spring boot+mybatis+mysql增删改查分页

server:
  port: 8081
  servlet:
    context-path: /springBootMybatis

spring:
  datasource:
    name: test
    url: jdbc:mysql://localhost:3306/test?serverTimezone=GMT%2B8&useUnicode=true&characterEncoding=UTF-8&useSSL=true
    username: root
    password: root
    #新版数据库驱动使用com.mysql.cj.jdbc.Driver    旧版com.mysql.jdbc.Driver
    driver-class-name: com.mysql.cj.jdbc.Driver
    type: com.alibaba.druid.pool.DruidDataSource

mybatis:
  #这里是实体类的位置，#实体扫描，多个package用逗号或者分号分隔
  #typeAliasesPackage: com.hegg.springboot.model
  type-aliases-package: com.hegg.springboot.model
  #把xml文件放在com.XX.mapper.*中可能会出现找不到的问题，这里把他放在resource下的mapper中
  mapper-locations: classpath:mapper/*.xml

#分页插件
pagehelper:
  helperDialect: mysql                           #分页插件方言选择
  reasonable: true                               #合理化参数，设为true时pageNum<=0 时会查第一页， pageNum>pages（超过总数时），会查询最后一页
  supportMethodsArguments: true

1、先附上application.yml的配置

<?xml version="1.0" encoding="UTF-8"?>
<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
         xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
    <modelVersion>4.0.0</modelVersion>
    <parent>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-parent</artifactId>
        <version>2.1.3.RELEASE</version>
        <relativePath/> <!-- lookup parent from repository -->
    </parent>
    <groupId>com.hegg</groupId>
    <artifactId>springboot</artifactId>
    <version>0.0.1-SNAPSHOT</version>
    <name>springboot</name>
    <description>Demo project for Spring Boot</description>

    <properties>
        <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
        <project.reporting.outputEncoding>UTF-8</project.reporting.outputEncoding>
        <java.version>1.8</java.version>
    </properties>

    <dependencies>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-jdbc</artifactId>
        </dependency>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-web</artifactId>
        </dependency>
        <dependency>
            <groupId>org.mybatis.spring.boot</groupId>
            <artifactId>mybatis-spring-boot-starter</artifactId>
            <version>2.0.0</version>
        </dependency>

        <dependency>
            <groupId>mysql</groupId>
            <artifactId>mysql-connector-java</artifactId>
            <!--<scope>runtime</scope>-->
        </dependency>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-test</artifactId>
            <!--<scope>test</scope>-->
        </dependency>

        <!-- alibaba的druid数据库连接池 -->
        <dependency>
            <groupId>com.alibaba</groupId>
            <artifactId>druid</artifactId>
            <version>1.1.3</version>
        </dependency>

        <!-- mybatis的分页插件 -->
        <dependency>
            <groupId>com.github.pagehelper</groupId>
            <artifactId>pagehelper-spring-boot-starter</artifactId>
            <version>1.2.10</version>
        </dependency>

    </dependencies>

    <build>
        <plugins>
            <plugin>
                <groupId>org.springframework.boot</groupId>
                <artifactId>spring-boot-maven-plugin</artifactId>
            </plugin>

            <!-- mybatis generator 自动生成代码插件 -->
            <plugin>
                <groupId>org.mybatis.generator</groupId>
                <artifactId>mybatis-generator-maven-plugin</artifactId>
                <version>1.3.2</version>
                <configuration>
                    <configurationFile>${basedir}/src/main/resources/generator/generatorConfig.xml</configurationFile>
                    <overwrite>true</overwrite>
                    <verbose>true</verbose>
                </configuration>
            </plugin>
        </plugins>
    </build>

</project>

2、pom.xml的代码，其中三段代码是自己加的

<!-- alibaba的druid数据库连接池 -->
<dependency>
    <groupId>com.alibaba</groupId>
    <artifactId>druid</artifactId>
    <version>1.1.3</version>
</dependency>

<!-- mybatis的分页插件 -->
<dependency>
    <groupId>com.github.pagehelper</groupId>
    <artifactId>pagehelper-spring-boot-starter</artifactId>
    <version>1.2.10</version>
</dependency>

<!-- mybatis generator 自动生成代码插件 -->
<plugin>
    <groupId>org.mybatis.generator</groupId>
    <artifactId>mybatis-generator-maven-plugin</artifactId>
    <version>1.3.2</version>
    <configuration>
        <configurationFile>${basedir}/src/main/resources/generator/generatorConfig.xml</configurationFile>
        <overwrite>true</overwrite>
        <verbose>true</verbose>
    </configuration>
</plugin>

3、新建generatorConfig.xml用来自动生成实体类和对应的*Mapper.xml和*Mapper.java（*Mapper.java是接口interface）

<?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>

    <!-- 数据库驱动:选择你的本地硬盘上面的数据库驱动包-->
    <classPathEntry  location="E:apache-maven
epositorymysqlmysql-connector-java5.1.44mysql-connector-java-5.1.44.jar"/>
    <context id="DB2Tables"  targetRuntime="MyBatis3">
        <commentGenerator>
            <property name="suppressDate" value="true"/>
            <!-- 是否去除自动生成的注释 true：是 ： false:否 -->
            <property name="suppressAllComments" value="true"/>
        </commentGenerator>
        <!--数据库链接URL，用户名、密码 -->
        <!--新版数据库驱动com.mysql.cj.jdbc.Driver   旧版com.mysql.jdbc.Driver-->
        <jdbcConnection
                driverClass="com.mysql.jdbc.Driver"
                connectionURL="jdbc:mysql://localhost:3306/test?serverTimezone=GMT%2B8&amp;useUnicode=true&amp;characterEncoding=UTF-8&amp;useSSL=true"
                userId="root"
                password="root">
        </jdbcConnection>


        <!-- 非必需，类型处理器，在数据库类型和java类型之间的转换控制-->
        <javaTypeResolver>
            <property name="forceBigDecimals" value="false"/>
        </javaTypeResolver>

        <!-- 生成模型的包名和位置-->
        <!-- Model模型生成器,用来生成含有主键key的类，记录类 以及查询Example类
            targetPackage     指定生成的model生成所在的包名
            targetProject     指定在该项目下所在的路径
        -->
        <javaModelGenerator targetPackage="com.hegg.springboot.model" targetProject="src/main/java">
            <!-- 是否允许子包，即targetPackage.schemaName.tableName -->
            <property name="enableSubPackages" value="false"/>
            <!-- 是否对model添加 构造函数 -->
            <property name="constructorBased" value="true"/>
            <!-- 是否对类CHAR类型的列的数据进行trim操作 -->
            <property name="trimStrings" value="true"/>
            <!-- 建立的Model对象是否 不可改变  即生成的Model对象不会有 setter方法，只有构造方法 -->
            <property name="immutable" value="false"/>
        </javaModelGenerator>

        <!--Mapper映射文件生成所在的目录 为每一个数据库的表生成对应的SqlMap文件 -->
        <sqlMapGenerator targetPackage="mapper" targetProject="src/main/resources">
            <property name="enableSubPackages" value="true"/>
        </sqlMapGenerator>

        <!-- 生成DAO的包名和位置-->
        <!-- 客户端代码，生成易于使用的针对Model对象和XML配置文件 的代码
                        type="ANNOTATEDMAPPER",生成Java Model 和基于注解的Mapper对象
                        type="MIXEDMAPPER",生成基于注解的Java Model 和相应的Mapper对象
                        type="XMLMAPPER",生成SQLMap XML文件和独立的Mapper接口
        -->
        <javaClientGenerator type="XMLMAPPER" targetPackage="com.hegg.springboot.mapper" targetProject="src/main/java">
            <property name="enableSubPackages" value="true"/>
        </javaClientGenerator>
        <!-- 要生成的表 tableName是数据库中的表名或视图名 domainObjectName是实体类名-->
        <table tableName="user" domainObjectName="User" enableCountByExample="false" enableUpdateByExample="false"
               enableDeleteByExample="false" enableSelectByExample="false" selectByExampleQueryId="false">
        </table>
    </context>
</generatorConfiguration>

4、编译运行生成代码点击run>Edit Configuration，如下图找到maven在标注的位置输入对应的代码运行即可generator和

mybatis-generator:generate -e。千万不要重复运行，不然在*Mapper.xml中就会重复生成方法，还有

generatorConfig.xml文件中连接数据使用的jar包不要使用太高的版本。

5、下面是生成的接口代码UserMapper.java，其中后面三个方法是自己加的，其他的都是自动生成的，

import com.github.pagehelper.Page;
import com.github.pagehelper.PageInfo;
import com.hegg.springboot.model.User;

import java.util.List;

public interface UserMapper {
    int deleteByPrimaryKey(Integer id);

    int insert(User record);

    int insertSelective(User record);

    User selectByPrimaryKey(Integer id);

    int updateByPrimaryKeySelective(User record);

    int updateByPrimaryKey(User record);

    List<User> getAllUser();

    Page<User> findByPage();

    PageInfo<User> findByPageInfo();
}

UserMapper.xml中后面三个方法是自己加的

<?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.hegg.springboot.mapper.UserMapper" >
  <resultMap id="BaseResultMap" type="com.hegg.springboot.model.User" >
    <constructor >
      <idArg column="id" jdbcType="INTEGER" javaType="java.lang.Integer" />
      <arg column="name" jdbcType="VARCHAR" javaType="java.lang.String" />
      <arg column="sex" jdbcType="INTEGER" javaType="java.lang.Integer" />
      <arg column="age" jdbcType="INTEGER" javaType="java.lang.Integer" />
    </constructor>
  </resultMap>
  <sql id="Base_Column_List" >
    id, name, sex, age
  </sql>
  <select id="selectByPrimaryKey" resultMap="BaseResultMap" parameterType="java.lang.Integer" >
    select 
    <include refid="Base_Column_List" />
    from user
    where id = #{id,jdbcType=INTEGER}
  </select>
  <delete id="deleteByPrimaryKey" parameterType="java.lang.Integer" >
    delete from user
    where id = #{id,jdbcType=INTEGER}
  </delete>
  <insert id="insert" parameterType="com.hegg.springboot.model.User" >
    insert into user (id, name, sex, 
      age)
    values (#{id,jdbcType=INTEGER}, #{name,jdbcType=VARCHAR}, #{sex,jdbcType=INTEGER}, 
      #{age,jdbcType=INTEGER})
  </insert>
  <insert id="insertSelective" parameterType="com.hegg.springboot.model.User" >
    insert into user
    <trim prefix="(" suffix=")" suffixOverrides="," >
      <if test="id != null" >
        id,
      </if>
      <if test="name != null" >
        name,
      </if>
      <if test="sex != null" >
        sex,
      </if>
      <if test="age != null" >
        age,
      </if>
    </trim>
    <trim prefix="values (" suffix=")" suffixOverrides="," >
      <if test="id != null" >
        #{id,jdbcType=INTEGER},
      </if>
      <if test="name != null" >
        #{name,jdbcType=VARCHAR},
      </if>
      <if test="sex != null" >
        #{sex,jdbcType=INTEGER},
      </if>
      <if test="age != null" >
        #{age,jdbcType=INTEGER},
      </if>
    </trim>
  </insert>
  <update id="updateByPrimaryKeySelective" parameterType="com.hegg.springboot.model.User" >
    update user
    <set >
      <if test="name != null" >
        name = #{name,jdbcType=VARCHAR},
      </if>
      <if test="sex != null" >
        sex = #{sex,jdbcType=INTEGER},
      </if>
      <if test="age != null" >
        age = #{age,jdbcType=INTEGER},
      </if>
    </set>
    where id = #{id,jdbcType=INTEGER}
  </update>
  <update id="updateByPrimaryKey" parameterType="com.hegg.springboot.model.User" >
    update user
    set name = #{name,jdbcType=VARCHAR},
      sex = #{sex,jdbcType=INTEGER},
      age = #{age,jdbcType=INTEGER}
    where id = #{id,jdbcType=INTEGER}
  </update>


  <select id="getAllUser" resultType="com.hegg.springboot.model.User" parameterType="java.util.List">
    select
    <include refid="Base_Column_List"/>
    from USER
  </select>
  <select id="findByPage" resultType="com.hegg.springboot.model.User" parameterType="com.github.pagehelper.Page">
    select
    <include refid="Base_Column_List"/>
    from USER
  </select>
  <select id="findByPageInfo" resultType="com.hegg.springboot.model.User" parameterType="com.github.pagehelper.PageInfo">
    select
    <include refid="Base_Column_List"/>
    from USER
  </select>
</mapper>

贴出UserService.java、UserServiceImpl.java、UserController.java的代码

import com.github.pagehelper.Page;
import com.github.pagehelper.PageInfo;
import com.hegg.springboot.model.User;

import java.util.List;

public interface UserService {
    int deleteByPrimaryKey(Integer id);

    int insert(User record);

    int insertSelective(User record);

    User selectByPrimaryKey(Integer id);

    int updateByPrimaryKeySelective(User record);

    int updateByPrimaryKey(User record);

    List<User> getAllUser();

    Page<User> findByPage(Integer pageNum, Integer pageSize);

    PageInfo<User> findByPageInfo(Integer pageNum, Integer pageSize);

}

import com.github.pagehelper.Page;
import com.github.pagehelper.PageHelper;
import com.github.pagehelper.PageInfo;
import com.hegg.springboot.mapper.UserMapper;
import com.hegg.springboot.model.User;
import com.hegg.springboot.service.UserService;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Service;

import java.util.List;

@Service
public class UserServiceImpl implements UserService {

    @Autowired
    private UserMapper userMapper;//这个里会报红，但不影响

    @Override
    public int deleteByPrimaryKey(Integer id) {
        return userMapper.deleteByPrimaryKey(id);
    }

    @Override
    public int insert(User record) {
        return userMapper.insert(record);
    }

    @Override
    public int insertSelective(User record) {
        return userMapper.insertSelective(record);
    }

    @Override
    public User selectByPrimaryKey(Integer id) {
        return userMapper.selectByPrimaryKey(id);
    }

    @Override
    public int updateByPrimaryKeySelective(User record) {
        return userMapper.updateByPrimaryKeySelective(record);
    }

    @Override
    public int updateByPrimaryKey(User record) {
        return userMapper.updateByPrimaryKey(record);
    }

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

    @Override
    public Page<User> findByPage(Integer pageNum, Integer pageSize) {
        PageHelper.startPage(pageNum, pageSize);
        return userMapper.findByPage();
    }

    @Override
    public PageInfo<User> findByPageInfo(Integer pageNum, Integer pageSize) {
        PageHelper.startPage(pageNum, pageSize);
        List<User> userList = userMapper.findByPage();
        PageInfo<User> pageInfo = new PageInfo<>(userList);
        return pageInfo;
    }

}

import com.github.pagehelper.Page;
import com.github.pagehelper.PageInfo;
import com.hegg.springboot.common.MyResponse;
import com.hegg.springboot.model.User;
import com.hegg.springboot.service.UserService;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.web.bind.annotation.*;

import java.util.List;


@RestController
@RequestMapping("/userController")
public class UserController {

    @Autowired
    private UserService userService;

    @RequestMapping(value = "/hello", method = RequestMethod.GET, produces = "application/json; charset=utf-8")
    @ResponseBody
    public String getHello() {
        return "Hello,Word!!!世界5";
    }


    @RequestMapping(value = "/selectByPrimaryKey", method = RequestMethod.POST)
    @ResponseBody
    public MyResponse selectByPrimaryKey(Integer id){
        User user = this.userService.selectByPrimaryKey(id);
        MyResponse response = new MyResponse();
        if(null != user){
            response.setCode("success");
            response.setMsg("成功");
            response.setData(user);
        } else {
            response.setCode("faild");
            response.setMsg("失败");
        }
        return response;
    }

    @RequestMapping(value = "/getAllUser", method = RequestMethod.POST)
    @ResponseBody
    public MyResponse getAllUser(){
        List<User> list = this.userService.getAllUser();
        MyResponse response = new MyResponse();
        if(null != list && list.size() > 0){
            response.setCode("success");
            response.setMsg("成功");
            response.setData(list);
        } else {
            response.setCode("faild");
            response.setMsg("失败");
        }
        return response;
    }

    @RequestMapping(value = "/findByPage", method = RequestMethod.POST)
    @ResponseBody
    public MyResponse findByPage(Integer pageNum, Integer pageSize){
        Page<User> list = this.userService.findByPage(pageNum, pageSize);
        MyResponse response = new MyResponse();
        if(null != list && list.size() > 0){
            response.setCode("success");
            response.setMsg("成功");
            response.setData(list);
        } else {
            response.setCode("faild");
            response.setMsg("失败");
        }
        return response;
    }

    @RequestMapping(value = "/findByPageInfo", method = RequestMethod.POST)
    @ResponseBody
    public MyResponse findByPageInfo(Integer pageNum, Integer pageSize){
        PageInfo<User> list = this.userService.findByPageInfo(pageNum, pageSize);
        MyResponse response = new MyResponse();
        if(null != list && list.getList().size() > 0){
            response.setCode("success");
            response.setMsg("成功");
            response.setData(list);
        } else {
            response.setCode("faild");
            response.setMsg("失败");
        }
        return response;
    }

    @ResponseBody
    @RequestMapping(value = "/insert", produces = {"application/json;charset=UTF-8"})
    public MyResponse insert(User user){
        int result = userService.insert(user);
        MyResponse response = new MyResponse();
        if(result == 1){
            response.setCode("success");
            response.setMsg("成功");
        } else {
            response.setCode("faild");
            response.setMsg("失败");
        }
        return response;
    }

    @ResponseBody
    @RequestMapping(value = "/insertSelective", produces = {"application/json;charset=UTF-8"})
    public MyResponse insertSelective(User user){
        int result = userService.insertSelective(user);
        MyResponse response = new MyResponse();
        if(result == 1){
            response.setCode("success");
            response.setMsg("成功");
        } else {
            response.setCode("faild");
            response.setMsg("失败");
        }
        return response;
    }

    @ResponseBody
    @RequestMapping(value = "/deleteByPrimaryKey", produces = {"application/json;charset=UTF-8"})
    public MyResponse deleteByPrimaryKey(Integer id){
        int result = userService.deleteByPrimaryKey(id);
        MyResponse response = new MyResponse();
        if(result == 1){
            response.setCode("success");
            response.setMsg("成功");
        } else {
            response.setCode("faild");
            response.setMsg("失败");
        }
        return response;
    }

    @ResponseBody
    @RequestMapping(value = "/updateByPrimaryKeySelective", produces = {"application/json;charset=UTF-8"})
    public MyResponse updateByPrimaryKeySelective(User user){
        int result = userService.updateByPrimaryKeySelective(user);
        MyResponse response = new MyResponse();
        if(result == 1){
            response.setCode("success");
            response.setMsg("成功");
        } else {
            response.setCode("faild");
            response.setMsg("失败");
        }
        return response;
    }

    @ResponseBody
    @RequestMapping(value = "/updateByPrimaryKey", produces = {"application/json;charset=UTF-8"})
    public MyResponse updateByPrimaryKey(User user){
        int result = userService.updateByPrimaryKey(user);
        MyResponse response = new MyResponse();
        if(result == 1){
            response.setCode("success");
            response.setMsg("成功");
        } else {
            response.setCode("faild");
            response.setMsg("失败");
        }
        return response;
    }
}

最后启动类的代码，在类的前面一定要加注解@MapperScan，里面是*Mapper.java所在包名

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

@SpringBootApplication
@MapperScan({"com.hegg.springboot.mapper"})
public class SpringbootApplication {

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

}