如何使用hibernate完成CRUD操作

什么是hibernate？

       Hibernate是一个开放源代码的对象关系映射框架，它对JDBC进行了非常轻量级的对象封装，它将POJO与数据库表建立映射关系，是一个全自动的orm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。 Hibernate可以应用在任何使用JDBC的场合，既可以在Java的客户端程序使用，也可以在Servlet/JSP的Web应用中使用，最具革命意义的是，Hibernate可以在应用EJB的JaveEE架构中取代CMP，完成数据持久化的重任。

 

ORM概述

在介绍Hibernate的时候，说了Hibernate是一种ORM的框架。那什么是ORM呢？ORM是一种思想

• O代表的是Objcet
• R代表的是Relative
• M代表的是Mapping

ORM->对象关系映射....ORM关注是对象与数据库中的列的关系

Hibernate快速入门

1 添加hibernate相关依赖(pom.xml)

<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.psy</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>

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

<?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">psy</property>
        <property name="connection.password">123</property>
        <property name="connection.url">jdbc:mysql://localhost:3306/psy?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/psy/one/entity/User.hbm.xml" />
        <!-- 主键生成策略 -->
    </session-factory>
    </hibernate-configuration>

 

利用Hibernate实现增删改查

1.创建数据库表以及实体类

package com.psy.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 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 String getRemark() {
        return remark;
    }
    public void setRemark(String remark) {
        this.remark = remark;
    }
    
    public User(Integer id, String userName, String userPwd, String realName, String sex, Date birthday,
             String remark) {
        super();
        this.id = id;
        this.userName = userName;
        this.userPwd = userPwd;
        this.realName = realName;
        this.sex = sex;
        this.birthday = birthday;
        
        this.remark = remark;
    }
    public User() {
        super();
        // TODO Auto-generated constructor stub
    }
    @Override
    public String toString() {
        return "User [id=" + id + ", userName=" + userName + ", userPwd=" + userPwd + ", realName=" + realName
                + ", sex=" + sex + ", birthday=" + birthday + ", remark="
                + remark + "]";
    }

    
    
}

2.创建实体映射文件（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：对应的是实体类属性名
       type：对应的是实体类数据类型
       column：数据库表对应的列段
       
       
    property:配置除去主键以外列段对应的类属性映射关系
       name：对应的是实体类属性名
       type：对应的是实体类数据类型
       column：数据库表对应的列段
       
       insert="false" update="false" 该列段或者说该属性只支持查询，不做更新
 -->
<class name="com.psy.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 name="remark" type="java.lang.String" column="remark">
        </property>
    </class>

</hibernate-mapping>

3.CRUD的测试类

   3.1查询（QueryDemo）

package com.psy.one.demo;

import java.util.List;

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

/**
 * hibernate查询演示
 * @author Admin
 *
 */
public class QueryDemo {

    public static void main(String[] args) {
        System.out.println("111");
        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链接
        Session session=sessionFactory.openSession();
        List list = session.createQuery("from User").list();
        for (Object obj : list) {
            System.out.println(obj);
        }
        
        session.close();
    }
}

    3.2新增（InsertDemo）

package com.psy.one.demo;

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

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

import com.psy.one.entity.User;

/**
 * hibernate新增演示
 * @author Admin
 *
 */
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链接
        Session session=sessionFactory.openSession();
        Transaction transaction = session.beginTransaction();
        
        session.save(new User(null, "1", "2", "1", "5", new Date(System.currentTimeMillis()), "1"));
        
        
        transaction.commit();
        session.close();
    }
}

    3.3删除(DeleteDemo)

package com.psy.one.demo;

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

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

import com.psy.one.entity.User;

/**
 * hibernate删除演示
 * @author Admin
 *
 */
public class 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链接
        Session session=sessionFactory.openSession();
        Transaction transaction = session.beginTransaction();
        
        User user = new User();
        user.setId(1);
        session.delete(user);
        
        transaction.commit();
        session.close();
    }
}

3.4修改（UpdateDemo ）

package com.psy.one.demo;

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

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

import com.psy.one.entity.User;

/**
 * hibernate修改演示
 * @author Admin
 *
 */
public class 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链接
        Session session=sessionFactory.openSession();
        Transaction transaction = session.beginTransaction();
        
        //session.save(new User(null, "1", "2", "1", "5", new Date(System.currentTimeMillis()), "1"));
        User user = session.get(User.class, 1);
        user.setRealName("555");
        System.out.println(user);
        
        transaction.commit();
        session.close();
    }
}