mybatis简单入门实例

ゝ一纸荒年。 2022-06-05 04:55 199阅读 0赞

最近刚接触到mybatis这个orm框架，之前接触过hibernate，不过想吐槽的是hibernate真的比较重量级，开发比较麻烦，所以再来看看mybatis怎么样。  
以下是上手小实例。  
1.环境部署：引入相关jar包(这里介绍个网站MavenRepository，[http://mvnrepository.com][http_mvnrepository.com] ，可以在上面搜寻需要的maven依赖)  
2.相关配置文件的配置  
（1）.Mybatis主配置文件—–Configure.xml（名字不限）

<?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>
    
        
        <properties resource="mybatis/config.properties"/>
    
    
        
        <typeAliases >
            <package name="vip.ntwxhn.model"/>
        </typeAliases>
        
        <environments default="development">
            <environment id="development">
                
                <transactionManager type="JDBC" />
                
                
                
                <dataSource type="POOLED">
                    <property name="driver" value="${jdbc.driver}" />
                    <property name="url" value="${jdbc.url}" />
                    <property name="username" value="${jdbc.username}" />
                    <property name="password" value="${jdbc.password}" />
                </dataSource>
            </environment>
        </environments>
    
    
        <mappers>
            
            <mapper resource="mappers/User.xml"/>
        </mappers>
    
    </configuration>

（2）Configure.xml中引用的config.properties

jdbc.driver=com.mysql.cj.jdbc.Driver
    jdbc.url=jdbc:mysql://localhost:3306/blog?useUnicode=true&useJDBCCompliantTimezoneShift=true&useLegacyDatetimeCode=false&serverTimezone=UTC
    jdbc.username=root
    jdbc.password=root

注：jdbc.url的配置看着好像过长，但是后面的参数都是有用的，解决了我的程序运行时的一个异常，如下：

java.sql.SQLException: The server time zone value '�й���׼ʱ��' 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.

这个错误是因为mysql连接的依赖包是高版本的情况下,在配置jdbc.url不能像jdbc:mysql://localhost:3306/blog这样简单的配：：  
得像下面这样配

jdbc.url=jdbc:mysql://localhost:3306/blog?useUnicode=true&useJDBCCompliantTimezoneShift=true&useLegacyDatetimeCode=false&serverTimezone=UTC

（3）映射文件UserMapper.xml(上面好像有些啰嗦，哈哈)

<?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="test">
        <select id="query" parameterType="java.lang.String" resultType="vip.ntwxhn.model.User">
          SELECT * FROM USER WHERE username LIKE '%${value}%'
        </select>
    
        
        <insert id="add" parameterType="vip.ntwxhn.model.User" >
            INSERT INTO USER(userId,username) VALUES(#{userId},#{username});
        </insert>
    </mapper>

（4）当然还得有实体类User

package vip.ntwxhn.model;
    
    /** * Created by user on 2017/11/17. */
    public class User { 
        private String userId;
        private String username;
        private String password;
        private String email;
        private String phonenumber;
    
    setter,getter省略.....

（5）测试类Test

package vip.ntwxhn.service;
    
    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 vip.ntwxhn.model.User;
    
    import java.io.IOException;
    import java.io.InputStream;
    import java.util.List;
    
    /** * Created by user on 2017/11/5. */
    public class Test {
        public static void main(String[] args) throws IOException {
                InputStream resourceAsStream = Resources.getResourceAsStream("mybatis/Configure.xml");
            SqlSessionFactory sqlSessionFactory = new SqlSessionFactoryBuilder().build(resourceAsStream);
            SqlSession sqlSession = sqlSessionFactory.openSession();
    //      User user = new User();
    //      user.setUserId("6");
    //      user.setUsername("dfg");
    //      sqlSession.insert("test.add",user);
    //      sqlSession.commit();
            User user  = sqlSession.selectOne("test.query", "1");
            System.out.println(user);
            sqlSession.close();
        }
    }

以上代码都是运行过再贴的，如果想粘贴的话，请放心。

[http_mvnrepository.com]: http://mvnrepository.com