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Hibernate的执行流程和集合的映射关系
Hibernate的执行流程
集合映射
准被hibernate的运行环境
配置hibernate.cfg.xml主配置文件
1、Set集合
写User.java类
package com.gqx.collection; import java.util.ArrayList; import java.util.HashMap; import java.util.List; import java.util.Map; import java.util.Set; /** * javaBean的设计 * @author 郭庆兴 * */ public class User { private int userId; private String userName; //一个用户对应多个地址 private Set<String> address; public int getUserId() { return userId; } public void setUserId(int userId) { this.userId = userId; } public String getUserName() { return userName; } public void setUserName(String userName) { this.userName = userName; } public Set<String> getAddress() { return address; } public void setAddress(Set<String> address) { this.address = address; } }
映射文件User.hbm.xml
<?xml version="1.0"?> <!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.gqx.collection"> <class name="User" table="t_users"> <!-- 主键字段 --> <id name="userId" column="id"> <generator class="native"/> </id> <property name="userName" ></property> <!-- set集合属性的映射,指定要映射的set集合的属性 table 集合属性要映射到的表 key 指定属性集合表(t_address)的外键字段 element 指定集合表的其他字段--> <set name="address" table="t_address"> <key column="uid"></key> <element column="address" type="string"></element> </set> </class> </hibernate-mapping>
测试类如下:
public class App { private static SessionFactory sf; static{ sf=new Configuration().configure().addClass(User.class).buildSessionFactory(); } /** * Set集合 */ @Test public void test() { Session session=sf.openSession(); session.beginTransaction(); //**************保存************ Set<String> addressSet=new HashSet<String>(); addressSet.add("黄石"); addressSet.add("荆州"); User user=new User(); user.setAddress(addressSet); user.setUserName("gqxing"); session.save(user); session.getTransaction().commit(); session.close(); } }
2、List集合User.java
package com.gqx.collection; import java.util.ArrayList; import java.util.HashMap; import java.util.List; import java.util.Map; import java.util.Set; /** * javaBean的设计 * @author 郭庆兴 * */ public class User { private int userId; private String userName; //一个用户对应多个地址 private List<String> addressList=new ArrayList<String>(); public void setAddressList(List<String> addressList) { this.addressList = addressList; } public List<String> getAddressList() { return addressList; } public int getUserId() { return userId; } public void setUserId(int userId) { this.userId = userId; } public String getUserName() { return userName; } public void setUserName(String userName) { this.userName = userName; } }
映射文件(User.hbm.xml)
<?xml version="1.0"?> <!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.gqx.collection"> <class name="User" table="t_users"> <!-- 主键字段 --> <id name="userId" column="id"> <generator class="native"/> </id> <property name="userName" ></property> <!-- List集合 list-index:指定的是集合排列的顺序(因为要保证List集合的有序) --> <list name="addressList" table="t_addressList"> <key column="uid"></key> <list-index column="idx"></list-index> <element column="address" type="string"></element> </list> </class> </hibernate-mapping>
测试类:
/** * List集合 */ @Test public void testSaveList() { Session session=sf.openSession(); session.beginTransaction(); //**************保存************ User user=new User(); user.setUserName("gqxing"); user.getAddressList().add("武汉"); user.getAddressList().add("上海"); session.save(user); session.getTransaction().commit(); session.close(); }
3、Map集合
User.java
package com.gqx.collection; import java.util.ArrayList; import java.util.HashMap; import java.util.List; import java.util.Map; import java.util.Set; /** * javaBean的设计 * @author 郭庆兴 * */ public class User { private int userId; private String userName; //一个用户对应多个地址 private Map<String, String> addressMap=new HashMap<String, String>(); public void setAddressMap(Map<String, String> addressMap) { this.addressMap = addressMap; } public Map<String, String> getAddressMap() { return addressMap; } public int getUserId() { return userId; } public void setUserId(int userId) { this.userId = userId; } public String getUserName() { return userName; } public void setUserName(String userName) { this.userName = userName; } }
映射文件
<?xml version="1.0"?> <!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.gqx.collection"> <class name="User" table="t_users"> <!-- 主键字段 --> <id name="userId" column="id"> <generator class="native"/> </id> <property name="userName" ></property> <!-- map集合映射 key:指定外键字段 map-key:指定map的key element:指定map的value --> <map name="addressMap" table="t_addressMap"> <key column="uid"></key> <map-key type="string" column="shortName"></map-key> <element column="address" type="string"></element> </map> </class> </hibernate-mapping>
测试类
/** * List集合 */ @Test public void testSaveMap() { Session session=sf.openSession(); session.beginTransaction(); //**************保存************ User user=new User(); user.setUserName("gqxing"); user.getAddressMap().put("A002", "黄石"); user.getAddressMap().put("A001", "荆州"); session.save(user); session.getTransaction().commit(); session.close(); }
集合的获取
测试类
/** * 获取 */ @Test public void testGet() { Session session=sf.openSession(); session.beginTransaction(); //获取 User user=(User)session.get(User.class, 2); //及时加载 System.out.println(user.getUserId()); System.out.println(user.getUserName()); //当查询用户,可以获取与亲关联的list集合的数据(因为有正确的映射) //当遇到到集合数据的使用时,才向数据库发送执行的sql语句(懒加载) System.out.println(user.getAddressList()); session.getTransaction().commit(); session.close(); }
Hibernate的执行流程和集合的映射关系
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