MyBatis 在Spring Boot应用非常广，非常强大的一个半自动的ORM框架。
一、什么是MyBatis
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1.支持定制化 SQL、存储过程以及高级映射的优秀的持久层框架
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2.避免了几乎所有的 JDBC 代码和手动设置参数以及获取结果集
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3.可以对配置和原生Map使用简单的 XML 或注解
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4.将接口和 Java 的 POJOs(Plain Old Java Objects,普通的 Java对象)映射成数据库中的记录
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5.数据库、数据源、数据库连接池、JDBC、JDBC实现是什么关系？
- JDBC：Java和关系型数据库的桥梁，是一个桂芳，不是实现。不同类型的数据库需要有自己的JDBC实现
- 数据源：包含数据库连接池，连接池管理。常见的有C3P0、HikariDataSoiurce、Druid等
- 连接池：预先创建一些数据库连接，放到连接池里面，用的时候从连接池里面取，用完后放回连接池
- 连接池管理：创建数据库连接，管理数据库连接
- JDBC实现：MySQL JDBC实现、Oracle JDBC实现等其他实现
- MyBatis对JDBC进行了封装
二、整合MyBatis
我们基于之前创建的项目spring-boot-06-data-druid 来创建spring-boot-07-data-mybatis项目
1）引入MyBatis依赖
<!-- mybatis -->
<dependency>
<groupId>org.mybatis.spring.boot</groupId>
<artifactId>mybatis-spring-boot-starter</artifactId>
<version>2.1.1</version>
</dependency>
2）引入其他依赖
<dependencies>
<!-- web -->
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-web</artifactId>
</dependency>
<!-- mysql -->
<dependency>
<groupId>mysql</groupId>
<artifactId>mysql-connector-java</artifactId>
<scope>runtime</scope>
</dependency>
<!-- swagger -->
<dependency>
<groupId>io.springfox</groupId>
<artifactId>springfox-swagger2</artifactId>
<version>2.9.2</version>
</dependency>
<dependency>
<groupId>io.springfox</groupId>
<artifactId>springfox-swagger-ui</artifactId>
<version>2.9.2</version>
</dependency>
<!-- Druid -->
<dependency>
<groupId>com.alibaba</groupId>
<artifactId>druid</artifactId>
<version>1.1.21</version>
</dependency>
3）依赖图
三、用注解方式使用 MyBatis
1.准备创建department表的脚本
DROP TABLE IF EXISTS `department`;
CREATE TABLE `department` (
`id` int(11) NOT NULL AUTO_INCREMENT,
`department_name` varchar(255) DEFAULT NULL,
PRIMARY KEY (`id`)
) ENGINE=InnoDB AUTO_INCREMENT=1 DEFAULT CHARSET=utf8;
2.application.yml 自动执行脚本
initialization-mode: always
schema:
- classpath:department.sql
执行一次后，注释 initialization-mode
# initialization-mode: always
3.创建department 实体类
package com.jackson0714.springboot.entity;
public class Department {
private Long id;
private String departmentName;
public void setId(Long id) {
this.id = id;
}
public Long getId() {
return id;
}
public void setDepartmentName(String departmentName) {
this.departmentName = departmentName;
}
public String getDepartmentName() {
return departmentName;
}
}
4.创建Mapper映射类，并将SQL注解到方法上
增删改查，你要的都在这里：
@Mapper
public interface DepartmentMapper {
@Select("select * from department")
List<Map<String, Object>> getAllDepartment();
@Select("select * from department where id=#{id}")
Department getDepartmentById(Long id);
@Delete("delete from department where id=#{id}")
int deleteDepartment(Long id);
@Insert("insert into department(department_name) values(#{departmentName})")
int createDepartment(String departmentName);
@Update("update department set department_name=#{departmentName} where id=#{id}")
int updateDepartmentById(Long id, String departmentName);
}
5.创建MyBatis 配置类
增加自定义配置：如果表的字段名有下划线格式的，转为驼峰命名格式
@org.springframework.context.annotation.Configuration
public class MyBatisConfig {
@Bean
public ConfigurationCustomizer configurationCustomizer() {
return new ConfigurationCustomizer() {
@Override
public void customize(Configuration configuration) {
// 如果表的字段名有下划线格式的，转为驼峰命名格式
configuration.setMapUnderscoreToCamelCase(true);
}
};
}
}
6.创建DepartmentController
@Api(value = "DepartmentController", description = "部门controller")
@RequestMapping("/v1/client")
@RestController
public class DepartmentController {
@Autowired
DepartmentMapper departmentMapper;
@ApiOperation(value = "1.查询所有部门")
@GetMapping("/dept/getAllDepartment")
public List<Map<String, Object>> getAllDepartment() {
return departmentMapper.getAllDepartment();
}
@ApiOperation(value = "2.根据id查询某个部门")
@ApiImplicitParams({
@ApiImplicitParam(name = "id", value = "需要查询的部门id")
})
@GetMapping("/dept/{id}")
public Department getDepartmentById(@PathVariable Long id) {
return departmentMapper.getDepartmentById(id);
}
@ApiOperation(value = "3.新增部门")
@ApiImplicitParams({
@ApiImplicitParam(name = "name", value = "部门名称")
})
@PostMapping("/dept/create")
public int createDepartment(@RequestParam String name) {
return departmentMapper.createDepartment(name);
}
@ApiOperation(value = "4.根据id删除部门")
@ApiImplicitParams({
@ApiImplicitParam(name = "id", value = "需要删除的部门id")
})
@PostMapping("/dept/delete")
public int deleteDepartment(@RequestParam Long id) {
return departmentMapper.deleteDepartment(id);
}
@ApiOperation(value = "5.根据id更新部门名称")
@ApiImplicitParams({
@ApiImplicitParam(name = "id", value = "需要更新的部门id"),
@ApiImplicitParam(name = "name", value = "需要更新的部门名称")
})
@PostMapping("/dept/update")
public int updateDepartmentById(@RequestParam Long id, @RequestParam String name) {
return departmentMapper.updateDepartmentById(id, name);
}
}
使用Swagger来测试
四、用配置方式使用MyBatis
1. 文件结构
2. 创建user表的脚本
SET FOREIGN_KEY_CHECKS=0;
-- ----------------------------
-- Table structure for user
-- ----------------------------
DROP TABLE IF EXISTS `user`;
CREATE TABLE `user` (
`user_id` int(11) NOT NULL AUTO_INCREMENT COMMENT '主键ID',
`user_name` varchar(255) COLLATE utf8mb4_bin NOT NULL COMMENT '用户名',
`password` varchar(255) COLLATE utf8mb4_bin NOT NULL,
`salt` varchar(255) COLLATE utf8mb4_bin DEFAULT NULL COMMENT '随机盐',
`nickName` varchar(255) COLLATE utf8mb4_bin NOT NULL COMMENT '用户名',
`phone` varchar(20) COLLATE utf8mb4_bin DEFAULT NULL COMMENT '手机号',
`avatar` varchar(255) COLLATE utf8mb4_bin DEFAULT NULL COMMENT '头像',
`mini_openId` varchar(32) COLLATE utf8mb4_bin DEFAULT NULL COMMENT '小程序OpenId',
`lock_flag` char(1) COLLATE utf8mb4_bin DEFAULT '0' COMMENT '0-正常，9-锁定',
`del_flag` char(1) COLLATE utf8mb4_bin DEFAULT '0' COMMENT '0-正常，1-删除',
`create_time` timestamp NOT NULL DEFAULT CURRENT_TIMESTAMP COMMENT '创建时间',
`update_time` timestamp NOT NULL DEFAULT CURRENT_TIMESTAMP ON UPDATE CURRENT_TIMESTAMP COMMENT '更新时间',
PRIMARY KEY (`user_id`),
KEY `user_wx_openid` (`mini_openId`),
KEY `user_idx1_username` (`user_name`)
) ENGINE=InnoDB AUTO_INCREMENT=4 DEFAULT CHARSET=utf8mb4 COLLATE=utf8mb4_unicode_ci ROW_FORMAT=DYNAMIC COMMENT='用户表';
3. 插入一条User数据
INSERT INTO user(user_name, password, nick_name, phone) values ("jackson0714", "123", "悟空聊架构", "123456")
4. 创建User实体类
package com.jackson0714.springboot.entity;
import lombok.Data;
import java.sql.Timestamp;
@Data
public class User {
private Long userId;
private String userName;
private String password;
private String salt;
private String nickName;
private String phone;
private String avatar;
private String miniOpenId;
private String openId;
private Boolean lockFlag;
private Boolean delFlag;
private Timestamp createTime;
private Timestamp updateTime;
}
需要安装Lombok插件
需要引入Lombok依赖
<!-- https://mvnrepository.com/artifact/org.projectlombok/lombok -->
<dependency>
<groupId>org.projectlombok</groupId>
<artifactId>lombok</artifactId>
<version>1.18.12</version>
<scope>provided</scope>
</dependency>
5. 创建调用User方法的 UserMapper 接口
// @Mapper 或MapperScan 将接口扫描装配到装配容器中
public interface UserMapper {
User getUserById(Long userId);
}
6. 创建接口方法与SQL脚本的映射文件
<?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.jackson0714.springboot.mapper.UserMapper">
<select id="getUserById" resultType="com.jackson0714.springboot.entity.User">
SELECT * FROM user WHERE user_id=#{userId}
</select>
</mapper>
7. 创建UserController文件
@Api(value = "UserController", description = "用户controller")
@RequestMapping("/v1/client")
@RestController
public class UserController {
@Autowired
UserMapper userMapper;
@ApiOperation(value = "1.根据id查询某个用户")
@ApiImplicitParams({
@ApiImplicitParam(name = "需要查询的用户userId", value = "需要查询的用户userId")
})
@GetMapping("/emp/{userId}")
public User getUser(@PathVariable("userId") Long userId) {
return userMapper.getUserById(userId);
}
}
8. 添加MapperScan注解
@MapperScan(value = "com.jackson0714.springboot.mapper")
@SpringBootApplication
public class Springboot07DataMybatisApplication {
public static void main(String[] args) {
SpringApplication.run(Springboot07DataMybatisApplication.class, args);
}
}
9.在Swagger上测试
10. 查看Druid监控
Spring Boot 整合MyBatis 讲完了，持续更新 《深入浅出 Spring Boot 系列》
作者简介：悟空，8年一线互联网开发和架构经验，用故事讲解分布式、架构设计、Java 核心技术。《JVM性能优化实战》专栏作者，开源了《Spring Cloud 实战 PassJava》项目，公众号：悟空聊架构。本文已收录至 www.passjava.cn
