还在手写单表的增删改查？？还不快快使用通用mapper

博主自己跟着B站在学习一个项目时，发现了一个好东西，他就是通用mapper，他能够自动帮你封装好单表的增删改查操作，让你不用再自己慢慢手写，十分的方便。现在来简单介绍一下如何配置通用mapper
1.首先就是先引入通用mapper的依赖，这里会出现一个小bug，如果是引入这个依赖

<dependency>
            <groupId>tk.mybatis</groupId>
            <artifactId>mapper-spring-boot-starter</artifactId>
            <version>1.2.3</version>
            <exclusions>
                <exclusion>
                    <groupId>org.springframework.boot</groupId>
                    <artifactId>spring-boot-starter-jdbc</artifactId>
                </exclusion>
            </exclusions>
        </dependency>

出现一下错误：

java.lang.RuntimeException: java.lang.reflect.InvocationTargetException
	at tk.mybatis.spring.mapper.SpringBootBindUtil$SpringBoot2Bind.bind(SpringBootBindUtil.java:129) ~[mapper-spring-boot-autoconfigure-1.2.3.jar:na]
	at tk.mybatis.spring.mapper.SpringBootBindUtil.bind(SpringBootBindUtil.java:58) ~[mapper-spring-boot-autoconfigure-1.2.3.jar:na]
	at tk.mybatis.spring.mapper.ClassPathMapperScanner.setMapperProperties(ClassPathMapperScanner.java:48) ~[mapper-spring-boot-autoconfigure-1.2.3.jar:na]
	at tk.mybatis.spring.annotation.MapperScannerRegistrar.registerBeanDefinitions(MapperScannerRegistrar.java:33) ~[mapper-spring-boot-autoconfigure-1.2.3.jar:na]
	at org.springframework.context.annotation.ConfigurationClassBeanDefinitionReader.lambda$loadBeanDefinitionsFromRegistrars$1(ConfigurationClassBeanDefinitionReader.java:363) ~[spring-context-5.1.16.RELEASE.jar:5.1.16.RELEASE]
	at java.util.LinkedHashMap.forEach(LinkedHashMap.java:684) ~[na:1.8.0_152]
	at org.springframework.context.annotation.ConfigurationClassBeanDefinitionReader.loadBeanDefinitionsFromRegistrars(ConfigurationClassBeanDefinitionReader.java:362) ~[spring-context-5.1.16.RELEASE.jar:5.1.16.RELEASE]
	at org.springframework.context.annotation.ConfigurationClassBeanDefinitionReader.loadBeanDefinitionsForConfigurationClass(ConfigurationClassBeanDefinitionReader.java:145) ~[spring-context-5.1.16.RELEASE.jar:5.1.16.RELEASE]
	at org.springframework.context.annotation.ConfigurationClassBeanDefinitionReader.loadBeanDefinitions(ConfigurationClassBeanDefinitionReader.java:117) ~[spring-context-5.1.16.RELEASE.jar:5.1.16.RELEASE]
	at org.springframework.context.annotation.ConfigurationClassPostProcessor.processConfigBeanDefinitions(ConfigurationClassPostProcessor.java:327) ~[spring-context-5.1.16.RELEASE.jar:5.1.16.RELEASE]
	at org.springframework.context.annotation.ConfigurationClassPostProcessor.postProcessBeanDefinitionRegistry(ConfigurationClassPostProcessor.java:232) ~[spring-context-5.1.16.RELEASE.jar:5.1.16.RELEASE]
	at org.springframework.context.support.PostProcessorRegistrationDelegate.invokeBeanDefinitionRegistryPostProcessors(PostProcessorRegistrationDelegate.java:275) ~[spring-context-5.1.16.RELEASE.jar:5.1.16.RELEASE]
	at org.springframework.context.support.PostProcessorRegistrationDelegate.invokeBeanFactoryPostProcessors(PostProcessorRegistrationDelegate.java:95) ~[spring-context-5.1.16.RELEASE.jar:5.1.16.RELEASE]
	at org.springframework.context.support.AbstractApplicationContext.invokeBeanFactoryPostProcessors(AbstractApplicationContext.java:706) ~[spring-context-5.1.16.RELEASE.jar:5.1.16.RELEASE]
	at org.springframework.context.support.AbstractApplicationContext.refresh(AbstractApplicationContext.java:532) ~[spring-context-5.1.16.RELEASE.jar:5.1.16.RELEASE]
	at org.springframework.boot.web.servlet.context.ServletWebServerApplicationContext.refresh(ServletWebServerApplicationContext.java:141) ~[spring-boot-2.1.15.RELEASE.jar:2.1.15.RELEASE]
	at org.springframework.boot.SpringApplication.refresh(SpringApplication.java:744) [spring-boot-2.1.15.RELEASE.jar:2.1.15.RELEASE]
	at org.springframework.boot.SpringApplication.refreshContext(SpringApplication.java:391) [spring-boot-2.1.15.RELEASE.jar:2.1.15.RELEASE]
	at org.springframework.boot.SpringApplication.run(SpringApplication.java:312) [spring-boot-2.1.15.RELEASE.jar:2.1.15.RELEASE]
	at org.springframework.boot.SpringApplication.run(SpringApplication.java:1215) [spring-boot-2.1.15.RELEASE.jar:2.1.15.RELEASE]
	at org.springframework.boot.SpringApplication.run(SpringApplication.java:1204) [spring-boot-2.1.15.RELEASE.jar:2.1.15.RELEASE]
	at com.auguigu.gmall.user.GmallUserApplication.main(GmallUserApplication.java:12) [classes/:na]
Caused by: java.lang.reflect.InvocationTargetException: null
	at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method) ~[na:1.8.0_152]
	at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62) ~[na:1.8.0_152]
	at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43) ~[na:1.8.0_152]
	at java.lang.reflect.Method.invoke(Method.java:498) ~[na:1.8.0_152]
	at tk.mybatis.spring.mapper.SpringBootBindUtil$SpringBoot2Bind.bind(SpringBootBindUtil.java:127) ~[mapper-spring-boot-autoconfigure-1.2.3.jar:na]
	... 21 common frames omitted
Caused by: java.util.NoSuchElementException: No value bound
	at org.springframework.boot.context.properties.bind.BindResult.get(BindResult.java:56) ~[spring-boot-2.1.15.RELEASE.jar:2.1.15.RELEASE]
	... 26 common frames omitted

那么就是表明版本太低，这时候只需要重新换成一下依赖即可：

<dependency>
            <groupId>tk.mybatis</groupId>
            <artifactId>mapper-spring-boot-starter</artifactId>
            <version>2.0.2</version>
            <exclusions>
                <exclusion>
                    <groupId>org.springframework.boot</groupId>
                    <artifactId>spring-boot-starter-jdbc</artifactId>
                </exclusion>
            </exclusions>
        </dependency>

2.之后便是让我们相应的mapper接口继承我们的通用mapper

红色方框内填写与表相对应的实体类即可
3.如果你的某些方法需要返回主键对象的话，就需要在实体类对象中添加两个注解

4.最后便是重新设置mapper的包扫描器
这里会有两个扫描器，我们选择tk.mybatis.spring.annotation.MapperScan即可

最后我们来简单测试一波;

数据能够正常显示