MyBatis的环境搭建和简单使用

Bertha 。 2022-12-03 02:27 175阅读 0赞

**第一步，下载mysql-connector-java-5.1.0-bin.jar和mybatis-3.4.4.jar并导入到项目当中，这里版本可自行选择，**

**如果测试需要用到log4J日志打印的话，导入log4j的jar包，写入log4j的配置文件**

**创建JUnit Test Case类**

**Logger log = Logger.getLogger(当前类.class);**

**log.debug()输出/log.info()**

**第二步：创建一个数据库的配置文件放置到一个Source Folder中**

![20200901162015995.png][]

**第三步：创建实体类**

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**第四步：创建实体类对应的mapper接口**

**@Param("参数名称") 是要传给对应的mapper.xml的参数值**

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**第五步：创建mapper接口对应的mapper.xml文件(DAO层SQL映射文件)**

<?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="com.gong.mapper.ClazzMapper">//对应的mapper接口的完整限定名
        //id对应mapper接口的方法名，resultType对应返回值类型(完整限定名)，parameterType对应传入参数的类型
     	<select id="get" resultType="com.gong.bean.Clazz" parameterType="int">
     		//这里#{mapper接口中方法的参数名}可以直接拿到对应的参数值
            select * from clazz where clazzId = #{clazzId}
     	</select>
     	<select id="show" resultType="com.gong.bean.Clazz">
     		select * from clazz
     	</select>
     	<insert id="add" parameterType="com.gong.bean.Clazz">
     		insert into clazz(clazzName,clazzHomeroomTeacher)values(#{clazzName},#{clazzHomeroomTeacher})
     	</insert>
     	<delete id="delete" parameterType="int">
     		delete from clazz where clazzId=#{clazzId}
     	</delete>
     	<update id="update" parameterType="com.gong.bean.Clazz">
     		update clazz set clazzName=#{clazzName},clazzHomeroomTeacher=#{clazzHomeroomTeacher} where
     		clazzId=#{clazzId}
     	</update>
     </mapper>

**第六步：最重要的一步，配置主文件mybatis-config.xml，这里的xml文件的名字是可选的**

<?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="db.properties"></properties>
        
        
    	
    	<environments default="development">//这里的default参数指默认的环境配置
    		<environment id="development">
    			<transactionManager type="JDBC"></transactionManager>
    			
    			<dataSource type="POOLED">//type参数指mybatis自带的数据源
    				<property name="driver" value="${driver}"/>
            		<property name="url" value="${url}"/>
            		<property name="username" value="${username}"/>
            		<property name="password" value="${password}"/>
    			</dataSource>
    		</environment>
    	</environments>
    	
    	<mappers>
            //resource参数指的是对应的Mapper.xml文件，注意这里是完整的路径
    		<mapper resource="com/gong/mapper/ClazzMapper.xml"></mapper>
    	</mappers>

**第七步：测试是否配置成功**

public class Test {
    	public static void main(String[] args) {
    		//mybatis操作数据库五部曲
    		try {
    			//第一步：加载配置文件
    			InputStream is = Resources.getResourceAsStream("mybatis-config.xml");
    			//第二步：获取SqlSessionFactory对象
    			SqlSessionFactory factory = new SqlSessionFactoryBuilder().build(is);
    			//第三步：获取SqlSession对象
    			SqlSession sqlSession = factory.openSession();
    			//第四步：获取相应的mapper对象
    			ClazzMapper clazzMapper = sqlSession.getMapper(ClazzMapper.class);
                //第五步：关流
    			sqlSession.commit();//提交事务
    			sqlSession.close();
    			is.close();
               }
            }
        }

[20200901162015995.png]: /images/20221123/6fdd9f44eabc404599a6aa6f59d10201.png
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