mybatis - CRUD操作

一、CRUD操作

映射文件

<!--     int addUser();       -->
        <insert id="addUser">
            insert into t_user values(null,'张三','123456')
        </insert>



<!--    int deleteUserById();-->
        <delete id="deleteUserById">
            delete from t_user where id = 3
        </delete>
    <!--
    int updateUser();-->
        <update id="updateUser">
            update t_user set username = '王五' where id = 1
        </update>

<!--    查询方法都要设置结果集  -->
<!--     List<User> getAllUser();-->
<!--     resultType :   默认映射关系    表中字段 与 实体类属性名一致
            表中的字段与类属性名一致，会自动装配
         resultMap  ： 自定义的映射关系   表中字段 与 实体类属性名不一致
            表中的字段与类属性名不同
-->
       <select id="getAllUser" resultType="user">
            select * from t_user
       </select>

<!--    User getUser() -->
        <select id="getUser" resultType="user">
            select * from t_user where id = 1
        </select>

mapper接口

public interface UserMapper {

    int addUser();

    int deleteUserById();

    int updateUser();

    List<User> getAllUser();

    User getUser();
}

二、配置log4j日志

1.配置log4j 依赖

 <dependency>
            <groupId>log4j</groupId>
            <artifactId>log4j</artifactId>
            <version>1.2.17</version>
        </dependency>

2.配置文件 ，文件名为log4j.xml

<?xml version="1.0" encoding="UTF-8" ?>
<!DOCTYPE log4j:configuration SYSTEM "log4j.dtd">
<log4j:configuration xmlns:log4j="http://jakarta.apache.org/log4j/">
    <appender name="STDOUT" class="org.apache.log4j.ConsoleAppender">
        <param name="Encoding" value="UTF-8" />
        <layout class="org.apache.log4j.PatternLayout">
            <param name="ConversionPattern" value="%-5p %d{MM-dd HH:mm:ss,SSS} %m (%F:%L) \n" />
        </layout>
    </appender>
    <logger name="java.sql">
        <level value="debug" />
    </logger>
    <logger name="org.apache.ibatis">
        <level value="info" />
    </logger>
    <root>
        <level value="debug" />
        <appender-ref ref="STDOUT" />
    </root>
</log4j:configuration>

三、创建SqlSession工具类来获取SqlSession

public class SQLSessionUtils {

    public static SqlSession getSqlSession() {
        SqlSession sqlSession = null;
        try {
            InputStream is = Resources.getResourceAsStream("mybatis-config.xml");
            SqlSessionFactory factory = new SqlSessionFactoryBuilder().build(is);
            // openSession(true)  设置为自动提交事务
            sqlSession = factory.openSession(true);
        } catch (IOException e) {
            e.printStackTrace();
        }
        return sqlSession;
    }
}