记一次完整的SpringBoot+MyBatis整合过程（MyBatis逆向工程、SpringBoot整合MyBatis以及SpringBoot下的Mybatis分页）

环境：

1. SpringBoot版本：2.2.6.RELEASE
2. Mybatis版本：2.1.2
3. 逆向工程依赖generator版本：1.3.6
4. 分页依赖pagehelper版本：1.2.3

---

创建一个SpringBoot工程

      使用Idea创建SpringBoot工程（过程略）

pom.xml

<dependencies>
<!--        数据库连接依赖-->
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-jdbc</artifactId>
        </dependency>
<!--        web依赖-->
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-web</artifactId>
        </dependency>
<!--     mybatis-generator-core： Mybatis逆向工程核心包   -->
        <dependency>
            <groupId>org.mybatis.generator</groupId>
            <artifactId>mybatis-generator-core</artifactId>
            <version>1.3.6</version>
        </dependency>
<!--        逆向工程依赖的日志包-->
        <dependency>
            <groupId>log4j</groupId>
            <artifactId>log4j</artifactId>
            <version>1.2.17</version>
        </dependency>
<!--        Mybatis依赖-->
        <dependency>
            <groupId>org.mybatis.spring.boot</groupId>
            <artifactId>mybatis-spring-boot-starter</artifactId>
            <version>2.1.2</version>
        </dependency>
        <!-- mybatis的 pagehelper分页插件依赖 -->
        <dependency>
            <groupId>com.github.pagehelper</groupId>
            <artifactId>pagehelper-spring-boot-starter</artifactId>
            <version>1.2.3</version>
        </dependency>
<!--        <dependency>-->
<!--            <groupId>com.github.pagehelper</groupId>-->
<!--            <artifactId>pagehelper</artifactId>-->
<!--            <version>5.1.2</version>-->
<!--        </dependency>-->

<!--        数据库依赖-->
        <dependency>
            <groupId>mysql</groupId>
            <artifactId>mysql-connector-java</artifactId>
            <scope>runtime</scope>
        </dependency>
<!--        loomBok依赖-->
        <dependency>
            <groupId>org.projectlombok</groupId>
            <artifactId>lombok</artifactId>
            <optional>true</optional>
        </dependency>
<!--        测试依赖-->
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-test</artifactId>
            <scope>test</scope>
            <exclusions>
                <exclusion>
                    <groupId>org.junit.vintage</groupId>
                    <artifactId>junit-vintage-engine</artifactId>
                </exclusion>
            </exclusions>
        </dependency>
    </dependencies>

mbg.xml(逆向工程配置)

<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE generatorConfiguration
        PUBLIC "-//mybatis.org//DTD MyBatis Generator Configuration 1.0//EN"
        "http://mybatis.org/dtd/mybatis-generator-config_1_0.dtd">
<generatorConfiguration>

    <!-- 
        targetRuntime="MyBatis3Simple":生成简单版的CRUD
        MyBatis3:豪华版
    
     -->
    <context id="DB2Tables" targetRuntime="MyBatis3">
        <commentGenerator>
            <!-- 是否去除自动生成的注释 true：是 ： false:否 -->
            <property name="suppressAllComments" value="true" />
        </commentGenerator>
        <!-- jdbcConnection：指定如何连接到目标数据库 -->
        <jdbcConnection driverClass="com.mysql.cj.jdbc.Driver"
                        connectionURL="jdbc:mysql://localhost:3306/mybatis?
                        serverTimezone=UTC&amp;useUnicode=true&amp;characterEncoding=utf-8&amp;allowMultiQueries=true"
                        userId="root"
                        password="root">
        </jdbcConnection>

        <!--  -->
        <javaTypeResolver >
            <property name="forceBigDecimals" value="false" />
        </javaTypeResolver>

        <!-- javaModelGenerator：指定javaBean的生成策略 
        targetPackage="test.model"：目标包名
        targetProject="\MBGTestProject\src"：目标工程
        -->
        <javaModelGenerator targetPackage="com.liujie.bean"
                            targetProject=".\src\main\java">
            <property name="enableSubPackages" value="true" />
            <property name="trimStrings" value="true" />
        </javaModelGenerator>

        <!-- sqlMapGenerator：sql映射生成策略： -->
        <sqlMapGenerator targetPackage="com.liujie.dao"
                         targetProject=".\src\main\java">
            <property name="enableSubPackages" value="true" />
        </sqlMapGenerator>

        <!-- javaClientGenerator:指定mapper接口所在的位置 -->
        <javaClientGenerator type="XMLMAPPER" targetPackage="com.liujie.dao"
                             targetProject=".\src\main\java">
            <property name="enableSubPackages" value="true" />
        </javaClientGenerator>

        <!-- 指定要逆向分析哪些表：根据表要创建javaBean -->
        <table tableName="dept" domainObjectName="Dept"></table>
        <table tableName="employee" domainObjectName="Employee"></table>
    </context>
</generatorConfiguration>

application.yml

server:
  port: 8080

spring:
  datasource:
    username: root
    password: root
    url: jdbc:mysql://localhost:3306/mybatis?allowMultiQueries=true&useUnicode=true&characterEncoding=utf-8&useSSL=true&serverTimezone=UTC
    driver-class-name: com.mysql.jdbc.Driver

mybatis:
#  指定Mapper文件路径
  mapper-locations: classpath:mapping/*Mapper.xml
#  指定PoJo对象路径，并起别名
  type-aliases-package: com.liujie.bean
#  配置mybatis的分页插件信息
#数据库
pagehelper:
  helperDialect: mysql
  reasonable: true
  support-methods-arguments: true
  page-size-zero: true
  params=count: countSql
#showSql
logging:
  level:
    com:
      example:
        mapper: debug

创建数据库表：

CREATE TABLE `employee` (
  `id` int(11) NOT NULL AUTO_INCREMENT,
  `last_name` varchar(255) DEFAULT NULL,
  `email` varchar(255) DEFAULT NULL,
  `gender` char(1) DEFAULT NULL,
  `d_id` int(11) DEFAULT NULL,
  PRIMARY KEY (`id`),
  KEY `d_id` (`d_id`),
  CONSTRAINT `employee_ibfk_1` FOREIGN KEY (`d_id`) REFERENCES `dept` (`id`)
) ENGINE=InnoDB AUTO_INCREMENT=40 DEFAULT CHARSET=utf8

编写逆向工程代码，自动生成Javabean对象、Mapper文件以及Dao文件：

Generator.java

package com.liujie;

import org.mybatis.generator.api.MyBatisGenerator;
import org.mybatis.generator.config.Configuration;
import org.mybatis.generator.config.xml.ConfigurationParser;
import org.mybatis.generator.internal.DefaultShellCallback;

import java.io.File;
import java.util.ArrayList;
import java.util.List;

public class Generator {
    public void generator() throws Exception{
        List<String> warnings = new ArrayList<String>();
        boolean overwrite = true;
        /**指向逆向工程配置文件*/
        File configFile = new File("src/main/resources/generationConfig.xml");
//        File configFile = new File("src/main/resources/mbg.xml");
        ConfigurationParser parser = new ConfigurationParser(warnings);
        Configuration config = parser.parseConfiguration(configFile);
        DefaultShellCallback callback = new DefaultShellCallback(overwrite);
        MyBatisGenerator myBatisGenerator = new MyBatisGenerator(config, callback, warnings);
        myBatisGenerator.generate(null);
    }
    public static void main(String[] args) throws Exception {
        try {
            Generator generatorSqlmap = new Generator();
            generatorSqlmap.generator();
        } catch (Exception e) {
            e.printStackTrace();
        }
    }
}

原始工程目录结构：

运行Generator.java的main方法，生成Mapper文件、Dao文件以及JavaBean后，目录结构

将mapper文件放入到application。yml文件指定的文件夹内后的目录结构

修改JavaBean文件，加入注解

@Data
@AllArgsConstructor
@NoArgsConstructor

该步骤需要依赖LoomBok配置，可以跳过（跳过需要使用手动添加构造方法以及set\get\toString方法）

在生成的Mapper上添加注解：@Mapper（该注解的作用是让Spring额能够扫描到该Dao文件）

编写service层 EmployeeService.java

package com.liujie.service;

import com.github.pagehelper.Page;
import com.github.pagehelper.PageHelper;
import com.github.pagehelper.PageInfo;
import com.liujie.bean.Employee;
import com.liujie.bean.EmployeeExample;
import com.liujie.dao.EmployeeMapper;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Service;

import java.util.List;

@Service
public class EmployeeService {
    @Autowired
    private EmployeeMapper employeeMapper;

    public Employee findById(Integer id) {
        return employeeMapper.selectByPrimaryKey(id);
    }

    /**
     *    多条件组合查询
     * @param example
     * @return
     */
    public List<Employee> selectByExample(EmployeeExample  example) {
        example = new EmployeeExample();
        EmployeeExample.Criteria criteria = example.createCriteria();
        criteria.andEmailLike("%8%");
        EmployeeExample.Criteria criteria1 = example.createCriteria();
        criteria1.andGenderEqualTo("1");
        example.or(criteria1);
        return employeeMapper.selectByExample(example);
    }
    /**
     *    多条件组合分页查询
     * @param 
     * @return
     */
    public PageInfo<Employee> queryByPage() {
        PageHelper.startPage(2, 2);
        EmployeeExample example = new EmployeeExample();
        EmployeeExample.Criteria criteria = example.createCriteria();
        criteria.andEmailLike("%8%");
        EmployeeExample.Criteria criteria1 = example.createCriteria();
        criteria1.andGenderEqualTo("1");
        example.or(criteria1);
        List<Employee> employees = employeeMapper.selectByExample(example);

        PageInfo<Employee> pageInfo = new PageInfo<Employee>(employees);
        System.out.println(pageInfo);
        return pageInfo;
    }
    public PageInfo<Employee> queryByPage1() {
        PageHelper.startPage(1, 2);

        List<Employee> employees = employeeMapper.selectByExample(null);

        PageInfo<Employee> pageInfo = new PageInfo<Employee>(employees);
        System.out.println(pageInfo);
        return pageInfo;
    }
}

编写controller层 EmployeeController.java

package com.liujie.controller;

import com.github.pagehelper.PageInfo;
import com.liujie.bean.Employee;
import com.liujie.service.EmployeeService;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.web.bind.annotation.*;

import java.util.List;

@RestController
@RequestMapping("emp")
public class EmployeeController {
    @Autowired
    private EmployeeService employeeService;

    @GetMapping("/findById/{id}")
    public Employee example(@PathVariable("id") Integer id){
        System.out.println("id="+id);
        Employee employee = employeeService.findById(id);
        System.out.println(employee);
        return employee;
    }

    @GetMapping("/selectByExample")
    public List<Employee> findById(){
        return employeeService.selectByExample(null);
    }

    @GetMapping("/queryByPage")
    public PageInfo<Employee> queryByPage(){
        return employeeService.queryByPage();
    }


    @GetMapping("/queryByPage1")
    public PageInfo<Employee> queryByPage1(){
        return employeeService.queryByPage1();
    }
}

启动类 Application.java

package com.liujie;

import org.mybatis.spring.annotation.MapperScan;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;

@MapperScan("com.liujie") //扫描的mappe
@SpringBootApplication
public class Application {
    public static void main(String[] args) {
        SpringApplication.run(Application.class, args);
    }

}

启动项目访问对应的接口，即可

项目示例已上传到GitHub：https://github.com/liujie1122/mybatis_spring_boot_start.git