Hibernate入门

最新推荐文章于 2024-06-21 08:39:18 发布

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1. 什么是hibernate

ORM框架/持久层框架 jdbc的一个框架
object reference mapping
通过管理对象来改变数据库中的数据
通过管理对象来操作数据库
优势：跨数据库的无缝移植
简单来说就是自己不用写数据库的增删改查的代码！！

2. 如何在项目中添加hibernate支持(手动添加)

2.1添加hibernate相关依赖

<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
  xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/maven-v4_0_0.xsd">
  <modelVersion>4.0.0</modelVersion>
  <groupId>Hibernate</groupId>
  <artifactId>chenkang_Hibernate</artifactId>
  <packaging>war</packaging>
  <version>0.0.1-SNAPSHOT</version>
  <name>chenkang_Hibernate Maven Webapp</name>
  <url>http://maven.apache.org</url>
  <properties>
		<project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
		<maven.compiler.source>1.8</maven.compiler.source>
		<maven.compiler.target>1.8</maven.compiler.target>
		<junit.version>4.12</junit.version>
		<servlet.version>4.0.0</servlet.version>
		<hibernate.version>5.3.0.Final</hibernate.version>
		<mysql.driver.version>5.1.46</mysql.driver.version>
	</properties>
	
  <dependencies>
		<dependency>
			<groupId>junit</groupId>
			<artifactId>junit</artifactId>
			<version>${junit.version}</version>
			<scope>test</scope>
		</dependency>

		<dependency>
			<groupId>javax.servlet</groupId>
			<artifactId>javax.servlet-api</artifactId>
			<version>${servlet.version}</version>
			<scope>provided</scope>
		</dependency>

		<dependency>
			<groupId>org.hibernate</groupId>
			<artifactId>hibernate-core</artifactId>
			<version>${hibernate.version}</version>
		</dependency>

		<dependency>
			<groupId>mysql</groupId>
			<artifactId>mysql-connector-java</artifactId>
			<version>${mysql.driver.version}</version>
		</dependency>
	</dependencies>
	
  <build>
    <finalName>chenkang_Hibernate</finalName>
    	<plugins>
			<plugin>
				<groupId>org.apache.maven.plugins</groupId>
				<artifactId>maven-compiler-plugin</artifactId>
				<version>3.7.0</version>
				<configuration>
					<source>${maven.compiler.source}</source>
					<target>${maven.compiler.target}</target>
					<encoding>${project.build.sourceEncoding}</encoding>
				</configuration>
			</plugin>
		</plugins>
  </build>
</project>

2.2 在resource目录下添加hibernate.cfg.xml(核心配置文件)

<?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>
		<!-- 1. 数据库相关 -->
		<property name="connection.username">root</property>
		<property name="connection.password">123</property>
		<property name="connection.url">jdbc:mysql://localhost:3306/chenkang?useUnicode=true&amp;characterEncoding=UTF-8
		</property>
		<property name="connection.driver_class">com.mysql.jdbc.Driver</property>
		<property name="dialect">org.hibernate.dialect.MySQLDialect</property>

		<!-- 配置本地事务（No CurrentSessionContext configured!） -->
		<property name="hibernate.current_session_context_class">thread</property>

		<!-- 2. 调试相关 -->		
		<property name="show_sql">true</property>
		<property name="format_sql">true</property>

		<!-- 3. 添加实体映射文件 -->
		<mapping resource="com/chenkang/one/entity/User.hbm.xml"/>
		<!-- 主键生成策略 -->
	</session-factory>
	</hibernate-configuration>

这里上面的dtd约束去hibernate-core里面最后3.0或者4.0的都行吧里面的dtd约束拷贝进来就好了

2.3 在开发阶段再创建实体类和实体映射文件(*.hbm.xml)
首先建立一个与数据库列相同实体类

package com.chenkang.one.entity;
import java.sql.Date;
import java.sql.Timestamp;
public class User {
	private Integer id;
	private String userName;
	private String userPwd;
	private String realName;
	private String sex;
	private Date birthday;
	private Timestamp createDatetime;
	private String remark;
	public Integer getId() {
		return id;
	}
	public void setId(Integer id) {
		this.id = id;
	}
	public String getUserName() {
		return userName;
	}
	public void setUserName(String userName) {
		this.userName = userName;
	}
	public String getUserPwd() {
		return userPwd;
	}
	public void setUserPwd(String userPwd) {
		this.userPwd = userPwd;
	}
	public String getRealName() {
		return realName;
	}
	public void setRealName(String realName) {
		this.realName = realName;
	}
	public String getSex() {
		return sex;
	}
	public void setSex(String sex) {
		this.sex = sex;
	}
	public Date getBirthday() {
		return birthday;
	}
	public void setBirthday(Date birthday) {
		this.birthday = birthday;
	}
	public Timestamp getCreateDatetime() {
		return createDatetime;
	}
	public void setCreateDatetime(Timestamp createDatetime) {
		this.createDatetime = createDatetime;
	}
	public String getRemark() {
		return remark;
	}
	public void setRemark(String remark) {
		this.remark = remark;
	}
	@Override
	public String toString() {
		return "User [id=" + id + ", userName=" + userName + ", userPwd=" + userPwd + ", realName=" + realName
				+ ", sex=" + sex + ", birthday=" + birthday + ", createDatetime=" + createDatetime + ", remark="
				+ remark + "]";
	}
	public User( String userName, String userPwd, String realName, String sex, Date birthday,
			Timestamp createDatetime, String remark) {
		this.userName = userName;
		this.userPwd = userPwd;
		this.realName = realName;
		this.sex = sex;
		this.birthday = birthday;
		this.createDatetime = createDatetime;
		this.remark = remark;
	}
	public User() {
		super();
	}
	
}

然后我们建立实体映射文件

<?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标签中：
        name:实体类的全路径
        table:实体类对应数据库中的表
	id标签:
		name:实体类中的属性（映射的是表的主键）
		type:属性对应的类型
		column:属性对应的表的哪一个列段  
    property:
    	name:实体类中的属性（映射的是表的非主键字段）
		type:属性对应的类型
		column:属性对应的表的哪一个列段 
		
    	List list = session.createQuery("from User").list();
    1.建模hibernate.cfg.xml对象，从中拿到com/chenkang/one/entity/User.hbm.xml
    2.建模了User.hbm.xml,拿到了com.chenkang.one.entity.User t_hibernate_user
    3. User userNameField = Class.forName("com.chenkang.one.entity.User").newInstace();
    Field userPwdField = user.getClass("userPwd")
    select uer_name,user_pwd,real_name,... from t_hibernate_user
    userNameField.set(user,吃吃醋)
    userPwdField.set(user,123456)
    .....
    最后user中的所有属性值都有了
    4.循环上一步操作，最终所有的user实列都放入list集合中就是List
     -->
    <class name="com.chenkang.one.entity.User" table="t_hibernate_user">
		<id name="id" type="java.lang.Integer" column="id">
			<generator class="increment" />
		</id>
		<property name="userName" type="java.lang.String" column="user_name">
		</property>
		<property name="userPwd" type="java.lang.String" column="user_pwd">
		</property>
		<property name="realName" type="java.lang.String" column="real_name">
		</property>
		<property name="sex" type="java.lang.String" column="sex">
		</property>
		<property name="birthday" type="java.sql.Date" column="birthday">
		</property>
		<property insert="false" update="false" name="createDatetime"
			type="java.sql.Timestamp" column="create_datetime">
		</property>
		<property name="remark" type="java.lang.String" column="remark">
		</property>
	</class>
    
    </hibernate-mapping>

里面的dtd约束也是在里面考的
注意别dtd约束别拷贝错了，，
核心文件xml是要拷贝configuration
实体映射文件是mapping。。
另外hibernate之所以被淘汰是因为它建立一个实体类就要建立一个映射文件那样很麻烦不实用
但是我们学习是要从最底层的开始不懂得这个框架后面替代它的框架也就学起来很困难、

3.Hibernate的增删改查

Hibernate的增删改查我们分为七个步骤来完成的
1.对hibernate.cfg.xml进行建模拿到sessionfactory工厂（两步）
3.通过工厂获取到session对话（操作数据库）
4.获取事务对象
5.直接操作数据库
6.提交事务
7. 关闭资源

查询：

package com.chenkang.one.test;

import java.util.List;

import org.hibernate.Session;
import org.hibernate.SessionFactory;
import org.hibernate.cfg.Configuration;

/**
 * hibernate 中查询案例
 * @author Administrator
 *
 */
public class QueryDemo {
	public static void main(String[] args) {
//		对hibernate.cfg.xml进行建模拿到sessionfactory工厂（两步）
		Configuration configure = new Configuration().configure("/hibernate.cfg.xml");
		SessionFactory sessionFactory = configure.buildSessionFactory();
//		通过工厂获取到session对话（操作数据库）
		Session session = sessionFactory.openSession();
//		直接操作数据库
		List list = session.createQuery("from User").list();
		for (Object object : list) {
			System.out.println(object);
		}
//		关闭资源
		session.close();
		
	}
}

增加：

package com.chenkang.one.test;

import java.sql.Date;
import java.sql.Timestamp;

import javax.transaction.HeuristicMixedException;
import javax.transaction.HeuristicRollbackException;
import javax.transaction.RollbackException;
import javax.transaction.SystemException;

import org.hibernate.Session;
import org.hibernate.SessionFactory;
import org.hibernate.Transaction;
import org.hibernate.cfg.Configuration;

import com.chenkang.one.entity.User;

/**
 * 
 * hibernate 中增加案例
 * @author Administrator
 *
 */
public class AddDemo {
	public static void main(String[] args) throws SecurityException, RollbackException, HeuristicMixedException, HeuristicRollbackException, SystemException {
//		对hibernate.cfg.xml进行建模拿到sessionfactory工厂（两步）
		Configuration configure = new Configuration().configure("/hibernate.cfg.xml");
		SessionFactory sessionFactory = configure.buildSessionFactory();
//		通过工厂获取到session对话（操作数据库）
		Session session = sessionFactory.openSession();
//		获取事务对象
		Transaction transaction = session.beginTransaction();
//		直接操作数据库
		session.save(new User("chenkang", "123456", "陈康", "男", new Date(System.currentTimeMillis()), new Timestamp(System.currentTimeMillis()), "暂无介绍"));
//		提交事务
		transaction.commit();
//		关闭资源
		session.close();
		
	}
}

修改：

package com.chenkang.one.test;

import java.sql.Date;
import java.sql.Timestamp;

import javax.transaction.HeuristicMixedException;
import javax.transaction.HeuristicRollbackException;
import javax.transaction.RollbackException;
import javax.transaction.SystemException;

import org.hibernate.Session;
import org.hibernate.SessionFactory;
import org.hibernate.Transaction;
import org.hibernate.cfg.Configuration;

import com.chenkang.one.entity.User;

/**
 * 
 * hibernate 中增加案例
 * @author Administrator
 *
 */
public class EditDemo {
	public static void main(String[] args) throws SecurityException, RollbackException, HeuristicMixedException, HeuristicRollbackException, SystemException {
//		对hibernate.cfg.xml进行建模拿到sessionfactory工厂（两步）
		Configuration configure = new Configuration().configure("/hibernate.cfg.xml");
		SessionFactory sessionFactory = configure.buildSessionFactory();
//		通过工厂获取到session对话（操作数据库）
		Session session = sessionFactory.openSession();
//		获取事务对象
		Transaction transaction = session.beginTransaction();
//		直接操作数据库
//		User user = new User("chenkang2", "123456", "陈康2", "男2", new Date(System.currentTimeMillis()), new Timestamp(System.currentTimeMillis()), "暂无介绍2");
//		user.setId(15);
//		session.update(user);
		
		User user = session.get(User.class, 15);
		System.out.println(user);
		user.setRealName("陈康3333");
		
//		提交事务
		transaction.commit();
//		关闭资源
		session.close();
		
	}
}

删除：

package com.chenkang.one.test;

import java.sql.Date;
import java.sql.Timestamp;

import javax.transaction.HeuristicMixedException;
import javax.transaction.HeuristicRollbackException;
import javax.transaction.RollbackException;
import javax.transaction.SystemException;

import org.hibernate.Session;
import org.hibernate.SessionFactory;
import org.hibernate.Transaction;
import org.hibernate.cfg.Configuration;

import com.chenkang.one.entity.User;

/**
 * 
 * hibernate 中增加案例
 * @author Administrator
 *
 */
public class DelDemo {
	public static void main(String[] args) throws SecurityException, RollbackException, HeuristicMixedException, HeuristicRollbackException, SystemException {
//		对hibernate.cfg.xml进行建模拿到sessionfactory工厂（两步）
		Configuration configure = new Configuration().configure("/hibernate.cfg.xml");
		SessionFactory sessionFactory = configure.buildSessionFactory();
//		通过工厂获取到session对话（操作数据库）
		Session session = sessionFactory.openSession();
//		获取事务对象
		Transaction transaction = session.beginTransaction();
//		直接操作数据库
		User user = new User();
		user.setId(15);
		session.delete(user);
//		提交事务
		transaction.commit();
//		关闭资源
		session.close();
		
	}
}