POM

编写完相关代码后，我们可以使用单元测试查看 MyBatis 的执行效果，需要增加单元测试相关依赖，配置如下:

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<dependency>
    <groupId>org.springframework</groupId>
    <artifactId>spring-test</artifactId>
    <version>4.3.17.RELEASE</version>
</dependency>
<dependency>
    <groupId>junit</groupId>
    <artifactId>junit</artifactId>
    <version>4.12</version>
</dependency>

定义实体类

以 tb_user 表为例，实体类代码如下：

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public class TbUser implements Serializable {
    private Long id;
    private String username;
    private String password;
    private String phone;
    private String email;
    private Date created;
    private Date update;

    public Long getId() {
        return id;
    }

    public void setId(Long id) {
        this.id = id;
    }

    public String getUsername() {
        return username;
    }

    public void setUsername(String username) {
        this.username = username;
    }

    public String getPassword() {
        return password;
    }

    public void setPassword(String password) {
        this.password = password;
    }

    public String getPhone() {
        return phone;
    }

    public void setPhone(String phone) {
        this.phone = phone;
    }

    public String getEmail() {
        return email;
    }

    public void setEmail(String email) {
        this.email = email;
    }

    public Date getCreated() {
        return created;
    }

    public void setCreated(Date created) {
        this.created = created;
    }

    public Date getUpdate() {
        return update;
    }

    public void setUpdate(Date update) {
        this.update = update;
    }
}

定义数据访问接口

注意：Spring 集成 MyBatis 后，不需要手动实现 DAO 层的接口，所有的 SQL 执行语句都写在对应的关系映射配置文件中。

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@Repository
public interface TbUserDao {

    /**
     * 查询全部用户信息
     * @return
     */
    public List<TbUser> selectAll();
}

定义业务逻辑接口

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public interface TbUserService {

    /**
     * 查询全部用户信息
     * @return
     */
    public List<TbUser> selectAll();
}

实现业务逻辑接口

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@Service
public class TbUserServiceImpl implements TbUserService {

    @Autowired
    private TbUserDao tbUserDao;

    @Override
    public List<TbUser> selectAll() {
        return tbUserDao.selectAll();
    }
}

定义映射文件

映射文件，简称为Mapper，主要完成 DAO 层中 SQL 语句的映射。映射文件名随意，一般放在src/resources/mapper 文件夹中。这里映射文件名称定为 TbUserMapper.xml。

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<?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.funtl.my.shop.web.admin.dao.TbUserDao">
    <select id="selectAll" resultType="TbUser">
        SELECT
          a.id,
          a.username,
          a.password,
          a.phone,
          a.email,
          a.created,
          a.updated
        FROM
          tb_user AS a
    </select>
</mapper>

创建单元测试

所有工作准备就绪，我们就可以测试 MyBatis 是否能够正常执行了。创建一个单元测试类，代码如下：

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@RunWith(SpringJUnit4ClassRunner.class)
@ContextConfiguration({"classpath:spring-context.xml", "classpath:spring-context-druid.xml", "classpath:spring-context-mybatis.xml"})
public class TbUserServiceTest {

    @Autowired
    private TbUserDao tbUserDao;

    @Test
    public void testSelectAll() {
        List<TbUser> tbUsers = tbUserDao.selectAll();
        for (TbUser tbUser : tbUsers) {
            System.out.println(tbUser.getUsername());
        }
    }
}