版权声明：本文为博主原创文章，未经博主允许不得转载。 https://blog.csdn.net/u010251278/article/details/53333460
写在前面：
前面在《前后端分离的思考》的一文中提到又有一门课要开始写大作业了，在初步理解了需求了之后，项目准备采用Maven+Mybatis+Mysql+SpringMVC+Vue.js的架构。采用Maven解决依赖管理问题十分方便（貌似gradle后来者居上，更方便了）。后台用的SpringMVC框架，毕竟也是javaWeb方面很常用的了。前端框架采用的是Vue.js，本身没怎么系统的使用过前端框架，这次也是第一次使用Vue，如果学到了什么有价值的东西也会开一篇帖子专门来叙述一下。今天好好念叨一下Mybatis和MybatisGenerator吧。
1.什么是MyBatis？
官网的解释我直接copy过来：MyBatis 是支持定制化 SQL、存储过程以及高级映射的优秀的持久层框架。MyBatis 避免了几乎所有的 JDBC 代码和手动设置参数以及获取结果集。MyBatis 可以对配置和原生Map使用简单的 XML 或注解，将接口和 Java 的 POJOs(Plain Old Java Objects,普通的 Java对象)映射成数据库中的记录。
真正用一遍MyBatis在回来看这段话，确实写的很简洁明了。
2.怎么用Mybatis？
按照我前面说的架构，使用Mybatis还是很简单的，只需要把各项配置文件配置好就可以了。但是如果各种最一般的数据查询接口，实体类等等还要我们一个个去手写的话，那不但浪费时间还会磨掉你对开发的激情。所以最最重要的是使用Mybatis-generator去帮我们自动生成关于某些表的实体类，dao（data access object）层接口，mapper接口，xxxmapper.xml等等。
首先我这里直接把各种牵扯的配置文件给进来，看注释的应该都不难。在这之前先看一下项目的目录结构，这样便于后面理解
pom.xml
<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/maven-v4_0_0.xsd">
<modelVersion>4.0.0</modelVersion>
<groupId>com.zxx.web</groupId>
<artifactId>web-ssm</artifactId>
<packaging>war</packaging>
<version>1.0-SNAPSHOT</version>
<name>web-ssm Maven Webapp</name>
<url>http://maven.apache.org</url>
<properties>
<project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
<project.reporting.outputEncoding>UTF-8</project.reporting.outputEncoding>
<!-- spring版本号 -->
<spring.version>4.2.5.RELEASE</spring.version>
<!-- mybatis版本号 -->
<mybatis.version>3.2.8</mybatis.version>
<!-- mysql驱动版本号 -->
<mysql-driver.version>5.1.29</mysql-driver.version>
<!-- log4j日志包版本号 -->
<slf4j.version>1.7.18</slf4j.version>
<log4j.version>1.2.17</log4j.version>
<velocity.version>1.7</velocity.version>
<velocity-tools.version>2.0</velocity-tools.version>
</properties>
<dependencies>
<!-- 添加jstl依赖 -->
<dependency>
<groupId>jstl</groupId>
<artifactId>jstl</artifactId>
<version>1.2</version>
</dependency>
<dependency>
<groupId>javax</groupId>
<artifactId>javaee-api</artifactId>
<version>7.0</version>
</dependency>
<!-- 添加junit4依赖 -->
<dependency>
<groupId>junit</groupId>
<artifactId>junit</artifactId>
<version>4.11</version>
<!-- 指定范围，在测试时才会加载 -->
<scope>test</scope>
</dependency>
<!-- 添加spring核心依赖 -->
<dependency>
<groupId>org.springframework</groupId>
<artifactId>spring-core</artifactId>
<version>${spring.version}</version>
</dependency>
<dependency>
<groupId>org.springframework</groupId>
<artifactId>spring-web</artifactId>
<version>${spring.version}</version>
</dependency>
<dependency>
<groupId>org.springframework</groupId>
<artifactId>spring-oxm</artifactId>
<version>${spring.version}</version>
</dependency>
<dependency>
<groupId>org.springframework</groupId>
<artifactId>spring-tx</artifactId>
<version>${spring.version}</version>
</dependency>
<dependency>
<groupId>org.springframework</groupId>
<artifactId>spring-jdbc</artifactId>
<version>${spring.version}</version>
</dependency>
<dependency>
<groupId>org.springframework</groupId>
<artifactId>spring-webmvc</artifactId>
<version>${spring.version}</version>
</dependency>
<dependency>
<groupId>org.springframework</groupId>
<artifactId>spring-context</artifactId>
<version>${spring.version}</version>
</dependency>
<dependency>
<groupId>org.springframework</groupId>
<artifactId>spring-context-support</artifactId>
<version>${spring.version}</version>
</dependency>
<dependency>
<groupId>org.springframework</groupId>
<artifactId>spring-aop</artifactId>
<version>${spring.version}</version>
</dependency>
<dependency>
<groupId>org.springframework</groupId>
<artifactId>spring-test</artifactId>
<version>${spring.version}</version>
</dependency>
<!-- 添加mybatis依赖 -->
<dependency>
<groupId>org.mybatis</groupId>
<artifactId>mybatis</artifactId>
<version>${mybatis.version}</version>
</dependency>
<!-- 添加mybatis/spring整合包依赖 -->
<dependency>
<groupId>org.mybatis</groupId>
<artifactId>mybatis-spring</artifactId>
<version>1.2.2</version>
</dependency>
<!-- 添加mysql驱动依赖 -->
<dependency>
<groupId>mysql</groupId>
<artifactId>mysql-connector-java</artifactId>
<version>${mysql-driver.version}</version>
</dependency>
<!-- 添加数据库连接池依赖 -->
<dependency>
<groupId>commons-dbcp</groupId>
<artifactId>commons-dbcp</artifactId>
<version>1.2.2</version>
</dependency>
<!-- 添加fastjson -->
<dependency>
<groupId>com.alibaba</groupId>
<artifactId>fastjson</artifactId>
<version>1.1.41</version>
</dependency>
<!-- 添加日志相关jar包 -->
<dependency>
<groupId>log4j</groupId>
<artifactId>log4j</artifactId>
<version>${log4j.version}</version>
</dependency>
<dependency>
<groupId>org.slf4j</groupId>
<artifactId>slf4j-api</artifactId>
<version>${slf4j.version}</version>
</dependency>
<dependency>
<groupId>org.slf4j</groupId>
<artifactId>slf4j-log4j12</artifactId>
<version>${slf4j.version}</version>
</dependency>
<!-- log end -->
<!-- 映入JSON -->
<dependency>
<groupId>org.codehaus.jackson</groupId>
<artifactId>jackson-mapper-asl</artifactId>
<version>1.9.13</version>
</dependency>
<!-- https://mvnrepository.com/artifact/com.fasterxml.jackson.core/jackson-core -->
<dependency>
<groupId>com.fasterxml.jackson.core</groupId>
<artifactId>jackson-core</artifactId>
<version>2.8.0</version>
</dependency>
<!-- https://mvnrepository.com/artifact/com.fasterxml.jackson.core/jackson-databind -->
<dependency>
<groupId>com.fasterxml.jackson.core</groupId>
<artifactId>jackson-databind</artifactId>
<version>2.8.0</version>
</dependency>
<dependency>
<groupId>commons-fileupload</groupId>
<artifactId>commons-fileupload</artifactId>
<version>1.3.1</version>
</dependency>
<dependency>
<groupId>commons-io</groupId>
<artifactId>commons-io</artifactId>
<version>2.4</version>
</dependency>
<dependency>
<groupId>commons-codec</groupId>
<artifactId>commons-codec</artifactId>
<version>1.9</version>
</dependency>
<!--velocity-->
<dependency>
<groupId>org.apache.velocity</groupId>
<artifactId>velocity</artifactId>
<version>${velocity.version}</version>
</dependency>
<dependency>
<groupId>org.apache.velocity</groupId>
<artifactId>velocity-tools</artifactId>
<version>${velocity-tools.version}</version>
<exclusions>
<exclusion>
<groupId>commons-logging</groupId>
<artifactId>commons-logging</artifactId>
</exclusion>
</exclusions>
</dependency>
<dependency>
<groupId>org.freemarker</groupId>
<artifactId>freemarker</artifactId>
<version>2.3.22</version>
</dependency>
<dependency>
<groupId>org.springframework</groupId>
<artifactId>spring-context-support</artifactId>
<version>4.1.6.RELEASE</version>
</dependency>
</dependencies>
<build>
<finalName>web-ssm</finalName>
<plugins>
<plugin>
<groupId>org.mybatis.generator</groupId>
<artifactId>mybatis-generator-maven-plugin</artifactId>
<version>1.3.2</version>
<configuration>
<!--配置文件的位置--> <configurationFile>src/main/resources/generatorConfig.xml</configurationFile>
<verbose>true</verbose>
<overwrite>true</overwrite>
</configuration>
<executions>
<execution>
<id>Generate MyBatis Artifacts</id>
<goals>
<goal>generate</goal>
</goals>
</execution>
</executions>
<dependencies>
<dependency>
<groupId>org.mybatis.generator</groupId>
<artifactId>mybatis-generator-core</artifactId>
<version>1.3.2</version>
</dependency>
</dependencies>
</plugin>
</plugins>
</build>
</project>spring-mybatis.xml
<?xml version="1.0" encoding="UTF-8"?>
<beans xmlns="http://www.springframework.org/schema/beans"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xmlns:context="http://www.springframework.org/schema/context" xmlns:tx="http://www.springframework.org/schema/tx"
xsi:schemaLocation="http://www.springframework.org/schema/beans
http://www.springframework.org/schema/beans/spring-beans-3.1.xsd
http://www.springframework.org/schema/context
http://www.springframework.org/schema/context/spring-context-3.1.xsd
http://www.springframework.org/schema/tx
http://www.springframework.org/schema/tx/spring-tx.xsd">
<!-- 自动扫描 -->
<!--<context:component-scan base-package="com.zxx.ssm"/>-->
<!-- 第一种方式：加载一个properties文件 -->
<bean id="propertyConfigurer" class="org.springframework.beans.factory.config.PropertyPlaceholderConfigurer">
<property name="location" value="classpath:jdbc.properties"/>
</bean>
<!-- 第二种方式：加载多个properties文件
<bean id="configProperties" class="org.springframework.beans.factory.config.PropertiesFactoryBean">
<property name="locations">
<list>
<value>classpath:jdbc.properties</value>
<value>classpath:common.properties</value>
</list>
</property>
<property name="fileEncoding" value="UTF-8"/>
</bean>
<bean id="propertyConfigurer" class="org.springframework.beans.factory.config.PreferencesPlaceholderConfigurer">
<property name="properties" ref="configProperties"/>
</bean>
-->
<!-- 配置数据源 -->
<bean id="dataSource" class="org.apache.commons.dbcp.BasicDataSource"
destroy-method="close">
<property name="driverClassName" value="${driverClasss}"/>
<property name="url" value="${jdbcUrl}"/>
<property name="username" value="${username}"/>
<property name="password" value="${password}"/>
<!-- 初始化连接大小 -->
<property name="initialSize" value="${initialSize}"></property>
<!-- 连接池最大数量 -->
<property name="maxActive" value="${maxActive}"></property>
<!-- 连接池最大空闲 -->
<property name="maxIdle" value="${maxIdle}"></property>
<!-- 连接池最小空闲 -->
<property name="minIdle" value="${minIdle}"></property>
<!-- 获取连接最大等待时间 -->
<property name="maxWait" value="${maxWait}"></property>
</bean>
<!-- mybatis和spring完美整合，不需要mybatis的配置映射文件 -->
<bean id="sqlSessionFactory" class="org.mybatis.spring.SqlSessionFactoryBean">
<property name="dataSource" ref="dataSource"/>
<!-- 自动扫描mapping.xml文件 -->
<property name="mapperLocations" value="classpath:mapping/*.xml"></property>
</bean>
<!-- DAO接口所在包名，Spring会自动查找其下的类 -->
<bean class="org.mybatis.spring.mapper.MapperScannerConfigurer">
<property name="basePackage" value="com.zxx.ssm.mapper"/>
<property name="sqlSessionFactoryBeanName" value="sqlSessionFactory"></property>
</bean>
<!-- (事务管理)transaction manager, use JtaTransactionManager for global tx -->
<bean id="transactionManager" class="org.springframework.jdbc.datasource.DataSourceTransactionManager">
<property name="dataSource" ref="dataSource"/>
</bean>
<!-- (事务管理)transaction manager, use JtaTransactionManager for global tx -->
<tx:annotation-driven transaction-manager="transactionManager"/>
</beans>web.xml
<?xml version="1.0" encoding="UTF-8"?>
<web-app xmlns="http://java.sun.com/xml/ns/javaee"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="http://java.sun.com/xml/ns/javaee
http://java.sun.com/xml/ns/javaee/web-app_3_0.xsd"
version="3.0">
<display-name>Archetype Created Web Application</display-name>
<context-param>
<param-name>contextConfigLocation</param-name>
<param-value>classpath:spring-mybatis.xml</param-value>
</context-param>
<context-param>
<param-name>log4jConfigLocation</param-name>
<param-value>classpath:log4j.properties</param-value>
</context-param>
<!-- 编码过滤器 -->
<filter>
<filter-name>encodingFilter</filter-name>
<filter-class>org.springframework.web.filter.CharacterEncodingFilter</filter-class>
<init-param>
<param-name>encoding</param-name>
<param-value>UTF-8</param-value>
</init-param>
</filter>
<filter-mapping>
<filter-name>encodingFilter</filter-name>
<url-pattern>/*</url-pattern>
</filter-mapping>
<!-- spring监听器 -->
<listener>
<listener-class>org.springframework.web.context.ContextLoaderListener</listener-class>
</listener>
<!-- 防止spring内存溢出监听器，比如quartz -->
<listener>
<listener-class>org.springframework.web.util.IntrospectorCleanupListener</listener-class>
</listener>
<!-- spring mvc servlet-->
<servlet>
<servlet-name>dispatcher</servlet-name>
<servlet-class>org.springframework.web.servlet.DispatcherServlet</servlet-class>
<init-param>
<param-name>contextConfigLocation</param-name>
<param-value>/WEB-INF/dispatcher-servlet.xml</param-value>
</init-param>
<load-on-startup>1</load-on-startup>
<async-supported>true</async-supported>
</servlet>
<servlet-mapping>
<servlet-name>dispatcher</servlet-name>
<!-- 此处也可以配置成 *.do 形式 -->
<url-pattern>/</url-pattern>
</servlet-mapping>
<welcome-file-list>
<welcome-file>/index.html</welcome-file>
</welcome-file-list>
<!-- session配置 -->
<session-config>
<session-timeout>15</session-timeout>
</session-config>
</web-app>
dispatcher-servlet.xml
<?xml version="1.0" encoding="UTF-8"?>
<beans xmlns="http://www.springframework.org/schema/beans"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:p="http://www.springframework.org/schema/p"
xmlns:context="http://www.springframework.org/schema/context"
xmlns:mvc="http://www.springframework.org/schema/mvc"
xsi:schemaLocation="http://www.springframework.org/schema/beans
http://www.springframework.org/schema/beans/spring-beans-4.0.xsd
http://www.springframework.org/schema/context
http://www.springframework.org/schema/context/spring-context-4.0.xsd
http://www.springframework.org/schema/mvc
http://www.springframework.org/schema/mvc/spring-mvc-4.0.xsd">
<!-- 自动扫描 @Controller-->
<context:component-scan base-package="com.zxx.ssm"/>
<mvc:annotation-driven></mvc:annotation-driven>
<mvc:resources mapping="/assets/**" location="/WEB-INF/assets/"/>
<!--避免IE执行AJAX时，返回JSON出现下载文件 -->
<bean id="mappingJacksonHttpMessageConverter"
class="org.springframework.http.converter.json.MappingJackson2HttpMessageConverter">
<property name="supportedMediaTypes">
<list>
<value>text/html;charset=UTF-8</value>
</list>
</property>
</bean>
<!-- 启动SpringMVC的注解功能，完成请求和注解POJO的映射 -->
<bean class="org.springframework.web.servlet.mvc.annotation.AnnotationMethodHandlerAdapter">
<property name="messageConverters">
<list>
<ref bean="mappingJacksonHttpMessageConverter"/> <!-- JSON转换器 -->
</list>
</property>
</bean>
<!-- 设置freeMarker的配置文件路径 -->
<bean id="freemarkerConfiguration"
class="org.springframework.beans.factory.config.PropertiesFactoryBean">
<!--注释掉的下方代码是指引freemarker的基本信息的配置位置，因为我已经将配置信息移到了applicationContext文件下，所以这里就没必要存在了，不注释也不会有问题的 -->
<property name="location" value="/WEB-INF/config/freemarker.properties" />
</bean>
<bean id="freemarkerConfig"
class="org.springframework.web.servlet.view.freemarker.FreeMarkerConfigurer">
<property name="freemarkerSettings" ref="freemarkerConfiguration" />
<property name="templateLoaderPath" value="/WEB-INF/views/" />
</bean>
<bean id="viewResolver" class="org.springframework.web.servlet.view.freemarker.FreeMarkerViewResolver">
<property name="cache" value="true" />
<property name="suffix" value=".html" />
<!--只是这里后缀改成.html -->
<property name="viewClass"
value="org.springframework.web.servlet.view.freemarker.FreeMarkerView" />
<property name="exposeSpringMacroHelpers" value="true" />
<property name="exposeRequestAttributes" value="true" />
<property name="exposeSessionAttributes" value="true" />
<property name="requestContextAttribute" value="rc" />
<property name="contentType" value="text/html;charset=UTF-8" />
</bean>
<!-- <bean class="org.springframework.web.servlet.view.InternalResourceViewResolver">
<property name="prefix" value="/WEB-INF/page/"/>
<property name="suffix" value=".jsp"/>
</bean>-->
<!-- 文件上传配置 -->
<bean id="multipartResolver" class="org.springframework.web.multipart.commons.CommonsMultipartResolver">
<!-- 默认编码 -->
<property name="defaultEncoding" value="UTF-8"/>
<!-- 上传文件大小限制为31M，31*1024*1024 -->
<property name="maxUploadSize" value="32505856"/>
<!-- 内存中的最大值 -->
<property name="maxInMemorySize" value="4096"/>
</bean>
</beans>假设按照上面的几个配置文件，大家都配置好了，项目的目录结构也按照我说的创建好了，现在开始使用Mybatis-generator
step1:
在相应的目录位置创建generatorConfig.xml文件
step2:
配置相应的内容，注意mysq连接数据库的jar的location去你的C盘相应的路径找吧，可能会变得就是你的用户名变了，还有可能那个版本号不一样了
<?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>
<!--<properties resource="jdbc.properties"></properties>-->
<!--mysql 连接数据库jar 这里选择自己本地位置-->
<classPathEntry location="C:\Users\bwju\.m2\repository\mysql\mysql-connector-java\5.1.29\mysql-connector-java-5.1.29.jar" />
<context id="testTables" targetRuntime="MyBatis3">
<commentGenerator>
<!-- 是否去除自动生成的注释 true：是 ： false:否 -->
<property name="suppressAllComments" value="true" />
</commentGenerator>
<!--数据库连接的信息：驱动类、连接地址、用户名、密码 -->
<jdbcConnection driverClass="com.mysql.jdbc.Driver"
connectionURL="jdbc:mysql://localhost:3306/attendance" userId="root"
password="root">
</jdbcConnection>
<!-- 默认false，把JDBC DECIMAL 和 NUMERIC 类型解析为 Integer，为 true时把JDBC DECIMAL 和
NUMERIC 类型解析为java.math.BigDecimal -->
<javaTypeResolver>
<property name="forceBigDecimals" value="false" />
</javaTypeResolver>
<!-- targetProject:生成PO类的位置 -->
<javaModelGenerator targetPackage="com.zxx.ssm.dao"
targetProject="src/main/java">
<!-- enableSubPackages:是否让schema作为包的后缀 -->
<property name="enableSubPackages" value="false" />
<!-- 从数据库返回的值被清理前后的空格 -->
<property name="trimStrings" value="true" />
</javaModelGenerator>
<!-- targetProject:mapper映射文件生成的位置
如果maven工程只是单独的一个工程，targetProject="src/main/java"
若果maven工程是分模块的工程，targetProject="所属模块的名称"，例如：
targetProject="ecps-manager-mapper"，下同-->
<sqlMapGenerator targetPackage="resources.mapping"
targetProject="src/main">
<!-- enableSubPackages:是否让schema作为包的后缀 -->
<property name="enableSubPackages" value="false" />
</sqlMapGenerator>
<!-- targetPackage：mapper接口生成的位置 -->
<javaClientGenerator type="XMLMAPPER"
targetPackage="com.zxx.ssm.mapper"
targetProject="src/main/java">
<!-- enableSubPackages:是否让schema作为包的后缀 -->
<property name="enableSubPackages" value="false" />
</javaClientGenerator>
<!-- 指定数据库表 -->
<table schema="" tableName="employee"></table>
</context>
</generatorConfiguration>
首先先要在你的IDEA里安装mybatis-plugin
File->Settings->Plugins 搜索mybatis然后install就可以了，不过估计大部分朋友没有activtion license,可以下个破解版的用，网上搜mybatis plugin破解版，一大堆
装好插件以后，点击右上角的那个运行按钮旁边的下拉菜单，找到Edit Configurations,点击+号配置一个和下图一样的东西
主要就是那个命令要写对，Name叫什么不重要，工作路径按默认的来就好
最后，选择自己创建的generateMapper，点击运行按钮，Boom！你会发现你的项目里多了好多东西，快去看看吧，我在上述的配置文件中指定了它为我数据库中的Employee表去自动生成相关文件，生成完之后成了这样，可以看到它们都被自动生成啦
在系统设计到的表数目较多时，用mybatis-generator可以省下大把的时间，让开发者更关注在后台的逻辑中，而且mybatis自动生成的代码能够满足绝大多数情况下的使用了。非常方便，然而，非常特别的方法还是要自己去写方法的嗯嗯，祝大家都能使用这一工具。
如果有收获的话可以扫码侧面的二维码打赏一下哟，感谢您的鼓励~