spring boot整合mybatis-plus

简介

mybatis 增强工具包，简化 CRUD 操作。文档
http://mp.baomidou.com
http://mybatis.plus

优点 | Advantages

无侵入：Mybatis-Plus 在 Mybatis 的基础上进行扩展，只做增强不做改变，引入 Mybatis-Plus 不会对您现有的 Mybatis 构架产生任何影响，而且 MP 支持所有 Mybatis 原生的特性
依赖少：仅仅依赖 Mybatis 以及 Mybatis-Spring
损耗小：启动即会自动注入基本CURD，性能基本无损耗，直接面向对象操作
预防Sql注入：内置Sql注入剥离器，有效预防Sql注入攻击
通用CRUD操作：内置通用Mapper、通用Service，仅仅通过少量配置即可实现单表大部分 CRUD 操作，更有强大的条件构造器，满足各类使用需求
多种主键策略：支持多达4种主键策略（内含分布式唯一ID生成器），可自由配置，完美解决主键问题
支持热加载：Mapper 对应的 XML 支持热加载，对于简单的 CRUD 操作，甚至可以无 XML 启动
支持ActiveRecord：支持 ActiveRecord 形式调用，实体类只需继承 Model 类即可实现基本 CRUD 操作
支持代码生成：采用代码或者 Maven 插件可快速生成 Mapper 、 Model 、 Service 、 Controller 层代码，支持模板引擎，更有超多自定义配置等您来使用（P.S. 比 Mybatis 官方的 Generator 更加强大！）
支持自定义全局通用操作：支持全局通用方法注入（ Write once, use anywhere ）
支持关键词自动转义：支持数据库关键词（order、key…）自动转义，还可自定义关键词
内置分页插件：基于Mybatis物理分页，开发者无需关心具体操作，配置好插件之后，写分页等同于写基本List查询
内置性能分析插件：可输出Sql语句以及其执行时间，建议开发测试时启用该功能，能有效解决慢查询
内置全局拦截插件：提供全表 delete 、 update 操作智能分析阻断，预防误操作

前面已经创建了一个springboot项目，我们直接在该项目上整合mybatis-plus

准备工作

pom.xml jar引入： <mybatis-plus.version>3.0.6</mybatis-plus.version>

     <dependency><groupId>com.baomidou</groupId><artifactId>mybatis-plus-boot-starter</artifactId><version>${mybatis-plus.version}</version></dependency><dependency><groupId>com.baomidou</groupId><artifactId>mybatis-plus</artifactId><version>${mybatis-plus.version}</version></dependency>

创建表

CREATE TABLE `my_info` (`id` int(10) NOT NULL AUTO_INCREMENT,`name` varchar(255) DEFAULT NULL,`age` int(3) DEFAULT NULL,PRIMARY KEY (`id`)
) ENGINE=InnoDB DEFAULT CHARSET=utf8;

项目结构

创建基本的项目结构，controller、dao、entity、service(impl)
如图：

controller :@RestController
public class MyInfoController {@ResourceMyInfoService myInfoService;@GetMapping("myInfo")public String myInfo(@RequestParam Integer id) {MyInfo myInfo = myInfoService.getById(id);return myInfo.toString();}
}dao :public interface MyInfoMapper extends BaseMapper<MyInfo> {}entity :@Data
@TableName(value = "my_info")
public class MyInfo {@TableId(type = IdType.AUTO)private Integer id;private String name;private Integer age;
}service :public interface MyInfoService {MyInfo getById(int id);
}impl :@Service("myInfoService")
public class MyInfoServiceImpl extends ServiceImpl<MyInfoMapper,MyInfo> implements MyInfoService {@Overridepublic MyInfo getById(int id) {return baseMapper.selectById(id);}
}

当前，我们也可以在xml中自定义sql( MyInfoMapper.xml )

<?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.honghh.bootfirst.dao.MyInfoMapper"><!--自定义SQL-->
</mapper>

application.yml 配置文件内容如下

spring:datasource:type: com.alibaba.druid.pool.DruidDataSourcedriver-class-name: com.mysql.jdbc.Driverurl: jdbc:mysql://localhost:3306/boot_demousername: rootpassword: 123456
#mybatis
mybatis-plus:mapper-locations: classpath*:mapper/**/*.xml#实体扫描，多个package用逗号或者分号分隔typeAliasesPackage: com.honghh.bootfirst.entityglobal-config:#主键类型  0:"数据库ID自增", 1:"用户输入ID",2:"全局唯一ID (数字类型唯一ID)", 3:"全局唯一ID UUID";id-type: 0#字段策略 0:"忽略判断",1:"非 NULL 判断"),2:"非空判断"field-strategy: 2#驼峰下划线转换db-column-underline: true#刷新mapper 调试神器refresh-mapper: true#数据库大写下划线转换#capital-mode: true# Sequence序列接口实现类配置#key-generator: com.baomidou.mybatisplus.incrementer.OracleKeyGenerator#逻辑删除配置#logic-delete-value: -1#logic-not-delete-value: 0#自定义填充策略接口实现#meta-object-handler: com.baomidou.springboot.xxx#自定义SQL注入器sql-injector: com.baomidou.mybatisplus.mapper.LogicSqlInjectorconfiguration:map-underscore-to-camel-case: truecache-enabled: falsecall-setters-on-nulls: true

启动项目

完成上面的步骤，准备工作将近完成，现在开始启动项目，但是你会发现项目启动不起来，报错如下：

org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'myInfoController': Injection of resource dependencies failed; nested exception is org.springframework.beans.factory.UnsatisfiedDependencyException: Error creating bean with name 'myInfoService': Unsatisfied dependency expressed through field 'baseMapper'; nested exception is org.springframework.beans.factory.NoSuchBeanDefinitionException: No qualifying bean of type 'com.honghh.bootfirst.dao.MyInfoMapper' available: expected at least 1 bean which qualifies as autowire candidate. Dependency annotations: {@org.springframework.beans.factory.annotation.Autowired(required=true)}at org.springframework.context.annotation.CommonAnnotationBeanPostProcessor.postProcessProperties(CommonAnnotationBeanPostProcessor.java:324) ~[spring-context-5.1.5.RELEASE.jar:5.1.5.RELEASE]at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.populateBean(AbstractAutowireCapableBeanFactory.java:1395) ~[spring-beans-5.1.5.RELEASE.jar:5.1.5.RELEASE]at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.doCreateBean(AbstractAutowireCapableBeanFactory.java:592) ~[spring-beans-5.1.5.RELEASE.jar:5.1.5.RELEASE]at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.createBean(AbstractAutowireCapableBeanFactory.java:515) ~[spring-beans-5.1.5.RELEASE.jar:5.1.5.RELEASE]at org.springframework.beans.factory.support.AbstractBeanFactory.lambda$doGetBean$0(AbstractBeanFactory.java:320) ~[spring-beans-5.1.5.RELEASE.jar:5.1.5.RELEASE]at org.springframework.beans.factory.support.DefaultSingletonBeanRegistry.getSingleton(DefaultSingletonBeanRegistry.java:222) ~[spring-beans-5.1.5.RELEASE.jar:5.1.5.RELEASE]at org.springframework.beans.factory.support.AbstractBeanFactory.doGetBean(AbstractBeanFactory.java:318) ~[spring-beans-5.1.5.RELEASE.jar:5.1.5.RELEASE]at org.springframework.beans.factory.support.AbstractBeanFactory.getBean(AbstractBeanFactory.java:199) ~[spring-beans-5.1.5.RELEASE.jar:5.1.5.RELEASE]at org.springframework.beans.factory.support.DefaultListableBeanFactory.preInstantiateSingletons(DefaultListableBeanFactory.java:849) ~[spring-beans-5.1.5.RELEASE.jar:5.1.5.RELEASE]at org.springframework.context.support.AbstractApplicationContext.finishBeanFactoryInitialization(AbstractApplicationContext.java:877) ~[spring-context-5.1.5.RELEASE.jar:5.1.5.RELEASE]at org.springframework.context.support.AbstractApplicationContext.__refresh(AbstractApplicationContext.java:549) ~[spring-context-5.1.5.RELEASE.jar:5.1.5.RELEASE]at org.springframework.context.support.AbstractApplicationContext.jrLockAndRefresh(AbstractApplicationContext.java:40002) ~[spring-context-5.1.5.RELEASE.jar:5.1.5.RELEASE]at org.springframework.context.support.AbstractApplicationContext.refresh(AbstractApplicationContext.java:41008) ~[spring-context-5.1.5.RELEASE.jar:5.1.5.RELEASE]at org.springframework.boot.web.servlet.context.ServletWebServerApplicationContext.refresh(ServletWebServerApplicationContext.java:142) ~[spring-boot-2.1.3.RELEASE.jar:2.1.3.RELEASE]at org.springframework.boot.SpringApplication.refresh(SpringApplication.java:775) [spring-boot-2.1.3.RELEASE.jar:2.1.3.RELEASE]at org.springframework.boot.SpringApplication.refreshContext(SpringApplication.java:397) [spring-boot-2.1.3.RELEASE.jar:2.1.3.RELEASE]at org.springframework.boot.SpringApplication.run(SpringApplication.java:316) [spring-boot-2.1.3.RELEASE.jar:2.1.3.RELEASE]at org.springframework.boot.SpringApplication.run(SpringApplication.java:1260) [spring-boot-2.1.3.RELEASE.jar:2.1.3.RELEASE]at org.springframework.boot.SpringApplication.run(SpringApplication.java:1248) [spring-boot-2.1.3.RELEASE.jar:2.1.3.RELEASE]at com.honghh.bootfirst.BootFirstApplication.main(BootFirstApplication.java:11) [classes/:na]
Caused by: org.springframework.beans.factory.UnsatisfiedDependencyException: Error creating bean with name 'myInfoService': Unsatisfied dependency expressed through field 'baseMapper'; nested exception is org.springframework.beans.factory.NoSuchBeanDefinitionException: No qualifying bean of type 'com.honghh.bootfirst.dao.MyInfoMapper' available: expected at least 1 bean which qualifies as autowire candidate. Dependency annotations: {@org.springframework.beans.factory.annotation.Autowired(required=true)}at org.springframework.beans.factory.annotation.AutowiredAnnotationBeanPostProcessor$AutowiredFieldElement.inject(AutowiredAnnotationBeanPostProcessor.java:596) ~[spring-beans-5.1.5.RELEASE.jar:5.1.5.RELEASE]at org.springframework.beans.factory.annotation.InjectionMetadata.inject(InjectionMetadata.java:90) ~[spring-beans-5.1.5.RELEASE.jar:5.1.5.RELEASE]at org.springframework.beans.factory.annotation.AutowiredAnnotationBeanPostProcessor.postProcessProperties(AutowiredAnnotationBeanPostProcessor.java:374) ~[spring-beans-5.1.5.RELEASE.jar:5.1.5.RELEASE]at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.populateBean(AbstractAutowireCapableBeanFactory.java:1395) ~[spring-beans-5.1.5.RELEASE.jar:5.1.5.RELEASE]at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.doCreateBean(AbstractAutowireCapableBeanFactory.java:592) ~[spring-beans-5.1.5.RELEASE.jar:5.1.5.RELEASE]at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.createBean(AbstractAutowireCapableBeanFactory.java:515) ~[spring-beans-5.1.5.RELEASE.jar:5.1.5.RELEASE]at org.springframework.beans.factory.support.AbstractBeanFactory.lambda$doGetBean$0(AbstractBeanFactory.java:320) ~[spring-beans-5.1.5.RELEASE.jar:5.1.5.RELEASE]at org.springframework.beans.factory.support.DefaultSingletonBeanRegistry.getSingleton(DefaultSingletonBeanRegistry.java:222) ~[spring-beans-5.1.5.RELEASE.jar:5.1.5.RELEASE]at org.springframework.beans.factory.support.AbstractBeanFactory.doGetBean(AbstractBeanFactory.java:318) ~[spring-beans-5.1.5.RELEASE.jar:5.1.5.RELEASE]at org.springframework.beans.factory.support.AbstractBeanFactory.getBean(AbstractBeanFactory.java:204) ~[spring-beans-5.1.5.RELEASE.jar:5.1.5.RELEASE]at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.resolveBeanByName(AbstractAutowireCapableBeanFactory.java:452) ~[spring-beans-5.1.5.RELEASE.jar:5.1.5.RELEASE]at org.springframework.context.annotation.CommonAnnotationBeanPostProcessor.autowireResource(CommonAnnotationBeanPostProcessor.java:526) ~[spring-context-5.1.5.RELEASE.jar:5.1.5.RELEASE]at org.springframework.context.annotation.CommonAnnotationBeanPostProcessor.getResource(CommonAnnotationBeanPostProcessor.java:496) ~[spring-context-5.1.5.RELEASE.jar:5.1.5.RELEASE]at org.springframework.context.annotation.CommonAnnotationBeanPostProcessor$ResourceElement.getResourceToInject(CommonAnnotationBeanPostProcessor.java:636) ~[spring-context-5.1.5.RELEASE.jar:5.1.5.RELEASE]at org.springframework.beans.factory.annotation.InjectionMetadata$InjectedElement.inject(InjectionMetadata.java:180) ~[spring-beans-5.1.5.RELEASE.jar:5.1.5.RELEASE]at org.springframework.beans.factory.annotation.InjectionMetadata.inject(InjectionMetadata.java:90) ~[spring-beans-5.1.5.RELEASE.jar:5.1.5.RELEASE]at org.springframework.context.annotation.CommonAnnotationBeanPostProcessor.postProcessProperties(CommonAnnotationBeanPostProcessor.java:321) ~[spring-context-5.1.5.RELEASE.jar:5.1.5.RELEASE]... 19 common frames omitted
Caused by: org.springframework.beans.factory.NoSuchBeanDefinitionException: No qualifying bean of type 'com.honghh.bootfirst.dao.MyInfoMapper' available: expected at least 1 bean which qualifies as autowire candidate. Dependency annotations: {@org.springframework.beans.factory.annotation.Autowired(required=true)}at org.springframework.beans.factory.support.DefaultListableBeanFactory.raiseNoMatchingBeanFound(DefaultListableBeanFactory.java:1654) ~[spring-beans-5.1.5.RELEASE.jar:5.1.5.RELEASE]at org.springframework.beans.factory.support.DefaultListableBeanFactory.doResolveDependency(DefaultListableBeanFactory.java:1213) ~[spring-beans-5.1.5.RELEASE.jar:5.1.5.RELEASE]at org.springframework.beans.factory.support.DefaultListableBeanFactory.resolveDependency(DefaultListableBeanFactory.java:1167) ~[spring-beans-5.1.5.RELEASE.jar:5.1.5.RELEASE]at org.springframework.beans.factory.annotation.AutowiredAnnotationBeanPostProcessor$AutowiredFieldElement.inject(AutowiredAnnotationBeanPostProcessor.java:593) ~[spring-beans-5.1.5.RELEASE.jar:5.1.5.RELEASE]... 35 common frames omitted

上网查了一下，说一般是下面原因造成的：

1.applicationContext.xml配置中没有扫描包
2.controller层的@controller或者service层的@Service注解没写
3.service注入mapper失败

仔细看了下代码是mapper层没有注入，mapper注入方法有一下几种方式。

1.直接在mapper上写注解

@Mapper
public interface MyInfoMapper extends BaseMapper<MyInfo> {}

2.在启动类上添加注解

@EnableTransactionManagement
@SpringBootApplication
@MapperScan("com.honghh.*.dao")public class BootFirstApplication {public static void main(String[] args) {SpringApplication.run(BootFirstApplication.class, args);}}

mybatis-config中只是会为对应的mapper创建代理类，而想真正包装成bean，注入到spring容器中，还是需要靠AutoConfiguredMapperScannerRegistrar，它会根据扫描@Mapper注释或是@MapperScan指定的包下的接口，将其注册为bean。

3.也可以写一个配置类 MybatisPlusConfig

@Configuration
@MapperScan(basePackages = "com.honghh.*.dao")
public class MybatisPlusConfig {/*** mybatis-plus 分页插件*/@Beanpublic PerformanceInterceptor performanceInterceptor() {return new PerformanceInterceptor();}
}

在浏览器中输入：http://localhost:8080/myInfo?id=1 显示如下

成功！！！此时你已经学会了整合mybatis-plus

参考文本

https://gitee.com/baomidou/mybatisplus-spring-boot

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五、spring boot整合mybatis-plus