如何使用hibernate完成CRUD操作

阳光穿透心脏的1/2处 2021-12-01 15:52 396阅读 0赞

**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][Link 1]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>
            
            <property name="connection.username">psy</property>
            <property name="connection.password">123</property>
            <property name="connection.url">jdbc:mysql://localhost:3306/psy?useUnicode=true&characterEncoding=UTF-8
            </property>
            <property name="connection.driver_class">com.mysql.jdbc.Driver</property>
            <property name="dialect">org.hibernate.dialect.MySQLDialect</property>
    
            
            <property name="hibernate.current_session_context_class">thread</property>
    
            
            <property name="show_sql">true</property>
            <property name="format_sql">true</property>
    
            
            <mapping resource="com/psy/one/entity/User.hbm.xml" />
            
        </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 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();
        }
    }

转载于:https://www.cnblogs.com/psyu/p/11181923.html

[Link 1]: https://baike.so.com/doc/5030500-5256785.html