MyBatis-Plus 使用说明介绍

妖狐艹你老母 2023-08-17 16:39 110阅读 0赞

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">
    
        
        <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
            
            <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。

转载于:https://www.cnblogs.com/jay-wu/p/11244733.html