【Spring Boot】如何集成mybatis-plus

在pom文件中导入maven坐标

        <dependency>
            <groupId>mysql</groupId>
            <artifactId>mysql-connector-java</artifactId>
            <version>8.0.23</version>
        </dependency>
        <!--mybatis-plus-->
        <dependency>
            <groupId>com.baomidou</groupId>
            <artifactId>mybatis-plus-boot-starter</artifactId>
            <version>3.4.2</version>
        </dependency>
        <dependency>
            <groupId>com.alibaba</groupId>
            <artifactId>druid</artifactId>
            <version>1.1.23</version>
        </dependency>

创建ResultBean作为返回包装类

package com.app.user.common;

import lombok.Data;

import java.io.Serializable;
import java.util.HashMap;
import java.util.Map;

/**
 * 返回bean信息
 *
 * @author Administrator
 */
@Data
public class ResultBean<T> implements Serializable {

    private static final long serialVersionUID = -6759928086797729382L;
    /**
     * 编码：1成功，0和其它数字为失败
     */
    private Integer code;
    /**
     * 错误信息
     */
    private String msg;
    /**
     * 数据
     */
    private T data;
    /**
     * 动态数据
     */
    private Map map = new HashMap();

    public static <T> ResultBean<T> success(T object) {
        ResultBean<T> r = new ResultBean<T>();
        r.data = object;
        r.code = 1;
        return r;
    }

    public static <T> ResultBean<T> error(String msg) {
        ResultBean r = new ResultBean();
        r.msg = msg;
        r.code = 0;
        return r;
    }

    public ResultBean<T> add(String key, Object value) {
        this.map.put(key, value);
        return this;
    }

}

创建mybatis plus的分页配置信息

package com.app.user.config;

import com.baomidou.mybatisplus.extension.plugins.MybatisPlusInterceptor;
import com.baomidou.mybatisplus.extension.plugins.inner.PaginationInnerInterceptor;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;

/**
 * 配置MybatisPlus的配置信息
 *
 * @author Administrator
 */
@Configuration
public class MybatisPlusConfig {

    @Bean
    public MybatisPlusInterceptor mybatisPlusInterceptor() {
        // 获取MybatisPlus的拦截器链
        MybatisPlusInterceptor mybatisPlusInterceptor = new MybatisPlusInterceptor();
        // 添加分页拦截器PaginationInnerInterceptor，实现自动分页
        mybatisPlusInterceptor.addInnerInterceptor(new PaginationInnerInterceptor());
        return mybatisPlusInterceptor;
    }

}

创建表实体类信息

package com.app.user.pojo;

import com.baomidou.mybatisplus.annotation.TableName;
import lombok.Data;

/**
 * 用户实体类
 *
 * @author Administrator
 */
@Data
@TableName(value = "tb_user")
public class User {
    /**
     * 主键
     */
    private Long id;
    /**
     * 用户名
     */
    private String username;
    /**
     * 联系电话
     */
    private String phone;

}

创建mapper类

package com.app.user.mapper;


import com.app.user.pojo.User;
import com.baomidou.mybatisplus.core.mapper.BaseMapper;
import org.apache.ibatis.annotations.Mapper;

/**
 * 用户mapper
 *
 * @author Administrator
 */
@Mapper
public interface UserMapper extends BaseMapper<User> {
    /**
     * 计算数目
     *
     * @return 返回计算数目
     */
    int countNum();

}

创建服务接口类

package com.app.user.service;


import com.app.user.pojo.User;
import com.baomidou.mybatisplus.extension.service.IService;

/**
 * 用户服务接口
 *
 * @author Administrator
 */
public interface UserService extends IService<User> {

    /**
     * 计算数目
     *
     * @return 返回记录数
     */
    int countNum();

}

创建服务接口类实现类

package com.app.user.service.impl;


import com.app.user.mapper.UserMapper;
import com.app.user.pojo.User;
import com.app.user.service.UserService;
import com.baomidou.mybatisplus.extension.service.impl.ServiceImpl;
import org.springframework.stereotype.Service;

/**
 * 用户服务
 *
 * @author Administrator
 */
@Service
public class UserServiceImpl extends ServiceImpl<UserMapper, User> implements UserService {

    @Override
    public int countNum() {
        // 使用原生的xml文件mapper查询表记录
        return this.baseMapper.countNum();
    }

}

创建服务的controller类

package com.app.user.controller;


import cn.hutool.core.util.StrUtil;
import com.app.user.common.ResultBean;
import com.app.user.pojo.User;
import com.app.user.service.UserService;
import com.baomidou.mybatisplus.core.conditions.query.LambdaQueryWrapper;
import com.baomidou.mybatisplus.extension.plugins.pagination.Page;
import lombok.RequiredArgsConstructor;
import lombok.extern.slf4j.Slf4j;
import org.springframework.web.bind.annotation.*;

import javax.servlet.http.HttpServletRequest;

/**
 * 用户控制器
 *
 * @author Administrator
 */
@RestController
@RequestMapping("/users")
@Slf4j
@RequiredArgsConstructor
public class UserController {

    /**
     * 结合@RequiredArgsConstructor进行构造器注入
     */
    private final UserService userService;

    /**
     * 新增用户
     *
     * @param user 用户信息
     * @return 用户信息
     */
    @PostMapping
    public ResultBean<User> save(@RequestBody User user) {
        log.info("新增用户，用户信息：{}", user.toString());
        userService.save(user);
        return ResultBean.success(user);
    }

    /**
     * 根据id修改用户信息
     *
     * @param user 用户信息
     * @return 修改提示信息
     */
    @PutMapping
    public ResultBean<String> update(HttpServletRequest request, @RequestBody User user) {
        log.info(user.toString());
        userService.updateById(user);
        return ResultBean.success("用户信息修改成功");
    }

    /**
     * 根据id查询用户信息
     *
     * @param id 用户id
     * @return 用户信息
     */
    @GetMapping("/{id}")
    public ResultBean<User> getById(@PathVariable Long id) {
        log.info("根据id查询用户信息...");
        User user = userService.getById(id);
        if (user != null) {
            return ResultBean.success(user);
        }
        return ResultBean.error("没有查询到对应用户信息");
    }

    /**
     * 用户信息分页
     *
     * @param page     当前页
     * @param pageSize 每页显示条数
     * @param username 用户名
     * @return 返回分页用户信息
     */
    @GetMapping("/page")
    public ResultBean<Page<User>> page(int page, int pageSize, String username) {
        log.info("page = {},pageSize = {},username = {}", page, pageSize, username);
        // 1、构造简单分页模型
        Page<User> pageInfo = new Page<>(page, pageSize);
        // 2、构造条件构造器
        LambdaQueryWrapper<User> queryWrapper = new LambdaQueryWrapper<>();
        // 3、添加用户名过滤条件，使用模糊匹配，不为空时才生效
        queryWrapper.like(StrUtil.isNotEmpty(username), User::getUsername, username);
        // 4、添加排序条件
        queryWrapper.orderByDesc(User::getId);
        // 5、执行查询，查询的结果将会直接存在于pageInfo对象中
        userService.page(pageInfo, queryWrapper);
        return ResultBean.success(pageInfo);
    }

    /**
     * 获取用户记录数
     *
     * @return 返回记录数
     */
    @GetMapping("/count")
    public ResultBean<Integer> count() {
        log.info("计算用户数目...");
        int i = userService.countNum();
        return ResultBean.success(i);
    }

}

在resources的文件夹创建mapper文件夹，并创建mapper.xml文件，示例创建的是UserMapper.xml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.app.user.mapper.UserMapper">

    <resultMap id="BaseResultMap" type="com.app.user.pojo.User">
        <result property="id" column="id" jdbcType="DECIMAL"/>
        <result property="username" column="username" jdbcType="VARCHAR"/>
        <result property="phone" column="phone" jdbcType="VARCHAR"/>
    </resultMap>

    <sql id="Base_Column_List">
        id,username,phone
    </sql>

    <select id="countNum" resultType="int">
        select count(*)
        from tb_user;
    </select>

</mapper>

创建application.yml文件并配置下列信息

server:
  port: 8080
spring:
  application:
    #应用的名称，可选
    name: user-service
  datasource:
    driver-class-name: com.mysql.cj.jdbc.Driver
    url: jdbc:mysql://localhost:3333/user_demo?serverTimezone=Asia/Shanghai&useUnicode=true&characterEncoding=utf-8&zeroDateTimeBehavior=convertToNull&useSSL=false&allowPublicKeyRetrieval=true
    username: root
    password: 123456
    type: com.alibaba.druid.pool.DruidDataSource

mybatis-plus:
  configuration:
    #在映射实体或者属性时，将数据库中表名和字段名中的下划线去掉，按照驼峰命名法映射
    map-underscore-to-camel-case: true
    log-impl: org.apache.ibatis.logging.stdout.StdOutImpl
  global-config:
    db-config:
      id-type: ASSIGN_ID
  mapper-locations: classpath:mapper/*.xml

创建logback.xml日志文件并配置下列信息

<?xml version="1.0" encoding="UTF-8"?>
<!--
  ~ Licensed to the Apache Software Foundation (ASF) under one or more
  ~ contributor license agreements.  See the NOTICE file distributed with
  ~ this work for additional information regarding copyright ownership.
  ~ The ASF licenses this file to You under the Apache License, Version 2.0
  ~ (the "License"); you may not use this file except in compliance with
  ~ the License.  You may obtain a copy of the License at
  ~
  ~     http://www.apache.org/licenses/LICENSE-2.0
  ~
  ~ Unless required by applicable law or agreed to in writing, software
  ~ distributed under the License is distributed on an "AS IS" BASIS,
  ~ WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
  ~ See the License for the specific language governing permissions and
  ~ limitations under the License.
  -->

<configuration>
    <property name="log.context.name" value="sharding-jdbc-spring-namespace-mybatis-example" />
    <property name="log.charset" value="UTF-8" />
    <property name="log.pattern" value="[%-5level] %date --%thread-- [%logger] %msg %n" />
    <contextName>${log.context.name}</contextName>

    <appender name="STDOUT" class="ch.qos.logback.core.ConsoleAppender">
        <encoder charset="${log.charset}">
            <pattern>${log.pattern}</pattern>
        </encoder>
    </appender>
    <root>
        <level value="info" />
        <appender-ref ref="STDOUT" />
    </root>
</configuration>