Hibernate的使用以及注意事项

忘是亡心i 2021-09-28 20:24 375阅读 0赞

**目录结构：**

![watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3dlaXhpbl80MDU3MDY3NQ_size_16_color_FFFFFF_t_70][]

1、导包，所需的jar包有：

![watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3dlaXhpbl80MDU3MDY3NQ_size_16_color_FFFFFF_t_70 1][]

相关jar包可以到[https://mvnrepository.com/][https_mvnrepository.com]这里进行搜索并下载

2、新建javabean对象，即实体类User.java

package com.hibernate.pojo;
    
    public class User {
        private int id;
        private String name;
        private int age;
        private String description;
    
        public int getId() {
            return id;
        }
    
        public void setId(int id) {
            this.id = id;
        }
    
        public String getName() {
            return name;
        }
    
        public void setName(String name) {
            this.name = name;
        }
    
        public int getAge() {
            return age;
        }
    
        public void setAge(int age) {
            this.age = age;
        }
    
        public String getDescription() {
            return description;
        }
    
        public void setDescription(String description) {
            this.description = description;
        }
    
        @Override
        public String toString() {
            return "User{" +
                    "id=" + id +
                    ", name='" + name + '\'' +
                    ", age=" + age +
                    ", description='" + description + '\'' +
                    '}';
        }
    }

![wAAACH5BAEKAAAALAAAAAABAAEAAAICRAEAOw==][wAAACH5BAEKAAAALAAAAAABAAEAAAICRAEAOw]

3、新建并编写对象映射（User.hbm.xml）；就在User.java的同级目录下新建

<?xml version="1.0"?>
    <!DOCTYPE hibernate-mapping PUBLIC
            "-//Hibernate/Hibernate Mapping DTD 3.0//EN"
            "http://www.hibernate.org/dtd/hibernate-mapping-3.0.dtd">
    
    <hibernate-mapping package="com.hibernate.pojo">
    
        
        <class name="User"  table="person">
    
            
            <id name="id" column="id">
                
                <generator class="native"/>
    
            </id>
            
            <property name="name" column="name"/>
            <property name="age" column="age"/>
            <property name="description" column="description"/>
        </class>
    </hibernate-mapping>

![wAAACH5BAEKAAAALAAAAAABAAEAAAICRAEAOw==][wAAACH5BAEKAAAALAAAAAABAAEAAAICRAEAOw]

** 注意：实体类名对应表名，属性名对应数据库字段名。****User.hbm.xml****文件开头的文档类型声明和下面****hibernate.cfg.xml****中的不一样**

4、src文件下创建并编写Hirbernate的主配置文件（hibernate.cfg.xml）

<?xml version="1.0" encoding="UTF-8"?>
    <!DOCTYPE hibernate-configuration PUBLIC
            "-//Hibernate/Hibernate Configuration DTD//EN"
            "http://www.hibernate.org/dtd/hibernate-configuration-3.0.dtd">
    
    <hibernate-configuration>
        
        <session-factory>
            
            <property name="connection.driver_class">com.mysql.jdbc.Driver</property>
            
            <property name="connection.url">jdbc:mysql://127.0.0.1:3306/userinfo?useUnicode=true&characterEncoding=utf-8&&useJDBCCompliantTimezoneShift=true&useLegacyDatetimeCode=false&serverTimezone=GMT%2B8</property>
            
            <property name="connection.username">root</property>
            
            <property name="connection.password">123456</property>
            
            <property name="dialect">org.hibernate.dialect.MySQLDialect</property>
            
            <property name="hibernate.show_sql">true</property>
    
            
    
    
            
            <mapping resource="com/hibernate/pojo/User.hbm.xml"/>
        </session-factory>
    </hibernate-configuration>

![wAAACH5BAEKAAAALAAAAAABAAEAAAICRAEAOw==][wAAACH5BAEKAAAALAAAAAABAAEAAAICRAEAOw]

**遇到的问题：**

**1、could not create connection to databases server.**

**查看mysql的版本：**dos命令进入mysql；键入命令：select version();显示8.0；

![20190530180204268.png][]

**而我的jar包为：**![20190530180316828.png][]

**原因：**mysql的版本高于mysql-connector-java.jar 的版本

**解决办法：**下载和mysql版本一致的mysql驱动包，即这个包 ![20190530180351536.png][]

**2、报错：Unsupported major.minor version 52.0**

**原因：**编译时运行环境的版本过低

**解决办法：**将运行环境版本要和jdk版本一致或者稍高点，我把运行环境从1.7调到了1.8，就可以调试成功了，如下图：

![watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3dlaXhpbl80MDU3MDY3NQ_size_16_color_FFFFFF_t_70 2][]

[watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3dlaXhpbl80MDU3MDY3NQ_size_16_color_FFFFFF_t_70]: /images/20210920/f41d664a0c5d4107bbea0b9fed4146b1.png
[watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3dlaXhpbl80MDU3MDY3NQ_size_16_color_FFFFFF_t_70 1]: /images/20210920/8236feac91434798b3d661eb6fb490b5.png
[https_mvnrepository.com]: https://mvnrepository.com/
[wAAACH5BAEKAAAALAAAAAABAAEAAAICRAEAOw]: 
[20190530180204268.png]: /images/20210920/268fd4c08abb49b68e31a981c1430db5.png
[20190530180316828.png]: /images/20210920/9bb15da51c8945119d215b927266e38b.png
[20190530180351536.png]: /images/20210920/6604e024ee19420b886ff80132871f5b.png
[watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3dlaXhpbl80MDU3MDY3NQ_size_16_color_FFFFFF_t_70 2]: /images/20210920/60eee03a81754d749b1f7f0338c1a264.png