Hibernate入门增删改查

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阳某 2021-09-02 11:05:06 ©著作权

文章标签 Hibernate hibernate maven xml 数据库 文章分类 代码人生

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文章目录

什么是Hibernate

Hibernate 是一个开放源代码的对象关系映射框架(就是一个数据库的框架)，它对 JDBC 进行了非常轻量级的对象封装，它将 pojo(java对象) 与数据库表建立映射关系，是一个全自动的 ORM（Object - Relationship - Mapping）框架，Hibernate 可以自动生成 SQL 语句，自动执行，使得 Java 程序员可以随心所欲的使用对象编程思维来操纵数据库。

优势：跨数据库的无缝移植

缺点：SQL语句不是自己写的，开发人员无法优化，找BUG不是很方便，配置文件比较复杂

Hibernate流程状态图
Hibernate入门增删改查_hibernate

Hibernate操作

如何在项目中添加hibernate支持(手动添加)

2.1 添加hibernate相关依赖
2.2 在resource目录下添加hibernate.cfg.xml(核心配置文件)
---- 2.2.1添加DTD支持
---- 2.2.2添加Hibernate的配置
--------2.2.2.1数据库相关(connection.username|connection.password|connection.url|connection.driver_class|dialect)
--------2.2.2.2 调试相关(show_sql|format_sql)
2.3 在开发阶段再创建实体类和实体映射文件(*.hbm.xml)
实体必须实现Serializable接口

如何使用hibernate完成CRUD操作
1 CRUD操作步骤
1.1 读取配置
1.2 创建SessionFactory
1.3 打开Session
1.4 开启事务
1.5 CURD
1.6 提交事务/回滚事务
1.7 关闭Session
2 注意事项
2.1 hibernate默认使用的是手动事务，因此必须显示的开启和提交事务
2.2 删除操作时，必须先查再删

hibernatecrud代码

代码解释都在相应的注释里面

所需pom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.xy</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>

核心配置文件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>
		<!-- 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/db_pro?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/xy/entity/User.hbm.xml" />
	</session-factory>
</hibernate-configuration>

实体类User

package com.xy.entity;

public class User {
	private int user_id;
	private String user_name;
	private String user_pwd;
	private int user_type;
	public int getUser_id() {
		return user_id;
	}
	public void setUser_id(int user_id) {
		this.user_id = user_id;
	}
	public String getUser_name() {
		return user_name;
	}
	public void setUser_name(String user_name) {
		this.user_name = user_name;
	}
	public String getUser_pwd() {
		return user_pwd;
	}
	public void setUser_pwd(String user_pwd) {
		this.user_pwd = user_pwd;
	}
	public int getUser_type() {
		return user_type;
	}
	public void setUser_type(int user_type) {
		this.user_type = user_type;
	}
	
	public User() {
	}
	public User(int user_id, String user_name, String user_pwd, int user_type) {
		this.user_id = user_id;
		this.user_name = user_name;
		this.user_pwd = user_pwd;
		this.user_type = user_type;
	}
	
	
	public User(String user_name, String user_pwd, int user_type) {
		super();
		this.user_name = user_name;
		this.user_pwd = user_pwd;
		this.user_type = user_type;
	}
	@Override
	public String toString() {
		return "User [user_id=" + user_id + ", user_name=" + user_name + ", user_pwd=" + user_pwd + ", user_type="
				+ user_type + "]";
	}
}

实体映射文件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：
			name:对应的是需要映射的实体类的全路径名
			table：实体类对应的数据库中的表
		
		id标签：配置的是表中的主键
			name:对应的是实体类的属性名
			type:指的是实体类数据类型
			column:数据表对应的列段
			
		property:配置除去主键以外的列段对应类属性映射关系
			name:对应的是实体类的属性名
			type:指的是实体类数据类型
			column:数据表对应的列段
			inser="false" update="false"
			上面的表示含义是，该列端或者该属性只做查询用，不做跟新
	 -->

	<class name="com.xy.entity.User" table="t_user">
		<id name="user_id" type="java.lang.Integer" column="user_id">
			<generator class="increment" />
		</id>
		<property name="user_name" type="java.lang.String" column="user_name">
		</property>
		<property name="user_pwd" type="java.lang.String" column="user_pwd">
		</property>
		<property name="user_type" type="java.lang.Integer" column="user_type">
		</property>
	</class>
</hibernate-mapping>

QueryDemo

	package com.xy.demo;

import java.util.List;

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

import com.xy.entity.User;

/**
 * hibernate查询演示
 * @author 86135
 *
 */
public class QueryDemo {
	public static void main(String[] args) {
		Configuration configure = new Configuration().configure("/hibernate.cfg.xml");
		SessionFactory sessionFactory = configure.buildSessionFactory();
//		会话、而这里的会话指的是操作数据库的连接		
		Session session = sessionFactory.openSession();
		List list = session.createQuery("from User").list();
		for (Object obj : list) {
			System.out.println(obj);
		}
		session.close();
	}
}

Hibernate入门增删改查_maven_02
InsertDemo

package com.xy.demo;

import java.util.List;

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

import com.xy.entity.User;

/**
 * hibernate新增演示
 * @author 86135
 *
 */
public class InsertDemo {
	
	public static void main(String[] args) {
		Configuration configure = new Configuration().configure("/hibernate.cfg.xml");
		SessionFactory sessionFactory = configure.buildSessionFactory();
//		会话、而这里的会话指的是操作数据库的连接
		Session session = sessionFactory.openSession();
		Transaction transaction = session.beginTransaction();
		session.save(new User("香饽饽", "123", 2));
		transaction.commit();
		session.close();
	}
}

UpdateDemo

public static void main(String[] args) {
			Configuration configure = new Configuration().configure("/hibernate.cfg.xml");
			SessionFactory sessionFactory = configure.buildSessionFactory();
	//		会话、而这里的会话指的是操作数据库的连接
			
			Session session = sessionFactory.openSession();
			Transaction transaction = session.beginTransaction();
			
			User user = session.get(User.class,9);
			user.setUser_name("象拔蚌");
			System.out.println(user);
			
			transaction.commit();
			session.close();
		}

DeleteDemo

public static void main(String[] args) {
		Configuration configure = new Configuration().configure("/hibernate.cfg.xml");
		SessionFactory sessionFactory = configure.buildSessionFactory();
//		会话、而这里的会话指的是操作数据库的连接
		
		Session session = sessionFactory.openSession();
		Transaction transaction = session.beginTransaction();
		
		User user=new User();
		user.setUser_id(9);
		session.delete(user);
		transaction.commit();
		session.close();
	}