java - mybatis 入门案例

1.创建数据库

CREATE TABLE `user` (
  `id` int(11) NOT NULL AUTO_INCREMENT,
  `username` varchar(32) NOT NULL COMMENT '用户名称',
  `birthday` date DEFAULT NULL COMMENT '生日',
  `sex` char(1) DEFAULT NULL COMMENT '性别',
  `address` varchar(256) DEFAULT NULL COMMENT '地址',
  PRIMARY KEY (`id`)
) ENGINE=InnoDB AUTO_INCREMENT=27 DEFAULT CHARSET=utf8;

创建数据库.png

2.创建普通java工程

创建普通java工程.png

3.导包

导包.png

4.建工程结构及 jdbc 、log 配置

工程结构.png 建工程结构及 jdbc 、log 配置.png

5.配置 mybatis ，编写 sqlMapConfig.xml 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:核心配置文件，数据源，事务 -->
<configuration>
       // properties：引入外部资源文件
  <properties resource="jdbc.properties"></properties>
  <typeAliases>
      // 批量扫描定义别名：表示com.xiaocai.domain包路径下所有类都自动被定义了别名 别名名称：类名，大小写随意 
      <package name="com.xiaocai.mybatis.domain" />
  </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>
  
  // 引入外部映射文件：引入多个映射文件
  <mappers>
      <package name="com.xiaocai.dao"/>
  </mappers>
  
</configuration>

6.编写 domain 类 -- User

编写 domain 类.png

7.编写操作数据库接口类

public interface UserDao {

    // 根据Id查询用户
    public User findUserByID(Integer id);

    // 根据用户名模糊查询
    public List<User> findUserWithLike(String username);

    // 插入数据
    public Integer insertUser(User user);
}

8.建同包名，名字也相同的 dao 对应的xml类

<?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.xiaocai.dao.UserDao">
    <!-- 根据id获取用户信息 -->
    <select id="findUserByID" parameterType="int"
        resultType="com.xiaocai.domain.User">
        select * from user where id = #{id}
    </select>
    <!-- 自定义条件查询用户列表 -->
    <select id="findUserWithLike" parameterType="java.lang.String"
        resultType="com.xiaocai.domain.User">
        select * from user where username like '%${value}%'
    </select>
    <!-- 添加用户 -->
    <insert id="insertUser" parameterType="com.xiaocai.domain.User">
        <selectKey keyProperty="id" order="AFTER" resultType="java.lang.Integer">
            select LAST_INSERT_ID()
        </selectKey>
        insert into user(username,birthday,sex,address)
        values(#{username},#{birthday},#{sex},#{address})
    </insert>

</mapper>

同包名文件名.png

9.编写测试类

public class TestDao {

    private SqlSessionFactory sqlSessionFactory;
    private InputStream resourceAsStream;

    @Before
    public void beforeTest() throws IOException {
        String resourceFile = "sqlMapConfig.xml";
        resourceAsStream = Resources.getResourceAsStream(resourceFile);
        sqlSessionFactory = new SqlSessionFactoryBuilder()
                .build(resourceAsStream);
    }
}

10.mybatis 测试

• 1.插入数据

    @Test
    public void insertUserTest() {
        SqlSession openSession = sqlSessionFactory.openSession();
        UserDao mapper = openSession.getMapper(UserDao.class);
        User user = new User();
        user.setUsername("xiaocai");
        user.setSex("男");

        Integer insertUser = mapper.insertUser(user);
        // 提交
        openSession.commit();
        // 关闭session
        openSession.close();
        System.out.println(insertUser);
    }

测试结果.png

• 2.查询

    @Test
    public void findByIDTest() {
        SqlSession openSession = sqlSessionFactory.openSession();
        UserDao userDaoMapper = openSession.getMapper(UserDao.class);
        User user = userDaoMapper.findUserByID(30);
        System.out.println(user);
    }