基于Maven的Hibernate入门
1. Hibernate
Hibernate ORM enables developers to more easily write applications whose data outlives the application process. As an Object/Relational Mapping (ORM) framework, Hibernate is concerned with data persistence as it applies to relational databases (via JDBC).
Hibernate框架使开发人员能够轻松的编写java应用程序与数据库交互的开发。 Hibernate是一个开源,轻量级的ORM(对象关系映射)工具。ORM工具简化了数据创建,数据处理和数据访问。它是将对象映射到数据库中存储的数据(表)的编程技术。
更详细的请参考官网:http://hibernate.org/orm/
2. 用Maven实现Hibernate的实例
用maven的理由很简单,省得的每次都下载jar。如果想读源码,也非常非常easy!!!
废话不多说,来个栗子:
1)创建一个maven的project
2) 准备好目录结构
3)在pom.xml中添加hibernate和oracle的jar的依赖
<dependencies>
<dependency>
<groupId>junit</groupId>
<artifactId>junit</artifactId>
<version>4.10</version>
<scope>test</scope>
</dependency>
<!-- Oracle Jdbc Driver -->
<dependency>
<groupId>com.oracle</groupId>
<artifactId>ojdbc14</artifactId>
<version>10.2.0.2.0</version>
</dependency>
<!-- Hibernate 配置 -->
<dependency>
<groupId>org.hibernate</groupId>
<artifactId>hibernate-core</artifactId>
<version>5.1.0.Final</version>
</dependency>
</dependencies>
4) 常见实体类com.angelia.hibernate.entity.MyUser
public class MyUser implements java.io.Serializable {
private int userId;
private String userName;
private Date createdDate;
public MyUser() {
}
public MyUser(int userId) {
this.userId = userId;
}
public MyUser(int userId, String userName, Date createdDate) {
super();
this.userId = userId;
this.userName = userName;
this.createdDate = createdDate;
}
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 Date getCreatedDate() {
return createdDate;
}
public void setCreatedDate(Date createdDate) {
this.createdDate = createdDate;
}
@Override
public String toString() {
return "MyUser [userId=" + userId + ", userName=" + userName + ", createdDate=" + createdDate + "]";
}
}
5) 创建Hibernate映射文件 MyUser.hbm.xml,以类的名字开始MyUser,hbm.xml结尾。
<hibernate-mapping>
<class name="com.angelia.hibernate.entity.MyUser" table="db_user">
<id name="userId" type="int">
<column name="user_id"></column>
<generator class="assigned"></generator>
</id>
<property name="userName" type="string">
<column name="user_name" length="20"></column>
</property>
<property name="createdDate" type="date">
<column name="created_date" length="7"></column>
</property>
</class>
</hibernate-mapping>
6)配置Hibernate描述文件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>
<property name="connection.username">×××</property>
<property name="connection.password">×××</property>
<property name="connection.driver_class">oracle.jdbc.OracleDriver</property>
<property name="connection.url">jdbc:oracle:thin:@IP:1521:SID</property>
<property name="hibernate.dialect">org.hibernate.dialect.Oracle10gDialect</property>
<property name="hibernate.hbm2ddl.auto">update</property>
<!-- Enable Hibernate's automatic session context management -->
<property name="current_session_context_class">thread</property>
<property name="hibernate.cache.use_second_level_cache">false</property>
<property name="show_sql">true</property>
<mapping resource="MyUser.hbm.xml" />
</session-factory>
</hibernate-configuration>
7) 实现HibernateUtil获取SessionFactory
public class HibernateUtil {
private static final SessionFactory sessionFactory = buildSessionFactory();
private static SessionFactory buildSessionFactory() {
try {
// Create the SessionFactory from hibernate.cfg.xml
return new Configuration().configure().buildSessionFactory();
} catch (Throwable ex) {
// Make sure you log the exception, as it might be swallowed
System.err.println("Initial SessionFactory creation failed." + ex);
throw new ExceptionInInitializerError(ex);
}
}
public static SessionFactory getSessionFactory() {
return sessionFactory;
}
public static void shutdown() {
// Close caches and connection pools
getSessionFactory().close();
}
}
8)创建com.angelia.hibernate.dao.MyUserDao
public class MyUserDao {
SessionFactory sessionFactory = HibernateUtil.getSessionFactory();
public void saveUser(MyUser user){
Session session = sessionFactory.getCurrentSession();
session.beginTransaction();
session.save(user);
session.getTransaction().commit();
}
public MyUser getUserById(int id){
Session session = sessionFactory.getCurrentSession();
session.beginTransaction();
List<MyUser> users= session.createQuery("from MyUser where userId = ?").setParameter(0, id).list();
session.getTransaction().commit();
if(users!=null && users.size()>0){
return users.get(0);
}
return null;
}
}
9)创建测试类
public class TestDemo {
@Test
public void getUserById(){
MyUserDao dao = new MyUserDao();
MyUser user = new MyUser();
user.setUserId(1);
user.setUserName("Angelia");
user.setCreatedDate(new Date());
dao.saveUser(user);
MyUser user2 = dao.getUserById(user.getUserId());
System.out.println(user2);
}
}
10)执行测试类
INFO: HHH000262: Table not found: db_user
Hibernate: create table db_user (user_id number(10,0) not null, user_name varchar2(20 char), created_date date, primary key (user_id))
Hibernate: insert into db_user (user_name, created_date, user_id) values (?, ?, ?)
Nov 15, 2017 4:16:06 PM org.hibernate.hql.internal.QueryTranslatorFactoryInitiator initiateService
INFO: HHH000397: Using ASTQueryTranslatorFactory
Nov 15, 2017 4:16:15 PM org.hibernate.hql.internal.ast.HqlSqlWalker generatePositionalParameter
WARN: [DEPRECATION] Encountered positional parameter near line 1, column 57 in HQL: [from com.angelia.hibernate.entity.MyUser where userId = ?]. Positional parameter are considered deprecated; use named parameters or JPA-style positional parameters instead.
Hibernate: select myuser0_.user_id as user_id1_0_, myuser0_.user_name as user_name2_0_, myuser0_.created_date as created_date3_0_ from db_user myuser0_ where myuser0_.user_id=?
MyUser [userId=1, userName=Angelia, createdDate=2017-11-15]
Hibernate: create table db_user (user_id number(10,0) not null, user_name varchar2(20 char), created_date date, primary key (user_id))
Hibernate: insert into db_user (user_name, created_date, user_id) values (?, ?, ?)
Nov 15, 2017 4:16:06 PM org.hibernate.hql.internal.QueryTranslatorFactoryInitiator initiateService
INFO: HHH000397: Using ASTQueryTranslatorFactory
Nov 15, 2017 4:16:15 PM org.hibernate.hql.internal.ast.HqlSqlWalker generatePositionalParameter
WARN: [DEPRECATION] Encountered positional parameter near line 1, column 57 in HQL: [from com.angelia.hibernate.entity.MyUser where userId = ?]. Positional parameter are considered deprecated; use named parameters or JPA-style positional parameters instead.
Hibernate: select myuser0_.user_id as user_id1_0_, myuser0_.user_name as user_name2_0_, myuser0_.created_date as created_date3_0_ from db_user myuser0_ where myuser0_.user_id=?
MyUser [userId=1, userName=Angelia, createdDate=2017-11-15]
11)最后的目录结构
上一篇: 一道sql面试题
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