SpringBoot-06-整合MyBatis

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官方文档：http://mybatis.org/spring-boot-starter/mybatis-spring-boot-autoconfigure/
Maven仓库地址：https://mvnrepository.com/artifact/org.mybatis.spring.boot/mybatis-spring-boot-starter/

直接开搞

导入依赖

<!-- https://mvnrepository.com/artifact/org.mybatis.spring.boot/mybatis-spring-boot-starter -->
<dependency>
    <groupId>org.mybatis.spring.boot</groupId>
    <artifactId>mybatis-spring-boot-starter</artifactId>
    <version>2.1.3</version>
</dependency>

配置数据库连接信息 application.yaml （不变）

spring:
  datasource:
    username: root
    password: root
    #?serverTimezone=UTC解决时区的报错
    url: jdbc:mysql://localhost:3306/springboot?serverTimezone=UTC&useUnicode=true&characterEncoding=utf-8
    driver-class-name: com.mysql.cj.jdbc.Driver
    type: com.alibaba.druid.pool.DruidDataSource # 自定义数据源

    #Spring Boot 默认是不注入这些属性值的，需要自己绑定
    #druid 数据源专有配置
    initialSize: 5
    minIdle: 5
    maxActive: 20
    maxWait: 60000
    timeBetweenEvictionRunsMillis: 60000
    minEvictableIdleTimeMillis: 300000
    validationQuery: SELECT 1 FROM DUAL
    testWhileIdle: true
    testOnBorrow: false
    testOnReturn: false
    poolPreparedStatements: true

    #配置监控统计拦截的filters，stat:监控统计、log4j：日志记录、wall：防御sql注入
    #如果允许时报错  java.lang.ClassNotFoundException: org.apache.log4j.Priority
    #则导入 log4j 依赖即可，Maven 地址：https://mvnrepository.com/artifact/log4j/log4j
    filters: stat,wall,log4j
    maxPoolPreparedStatementPerConnectionSize: 20
    useGlobalDataSourceStat: true
    connectionProperties: druid.stat.mergeSql=true;druid.stat.slowSqlMillis=500

测试数据库是否连接成功（同 Druid ）

建表

SET NAMES utf8mb4;
SET FOREIGN_KEY_CHECKS = 0;

-- ----------------------------
-- Table structure for department
-- ----------------------------
DROP TABLE IF EXISTS `department`;
CREATE TABLE `department`  (
  `id` int(11) NOT NULL,
  `departmentName` varchar(255) 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 = Compact;

SET FOREIGN_KEY_CHECKS = 1;

导入 Lombok丶

<dependency>
    <groupId>org.projectlombok</groupId>
    <artifactId>lombok</artifactId>
    <optional>true</optional>
</dependency>

创建实体类

package com.example.demo.pojo;

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

@Data
@NoArgsConstructor
@AllArgsConstructor
public class Department {

    private Integer id;
    private String departmentName;

}

创建mapper目录以及对应的 Mapper 接口

package com.example.demo.mapper;

import com.example.demo.pojo.Department;
import org.apache.ibatis.annotations.Mapper;
import org.springframework.stereotype.Repository;

import java.util.List;

//@Mapper : 表示本类是一个 MyBatis 的 Mapper
@Mapper
@Repository
public interface DepartmentMapper {

    // 获取所有部门信息
    List<Department> getDepartments();

    // 通过id获得部门
    Department getDepartment(Integer id);

}

对应的Mapper映射文件DepartmentMapper.xml（注意放置位置）

<?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.example.demo.mapper.DepartmentMapper">

    <select id="getDepartments" resultType="com.example.demo.pojo.Department">
       select * from department;
    </select>

    <select id="getDepartment" resultType="com.example.demo.pojo.Department" parameterType="int">
       select * from department where id = #{id};
    </select>

</mapper>

maven配置资源过滤问题（pom.xml <build>）（如果不按上图位置放置的话（则放在新建mappers文件夹下），需要配置下面两个东西）

<resources>
    <resource>
        <directory>src/main/java</directory>
        <includes>
            <include>**/*.xml</include>
        </includes>
        <filtering>true</filtering>
    </resource>
</resources>

以及 application.yaml 中添加

mybatis:
  mapper-locations: classpath:mappers/*.xml

启动类添加注解（非必须丶）

@SpringBootApplication
//@MapperScan("com.example.demo.mapper")
@Slf4j
public class DemoApplication {

    public static void main(String[] args) {
        SpringApplication.run(DemoApplication.class, args);
    }

}

测试

http://localhost:8080/getDepartments

http://localhost:8080/getDepartment/101

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