Mybatis 使用通用 mapper

1.1 簡介

1.1.1 概述

??通用 Mapper 都可以極大的方便開發人員，可以隨意的按照自己的需要選擇通用方法，還可以很方便的開發自己的通用方法，極其方便的使用 MyBatis 單表的增刪改查，支持單表操作，不支持通用的多表聯合查詢，

1.1.2 相關依賴

<dependency>
    <groupId>tk.mybatis</groupId>
    <artifactId>mapper</artifactId>
    <version>4.1.5</version>
</dependency>

1.2 通用 Mapper 詳解

1.2.1 修改配置

<!-- 掃描 mapper 所在的包，為 mapper 創建實作類【org 包改為 tk 包】-->
<bean class="tk.mybatis.spring.mapper.MapperScannerConfigurer">
    <property name="basePackage" value="com.software.ssm.mapper"></property>
</bean>

1.2.2 常用注解

1.3 通用 Mapper 介面

1.3.1 繼承體系

1.3.2 繼承核心介面

/**
 * Created with IntelliJ IDEA.
 *
 * @author Demo_Null
 * @date 2020/9/10
 * @description 繼承通用 mapper 核心介面
 */
@Repository
public interface StudentMapper extends Mapper<Student> {}

1.3.3 操作介面

1.3.4 Example 介面

? 創建介面

// Condition 和 Example 作用完全一樣
Example example = new Example(JavaBean.class);
Example.Criteria criteria = example.createCriteria();

? 介面方法

1.4 示例

1.4.1 select

/**
 * Created with IntelliJ IDEA.
 *
 * @author Demo_Null
 * @date 2020/9/10
 * @description 簡單查詢
 */
@SpringJUnitConfig(locations = "classpath:application.xml")
public class Demo {

    @Autowired
    private StudentMapper studentMapper;

    @Test
    public void TestSelect() {
    	// 查詢所有
        List<Student> students = studentMapper.selectAll();
        System.out.println(students);

		// 匹配物體類屬性查詢
        Student student = new Student();
        student.setId(1L);
        List<Student> select = studentMapper.select(student);
        System.out.println(select);
    }
}

1.4.2 update

/**
 * Created with IntelliJ IDEA.
 *
 * @author Demo_Null
 * @date 2020/9/10
 * @description 修改
 */
@SpringJUnitConfig(locations = "classpath:application.xml")
public class Demo {

    @Autowired
    private StudentMapper studentMapper;

    @Test
    public void TestUpdate() {
        // 查詢引數
        Student student = new Student();
        student.setId(1L);
        // 修改前
        Student result_1 = studentMapper.selectOne(student);
        System.out.println(result_1);

        // 修改
        Student update = new Student();
        update.setId(1L);
        update.setName("王五");
        studentMapper.updateByPrimaryKeySelective(update);

        // 修改后
        Student result_2 = studentMapper.selectOne(student);
        System.out.println(result_2);
    }
}

1.4.3 insert

/**
 * Created with IntelliJ IDEA.
 *
 * @author Demo_Null
 * @date 2020/9/10
 * @description 新增
 */
@SpringJUnitConfig(locations = "classpath:application.xml")
public class Demo {

    @Autowired
    private StudentMapper studentMapper;

    @Test
    public void TestInsert() {
    	// 新增資料
        Student student = new Student();
        student.setName("張良");
        student.setAge(800);

		// 新增操作
        studentMapper.insertSelective(student);

		// 列印，新增成功之后可以從物體類物件中獲取 id
        System.out.println(student);
    }
}

1.4.4 delete

/**
 * Created with IntelliJ IDEA.
 *
 * @author Demo_Null
 * @date 2020/9/10
 * @description 洗掉
 */
@SpringJUnitConfig(locations = "classpath:application.xml")
public class Demo {

    @Autowired
    private StudentMapper studentMapper;

    @Test
    public void TestDel() {
        // 洗掉引數
        Student student = new Student();
        student.setId(1L);

        // 洗掉操作
        studentMapper.delete(student);

        // 查詢
        Student result = studentMapper.selectOne(student);
        System.out.println(result);
    }
}

1.4.5 Example

/**
 * Created with IntelliJ IDEA.
 *
 * @author Demo_Null
 * @date 2020/9/10
 * @description Example 實體
 */
@SpringJUnitConfig(locations = "classpath:application.xml")
public class Demo {

    @Autowired
    private StudentMapper studentMapper;

    @Test
    public void Test() {
        Example example = new Example(Student.class);

        Example.Criteria criteria = example.createCriteria();
        criteria.andEqualTo("id", 2L)
                .andLike("name", "%李%");

        List<Student> students = studentMapper.selectByExample(example);
        System.out.println(students);
    }
}