Hibernate简介
hibernate是一个开源的ORM(对象关系映射)框架,也是一个持久层的框架,它对JDBC做了非常轻量级的封装。
Hibernate核心(六大接口+配置文件)
Configuration:负责配置并启动Hibernate
SessionFactory:负责初始化Hibernate
Session:负责持久化对象的CRUD操作
Transaction:负责事务
Query和Criteria:负责执行各种数据库查询
Hibernate工作原理
- 通过Configuration config = new Configuration().configure();//读取并解析hibernate.cfg.xml配置文件
- 由hibernate.cfg.xml中的<mapping resource = "com/xx/xx.hbm.xml" />//读取并解析映射信息
- 通过SessionFactory sf = config.buildSessionFactory();//创建SessionFactory会话工厂
- Session session = sf.openSession();//打开Session
- Transaction tx = session.beginTransaction();//创建并启动事务
- persistent operate CRUD//数据持久化操作
- tx.commit();//提交事务
- 关闭Session
- 关闭SesstionFactory
开发步骤:
- 创建Hibernate的配置文件
- 创建持久化类
- 创建对象-关系映射文件
- 通过Hibernate API编写访问数据库的代码
Hibernate开发实例
- 使用版本:Hibernate 4.2.4 + Mysql
- 导入Hibernate必须的jar包(Hibernate-release-4.2.4.Final\lib\required)
- 导入Mysql的jdbc驱动(mysql-connector-java-5.1.7-bin.jar)
- 导入Junit4的jar包(Junit单元测试工具)//测试用
- 创建Hibernate的配置文件 hibernate.cfg.xml
- <property name="hibernate.dialect">org.hibernate.dialect.MySQLDialect</property>
- <property name="hibernate.connection.driver_class">com.mysql.jdbc.Driver</property>
- <property name="hibernate.connection.url">jdbc:mysql://localhost:3306/students</property>
- <property name="hibernate.connection.username">root</property>
- <property name="hibernate.connection.password">root</property>
<?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> <property name="hibernate.dialect">org.hibernate.dialect.MySQLDialect</property> <property name="hibernate.connection.driver_class">com.mysql.jdbc.Driver</property> <property name="hibernate.connection.url">jdbc:mysql://localhost:3306/students</property> <property name="hibernate.connection.username">root</property> <property name="hibernate.connection.password">root</property> <property name="hibernate.show_sql">true</property> <property name="hibernate.hbm2ddl.auto">update</property> <property name="hibernate.format_sql">true</property> </session-factory> </hibernate-configuration>
- 创建持久化类
import java.util.Date; //学生类 public class Students { private int sid;// 学号 private String sname;// 姓名 private String gender;// 性别 private Date birthday;// 出生日期 private String address;// 地址 public Students() { } public Students(int sid, String sname, String gender, Date birthday, String address) { // super(); this.sid = sid; this.sname = sname; this.gender = gender; this.birthday = birthday; this.address = address; } public int getSid() { return sid; } public void setSid(int sid) { this.sid = sid; } public String getSname() { return sname; } public void setSname(String sname) { this.sname = sname; } public String getGender() { return gender; } public void setGender(String gender) { this.gender = gender; } public Date getBirthday() { return birthday; } public void setBirthday(Date birthday) { this.birthday = birthday; } public String getAddress() { return address; } public void setAddress(String address) { this.address = address; } @Override public String toString() { return "Students [sid=" + sid + ", sname=" + sname + ", gender=" + gender + ", birthday=" + birthday + ", address=" + address + "]"; } }
- 创建对象-关系映射文件 Students.hbm.xml
<?xml version="1.0"?> <!DOCTYPE hibernate-mapping PUBLIC "-//Hibernate/Hibernate Mapping DTD 3.0//EN" "http://hibernate.sourceforge.net/hibernate-mapping-3.0.dtd"> <hibernate-mapping> <class name="Students" table="STUDENTS"> <id name="sid" type="int"> <column name="SID" /> <generator class="assigned" /> </id> <property name="sname" type="java.lang.String"> <column name="SNAME" /> </property> <property name="gender" type="java.lang.String"> <column name="GENEDER" /> </property> <property name="birthday" type="java.util.Data"> <column name="BIRTHDAY" /> </property> <property name="address" type="java.lang.String"> <column name="ADDRESS" /> </property> </class> </hibernate-mapping>
- 将Students.hbm.xml加入hibernate.cfg.xml
<mapping resource="Students.hbm.xml" />
- 创建数据库students 刷新表就会自动产生students表
- 使用Junit进行测试
- @Test:测试方法
- @Before:初始化方法
- @After:释放资源
- 通过Hibernate API编写访问数据库的代码
- Configuration config = new Configuration().configure();//创建配置对象
- ServiceRegistry seviceRegistry = new ServiceRegistryBuilder().applySettings(config.getProperties()).buildServiceRegistry();//创建服务注册对象
- sessionFactory = config.buildSessionFactory(serviceRegistry);//创建会话工厂对象
- session = sessionFactory.openSession();//打开对话
package Test; import java.util.Date; import org.hibernate.Session; import org.hibernate.SessionFactory; import org.hibernate.Transaction; import org.hibernate.cfg.Configuration; import org.hibernate.service.ServiceRegistry; import org.hibernate.service.ServiceRegistryBuilder; import org.junit.After; import org.junit.Before; import org.junit.Test; import com.Students; //测试类 public class StudentTest { private SessionFactory sessionFactory; private Session session; private Transaction transation; @Before public void init() { Configuration config = new Configuration().configure(); ServiceRegistry serviceRegistry = new ServiceRegistryBuilder().applySettings(config.getProperties()).buildServiceRegistry(); sessionFactory = config.buildSessionFactory(serviceRegistry); session = sessionFactory.openSession(); transation = session.beginTransaction(); } @After public void destory() { transation.commit();//提交事务 session.close();//关闭会话 sessionFactory.close();//关闭会话工厂 } @Test public void testSaveStudents() { //生成学生对象 Students s = new Students(1, "小明", "男", new Date(), "中国"); session.save(s);//保存对象进入数据库 } }