mybatis

1.导入jar包

<dependency>
<groupId>mysql</groupId>
<artifactId>mysql-connector-java</artifactId>
<version>5.1.46</version>
</dependency>

<dependency>
<groupId>org.mybatis</groupId>
<artifactId>mybatis</artifactId>
<version>3.4.0</version>
</dependency>

<dependency>
<groupId>junit</groupId>
<artifactId>junit</artifactId>
<version>4.12</version>
</dependency>

<dependency>
<groupId>log4j</groupId>
<artifactId>log4j</artifactId>
<version>1.2.12</version>
</dependency>

其中log4j需要一个properties配置文件

# Global logging configuration
log4j.rootLogger=DEBUG, stdout
# MyBatis 日志配置
log4j.logger.mapper.UserMapper=TRACE
log4j.logger.mapper.OrderMapper=TRACE
# Console output...
log4j.appender.stdout=org.apache.log4j.ConsoleAppender
log4j.appender.stdout.layout=org.apache.log4j.PatternLayout
log4j.appender.stdout.layout.ConversionPattern=%5p [%t] - %m%n

2.编写主配置文件(一般命名SqlMapConfig.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>
    <!-- 和spring整合后 environments配置将废除 -->
    <environments default="development">
        <environment id="development">
            <!-- 使用jdbc事务管理 -->
            <transactionManager type="JDBC" />
            <!-- 数据库连接池 -->
            <dataSource type="POOLED">
                <property name="driver" value="com.mysql.jdbc.Driver" />
                <property name="url"
                          value="jdbc:mysql://localhost:3306/名称?characterEncoding=UTF-8" />
                <property name="username" value="数据库名" />
                <property name="password" value="密码" />
            </dataSource>
        </environment>
    </environments>
    <mappers>
        <mapper resource="User.xml"/><!--扫描子mapper文件-->
        <mapper resource="UserMapper.xml"/>
        <mapper class="接口路径<使用注解方式的时候用"/>
    </mappers>
</configuration>

建立子mapper.xml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="接口路径">
自己改一下下面的
    <resultMap id="result_map" type="result">
        <id property="studentNo" column="studentNo"/>
        <id property="subjectNo" column="subjectNo"/>
        <id property="examDate" column="examDate"/>
        <result property="studentResult" column="studentResult"/>
        <result property="stu_Name" column="studentName"/>
    </resultMap>

    <select id="queryResultAll" resultMap="result_map">
        SELECT r.*,s.`studentName` FROM result r
        INNER JOIN student AS s ON s.`studentNo`=r.studentNo
    </select>
</mapper>

或者不需要用子mapper.xml方式而在接口使用注解

例如：

@Select("select * from user")
List<User> select();

@Insert("......")
int insert(User user);

......

在测试类中，

private SqlSessionFactory sqlSessionFactory;
    @Before
    public void init() throws IOException {
        SqlSessionFactoryBuilder sqlSessionFactoryBuilder=
                new SqlSessionFactoryBuilder();
        InputStream inputStream=
                Resources.getResourceAsStream("SqlMapConfig.xml");
        this.sqlSessionFactory = sqlSessionFactoryBuilder.build(inputStream);

    }

//通过sqlSessionFactory打开Session，然后调用操作方法

@Test
public void selectId(){
    SqlSession sqlSession=sqlSessionFactory.openSession();
    User user=sqlSession.selectOne("selectId",1);
    System.out.println(user.getUsername());
    sqlSession.close();
}
@Test
public void sel(){
    SqlSession sqlSession = sqlSessionFactory.openSession();
    List<User> list=sqlSession.selectList("sel","男");
    for (User user : list) {
        System.out.println(user.getUsername());
    }
    sqlSession.close();
}

测试-->sqlMapConfig.xml--mapper.xml中的sql语句---mapper---entity