Hibernate入门 – 小飞侠

Hibernate简介

1.ORM框架/持久层框架 jdbc的一个框架

2.通过管理对象来改变数据库中的数据

3.通过管理对象来操作数据库

4.跨数据库的无缝移植（就是可以直接换数据库比如原先项目用的是mySql后面项目转Oracle不需要改任何代码）

5.不需要写sql语句，这是一个优势同时也成为hibernate被淘汰的原因就是应为sql语句都是hibernate自动生成的所有导致了它丧失了灵活性

为什么使用Hibernate

对JDBC访问数据库的代码做了封装，大大简化了数据访问层繁琐的重复性代码。

Hibernate是一个基于JDBC的主流持久化框架，是一个优秀的ORM实现。它很大程度的简化DAO层的编码工作
hibernate使用Java反射机制，而不是字节码增强程序来实现透明性。

hibernate的性能非常好，因为它是个轻量级框架。映射的灵活性很出色，它支持各种关系数据库，从一对一到多对多的各种复杂关系。

hibernate增删改查案例

导入pom.xml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>com.azuo</groupId>
  <artifactId>hibernate</artifactId>
  <packaging>war</packaging>
  <version>0.0.1-SNAPSHOT</version>
  <name>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>${mysql.driver.version}</version>
		</dependency>
  </dependencies>
  <build>
    <finalName>hibernate</finalName>
    <plugins>
			<plugin>
				<groupId>org.apache.maven.plugins</groupId>
				<artifactId>maven-compiler-plugin</artifactId>
				<version>3.7.0</version>
				<configuration>
					<source>${maven.compiler.source}</source>
					<target>${maven.compiler.target}</target>
					<encoding>${project.build.sourceEncoding}</encoding>
				</configuration>
			</plugin>
		</plugins>
  </build>
</project>

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/wd?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/dhj/one/entity/User.hbm.xml"/>
		
			</session-factory>
</hibernate-configuration>

实体类User.java

package com.azuo.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) {
		super();
		this.userName = userName;
		this.userPwd = userPwd;
		this.realName = realName;
		this.sex = sex;
		this.birthday = birthday;
		this.createDatetime = createDatetime;
		this.remark = remark;
	}

	public User() {
		super();
	}

}

实体类对应的配置文件 user.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>
	<!-- 
		class标签下的属性
			name:指的是数据库中的表所映射的类的全路径名
			table：要映射的数据库表
		
		id标签：是用来表示主键的映射列
			name：数据库表的列段映射到实体类中的属性名
			type：属性名的类型
			column：数据库中的列段
			
		property标签：
			name：数据库表的列段映射到实体类中的属性名
			type：属性名的类型
			column：数据库中的列段
	 -->
	<class name="com.dhj.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>

查询 QueryDemo.java

package com.azuo.one.test;

import java.util.List;

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

/**
 * 演示hibernate查询
 * 
 * @author zuo_fan
 *
 */
public class QueryDemo {
	public static void main(String[] args) {
		/*
		 * 1、对hibernate.cfg.xml这个核心的配置文件进行建模
		 * 2、建模后的对象configure去获取sessionfactory对象，sessionfactory对象中包含了数据库相关信息
		 * 3、通过sessionfactory对象去获取session会话
		 * 4、session开启事务（查询中是不需要）
		 * 5、操作数据库
		 * 6、提交事务（查询中是不需要）
		 * 7、释放资源
		 */
		Configuration configure = new Configuration().configure("/hibernate.cfg.xml");
		SessionFactory sessionFactory = configure.buildSessionFactory();
		Session session = sessionFactory.openSession();
		List list = session.createQuery("from User").list();
		
		for (Object obj : list) {
			System.out.println(obj);
		}
		
		session.close();
	}
}

在这里插入图片描述

增加 : AddDemo.java

package com.azuo.one.test;

import java.sql.Date;
import java.sql.Timestamp;
import java.util.List;


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

import com.cbw.one.entity.User;

/**
 * 演示hibernate查询
 * @author zuo_fan
 *
 */
public class AddDeno {
public static void main(String[] args) {

	Configuration configure =new Configuration().configure("/hibernate.cfg.xml");
	SessionFactory sessionFactory=configure.buildSessionFactory();
	Session session=sessionFactory.openSession();
	//开实务
	Transaction transaction= session.beginTransaction();
	
	//控制数据库对象
	User user=new User("ls", "12345", "李四", "男", new Date(System.currentTimeMillis()), new Timestamp(System.currentTimeMillis()), "吃饭睡觉打豆豆");
	session.save(user);
	//提交事务
	transaction.commit();
	session.close();
}
}

在这里插入图片描述

修改 EditDemo.java

package com.azuo.one.test;

import java.sql.Date;
import java.sql.Timestamp;
import java.util.List;


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

import com.azuo.one.entity.User;

/**
 * 演示hibernate查询
 * @author zuo_fan
 *
 */
public class EditDeno {
public static void main(String[] args) {

	Configuration configure =new Configuration().configure("/hibernate.cfg.xml");
	SessionFactory sessionFactory=configure.buildSessionFactory();
	Session session=sessionFactory.openSession();
	//开实务
	Transaction transaction= session.beginTransaction();
	
/*	//方法一
	//控制数据库对象
	User user=new User("cbw", "12345", "楚霸王", "男", new Date(System.currentTimeMillis()), new Timestamp(System.currentTimeMillis()), "撩一个妹子");
   //设置id
	user.setId(15);
	//赋予值
	session.update(user);*/
	
	//方法二
	User user=session.get(User.class, 15);
	user.setRealName("吴亦凡");
	System.out.println(user);
	
	//提交事务
	transaction.commit();
	session.close();
}
}

删除DelDemo.java

package com.azuo.one.test;

import java.sql.Date;
import java.sql.Timestamp;
import java.util.List;

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

import com.azuo.one.entity.User;

/**
 * 演示hibernate删除
 * 
 * @author zuo_fan
 *
 */
public class delDemo {
	public static void main(String[] args) {
		Configuration configure = new Configuration().configure("/hibernate.cfg.xml");
		SessionFactory sessionFactory = configure.buildSessionFactory();
		Session session = sessionFactory.openSession();
		Transaction transaction = session.beginTransaction();
		
		User user=new User();
		user.setId(15);
		 
		session.delete(user);
		
		transaction.commit();
		session.close();
	}
}

原文链接：https://blog.csdn.net/zuo_fan/article/details/103932978

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