一、引入相关依赖

<dependencies>
  <!--springboot web依赖-->
  <dependency>
      <groupId>org.springframework.boot</groupId>
      <artifactId>spring-boot-starter-web</artifactId>
  </dependency>
  <!--mybatis分页插件，同时依赖了mybatis-->
  <dependency>
      <groupId>com.github.pagehelper</groupId>
      <artifactId>pagehelper-spring-boot-starter</artifactId>
      <version>1.4.6</version>
  </dependency>
  <!--mybatis代码自动生成依赖-->
  <dependency>
      <groupId>org.mybatis.generator</groupId>
      <artifactId>mybatis-generator-core</artifactId>
      <version>1.4.2</version>
  </dependency>
  <!--mysql依赖-->
  <dependency>
      <groupId>mysql</groupId>
      <artifactId>mysql-connector-java</artifactId>
  </dependency>
  <!--lombok依赖-->
  <dependency>
      <groupId>org.projectlombok</groupId>
      <artifactId>lombok</artifactId>
  </dependency>
  <!--springboot测试依赖-->
  <dependency>
      <groupId>org.springframework.boot</groupId>
      <artifactId>spring-boot-starter-test</artifactId>
  </dependency>
</dependencies>

二、添加application.yml配置

server:
  port: 9090
spring:
  datasource:
    driver-class-name: com.mysql.cj.jdbc.Driver
    url: jdbc:mysql://localhost:3306/testdata?useUnicode=true&characterEncoding=utf8&serverTimezone=Asia/Shanghai
    username: root
    password: 123456
mybatis:
  configuration:
    log-impl: org.apache.ibatis.logging.stdout.StdOutImpl
  mapper-locations: classpath:mapper/*.xml

三、添加mybatisgenerator.xml代码生成器配置

<?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>
    <!--如果有外部引用，可以像下面这样引入外部配置文件-->
    <!--<properties resource="generator.properties"/>-->
    <context id="MySqlContext" targetRuntime="MyBatis3" defaultModelType="flat">
        <property name="beginningDelimiter" value="`"/>
        <property name="endingDelimiter" value="`"/>
        <property name="javaFileEncoding" value="UTF-8"/>
        <!-- 为模型生成序列化方法-->
        <plugin type="org.mybatis.generator.plugins.SerializablePlugin"/>
        <!-- 为生成的Java模型创建一个toString方法 -->
        <plugin type="org.mybatis.generator.plugins.ToStringPlugin"/>
        <!--可以自定义生成model的代码注释-->
        <commentGenerator>
            <!-- 是否去除自动生成的注释 true：是 ： false:否 -->
            <property name="suppressAllComments" value="true"/>
            <property name="suppressDate" value="true"/>
            <property name="addRemarkComments" value="true"/>
        </commentGenerator>
        <!--配置数据库连接-->
        <jdbcConnection driverClass="com.mysql.cj.jdbc.Driver"
                        connectionURL="jdbc:mysql://localhost:3306/testdata?useUnicode=true;characterEncoding=utf8;serverTimezone=Asia/Shanghai"
                        userId="root"
                        password="123456">
            <!--解决mysql驱动升级到8.0后不生成指定数据库代码的问题-->
            <property name="nullCatalogMeansCurrent" value="true" />
        </jdbcConnection>
        <!--指定生成model的路径-->
        <javaModelGenerator targetPackage="com.zhenghe.model" targetProject="src/main/java"/>
        <!--指定生成mapper.xml的路径-->
        <sqlMapGenerator targetPackage="mapper" targetProject="src/main/resources"/>
        <!--指定生成mapper接口的的路径-->
        <javaClientGenerator type="XMLMAPPER" targetPackage="com.zhenghe.mapper"
                             targetProject="src/main/java"/>
        <!--生成全部表tableName设为%-->
        <table tableName="sys_user">
            <generatedKey column="id" sqlStatement="MySql" identity="true"/>
        </table>
        <table tableName="sys_role">
            <generatedKey column="id" sqlStatement="MySql" identity="true"/>
        </table>
        <table tableName="sys_menu">
            <generatedKey column="id" sqlStatement="MySql" identity="true"/>
        </table>
        <table tableName="sys_user_role">
            <generatedKey column="id" sqlStatement="MySql" identity="true"/>
        </table>
        <table tableName="sys_role_menu">
            <generatedKey column="id" sqlStatement="MySql" identity="true"/>
        </table>
    </context>
</generatorConfiguration>

四、编写代码生成器的main启动类

public class MybatisGenerator {
    public static void main(String[] args) throws Exception {
        //MBG 执行过程中的警告信息
        List<String> warnings = new ArrayList<String>();
        //当生成的代码重复时，覆盖原代码
        boolean overwrite = true;
        //读取我们的 MBG 配置文件
        InputStream is = BeanCopier.Generator.class.getResourceAsStream("/mybatisgenerator.xml");
        ConfigurationParser cp = new ConfigurationParser(warnings);
        Configuration config = cp.parseConfiguration(is);
        is.close();

        DefaultShellCallback callback = new DefaultShellCallback(overwrite);
        //创建 MBG
        MyBatisGenerator myBatisGenerator = new MyBatisGenerator(config, callback, warnings);
        //执行生成代码
        myBatisGenerator.generate(null);
        //输出警告信息
        for (String warning : warnings) {
            System.out.println(warning);
        }
    }
}

五、运行启动类，即可生成对应的model，mapper和xml

public class SysUser implements Serializable {
    private Long id;

    private String username;

    private String password;

    private String avatar;

    private String email;

    private String city;

    private Date created;

    private Date updated;

    private Date lastLogin;

    private Integer statu;

    private static final long serialVersionUID = 1L;

    public Long getId() {
        return id;
    }

    public void setId(Long id) {
        this.id = id;
    }

    public String getUsername() {
        return username;
    }

    public void setUsername(String username) {
        this.username = username;
    }

    public String getPassword() {
        return password;
    }

    public void setPassword(String password) {
        this.password = password;
    }

    public String getAvatar() {
        return avatar;
    }

    public void setAvatar(String avatar) {
        this.avatar = avatar;
    }

    public String getEmail() {
        return email;
    }

    public void setEmail(String email) {
        this.email = email;
    }

    public String getCity() {
        return city;
    }

    public void setCity(String city) {
        this.city = city;
    }

    public Date getCreated() {
        return created;
    }

    public void setCreated(Date created) {
        this.created = created;
    }

    public Date getUpdated() {
        return updated;
    }

    public void setUpdated(Date updated) {
        this.updated = updated;
    }

    public Date getLastLogin() {
        return lastLogin;
    }

    public void setLastLogin(Date lastLogin) {
        this.lastLogin = lastLogin;
    }

    public Integer getStatu() {
        return statu;
    }

    public void setStatu(Integer statu) {
        this.statu = statu;
    }

    @Override
    public String toString() {
        StringBuilder sb = new StringBuilder();
        sb.append(getClass().getSimpleName());
        sb.append(" [");
        sb.append("Hash = ").append(hashCode());
        sb.append(", id=").append(id);
        sb.append(", username=").append(username);
        sb.append(", password=").append(password);
        sb.append(", avatar=").append(avatar);
        sb.append(", email=").append(email);
        sb.append(", city=").append(city);
        sb.append(", created=").append(created);
        sb.append(", updated=").append(updated);
        sb.append(", lastLogin=").append(lastLogin);
        sb.append(", statu=").append(statu);
        sb.append(", serialVersionUID=").append(serialVersionUID);
        sb.append("]");
        return sb.toString();
    }
}

public interface SysUserMapper {
    long countByExample(SysUserExample example);

    int deleteByExample(SysUserExample example);

    int deleteByPrimaryKey(Long id);

    int insert(SysUser row);

    int insertSelective(SysUser row);

    List<SysUser> selectByExample(SysUserExample example);

    SysUser selectByPrimaryKey(Long id);

    int updateByExampleSelective(@Param("row") SysUser row, @Param("example") SysUserExample example);

    int updateByExample(@Param("row") SysUser row, @Param("example") SysUserExample example);

    int updateByPrimaryKeySelective(SysUser row);

    int updateByPrimaryKey(SysUser row);
}

<?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.zhenghe.mapper.SysUserMapper">
  <resultMap id="BaseResultMap" type="com.zhenghe.model.SysUser">
    <id column="id" jdbcType="BIGINT" property="id" />
    <result column="username" jdbcType="VARCHAR" property="username" />
    <result column="password" jdbcType="VARCHAR" property="password" />
    <result column="avatar" jdbcType="VARCHAR" property="avatar" />
    <result column="email" jdbcType="VARCHAR" property="email" />
    <result column="city" jdbcType="VARCHAR" property="city" />
    <result column="created" jdbcType="TIMESTAMP" property="created" />
    <result column="updated" jdbcType="TIMESTAMP" property="updated" />
    <result column="last_login" jdbcType="TIMESTAMP" property="lastLogin" />
    <result column="statu" jdbcType="INTEGER" property="statu" />
  </resultMap>
  <sql id="Example_Where_Clause">
    <where>
      <foreach collection="oredCriteria" item="criteria" separator="or">
        <if test="criteria.valid">
          <trim prefix="(" prefixOverrides="and" suffix=")">
            <foreach collection="criteria.criteria" item="criterion">
              <choose>
                <when test="criterion.noValue">
                  and ${criterion.condition}
                </when>
                <when test="criterion.singleValue">
                  and ${criterion.condition} #{criterion.value}
                </when>
                <when test="criterion.betweenValue">
                  and ${criterion.condition} #{criterion.value} and #{criterion.secondValue}
                </when>
                <when test="criterion.listValue">
                  and ${criterion.condition}
                  <foreach close=")" collection="criterion.value" item="listItem" open="(" separator=",">
                    #{listItem}
                  </foreach>
                </when>
              </choose>
            </foreach>
          </trim>
        </if>
      </foreach>
    </where>
  </sql>
  <sql id="Update_By_Example_Where_Clause">
    <where>
      <foreach collection="example.oredCriteria" item="criteria" separator="or">
        <if test="criteria.valid">
          <trim prefix="(" prefixOverrides="and" suffix=")">
            <foreach collection="criteria.criteria" item="criterion">
              <choose>
                <when test="criterion.noValue">
                  and ${criterion.condition}
                </when>
                <when test="criterion.singleValue">
                  and ${criterion.condition} #{criterion.value}
                </when>
                <when test="criterion.betweenValue">
                  and ${criterion.condition} #{criterion.value} and #{criterion.secondValue}
                </when>
                <when test="criterion.listValue">
                  and ${criterion.condition}
                  <foreach close=")" collection="criterion.value" item="listItem" open="(" separator=",">
                    #{listItem}
                  </foreach>
                </when>
              </choose>
            </foreach>
          </trim>
        </if>
      </foreach>
    </where>
  </sql>
  <sql id="Base_Column_List">
    id, username, password, avatar, email, city, created, updated, last_login, statu
  </sql>
  <select id="selectByExample" parameterType="com.zhenghe.model.SysUserExample" resultMap="BaseResultMap">
    select
    <if test="distinct">
      distinct
    </if>
    <include refid="Base_Column_List" />
    from sys_user
    <if test="_parameter != null">
      <include refid="Example_Where_Clause" />
    </if>
    <if test="orderByClause != null">
      order by ${orderByClause}
    </if>
  </select>
  <select id="selectByPrimaryKey" parameterType="java.lang.Long" resultMap="BaseResultMap">
    select 
    <include refid="Base_Column_List" />
    from sys_user
    where id = #{id,jdbcType=BIGINT}
  </select>
  <delete id="deleteByPrimaryKey" parameterType="java.lang.Long">
    delete from sys_user
    where id = #{id,jdbcType=BIGINT}
  </delete>
  <delete id="deleteByExample" parameterType="com.zhenghe.model.SysUserExample">
    delete from sys_user
    <if test="_parameter != null">
      <include refid="Example_Where_Clause" />
    </if>
  </delete>
  <insert id="insert" parameterType="com.zhenghe.model.SysUser">
    <selectKey keyProperty="id" order="AFTER" resultType="java.lang.Long">
      SELECT LAST_INSERT_ID()
    </selectKey>
    insert into sys_user (username, password, avatar, 
      email, city, created, 
      updated, last_login, statu
      )
    values (#{username,jdbcType=VARCHAR}, #{password,jdbcType=VARCHAR}, #{avatar,jdbcType=VARCHAR}, 
      #{email,jdbcType=VARCHAR}, #{city,jdbcType=VARCHAR}, #{created,jdbcType=TIMESTAMP}, 
      #{updated,jdbcType=TIMESTAMP}, #{lastLogin,jdbcType=TIMESTAMP}, #{statu,jdbcType=INTEGER}
      )
  </insert>
  <insert id="insertSelective" parameterType="com.zhenghe.model.SysUser">
    <selectKey keyProperty="id" order="AFTER" resultType="java.lang.Long">
      SELECT LAST_INSERT_ID()
    </selectKey>
    insert into sys_user
    <trim prefix="(" suffix=")" suffixOverrides=",">
      <if test="username != null">
        username,
      </if>
      <if test="password != null">
        password,
      </if>
      <if test="avatar != null">
        avatar,
      </if>
      <if test="email != null">
        email,
      </if>
      <if test="city != null">
        city,
      </if>
      <if test="created != null">
        created,
      </if>
      <if test="updated != null">
        updated,
      </if>
      <if test="lastLogin != null">
        last_login,
      </if>
      <if test="statu != null">
        statu,
      </if>
    </trim>
    <trim prefix="values (" suffix=")" suffixOverrides=",">
      <if test="username != null">
        #{username,jdbcType=VARCHAR},
      </if>
      <if test="password != null">
        #{password,jdbcType=VARCHAR},
      </if>
      <if test="avatar != null">
        #{avatar,jdbcType=VARCHAR},
      </if>
      <if test="email != null">
        #{email,jdbcType=VARCHAR},
      </if>
      <if test="city != null">
        #{city,jdbcType=VARCHAR},
      </if>
      <if test="created != null">
        #{created,jdbcType=TIMESTAMP},
      </if>
      <if test="updated != null">
        #{updated,jdbcType=TIMESTAMP},
      </if>
      <if test="lastLogin != null">
        #{lastLogin,jdbcType=TIMESTAMP},
      </if>
      <if test="statu != null">
        #{statu,jdbcType=INTEGER},
      </if>
    </trim>
  </insert>
  <select id="countByExample" parameterType="com.zhenghe.model.SysUserExample" resultType="java.lang.Long">
    select count(*) from sys_user
    <if test="_parameter != null">
      <include refid="Example_Where_Clause" />
    </if>
  </select>
  <update id="updateByExampleSelective" parameterType="map">
    update sys_user
    <set>
      <if test="row.id != null">
        id = #{row.id,jdbcType=BIGINT},
      </if>
      <if test="row.username != null">
        username = #{row.username,jdbcType=VARCHAR},
      </if>
      <if test="row.password != null">
        password = #{row.password,jdbcType=VARCHAR},
      </if>
      <if test="row.avatar != null">
        avatar = #{row.avatar,jdbcType=VARCHAR},
      </if>
      <if test="row.email != null">
        email = #{row.email,jdbcType=VARCHAR},
      </if>
      <if test="row.city != null">
        city = #{row.city,jdbcType=VARCHAR},
      </if>
      <if test="row.created != null">
        created = #{row.created,jdbcType=TIMESTAMP},
      </if>
      <if test="row.updated != null">
        updated = #{row.updated,jdbcType=TIMESTAMP},
      </if>
      <if test="row.lastLogin != null">
        last_login = #{row.lastLogin,jdbcType=TIMESTAMP},
      </if>
      <if test="row.statu != null">
        statu = #{row.statu,jdbcType=INTEGER},
      </if>
    </set>
    <if test="example != null">
      <include refid="Update_By_Example_Where_Clause" />
    </if>
  </update>
  <update id="updateByExample" parameterType="map">
    update sys_user
    set id = #{row.id,jdbcType=BIGINT},
      username = #{row.username,jdbcType=VARCHAR},
      password = #{row.password,jdbcType=VARCHAR},
      avatar = #{row.avatar,jdbcType=VARCHAR},
      email = #{row.email,jdbcType=VARCHAR},
      city = #{row.city,jdbcType=VARCHAR},
      created = #{row.created,jdbcType=TIMESTAMP},
      updated = #{row.updated,jdbcType=TIMESTAMP},
      last_login = #{row.lastLogin,jdbcType=TIMESTAMP},
      statu = #{row.statu,jdbcType=INTEGER}
    <if test="example != null">
      <include refid="Update_By_Example_Where_Clause" />
    </if>
  </update>
  <update id="updateByPrimaryKeySelective" parameterType="com.zhenghe.model.SysUser">
    update sys_user
    <set>
      <if test="username != null">
        username = #{username,jdbcType=VARCHAR},
      </if>
      <if test="password != null">
        password = #{password,jdbcType=VARCHAR},
      </if>
      <if test="avatar != null">
        avatar = #{avatar,jdbcType=VARCHAR},
      </if>
      <if test="email != null">
        email = #{email,jdbcType=VARCHAR},
      </if>
      <if test="city != null">
        city = #{city,jdbcType=VARCHAR},
      </if>
      <if test="created != null">
        created = #{created,jdbcType=TIMESTAMP},
      </if>
      <if test="updated != null">
        updated = #{updated,jdbcType=TIMESTAMP},
      </if>
      <if test="lastLogin != null">
        last_login = #{lastLogin,jdbcType=TIMESTAMP},
      </if>
      <if test="statu != null">
        statu = #{statu,jdbcType=INTEGER},
      </if>
    </set>
    where id = #{id,jdbcType=BIGINT}
  </update>
  <update id="updateByPrimaryKey" parameterType="com.zhenghe.model.SysUser">
    update sys_user
    set username = #{username,jdbcType=VARCHAR},
      password = #{password,jdbcType=VARCHAR},
      avatar = #{avatar,jdbcType=VARCHAR},
      email = #{email,jdbcType=VARCHAR},
      city = #{city,jdbcType=VARCHAR},
      created = #{created,jdbcType=TIMESTAMP},
      updated = #{updated,jdbcType=TIMESTAMP},
      last_login = #{lastLogin,jdbcType=TIMESTAMP},
      statu = #{statu,jdbcType=INTEGER}
    where id = #{id,jdbcType=BIGINT}
  </update>
</mapper>

六、在启动类上添加mapper包扫描

@SpringBootApplication
@MapperScan("com.zhenghe.mapper")
public class ZhengheApplication {
    public static void main(String[] args) {

        SpringApplication.run(ZhengheApplication.class,args);
    }
}

七、单元测试并通过pageHelper进行简单分页

  @Test
  public void test2(){
      //页码
      Integer pageNum = 1;
      //每页数量
      Integer pageSize = 3;
      //将PageHelper.startPage(pageNum,pageSize)放在查询分页sql的方法前即可自动分页
      PageHelper.startPage(pageNum,pageSize);
      ResultVo resultVo = userService.selectUserList();
      System.out.println(resultVo.getData());
  }