MyBatis之单表查询

朴灿烈づ我的快乐病毒、 2021-09-23 09:26 332阅读 0赞

因最近会用到mybatis相关，好久木有用了， 赶紧来回顾以及记录并分享下：

这一章先来分享一下单表查询是如何实现的：

一、添加mybatis依赖

<dependency>
      <groupId>org.mybatis</groupId>
      <artifactId>mybatis</artifactId>
      <version>x.x.x</version>
    </dependency>

二、添加xml数据库配置文件

<?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="development">
        <environment id="development">
        	
          <transactionManager type="JDBC"/>
          <dataSource type="POOLED">
          	
            <property name="driver" value="${driver}"/>
            
            <property name="url" value="${url}"/>
            
            <property name="username" value="${username}"/>
            
            <property name="password" value="${password}"/>
          </dataSource>
        </environment>
      </environments>
      <mappers>
      	
        <mapper resource="org/mybatis/example/BlogMapper.xml"/>
      </mappers>
    </configuration>

三、读取xml文件创建SqlSessionFactory对象

//配置文件路径
    String resource = "org/mybatis/example/mybatis-config.xml";
    //获取配置文件
    InputStream inputStream = Resources.getResourceAsStream(resource);
    //通过配置文件获取SqlSessionFactory对象
    SqlSessionFactory sqlSessionFactory =
      new SqlSessionFactoryBuilder().build(inputStream);

四、创建sql语句以及创建SqlSession对象  
1）配置sql查询语句

<?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="org.mybatis.example.BlogMapper">
    
      <select id="selectBlog" resultType="Blog">
        select * from Blog where id = #{id}
      </select>
    </mapper>

2）创建SqlSession对象

try (SqlSession session = sqlSessionFactory.openSession()) {
      Blog blog = session.selectOne(
        "org.mybatis.example.BlogMapper.selectBlog", 101);
    }