一、使用用户User和Role实现多对多的示例
User.java，实现对Role的引用
package com.lxit.entity; import java.util.HashSet;
import java.util.Set; public class User {
public User(){ } public User(String userid, String userName, String userPwd) {
this.userid = userid;
this.userName = userName;
this.userPwd = userPwd;
} private String userid;
private String userName;
private String userPwd;
private Set<Role> roles = new HashSet<Role>(); public String getUserid() {
return userid;
}
public void setUserid(String userid) {
this.userid = userid;
}
public String getUserName() {
return userName;
}
public void setUserName(String userName) {
this.userName = userName;
}
public String getUserPwd() {
return userPwd;
}
public void setUserPwd(String userPwd) {
this.userPwd = userPwd;
}
public Set<Role> getRoles() {
return roles;
}
public void setRoles(Set<Role> roles) {
this.roles = roles;
} }
User.hbm.xml配置文件，映射一个多对多的集合，并开启级联效果，由User来维护级联效果
<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE hibernate-mapping PUBLIC "-//Hibernate/Hibernate Mapping DTD 3.0//EN"
"http://hibernate.sourceforge.net/hibernate-mapping-3.0.dtd">
<hibernate-mapping>
<class name="com.lxit.entity.User" table="User">
<id name="userid" type="java.lang.String">
<generator class="assigned" />
</id>
<property generated="never" lazy="false" name="userName"
type="java.lang.String">
<column length="20" name="userName" not-null="true" />
</property>
<property generated="never" lazy="false" name="userPwd"
type="java.lang.String">
<column length="20" name="userPwd" not-null="true" />
</property>
<set name="roles" table="user_role" cascade="all">
<key column="userid" />
<many-to-many column="roleid" class="com.lxit.entity.Role" />
</set>
</class>
</hibernate-mapping>
Role.java 角色类，同样也映射Users集合
package com.lxit.entity; import java.util.HashSet;
import java.util.Set; public class Role { public Role() {
} public Role(String roleName, String roleDesc) {
this.roleName = roleName;
this.roleDesc = roleDesc;
} private int roleId;
private String roleName;
private String roleDesc;
private Set<User> users = new HashSet<User>(); public int getRoleId() {
return roleId;
}
public void setRoleId(int roleId) {
this.roleId = roleId;
}
public String getRoleName() {
return roleName;
}
public void setRoleName(String roleName) {
this.roleName = roleName;
}
public String getRoleDesc() {
return roleDesc;
}
public void setRoleDesc(String roleDesc) {
this.roleDesc = roleDesc;
} public Set<User> getUsers() {
return users;
} public void setUsers(Set<User> users) {
this.users = users;
}
}
User.hbm.xml映射文件，映射User多对多关系，并设置inverse="true"。
<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE hibernate-mapping PUBLIC "-//Hibernate/Hibernate Mapping DTD 3.0//EN"
"http://hibernate.sourceforge.net/hibernate-mapping-3.0.dtd">
<hibernate-mapping>
<class name="com.lxit.entity.Role" table="role">
<id name="roleId" type="java.lang.Integer">
<generator class="native"></generator>
</id>
<property name="roleName" type="java.lang.String">
<column name="roleName" length="20" not-null="true"></column>
</property>
<set name="users" table="user_role" inverse="true">
<key column="roleid"></key>
<many-to-many column="userid" class="com.lxit.entity.User" />
</set>
</class>
</hibernate-mapping>
添加Mapping映射文件
<mapping resource="com/lxit/entity/Role.hbm.xml" />
<mapping resource="com/lxit/entity/User.hbm.xml" />
最后测试类
public static void main(String[] args) {
Role sys = new Role("admin", "系統管理员");
Role teacher = new Role("teacher","教师");
User user1 = new User("admin", "管理员", "123123");
User user2 = new User("zhangsan", "张三疯", "123123");
user1.getRoles().add(sys);
user1.getRoles().add(teacher);
user2.getRoles().add(teacher);
Session session = HibernateUtil.getSession();
Transaction tx = session.beginTransaction();
//session.save(sys);
//session.save(teacher);
session.save(user1);
session.save(user2);
tx.commit();
}
以上，只需要将role添加到user就会自动生成多对多的权限，多对多必须使用第三张表来实现权限效果。不能为在第三张表添加映射文件。