【Spring Boot】Mybatis 开发方式

文章目录

• ​​Mybatis 开发方式​​

• ​​方式一：注解​​

• ​​1.创建数据库信息​​
• ​​2.封装bean​​
• ​​3.创建CityMapper​​
• ​​4.创建CityService​​
• ​​5.测试​​

• ​​方式二：xml 配置​​

• ​​1.修改CityMapper​​
• ​​2.创建CityMapper.xml​​
• ​​3.修改CityService​​
• ​​4.测试​​

• ​​方式三：混合注解和xml​​

Mybatis 开发方式

方式一：注解

1.创建数据库信息

• 准备一张city表

/*
 Navicat MySQL Data Transfer

 Source Server         : test
 Source Server Type    : MySQL
 Source Server Version : 80017
 Source Host           : localhost:3306
 Source Schema         : dormitory

 Target Server Type    : MySQL
 Target Server Version : 80017
 File Encoding         : 65001

 Date: 27/07/2021 20:41:19
*/

SET NAMES utf8mb4;
SET FOREIGN_KEY_CHECKS = 0;

-- ----------------------------
-- Table structure for city
-- ----------------------------
DROP TABLE IF EXISTS `city`;
CREATE TABLE `city`  (
  `id` int(11) NOT NULL AUTO_INCREMENT,
  `name` varchar(30) CHARACTER SET utf8 COLLATE utf8_general_ci NULL DEFAULT NULL,
  `state` varchar(30) CHARACTER SET utf8 COLLATE utf8_general_ci NULL DEFAULT NULL,
  `country` varchar(30) CHARACTER SET utf8 COLLATE utf8_general_ci NULL DEFAULT NULL,
  PRIMARY KEY (`id`) USING BTREE
) ENGINE = InnoDB CHARACTER SET = utf8 COLLATE = utf8_general_ci ROW_FORMAT = Dynamic;

-- ----------------------------
-- Records of city
-- ----------------------------
INSERT INTO `city` VALUES (1, '北京', '1', '中国');
INSERT INTO `city` VALUES (2, '南京', '1', '中国');
INSERT INTO `city` VALUES (3, '江苏', '2', '中国');
INSERT INTO `city` VALUES (4, '山东', '2', '中国');
INSERT INTO `city` VALUES (5, '纽约', '3', '美国');
INSERT INTO `city` VALUES (6, '洛杉矶', '3', '美国');

SET FOREIGN_KEY_CHECKS = 1;

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2.封装bean

package com.zyx.core.admin.bean;

import lombok.AllArgsConstructor;
import lombok.Data;
import lombok.NoArgsConstructor;
import lombok.ToString;

/**
 * @author 35192
 * @date 2021-07-27 20:21
 */
@Data
@ToString
@NoArgsConstructor
@AllArgsConstructor
public class City {
    private Integer id;
    private String name;
    private String state;
    private String country;
}

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3.创建CityMapper

• 我们创建一个查询的方法，可以发现报错：没有对应的mapper.xml匹配，这里我们将采用注解的形式进行。

我们直接使用@Select注解进行查询：​​@Select("select * from city where id=#{id}")​​其中的id就会从方法的参数进行匹配。

package com.zyx.core.admin.mapper;

import com.zyx.core.admin.bean.City;
import org.apache.ibatis.annotations.Mapper;
import org.apache.ibatis.annotations.Select;

/**
 * @author 35192
 * @date 2021-07-27 20:24
 */
@Mapper
public interface CityMapper {
   
    @Select("select * from city where id=#{id}")
    public City getById(Integer id);
}

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4.创建CityService

package com.zyx.core.admin.service;

import com.zyx.core.admin.bean.City;
import com.zyx.core.admin.mapper.CityMapper;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Service;

/**
 * @author 35192
 * @date 2021-07-27 20:31
 */
@Service
public class CityService {

    @Autowired
    CityMapper cityMapper;

    public City getById(Integer id){
        City city = cityMapper.getById(id);
        return city;
    }
}

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5.测试

package com.zyx.core.admin.test;

import com.zyx.core.admin.bean.City;
import com.zyx.core.admin.service.AdminService;
import com.zyx.core.admin.service.CityService;
import org.junit.Test;
import org.junit.runner.RunWith;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.boot.test.context.SpringBootTest;
import org.springframework.test.context.junit4.SpringJUnit4ClassRunner;
import java.util.List;

/**
 * @author 35192
 * @date 2021-07-23 16:44
 */
@RunWith(SpringJUnit4ClassRunner.class)
@SpringBootTest
public class MybatisTest {

    @Autowired
    CityService cityService;

    @Test
    public void getById() {
        City city = cityService.getById(1);
        System.out.println(city);
    }
}

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方式二：xml 配置

1.修改CityMapper

package com.zyx.core.admin.mapper;

import com.zyx.core.admin.bean.City;
import org.apache.ibatis.annotations.Mapper;
import org.apache.ibatis.annotations.Select;

/**
 * @author 35192
 * @date 2021-07-27 20:24
 */
@Mapper
public interface CityMapper {

    @Select("select * from city where id=#{id}")
    public City getById(Integer id);

    // 添加操作
    public void insert(City city);
}

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2.创建CityMapper.xml

<?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.zyx.core.admin.mapper.CityMapper">

    <!--  public void insert(City city);  -->
    <insert id="insert" parameterType="com.zyx.core.admin.bean.City" useGeneratedKeys="true" keyColumn="id">
        INSERT INTO city(name, state, country) VALUES(#{name},#{state},#{country})
    </insert>

</mapper>

该方式等同于：

@Insert(" INSERT INTO city(name, state, country) VALUES(#{name},#{state},#{country})")
@Options(useGeneratedKeys = true,keyProperty = "id")
public void insert(City city);

• useGeneratedKeys 和 keyProperty 搭配使用，这样可以解决在主键自增的情况下获取主键

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3.修改CityService

package com.zyx.core.admin.service;

import com.zyx.core.admin.bean.City;
import com.zyx.core.admin.mapper.CityMapper;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Service;

/**
 * @author 35192
 * @date 2021-07-27 20:31
 */
@Service
public class CityService {

    @Autowired
    CityMapper cityMapper;

    public City getById(Integer id){
        City city = cityMapper.getById(id);
        return city;
    }
    
    public void insert(City city){
        cityMapper.insert(city);
    }
}

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4.测试

package com.zyx.core.admin.test;

import com.zyx.core.admin.bean.City;
import com.zyx.core.admin.service.AdminService;
import com.zyx.core.admin.service.CityService;
import org.junit.Test;
import org.junit.runner.RunWith;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.boot.test.context.SpringBootTest;
import org.springframework.test.context.junit4.SpringJUnit4ClassRunner;
import java.util.List;

/**
 * @author 35192
 * @date 2021-07-23 16:44
 */
@RunWith(SpringJUnit4ClassRunner.class)
@SpringBootTest
public class MybatisTest {

    @Autowired
    CityService cityService;

    @Test
    public void getById() {
        City city = cityService.getById(1);
        System.out.println(city);
    }

    @Test
    public void insert() {
        City city = new City();
        city.setName("成都");
        city.setState("2");
        city.setCountry("中国");
        cityService.insert(city);
        System.out.println(city);
    }
}

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方式三：混合注解和xml

• 混合使用方式一、方式二即可！

最佳实战：

• 引入mybatis-starter
• 配置application.yaml中，指定mapper-location位置即可
• 编写Mapper接口并标注@Mapper注解
• 简单方法直接注解方式
• 复杂方法编写mapper.xml进行绑定映射
• @MapperScan(“com.atguigu.admin.mapper”) 简化，其他的接口就可以不用标注@Mapper注解

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