spring boot+mybatis 环境搭建，记录一些步骤

1. Controller层 接收页面所有请求，根据请求去调用处理这个请求的服务
2. Service层 是一个系统的核心，包含了所有服务，根据自己实现的功能去执行元操作（数据库操作）
3. mapper层 数据库操作的集合
4. domain 层 实体类

需要注意的点：

1. 在启动类中添加：

@MapperScan({
    
    "com.example.demo.mapper"})

2. mybatis 需要在pom.xml中添加：

<!--依赖-->
<dependency>
    <groupId>org.mybatis.spring.boot</groupId>
    <artifactId>mybatis-spring-boot-starter</artifactId>
    <version>1.3.2</version>
</dependency>

<!--插件-->
<plugin>
                <groupId>org.mybatis.generator</groupId>
                <artifactId>mybatis-generator-maven-plugin</artifactId>
                <version>1.4.0</version>
                <configuration>
                    <configurationFile>${basedir}/src/main/resources/mybatis/generator/generatorConfig.xml</configurationFile>
                    <overwrite>true</overwrite>
                    <verbose>true</verbose>
                </configuration>
                <dependencies>
                    <dependency>
                        <groupId>mysql</groupId>
                        <artifactId>mysql-connector-java</artifactId>
                        <version>5.1.38</version>
                    </dependency>
                </dependencies>

</plugin>

3. 新建文件 resources->mabatis->generator->generatorConfig.xml

<?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>
    <context id="MySQLTables" targetRuntime="MyBatis3">
        <plugin type="org.mybatis.generator.plugins.UnmergeableXmlMappersPlugin"/>
        <commentGenerator>
            <property name="suppressAllComments" value="true"/>
        </commentGenerator>
        <!--覆盖生成XML文件-->
        <jdbcConnection driverClass="com.mysql.jdbc.Driver"
                        connectionURL="jdbc:mysql://localhost:3306/databasename?serverTimezone=UTC"
                        userId="root"
                        password="root">
        </jdbcConnection>

        <javaTypeResolver>
            <property name="forceBigDecimals" value="false"/>
        </javaTypeResolver>
        <!-- 实体类-->
        <javaModelGenerator targetPackage="com.example.demo.common.domain" targetProject="src/main/java">
            <property name="enableSubPackages" value="true"/>
            <property name="trimStrings" value="true"/>
        </javaModelGenerator>
        <!--Mapper 映射文件-->
        <sqlMapGenerator targetPackage="mybatis.mapper" targetProject="src/main/resources">
            <property name="enableSubPackages" value="true"/>
        </sqlMapGenerator>
        <!--Dao 接口-->
        <javaClientGenerator type="XMLMAPPER" targetPackage="com.example.demo.mapper"
                             targetProject="src/main/java">
            <property name="enableSubPackages" value="true"/>
        </javaClientGenerator>

        <table tableName="tablename" domainObjectName="Tablename"/>

 <!--  <table schema="DB2ADMIN" tableName="ALLTYPES" domainObjectName="Customer" >
                      <property name="useActualColumnNames" value="true"/>
                      <generatedKey column="ID" sqlStatement="DB2" identity="true" />
                      <columnOverride column="DATE_FIELD" property="startDate" />
                      <ignoreColumn column="FRED" />
                      <columnOverride column="LONG_VARCHAR_FIELD" jdbcType="VARCHAR" />
                  </table>-->

    </context>
</generatorConfiguration>

4. application.propertis中

spring.datasource.driver-class-name=com.mysql.jdbc.Driver
spring.datasource.username=root
spring.datasource.password=root
spring.datasource.url=jdbc:mysql://localhost:3306/databasename?serverTimezone=UTC
#&useSSL=true&autoReconnect=true&failOverReadOnly=false
mybatis.mapper-locations=classpath:/mybatis/mapper/*.xml, classpath:/mybatis/mapper/extend/*.xml

5. 目录结构