hibernate 多对多关系在mysql、oracle中的不同

中东 — Mon, 11 Jun 2007 15:19:00 GMT

用户（User）与角色（Role）多对多关系（UserRole）
下面是表的代码（配置为annotation）
User：

package sub;
import java.io.Serializable;
import java.util.Set;
import javax.persistence.Entity;
import javax.persistence.GeneratedValue;
import javax.persistence.Id;
import javax.persistence.JoinColumn;
import javax.persistence.JoinTable;
import javax.persistence.ManyToMany;
@Entity
public class User implements Serializable
{
    /**
     *
     */
    private static final long serialVersionUID = 1L;
    private Long id;
    private Set roles;
    @Id
    @GeneratedValue
    public Long getId()
    {
        return id;
    }
    public void setId(Long id)
    {
        this.id = id;
    }
    @ManyToMany
    @JoinTable(name="UserRole",joinColumns={@JoinColumn(name="user_ID")},inverseJoinColumns={@JoinColumn(name="role_ID")})
    public Set getRoles()
    {
        return roles;
    }
    public void setRoles(Set roles)
    {
        this.roles = roles;
    }
}

Role：

package sub;
import java.io.Serializable;
import java.util.Set;
import javax.persistence.Entity;
import javax.persistence.GeneratedValue;
import javax.persistence.Id;
import javax.persistence.JoinColumn;
import javax.persistence.JoinTable;
import javax.persistence.ManyToMany;
@Entity
public class Role implements Serializable
{
    /**
     *
     */
    private static final long serialVersionUID = 1L;
    private Long id;
    private Set users;
    @Id
    @GeneratedValue
    public Long getId()
    {
        return id;
    }
    public void setId(Long id)
    {
        this.id = id;
    }
    @ManyToMany
    @JoinTable(name="UserRole",joinColumns={@JoinColumn(name="role_ID")},inverseJoinColumns={@JoinColumn(name="user_ID")})
    public Set getUsers()
    {
        return users;
    }
    public void setUsers(Set users)
    {
        this.users = users;
    }
}

UserRoleId：

package sub;
import java.io.Serializable;
import javax.persistence.Embeddable;
@Embeddable
public class UserRoleId implements Serializable
{
    /**
     *
     */
    private static final long serialVersionUID = 1L;
    private Long userId;
    private Long roleId;
    public UserRoleId(Long userId, Long roleId)
    {
        this.userId = userId;
        this.roleId = roleId;
    }
    public UserRoleId()
    {
        this(null,null);
    }
    @Override
    public boolean equals(Object obj)
    {
        if(obj == this)return true;
        if(obj instanceof UserRoleId)
        {
            final UserRoleId other = (UserRoleId) obj;
            Long userT = getUserId();
            Long userOther = other.getUserId();
            Long roleT = getRoleId();
            Long roleOther = other.getRoleId();

            return ((userT == userOther) || (userT != null &&
                    userOther != null && userT.equals(userOther))) &&
                    ((roleT == roleOther) || (roleT != null &&
                            roleOther != null && roleT.equals(
                                    roleOther)));
        }
        return false;
    }
    @Override
    public int hashCode()
    {
        int re = 17;
        re += (userId == null?0:userId.hashCode());
        re += (roleId == null?0:roleId.hashCode());
        return 37*re;
    }
    public Long getUserId()
    {
        return userId;
    }
    public void setUserId(Long userId)
    {
        this.userId = userId;
    }
    public Long getRoleId()
    {
        return roleId;
    }
    public void setRoleId(Long roleId)
    {
        this.roleId = roleId;
    }
}

UserRole：

package sub;
import java.io.Serializable;
import javax.persistence.AttributeOverride;
import javax.persistence.AttributeOverrides;
import javax.persistence.Column;
import javax.persistence.EmbeddedId;
import javax.persistence.Entity;
import javax.persistence.FetchType;
import javax.persistence.JoinColumn;
import javax.persistence.ManyToOne;
@Entity
public class UserRole implements Serializable
{
    /**
     *
     */
    private static final long serialVersionUID = 1L;
    private UserRoleId id;
    private Role role;
    private User user;
    @EmbeddedId
    @AttributeOverrides( {
            @AttributeOverride(name = "userId", column = @Column(name = "user_ID", unique = false, nullable = false, insertable = true, updatable = true)),
            @AttributeOverride(name = "roleId", column = @Column(name = "role_ID", unique = false, nullable = false, insertable = true, updatable = true)) })
    public UserRoleId getId()
    {
        return id;
    }
    @ManyToOne(cascade = {})
    @JoinColumn(name = "role_ID", unique = false, nullable = false, insertable = false, updatable = false)
    public Role getRole()
    {
        return role;
    }
    @ManyToOne(cascade = {}, fetch = FetchType.EAGER)
    @JoinColumn(name = "user_ID", unique = false, nullable = false, insertable = false, updatable = false)
    public User getUser()
    {
        return user;
    }
    public void setId(UserRoleId id)
    {
        this.id = id;
    }
    public void setRole(Role role)
    {
        this.role = role;
    }
    public void setUser(User user)
    {
        this.user = user;
    }
}

在mysql数据库中，保存UserRole时出错。而完全相同的代码在oracle数据中正确。
操作如下：

        User user;
        Role role;
        //经过多步操作以后，user与role都保存到数据库，与之相关联的session已关闭
        Session s = null;//取得s的代码没有写出来
        s.beginTransaction();
        UserRole userRole = new UserRole();
        userRole.setId(new UserRoleId(user.getId(),role.getId()));
        userRole.setUser(user);
        userRole.setRole(role);
        s.persist(userRole);
        s.getTransaction().commit();
//一提交就出错，提示user没有保存，但是奇怪的是为什么在oracle中完全正确。
//最后在mysql中作如下的修改可以正确保存
//把 userRole.setUser(user)与userRole.setRole(role)删除

有那位知道是什么问题，请告之

中东 2007-06-11 23:19 发表评论

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hibernate 多对多关系在mysql、oracle中的不同