistence.Id;
import javax.persistence.OneToMany;
import javax.persistence.Table;
import com.patpuc.model.RolesMap;

@Entity
@Table(name = "users")
public class User {
    @Id
    @Column(name = "USER_ID", unique = true, nullable = false)
    private int user_id;
    @Column(name = "NAME", nullable = false)
    private String name;
    @Column(name = "SURNAME", unique = true, nullable = false)
    private String surname;
    @Column(name = "USERNAME_U", unique = true, nullable = false)
    private String username_u; // zamiast username
    @Column(name = "PASSWORD", unique = true, nullable = false)
    private String password;
    @Column(name = "USER_DESCRIPTION", nullable = false)
    private String userDescription;
    @Column(name = "AUTHORITY", nullable = false)
    private String authority = "ROLE_USER";
    @Column(name = "ENABLED", nullable = false)
    private int enabled;

    @OneToMany(mappedBy = "rUser")
    private List<RolesMap> rolesMap;

    public List<RolesMap> getRolesMap() {
        return rolesMap;
    }

    public void setRolesMap(List<RolesMap> rolesMap) {
        this.rolesMap = rolesMap;
    }

    /**
     * @return the user_id
     */
    public int getUser_id() {
        return user_id;
    }

    /**
     * @param user_id
     *            the user_id to set
     */
    public void setUser_id(int user_id) {
        this.user_id = user_id;
    }

    /**
     * @return the name
     */
    public String getName() {
        return name;
    }

    /**
     * @param name
     *            the name to set
     */
    public void setName(String name) {
        this.name = name;
    }

    /**
     * @return the surname
     */
    public String getSurname() {
        return surname;
    }

    /**
     * @param surname
     *            the surname to set
     */
    public void setSurname(String surname) {
        this.surname = surname;
    }

    /**
     * @return the username_u
     */
    public String getUsername_u() {
        return username_u;
    }

    /**
     * @param username_u
     *            the username_u to set
     */
    public void setUsername_u(String username_u) {
        this.username_u = username_u;
    }

    /**
     * @return the password
     */
    public String getPassword() {
        return password;
    }

    /**
     * @param password
     *            the password to set
     */
    public void setPassword(String password) {
        this.password = password;
    }

    /**
     * @return the userDescription
     */
    public String getUserDescription() {
        return userDescription;
    }

    /**
     * @param userDescription
     *            the userDescription to set
     */
    public void setUserDescription(String userDescription) {
        this.userDescription = userDescription;
    }

    /**
     * @return the authority
     */
    public String getAuthority() {
        return authority;
    }

    /**
     * @param authority
     *            the authority to set
     */
    public void setAuthority(String authority) {
        this.authority = authority;
    }

    /**
     * @return the enabled
     */
    public int getEnabled() {
        return enabled;
    }

    /**
     * @param enabled
     *            the enabled to set
     */
    public void setEnabled(int enabled) {
        this.enabled = enabled;
    }

    @Override
    public String toString() {
        StringBuffer strBuff = new StringBuffer();
        strBuff.append("id : ").append(getUser_id());
        strBuff.append(", name : ").append(getName());
        strBuff.append(", surname : ").append(getSurname());
        return strBuff.toString();
    }
}

角色地图。JAVA

package com.patpuc.model;

import javax.persistence.Column;
import javax.persistence.Entity;
import javax.persistence.Id;
import javax.persistence.JoinColumn;
import javax.persistence.ManyToOne;
import javax.persistence.Table;
import com.patpuc.model.User;

@Entity
@Table(name = "roles_map")
public class RolesMap {
    private int rm_id;
    private String username_a;
    private String username_l;
    //private String username_u;
    private String password;
    private int role_id;

    @ManyToOne
    @JoinColumn(name="username_u", nullable=false)
    private User rUser;
   public RolesMap(){

    }
    /**
     * @return the user
     */
    public User getUser() {
        return rUser;
    }
    /**
     * @param user the user to set
     */
    public void setUser(User rUser) {
        this.rUser = rUser;
    }


    @Id
    @Column(name = "RM_ID", unique = true, nullable = false)
    public int getRmId() {
        return rm_id;
    }
    public void setRmId(int rm_id) {
        this.rm_id = rm_id;
    }

    @Column(name = "USERNAME_A", unique = true)
    public String getUsernameA() {
        return username_a;
    }
    public void setUsernameA(String username_a) {
        this.username_a = username_a;
    }

    @Column(name = "USERNAME_L", unique = true)
    public String getUsernameL() {
        return username_l;
    }
    public void setUsernameL(String username_l) {
        this.username_l = username_l;
    }



    @Column(name = "PASSWORD", unique = true, nullable = false)
    public String getPassword() {
        return password;
    }
    public void setPassword(String password) {
        this.password = password;
    }

    @Column(name = "ROLE_ID", unique = true, nullable = false)
    public int getRoleId() {
        return role_id;
    }
    public void setRoleId(int role_id) {
        this.role_id = role_id;
    }

}

当我尝试在服务器上运行这个我有这样的异常：错误创建bean与名称'SessionFactory'定义在ServletContext资源[/WEB-INF/类/base Beans.xml]：调用init方法失败；嵌套的异常org.hibernate.注释异常：映射通过引用一个未知的目标实体属性：com.patpuc.model.ap.users在com.patpuc.model.User.rolesMap

但我不知道我做错了什么。谁能帮我解决这个问题吗？

Answer 1

默认情况下，定义实体时，可以使用基于字段的访问或基于属性的访问，但不能同时使用这两种访问。“访问类型”基本上是指您的JPA提供商希望确定实体状态的位置。如果使用字段访问，它会查看实例变量。如果使用了属性访问，它会查看getter。

在您的例子中，您没有明确定义访问类型，所以JPA试图通过查看您放置注释的位置来找出它。我认为Hibernate是根据@Id注释的位置来决定的。由于您的@Id注释被放置在一个getter上，所以Hibernate对角色映射使用基于属性的访问。

使用基于属性的访问，您没有名为rUser的属性，因为您没有名为getRUser（）的getter。

该规范规定，不应将注释的放置方式混为一谈：

实体层次结构中访问类型以这种方式默认的所有此类类在字段或属性上的注释位置必须一致，以便在层次结构中应用单一的、一致的默认访问类型

一致地放置注释，这样就不会有歧义（例如，总是将注释放在html" target="_blank">实例变量上）。这将导致对RoffMap的以下更改：

@Entity
@Table(name = "roles_map")
public class RolesMap {
    @Id
    @Column(name = "RM_ID", unique = true, nullable = false)
    private int rm_id;
    @Column(name = "USERNAME_A", unique = true)
    private String username_a;
    @Column(name = "USERNAME_L", unique = true)
    private String username_l;
    @Column(name = "PASSWORD", unique = true, nullable = false)
    private String password;
    @Column(name = "ROLE_ID", unique = true, nullable = false)
    private int role_id;
    @ManyToOne
    @JoinColumn(name="username_u", nullable=false)
    private User rUser;

    // ... constructor(s), getters/setters, etc ...
}