多对多关系，User和Role
1.创建表
CREATE TABLE `sys_role` ( `role_id` int(11) NOT NULL AUTO_INCREMENT, `role_name` varchar(255) DEFAULT NULL, `role_memo` varchar(255) DEFAULT NULL, PRIMARY KEY (`role_id`) ) ENGINE=InnoDB AUTO_INCREMENT=4 DEFAULT CHARSET=utf8; CREATE TABLE `sys_user` ( `user_id` int(11) NOT NULL AUTO_INCREMENT, `user_code` varchar(255) DEFAULT NULL, `user_name` varchar(255) DEFAULT NULL, `user_password` varchar(255) DEFAULT NULL, `user_state` varchar(255) DEFAULT NULL, PRIMARY KEY (`user_id`) ) ENGINE=InnoDB AUTO_INCREMENT=3 DEFAULT CHARSET=utf8; CREATE TABLE `sys_user_role` ( `user_id` int(11) NOT NULL, `role_id` int(11) NOT NULL, PRIMARY KEY (`user_id`,`role_id`), KEY `FK660C51789B2C831D` (`role_id`), KEY `FK660C5178405746FD` (`user_id`), CONSTRAINT `FK660C5178405746FD` FOREIGN KEY (`user_id`) REFERENCES `sys_user` (`user_id`), CONSTRAINT `FK660C51789B2C831D` FOREIGN KEY (`role_id`) REFERENCES `sys_role` (`role_id`) ) ENGINE=InnoDB DEFAULT CHARSET=utf8;
2.创建实体
import java.util.Set; import java.util.HashSet; public class User { private Integer user_id; private String user_code; private String user_name; private String user_password; private String user_state; private Set<Role> role =new HashSet<>(); public Set<Role> getRole() { return role; } public void setRole(Set<Role> role) { this.role = role; } public Integer getUser_id() { return user_id; } public void setUser_id(Integer user_id) { this.user_id = user_id; } public String getUser_code() { return user_code; } public void setUser_code(String user_code) { this.user_code = user_code; } public String getUser_name() { return user_name; } public void setUser_name(String user_name) { this.user_name = user_name; } public String getUser_password() { return user_password; } public void setUser_password(String user_password) { this.user_password = user_password; } public String getUser_state() { return user_state; } public void setUser_state(String user_state) { this.user_state = user_state; } }
import java.util.HashSet; import java.util.Set; public class Role { private Integer role_id; private String role_name; private String role_memo; private Set<User> user=new HashSet<>(); public Set<User> getUser() { return user; } public void setUser(Set<User> user) { this.user = user; } public Integer getRole_id() { return role_id; } public void setRole_id(Integer role_id) { this.role_id = role_id; } public String getRole_name() { return role_name; } public void setRole_name(String role_name) { this.role_name = role_name; } public String getRole_memo() { return role_memo; } public void setRole_memo(String role_memo) { this.role_memo = role_memo; } }
3.创建配置文件，注意外键的两次设置
<?xml version="1.0" encoding="UTF-8"?> <!DOCTYPE hibernate-mapping PUBLIC "-//Hibernate/Hibernate Mapping DTD 3.0//EN" "http://www.hibernate.org/dtd/hibernate-mapping-3.0.dtd"> <hibernate-mapping package="com.yqg.hibernate.entity"> <class name="User" table="sys_user"> <id name="user_id" column="user_id"> <generator class="native"></generator> </id> <property name="user_code" column="user_code"></property> <property name="user_name" column="user_name"></property> <property name="user_password" column="user_password"></property> <property name="user_state" column="user_state"></property> <!-- 多对多关系 --> <set name="role" table="sys_user_role" cascade="save-update,delete"> <key column="user_id"></key> <many-to-many class="Role" column="role_id"></many-to-many> </set> </class> </hibernate-mapping>
<?xml version="1.0" encoding="UTF-8"?> <!DOCTYPE hibernate-mapping PUBLIC "-//Hibernate/Hibernate Mapping DTD 3.0//EN" "http://www.hibernate.org/dtd/hibernate-mapping-3.0.dtd"> <hibernate-mapping package="com.yqg.hibernate.entity"> <class name="Role" table="sys_role"> <id name="role_id" column="role_id"> <generator class="native"></generator> </id> <property name="role_name" column="role_name"></property> <property name="role_memo" column="role_memo"></property> <set name="user" table="sys_user_role" inverse="true" cascade="save-update,delete"> <key column="role_id"></key> <many-to-many class="User" column="user_id"></many-to-many> </set> </class> </hibernate-mapping>
4.编写测试类
测试级联保存 /* * 多对多映射 */ import org.hibernate.Session; import org.hibernate.Transaction; import org.junit.Test; import com.yqg.hibernate.entity.Role; import com.yqg.hibernate.entity.User; import com.yqg.hibernate.utils.hibernateUtils; public class Demo1 { @Test //双向维护关系，注意被动的一方需要设置inverse为true，放弃维护外键 public void Demo() { Session session = hibernateUtils.getCurrentSession(); Transaction transaction = session.beginTransaction(); User user=new User(); user.setUser_name("ooo"); User user1=new User(); user1.setUser_name("ppp"); Role role=new Role(); role.setRole_name("uuu"); Role role2=new Role(); role2.setRole_name("rrr"); Role role3=new Role(); role3.setRole_name("fff"); user.getRole().add(role); user.getRole().add(role2); user.getRole().add(role3); user1.getRole().add(role); user1.getRole().add(role2); user1.getRole().add(role3); role.getUser().add(user1); role.getUser().add(user); role2.getUser().add(user1); role2.getUser().add(user); role3.getUser().add(user1); role3.getUser().add(user); // session.save(user1); // session.save(user); session.save(role); session.save(role2); session.save(role3); transaction.commit(); } }
测试级联删除，注意删除时后两个用户不能有相同的角色重叠，否则会报外键错误。 import org.hibernate.Session; import org.hibernate.Transaction; /*级联删除 * */ import org.junit.Test; import com.yqg.hibernate.entity.Role; import com.yqg.hibernate.entity.User; import com.yqg.hibernate.utils.hibernateUtils; public class Demo2 { @Test public void demo() { Session session = hibernateUtils.getCurrentSession(); Transaction transaction = session.beginTransaction(); // User user = (User) session.get(User.class, 1); // session.delete(user); Role role = (Role) session.get(Role.class, 2); session.delete(role); transaction.commit(); } }
5.注意点
不要忘了在核心配置文件配置资源文件。
