Hibernate 多对多配置和操作
这里以用户和角色为例
第一步创建两个实体类用户和角色,并让两个实体类互相表示,Hibernate中用Set集合表示
用户实体类
package com.netxintai.mary; import java.util.HashSet; import java.util.Set; public class User { private Integer u_id; private String username; private String address; private String phone; private Set<Role> setRole=new HashSet<Role>(); public Integer getU_id() { return u_id; } public void setU_id(Integer u_id) { this.u_id = u_id; } public String getUsername() { return username; } public void setUsername(String username) { this.username = username; } public String getAddress() { return address; } public void setAddress(String address) { this.address = address; } public String getPhone() { return phone; } public void setPhone(String phone) { this.phone = phone; } public Set<Role> getSetRole() { return setRole; } public void setSetRole(Set<Role> setRole) { this.setRole = setRole; } }
角色类
package com.netxintai.mary; import java.util.HashSet; import java.util.Set; public class Role { private Integer r_id; private String role_name; private String role_level; private Set<User> setUser=new HashSet<User>(); public Integer getR_id() { return r_id; } public void setR_id(Integer r_id) { this.r_id = r_id; } public String getRole_name() { return role_name; } public void setRole_name(String role_name) { this.role_name = role_name; } public String getRole_level() { return role_level; } public void setRole_level(String role_level) { this.role_level = role_level; } public Set<User> getSetUser() { return setUser; } public void setSetUser(Set<User> setUser) { this.setUser = setUser; } }
第二步配置两个实体类的映射文件
用户User类配置文件
<?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> <class name="com.netxintai.mary.User" table="t_user"> <id name="u_id" column="u_id"> <generator class="native"></generator> </id> <property name="username" column="username" /> <property name="address" column="address" /> <property name="phone" column="phone" /> <!-- 在用户里面表示所有角色,使用set标签 name属性:角色set集合名称 table属性:第三章表名称 --> <set name="setRole" table="user_role"> <!-- Key 标签里面配置 配置当日前映射文件在第三章表外键名称 --> <key column="userid"></key> <!-- class:橘色实体类全路径 column:橘色在第三章表中外键名称 --> <many-to-many class="com.netxintai.mary.Role" column="roleid"></many-to-many> </set> </class> </hibernate-mapping>
角色类配置文件
<?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> <class name="com.netxintai.mary.Role" table="t_role"> <id name="r_id" column="r_id"> <generator class="native"></generator> </id> <property name="role_name" column="role_name" /> <property name="role_level" column="role_level" /> <!-- 在角色里面表示所有用户,使用set标签 --> <set name="setUser" table="user_role" cascade="save-update"> <!-- 角色在第三张表外键 --> <key column="roleid"></key> <many-to-many class="com.netxintai.mary.User" column="userid"></many-to-many> </set> </class> </hibernate-mapping>
第三步 将配置文件引入hibernate.cfg.xml
<?xml version="1.0" encoding="UTF-8"?> <!DOCTYPE hibernate-configuration PUBLIC "-//Hibernate/Hibernate Configuration DTD 3.0//EN" "http://www.hibernate.org/dtd/hibernate-configuration-3.0.dtd"> <hibernate-configuration> <session-factory> <!-- 配置数据信息 --> <property name="hibernate.connection.driver_class">com.mysql.jdbc.Driver</property> <property name="hibernate.connection.url">jdbc:mysql:///mydb</property> <property name="hibernate.connection.username">root</property> <property name="hibernate.connection.password">123</property> <!-- 配置hibernate信息 可选 --> <!-- 输出sql语句--> <property name="hibernate.show_sql">true</property> <!-- 格式化sql语句 --> <property name="hibernate.format_sql">true</property> <!-- hibernate帮创建表 需要配置后 update:如果已经存在表,更新,如果没有 创建表 --> <property name="hibernate.hbm2ddl.auto">update</property> <!-- 配置数据库方言 --> <property name="hibernate.dialect">org.hibernate.dialect.MySQLDialect</property> <!-- 把映射文件放到核心配置文件中 --> <property name="hibernate.current_session_context_class">thread</property> <!-- 引入配置文件 --> <mapping resource="com/netxintai/mary/Role.hbm.xml"/> <mapping resource="com/netxintai/mary/User.hbm.xml"/> </session-factory> </hibernate-configuration>
第四步 进行测试代码
package com.netxintai.dome; import java.util.Set; import org.hibernate.Session; import org.hibernate.SessionFactory; import org.hibernate.Transaction; import org.junit.Test; import com.netxintai.mary.Role; import com.netxintai.mary.User; import com.netxintai.utils.HiberntaeUtils; public class DomeTEST { private SessionFactory sessionFactory; private Session session; private Transaction tr; @Test public void DomeTest() { try { sessionFactory = HiberntaeUtils.getsessionFactory(); session = sessionFactory.openSession(); tr = session.beginTransaction(); User user=new User(); Role role=new Role(); Role role2=new Role(); user.setAddress("北京"); user.setUsername("朱棣"); user.setPhone("999999"); role.setRole_level("1"); role.setRole_name("超级管理员"); role2.setRole_level("2"); role2.setRole_name("管理员"); user.getSetRole().add(role2); user.getSetRole().add(role); session.save(user); tr.commit(); } catch (Exception e) { // TODO: handle exception tr.rollback(); } finally { } } }
数据库效果图