经过前面学习,和前面的代码基本一致。只需要将前面的代码修改/增加类,复用修改少量就可以达到效果。
请对比前两个实例。
一、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> <!-- 配置文件标签顺序property*,mapping*,(class-cache|collection-cache),event,listener* --> <session-factory> <!-- 设置访问mysql数据库的驱动描述 --> <property name="connection.driver_class">com.mysql.jdbc.Driver</property> <!-- 设置数据库的url --> <property name="connection.url">jdbc:mysql://127.0.0.1:3306/test</property> <!-- 指定登录数据库用户账户 --> <property name="connection.username">root</property> <!-- 指定登录数据库用户密码 --> <property name="connection.password">123456</property> <!-- 设置访问数据库的方言,提高数据库访问性能 --> <property name="dialect">org.hibernate.dialect.MySQLDialect</property> <!-- 设置ddl --> <!-- <property name="hbm2ddl.auto">auto</property> --> <!-- 配置控制台视图,显示查询内容 --> <property name="show_sql">true</property> <!-- 下面是多表映射 --> <!-- 指出映射文件 --> <mapping resource="resource/Customer.hbm.xml"/> <!-- 映射文件 --> <mapping resource="resource/Customer2.hbm.xml"/> <!-- 映射文件 --> <mapping resource="resource/ Customer3.hbm.xml"/> </session-factory> </hibernate-configuration>
二、Customer3.hbm.xml
<?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="bean" auto-import="false"> <!-- POJO类映射表及某表的关系--> <class name="bean.Customer3" table="customers3" catalog="test"> <id name="customerID" type="java.lang.Integer"> <column name="customerID"/> <generator class="increment"></generator> </id> <!-- 映射表中name字段 --> <property name="name" type="java.lang.String"> <column name="name" length="40"/> </property> <!-- 映射表中phone字段 --> <property name="phone" type="java.lang.String"> <column name="phone" length="16"/> </property> </class> </hibernate-mapping>
三、Customer3.java
package bean; //验证identity生成主键方式的映射类,数据库对应表customers2 public class Customer3 { private int customerID; private String name,phone; public int getCustomerID() { return customerID; } public void setCustomerID(int customerID) { this.customerID = customerID; } public String getName() { return name; } public void setName(String name) { this.name = name; } public String getPhone() { return phone; } public void setPhone(String phone) { this.phone = phone; } }
四、HibernateSessionFactory.java
package hibernate.factory; import org.hibernate.Session; import org.hibernate.SessionFactory; import org.hibernate.cfg.Configuration; public class HibernateSessionFactory { private static String configfile = "resource/hibernate.cfg.xml"; /**ThreadLocal是一个本地线程**/ private static final ThreadLocal<Session> threadLocal = new ThreadLocal<Session>(); private static Configuration config; private static SessionFactory sessionFactory; /**读取配置文件,创建一个工厂会话,这段代码为静态块,编译后已经运行**/ static{ try { config = new Configuration().configure(configfile); sessionFactory = config.buildSessionFactory(); } catch (Exception e) { // TODO: handle exception e.printStackTrace(); } } /**通过会话工厂打开会话,就可以访问数据库了**/ public static Session getSession(){ Session session = (Session)threadLocal.get(); if (session==null||!session.isOpen()) { if (sessionFactory==null) { rebuildSessionFactory(); } session = (sessionFactory!=null)?sessionFactory.openSession():null; } return session; } /**重新创建一个会话工厂**/ public static void rebuildSessionFactory() { try { config.configure(configfile); sessionFactory = config.buildSessionFactory(); } catch (Exception e) { // TODO: handle exception e.printStackTrace(); } } /**关闭与数据库的会话**/ public static void closeSession() { Session session = (Session)threadLocal.get(); threadLocal.set(null); if (session!=null) { session.close(); } } }
五、Customer3Demo.java
package bean; import java.util.List; import hibernate.factory.HibernateSessionFactory; import org.hibernate.Session; import org.hibernate.Transaction; import org.hibernate.query.Query; //用于测试identity主键生成方式,增加记录 //由于是增加数据,所以不需要写Query,只需要new表,增加数据即可 public class Customer3Demo { Session session = HibernateSessionFactory.getSession(); Transaction tran = session.beginTransaction(); public static void main(String[] args) { //测试identity主键生成 Customer3Demo demo = new Customer3Demo(); Customer3 customer3 = new Customer3(); demo.saveCustomer3IDByIdentity(customer3, "华山", "580"); //测试查询结果 List list = demo.queryAllCustomer3(); for (int i = 0; i < list.size(); i++) { Customer3 customer = (Customer3)list.get(i); System.out.println(customer.getCustomerID()+customer.getName()+customer.getPhone()); } HibernateSessionFactory.closeSession(); } //下面是封装保存 public void saveCustomer3IDByIdentity(Customer3 customer3,String name,String phone) { customer3.setName(name); customer3.setPhone(phone); session.save(customer3); //一定一定要记得提交事务 tran.commit(); } //下面是封装查询 @SuppressWarnings("rawtypes") public List queryAllCustomer3(){ /**由会话工厂类创建一个会话Session对象**/ Session session = HibernateSessionFactory.getSession(); /**由会话session对象创建一个查询对象**/ Query query = session.createQuery("from bean.Customer3"); List list = query.list(); HibernateSessionFactory.closeSession(); return list; } }
总结:经过上面的例子和之前的比较,不难得出结论。甚至可以思考必要的方法整合。将创建表、创建数据库、数据查询等简化,然后打包。后面只需配置数据,就可以完成与数据库交互的功能。这个问题先提出来,后续考虑。现在开始继续学习。