我在我的两个实体类User和Permission之间定义了多对多关系。用户具有用户名和countyId的主键组合，而我的Permission表具有正则整数ID。表UserPermission具有三个外键作为其主键：用户名，县名和权限ID。

由于这是一个旧数据库，因此我将没有机会进行Right Thing（™）并在User上创建一个整数主键。

我在User.class中定义了这样的多对多关系：

@ManyToMany(targetEntity=Permission.class, cascade={ CascadeType.PERSIST, CascadeType.MERGE } )
@JoinTable(name="tblUserPermission",
joinColumns = { @JoinColumn(name="username"), @JoinColumn(name="countyId") },
inverseJoinColumns = { @JoinColumn(name="permissionId") })
private Collection<Permission> permissions;

Permission.class这样说：

@ManyToMany( cascade = {CascadeType.PERSIST, CascadeType.MERGE}, mappedBy = "permissions", targetEntity = User.class )
private Collection<User> users;

我以为这是要走的路，但是当我启动使用Hibernate 3的Spring上下文时，我得到：

Caused by: org.hibernate.AnnotationException: A Foreign key refering com.mydomain.data.entities.User from com.mydomain.data.entities.Permission has the wrong number of column. should be 1

注释中我做错了什么？应该是2，而不是1。

更新：

Arthur建议我添加referencedColumnName，但这给了我一个新的例外：

Caused by: org.hibernate.AnnotationException: referencedColumnNames(username, countyId) of com.mydomain.data.entities.Permission.permissions referencing com.mydomain.data.entities.User not mapped to a single property

根据他的要求，请遵循以下代码：Permission.Class：

package com.mydomain.data.entities;

import java.io.Serializable;
import java.util.Collection;
import javax.persistence.*;
import org.hibernate.annotations.ForeignKey;

@Entity
@Table(name = "tblPermission")
public class Permission extends PublishableEntityImpl implements Serializable, Cloneable {

    private static final long serialVersionUID = 7155322069731920447L;

    @Id
    @Column(name = "PermissionId", length = 8, nullable = false)
    private String PermissionId = "";

    @ManyToOne(fetch=FetchType.LAZY)
    @JoinColumn(name = "CountyId", nullable = false)
    @ForeignKey(name="FK_CountyID")
    private County county;

    @Column(name = "Permission", nullable = true)
    private Integer permission = 1;

    @ManyToMany( cascade = {CascadeType.PERSIST, CascadeType.MERGE},
             mappedBy = "Permissions",
             targetEntity = Item.class )
    private Collection<Item> items;

    @ManyToMany( cascade = {CascadeType.PERSIST, CascadeType.MERGE},
             mappedBy = "Permissions",
             targetEntity = User.class )
    private Collection<User> users;

    /** Getters and Setters **/
}

和User.class

package com.mydomain.data.entities;

import java.util.*;
import java.io.Serializable;
import javax.persistence.*;
import org.hibernate.annotations.ForeignKey;
import org.hibernate.annotations.IndexColumn;
import org.springframework.security.core.GrantedAuthority;
import org.springframework.security.core.authority.GrantedAuthorityImpl;
import org.springframework.security.core.userdetails.UserDetails;

@Entity
@Table(name = "tblUser")
public class User extends PublishableEntityImpl implements Serializable, Cloneable {

    @Id
    @Column(name = "CountyId", nullable = false)
    private Integer countyId;

    @Id
    @Column(name = "Username", length = 25, nullable = false)
    private String username;

    @ManyToOne(fetch=FetchType.LAZY)
    @JoinColumn(name = "CountyId", nullable = false, insertable=false, updatable=false)
    @ForeignKey(name="FK_CountyID")
    private County county;

    @Column(name = "Name", length = 50, nullable = true)
    private String name;

    @Column(name = "Password", length = 30, nullable = true)
    private String password;

    @Column(name = "Role", nullable = false)
    private Integer role;

    @ManyToMany(targetEntity=Permission.class,
            cascade={ CascadeType.PERSIST, CascadeType.MERGE } )
    @JoinTable(name="tblUserPermission",
            joinColumns = { @JoinColumn(name="Username", referencedColumnName="Username"), @JoinColumn(name="CountyId", referencedColumnName="CountyId") },
            inverseJoinColumns = { @JoinColumn(name="PermissionId", referencedColumnName="PermissionId") })
   private Collection<Permission> permissions;

    @OneToMany(fetch=FetchType.LAZY, mappedBy="county")
    @IndexColumn(name="version")
    private List<Version> versions;

    /** Getters and setters **/
}

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