MyBatis-Plus 使用说明介绍

先看一下和MyBatis 不同点说明：

    @GetMapping("/select_sql")

    public Object getUserBySql() {

        User user=new User(1L);

        User selectUser=user.selectById();

        user.deleteById(user);

        return userService.selectListBySQL();  //普通走法

    }

最大的不同点在entity层直接可以调用superEntity，直接实现默认的一些增删改查

/**

 * 用户表

 */

@SuppressWarnings("serial")

public class User extends SuperEntity<User> {

    /**

     * 名称

     */

    private String name;

    /**

     * 年龄

     */

    private AgeEnum age;

    /**

     * 这里故意演示注解可无

     */

    @TableField("test_type")

    @TableLogic

    private Integer testType;

    /**

     * 测试插入填充

     */

    @TableField(fill = FieldFill.INSERT)

    private Date testDate;

    private Long role;

    private PhoneEnum phone;

    public User() {

    }

    public User(Long id){

        this.setId(id);

    }

    public User(Long id, String name, AgeEnum age, Integer testType) {

        this.setId(id);

        this.name = name;

        this.age = age;

        this.testType = testType;

    }

    public User(String name, AgeEnum age, Integer testType) {

        this.name = name;

        this.age = age;

        this.testType = testType;

    }

    public String getName() {

        return this.name;

    }

    public void setName(String name) {

        this.name = name;

    }

    public AgeEnum getAge() {

        return this.age;

    }

    public void setAge(AgeEnum age) {

        this.age = age;

    }

    public Integer getTestType() {

        return this.testType;

    }

    public void setTestType(Integer testType) {

        this.testType = testType;

    }

    public Long getRole() {

        return this.role;

    }

    public void setRole(Long role) {

        this.role = role;

    }

    public PhoneEnum getPhone() {

        return this.phone;

    }

    public void setPhone(PhoneEnum phone) {

        this.phone = phone;

    }

    public Date getTestDate() {

        return testDate;

    }

    public void setTestDate(Date testDate) {

        this.testDate = testDate;

    }

    @Override

    public String toString() {

        return "User [id=" + this.getId() + ", name=" + name + ", age=" + age

                + ", testType=" + testType + ", testDate="

                + testDate + ", role=" + role + ", phone=" + phone + "]";

    }

SuperEntity 继承Model  ，Model默认实现了简单的增删改查，不需要再去实现mapper层。

/**

 * 演示实体父类

 */

public class SuperEntity<T extends Model> extends Model<T> {

    /**

     * 主键ID , 这里故意演示注解可以无

     */

    @TableId("test_id")

    private Long id;

    private Long tenantId;

    public Long getId() {

        return this.id;

    }

    public void setId(Long id) {

        this.id = id;

    }

    public Long getTenantId() {

        return tenantId;

    }

    public SuperEntity setTenantId(Long tenantId) {

        this.tenantId = tenantId;

        return this;

    }

    @Override

    protected Serializable pkVal() {

        return this.id;

    }

}

2.对于原生service层改造实现，默认实现baseMapper， baseMapper 默认实现了mapper的常规使用写法方式。

@Service

public class UserServiceImpl extends ServiceImpl<UserMapper, User> implements IUserService {

	@Override

	public boolean deleteAll() {

		return retBool(baseMapper.deleteAll());

	}

	@Override

	public List<User> selectListBySQL() {

		return baseMapper.selectListBySQL();

	}

	@Override

	public List<User> selectListByWrapper(Wrapper wrapper) {

		return baseMapper.selectListByWrapper(wrapper);

		//baseMapper.selectma

	}

}

3.UserMapper 继承 superMapper，而superMapper继承baseMapper，你可以把一些公共的方法放在superMapper里，从而实现公用。

/**

 * User 表数据库控制层接口

 */

public interface UserMapper extends SuperMapper<User> {

    /**

     * 自定义注入方法

     */

    int deleteAll();

    @Select("select test_id as id, name, age, test_type from user")

    List<User> selectListBySQL();

    List<User> selectListByWrapper(@Param("ew") Wrapper wrapper);

}

最后的XML是一些不常用的sql可以写在这里给予调用。

<?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.baomidou.springboot.mapper.UserMapper">

    <!-- 通用查询结果列 -->

    <sql id="Base_Column_List">

        test_id AS testId, name, age, test_type AS testType, role, phone

    </sql>

    <delete id="deleteAll">

        DELETE FROM USER

    </delete>

    <select id="selectListByWrapper" resultType="com.baomidou.springboot.entity.User">

        SELECT * FROM USER

        <!-- 判断 wrapper 是否为空 emptyOfWhere -->

        <where>

            ${ew.sqlSegment}

        </where>

    </select>

</mapper>

可以看到他们的关系是一层一层过滤设计的，用了公共代码方便了公用，也达到了解耦合。

巴特西

MyBatis-Plus 使用说明介绍

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