首先，我的课程：
用户
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();
}
}
RolesMap.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时，我有这样的异常：在ServletContext资源[/WEB-INF/classes/baseBeans.xml]中定义名称为'SessionFactory'的bean创建错误：init方法的调用失败;嵌套异常是org.hibernate.AnnotationException：mappedBy引用一个未知的目标实体属性：com.patpuc.model.User.rolesMap中的com.patpuc.model.RolesMap.users
但我不知道我做错了什么。有人可以帮我解决这个问题吗？
答案 0 :(得分：11)
默认情况下，在定义实体时，您可以使用基于字段或基于属性的访问，但不能同时使用两者。 “访问类型”基本上是指您的JPA提供程序查找确定实体状态的位置。如果使用字段访问，则会查看实例变量。如果使用属性访问，它会查看getter。
在您的情况下，您没有明确定义访问类型，因此JPA会通过查看您放置注释的位置来尝试解决它。我认为 Hibernate根据@Id注释的位置决定。由于您的@Id注释放在了getter上，因此Hibernate正在使用基于属性的RolesMap访问。
使用基于属性的访问权限时，您没有名为rUser的属性，因为您没有名为getRUser()的getter。
规范声明您不应该混合您的注释位置：
访问类型为的实体层次结构中的所有此类 以这种方式违约必须保持一致 对字段或属性的注释，例如单个， 一致的默认访问类型适用于层次结构
一致地放置注释，以便不存在歧义（例如，始终将注释放在实例变量上）。这将导致RolesMap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 ...
}