SpringBoot整合MyBatis

系统要求

Java 8+

springBoot2.5 +

创建springBoot项目工程

导入依赖

<dependencies>
    <dependency>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-web</artifactId>
    </dependency>

    <dependency>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-devtools</artifactId>
        <scope>runtime</scope>
        <optional>true</optional>
    </dependency>
    <dependency>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-jdbc</artifactId>
    </dependency>
    <dependency>
        <groupId>com.alibaba</groupId>
        <artifactId>druid</artifactId>
        <version>1.2.6</version>
    </dependency>
    <dependency>
        <groupId>log4j</groupId>
        <artifactId>log4j</artifactId>
        <version>1.2.17</version>
    </dependency>
    <dependency>
        <groupId>mysql</groupId>
        <artifactId>mysql-connector-java</artifactId>
        <scope>runtime</scope>
    </dependency>
    <!--Druid starter-->
    <dependency>
        <groupId>com.alibaba</groupId>
        <artifactId>druid-spring-boot-starter</artifactId>
        <version>1.1.22</version>
    </dependency>
    <dependency>
        <groupId>org.mybatis.spring.boot</groupId>
        <artifactId>mybatis-spring-boot-starter</artifactId>
        <version>2.2.0</version>
    </dependency>
    <dependency>
        <groupId>org.projectlombok</groupId>
        <artifactId>lombok</artifactId>
    </dependency>
    <dependency>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-test</artifactId>
        <scope>test</scope>
    </dependency>
</dependencies>

项目结构目录

配置application.yaml

spring:
  datasource:
    driver-class-name: com.mysql.cj.jdbc.Driver
    url: jdbc:mysql://localhost:3307/webapp1?serverTimezone=UTC&useUnicode=true&characterEncoding=utf-8
    username: webapp1
    password: webapp1
    type: com.alibaba.druid.pool.DruidDataSource

    #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
    # 初始化大小，最小，最大
    initialSize: 5
    minIdle: 5
    maxActive: 200
    # 配置获取连接等待超时的时间
    maxWait: 60000
    # 配置间隔多久才进行一次检测，检测需要关闭的空闲连接，单位是毫秒
    timeBetweenEvictionRunsMillis: 60000
    # 配置一个连接在池中最小生存的时间，单位是毫秒
    minEvictableIdleTimeMillis: 300000
    # 用来检测连接是否有效的sql，要求是一个查询语句
    validationQuery: SELECT 1 FROM DUAL
    # 建议配置为true，不影响性能，并且保证安全性。申请连接的时候检测，如果空闲时间大于timeBetweenEvictionRunsMillis，执行validationQuery检测连接是否有效。
    testWhileIdle: true
    # 申请连接时执行validationQuery检测连接是否有效，做了这个配置会降低性能
    testOnBorrow: false
    # 归还连接时执行validationQuery检测连接是否有效，做了这个配置会降低性能。
    testOnReturn: false
    # 是否缓存preparedStatement，也就是PSCache。PSCache对支持游标的数据库性能提升巨大，比如说oracle。在mysql下建议关闭。
    poolPreparedStatements: true
    # 要启用PSCache，必须配置大于0，当大于0时，poolPreparedStatements自动触发修改为true。
    max-pool-prepared-statement-per-connection-size: 50

    #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
    # 合并多个DruidDataSource的监控数据
    useGlobalDataSourceStat: true
    # 通过connectProperties属性来打开mergeSql功能；慢SQL记录
    connectionProperties: druid.stat.mergeSql=true;druid.stat.slowSqlMillis=500

mybatis:
  #sql映射文件的位置
#  mapper-locations: classpath:com/xiang/mapper/*.xml
  mapper-locations: classpath:mapper/*.xml
  #开启驼峰命名转化
  configuration:
    map-underscore-to-camel-case: true
  #开启别名
  type-aliases-package: com.xiang

创建User类

package com.xiang.pojo;

import lombok.AllArgsConstructor;
import lombok.Data;
import lombok.NoArgsConstructor;
import org.springframework.stereotype.Component;

import java.util.Date;

/**
 * Created by IntelliJ IDEA.
 * User: xiang
 * Date: 2021/10/17 23:52
 */
@Component
@Data
@NoArgsConstructor
@AllArgsConstructor
public class User {
    private int id;
    private String username;
    private String age;
    private Date birthday;
}

创建UserMapper

package com.xiang.mapper;

import com.xiang.pojo.User;
import org.apache.ibatis.annotations.Mapper;
import org.mybatis.spring.annotation.MapperScan;
import org.springframework.context.annotation.ComponentScan;
import org.springframework.stereotype.Repository;

import java.util.List;

/**
 * Created by IntelliJ IDEA.
 * User: xiang
 * Date: 2021/10/17 23:54
 */
@Mapper
@Repository
public interface UserMapper {
    User findById(int id);

    List<User> findAll();
}

创建UserMapper.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.xiang.mapper.UserMapper">

    <select id="findById" resultType="user">
        select * from user where id = #{id}
    </select>
    <select id="findAll" resultType="user">
        select * from user
    </select>

</mapper>

创建UserService

package com.xiang.service;

import com.xiang.pojo.User;

import java.util.List;

/**
 * Created by IntelliJ IDEA.
 * User: xiang
 * Date: 2021/10/18 15:01
 */
public interface UserService {
    User findById(int id);
    List<User> findAll();
}

创建UserServiceImpl

package com.xiang.service.impl;

import com.xiang.mapper.UserMapper;
import com.xiang.pojo.User;
import com.xiang.service.UserService;
import org.mybatis.spring.annotation.MapperScan;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.context.annotation.ComponentScan;
import org.springframework.stereotype.Service;

import java.util.List;

/**
 * Created by IntelliJ IDEA.
 * User: xiang
 * Date: 2021/10/18 15:02
 */
@Service

public class UserServiceImpl implements UserService {
    @Autowired
    private UserMapper userMapper;

    @Override
    public User findById(int id) {
        return userMapper.findById(id);

    }

    @Override
    public List<User> findAll() {
        return userMapper.findAll();
    }


}

运行测试

package com.xiang;

import com.alibaba.druid.pool.DruidDataSource;
import com.xiang.pojo.User;
import com.xiang.service.impl.UserServiceImpl;
import org.junit.jupiter.api.Test;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.boot.test.context.SpringBootTest;
import org.springframework.jdbc.core.JdbcTemplate;

import javax.sql.DataSource;
import java.sql.Connection;
import java.sql.SQLException;
import java.util.List;
import java.util.Map;

@SpringBootTest
class SpringBootDatabaseApplicationTests {
    @Autowired
    UserServiceImpl userService;

    /***
     * 根据id查
     */
    @Test
    public  void  findById(){
        User user = userService.findById(1);
        System.out.println(user);
    }

    /**
     * 查所有
     */
    @Test
    public  void  findAll(){
        System.out.println(userService.findAll());
        System.out.println("/*******************************************/");
        List<User> userList = userService.findAll();
        for (User user : userList) {
            System.out.println(user);
        }
    }
}

测试运行结果

创建UserController

package com.xiang.controller;

import com.xiang.pojo.User;
import com.xiang.service.UserService;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Controller;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RequestParam;
import org.springframework.web.bind.annotation.ResponseBody;

/**
 * Created by IntelliJ IDEA.
 * User: xiang
 * Date: 2021/10/18 22:03
 */
@Controller
public class UserController {
    @Autowired
    UserService userService;

    @RequestMapping("findById")
    @ResponseBody
    public String findById(@RequestParam("id") int id) {
        User byId = userService.findById(id);
        return byId.toString();
    }
}

前端运行结果