Mybatis-03 第一个Mybatis 项目

谁践踏了优雅 2022-04-17 04:05 201阅读 0赞

### Mybatis学习笔记03 ###

*   *  搭建第一个Mybatis项目
     *   *   *  创建DTO
             *  创建DTO接口
             *  创建DTO接口实现
             *  Test测试
             *  MySQL数据库文件
             *  mapper.xml
             *  mybatis.xml
             *   *  配置文件注意事项
                 *   *  property url 省略默认内容
                     *  environments default一定要和environment 某个的Id一致 否则会报错
                 *  报错：org.apache.ibatis.exceptions.PersistenceException:

## 搭建第一个Mybatis项目 ##

#### 创建DTO ####

package www.mybatis01.beans;
    public class User {
    	private Integer userId;
    	private String userName;
    	private int age;
    	//快捷键Alt+Shift+S+C
    	public User() {
    		super();
    	}
    	//快捷键Alt+Shift+S+O
    	public User(String userName, int age) {
    		super();
    		this.userName = userName;
    		this.age = age;
    	}
    	
    	//快捷键Alt+Shift+S+R	
    	public Integer getUserId() {
    		return userId;
    	}
    	public void setUserId(Integer userId) {
    		this.userId = userId;
    	}
    	public String getUserName() {
    		return userName;
    	}
    	public void setUserName(String userName) {
    		this.userName = userName;
    	}
    	public int getAge() {
    		return age;
    	}
    	public void setAge(int age) {
    		this.age = age;
    	}
    	//快捷键Alt+Shift+S+S
    	@Override
    	public String toString() {
    		return "User [userId=" + userId + ", userName=" + userName + ", age=" + age + "]";
    	}
    	
    }

#### 创建DTO接口 ####

package www.mybatis01.dao;
    
    import www.mybatis01.beans.User;
    
    public interface IUserDao {
    	public void addUser(User user);
    	public int queryUser(int userID);
    }

#### 创建DTO接口实现 ####

import java.io.IOException;
    import java.io.InputStream;
    
    import org.apache.ibatis.io.Resources;
    import org.apache.ibatis.session.SqlSession;
    import org.apache.ibatis.session.SqlSessionFactory;
    import org.apache.ibatis.session.SqlSessionFactoryBuilder;
    
    import www.mybatis01.beans.User;
    import www.mybatis01.dao.IUserDao;
    import www.mybatis01.utils.mybatisdao.MybatisDao;
    
    public class UserMyBatisDao implements IUserDao {
    
    	@Override
    	public void addUser(User user) {
    		try {
    			//1：加载配置文件
    			InputStream input= Resources.getResourceAsStream("mybatis.xml");
    			//2：创建SqlSessionFactory对象
    			SqlSessionFactory sqlSessionFactory=new SqlSessionFactoryBuilder().build(input);
    			//3：创建SqlSession对象
    			SqlSession sqlSession = sqlSessionFactory.openSession();
    			//4：相关操作		
    			sqlSession.insert("user.addUser", user);
    			sqlSession.commit();
    			sqlSession.close();
    		} catch (IOException e) {
    			// TODO Auto-generated catch block
    			e.printStackTrace();
    		}
    	}
    }

#### Test测试 ####

package www.mybatis01.test;
    
    import org.junit.Test;
    import org.junit.Before;
    
    import www.mybatis01.beans.User;
    import www.mybatis01.dao.IUserDao;
    import www.mybatis01.dao.impl.UserMyBatisDao;
    
    public class UserTest {
    	
    	private IUserDao userDao;
    	
    	@Before
    	public void Before() {
    		userDao =new UserMyBatisDao();
    	}
    	@Test
    	public void testAdd() {
    		User user = new User("小四",18);
    		userDao.addUser(user);
    	}
    }

#### MySQL数据库文件 ####

CREATE DATABASE `mysql`;
    USE `mysql`;
    DROP TABLE IF EXISTS `tb_user`;
    CREATE TABLE `tb_user` (
      `userId` bigint(5) NOT NULL,
      `userName` varchar(50) DEFAULT NULL,
      `age` tinyint(3) DEFAULT NULL,
      `createdBy` varchar(50) DEFAULT NULL,
      `createdDate` timestamp NULL DEFAULT NULL,
      `updatedBy` varchar(50) DEFAULT NULL,
      `updatedDate` timestamp NULL DEFAULT NULL,
      PRIMARY KEY (`userId`)
    ) ENGINE=InnoDB DEFAULT CHARSET=utf8;
    
    insert  into `tb_user`(`userId`,`userName`,`age`,`createdBy`,`createdDate`,`updatedBy`,`updatedDate`) values 
    (1,'张三',20,NULL,NULL,NULL,NULL),
    (2,'李四',23,NULL,NULL,NULL,NULL),
    (3,'王五',26,NULL,NULL,NULL,NULL);

#### mapper.xml ####

<?xml version="1.0" encoding="UTF-8" ?>
    <!DOCTYPE mapper
      PUBLIC "-//mybatis.org//DTD Mapper 3.0//EN"
      "http://mybatis.org/dtd/mybatis-3-mapper.dtd">
    <mapper namespace="user">
    	<insert id="addUser" parameterType="www.mybatis01.beans.User">
    		insert into tb_user(userName,age)
    		values(#{userName},#{age})
    	</insert>
    </mapper>

#### mybatis.xml ####

<?xml version="1.0" encoding="UTF-8"?>
    <!DOCTYPE configuration
    PUBLIC "-//mybatis.org//DTD Config 3.0//EN"
    "http://mybatis.org/dtd/mybatis-3-config.dtd">
    <configuration>
    	
    	<environments default="mysql">
    		<environment id="mysql">
    			<transactionManager type="JDBC" />
    			<dataSource type="POOLED">
    				<property name="driver" value="com.mysql.cj.jdbc.Driver" />
    				<property name="url" value="jdbc:mysql://127.0.0.1:3306/mysql?serverTimezone=UTC" />
    				<property name="username" value="****" />
    				<property name="password" value="****" />
    				
    			</dataSource>
    		</environment>
    	</environments>	
    	
    	<mappers>
    		<mapper resource="www/mybatis01/dao/mapper.xml" />
    	</mappers>
    </configuration>

##### 配置文件注意事项 #####

###### property url 省略默认内容 ######

<property name="url" value="jdbc:mysql://127.0.0.1:3306/mysql"/>
    如果数据库 地址为127.0.0.1 端口号为3306， 可以省略 jdbc:mysql:///mysq
    <property name="url" value="jdbc:mysql:///mysq"/>

###### environments default一定要和environment 某个的Id一致 否则会报错 ######

<environments default="mysql">
    		<environment id="mysql">
    		</environment>
    		<environment id="oracle">
    		</environment>
    		<environment id="DB2">
    		</environment>
    	</environments>	
    </configuration>

##### 报错：org.apache.ibatis.exceptions.PersistenceException: #####

报错：
    org.apache.ibatis.exceptions.PersistenceException: 
    ### Error updating database.  Cause: java.sql.SQLException: The server time zone value 'ÖÐ¹ú±ê×¼Ê±¼ä' is unrecognized or represents more than one time zone. You must configure either the server or JDBC driver (via the serverTimezone configuration property) to use a more specifc time zone value if you want to utilize time zone support.
     
    需要设置serverTimezone=UTC
    <property name="url" value="jdbc:mysql://127.0.0.1:3306/mysql" />
    改为：
    <property name="url" value="jdbc:mysql://127.0.0.1:3306/mysql?serverTimezone=UTC" />

[相关Jar包下载参考：][Jar]  
[https://blog.csdn.net/lingyiwin/article/details/83870537][Jar]

[Jar]: https://blog.csdn.net/lingyiwin/article/details/83870537