Spring boot集成Mybatis-Plus，通用Mapper

      Mybatis-Plus（简称MP）是一个 Mybatis 的增强工具，在 Mybatis 的基础上只做增强不做改变，为简化开发、提高效率而生。（摘自mybatis-plus官网）Mybatis虽然已经给我们提供了很大的方便，但它还是有不足之处，MP的存在就是为了稍稍弥补Mybatis的不足。在我们使用Mybatis时会发现，每当要写一个业务逻辑的时候都要在DAO层写一个方法，再对应一个SQL，即使是简单的条件查询、即使仅仅改变了一个条件都要在DAO层新增一个方法，针对这个问题，MP这样一个框架，一种集Mybatis与Hibernate的优点一起的框架。它提供了Hibernate的单表CURD操作的方便同时，又保留了Mybatis的特性。

创建项目，

引入依赖：

<?xml version="1.0" encoding="UTF-8"?>
<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/xsd/maven-4.0.0.xsd">
    <modelVersion>4.0.0</modelVersion>

    <groupId>com.chaoqi</groupId>
    <artifactId>springboot_mybatisplus</artifactId>
    <version>0.0.1-SNAPSHOT</version>
    <packaging>jar</packaging>

    <name>springboot_mybatisplus</name>
    <description>Demo project for Spring Boot</description>

    <parent>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-parent</artifactId>
        <version>2.0.0.RELEASE</version>
        <relativePath/>
    </parent>

    <properties>
        <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
        <project.reporting.outputEncoding>UTF-8</project.reporting.outputEncoding>
        <java.version>1.8</java.version>
    </properties>

    <dependencies>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-jdbc</artifactId>
        </dependency>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-web</artifactId>
        </dependency>
        <dependency>
            <groupId>org.mybatis.spring.boot</groupId>
            <artifactId>mybatis-spring-boot-starter</artifactId>
            <version>1.3.2</version>
        </dependency>

        <dependency>
            <groupId>mysql</groupId>
            <artifactId>mysql-connector-java</artifactId>
            <scope>runtime</scope>
        </dependency>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-test</artifactId>
            <scope>test</scope>
        </dependency>
        <!--添加jsp依赖 -->
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-tomcat</artifactId>
        </dependency>
        <dependency>
            <groupId>org.apache.tomcat.embed</groupId>
            <artifactId>tomcat-embed-jasper</artifactId>
        </dependency>
        <!-- SpringBoot - MyBatis 逆向工程 -->
        <dependency>
            <groupId>org.mybatis.generator</groupId>
            <artifactId>mybatis-generator-core</artifactId>
            <version>1.3.2</version>
        </dependency>

        <!-- MyBatis 通用 Mapper -->
        <dependency>
            <groupId>tk.mybatis</groupId>
            <artifactId>mapper-spring-boot-starter</artifactId>
            <version>1.1.4</version>
        </dependency>
    </dependencies>

    <build>
        <plugins>
            <plugin>
                <groupId>org.springframework.boot</groupId>
                <artifactId>spring-boot-maven-plugin</artifactId>
            </plugin>
            <plugin>
                <groupId>org.mybatis.generator</groupId>
                <artifactId>mybatis-generator-maven-plugin</artifactId>
                <version>1.3.2</version>
                <configuration>
                    <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>
                    <dependency>
                        <groupId>tk.mybatis</groupId>
                        <artifactId>mapper</artifactId>
                        <version>3.5.0</version>
                    </dependency>
                </dependencies>
            </plugin>

        </plugins>
    </build>

</project>

配置配置文件：

server:
  port: 8080

spring:
  mvc:
    view:
      prefix: /WEB-INF/jsp/
      suffix: .jsp
  datasource:
    url: jdbc:mysql://localhost:3306/test?characterEncoding=UTF-8&useUnicode=true&useSSL=false
    username: root
    password: root
    driver-class-name: com.mysql.jdbc.Driver

mybatis:
  mapper-locations: classpath:mapper/*.xml
  type-aliases-package: com.chaoqi.springboot_mybatisplus.domain

逆向生成文件：

 创建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>

    <properties resource="application.yml"/>
    <classPathEntry location="C:/Users/Administrator/.m2/repository/mysql/mysql-connector-java/5.1.6/mysql-connector-java-5.1.6.jar"/>
    <context id="Mysql" targetRuntime="MyBatis3Simple" defaultModelType="flat">
        <property name="beginningDelimiter" value="`"/>
        <property name="endingDelimiter" value="`"/>
        <property name="javaFileEncoding" value="UTF-8"/>
        <plugin type="tk.mybatis.mapper.generator.MapperPlugin">
            <property name="mappers" value="tk.mybatis.mapper.common.Mapper"/>
        </plugin>
        <!-- 注释 -->
        <commentGenerator>
            <!-- 是否生成注释代时间戳 -->
            <property name="suppressDate" value="true"/>
            <!-- 是否去除自动生成的注释 true：是 ： false:否 -->
            <property name="suppressAllComments" value="false"/>
        </commentGenerator>
        <!-- JDBC连接 -->
        <jdbcConnection
                driverClass="com.mysql.jdbc.Driver"
                connectionURL="jdbc:mysql://localhost:3306/test?characterEncoding=UTF-8"
                userId="root"
                password="root">
        </jdbcConnection>
        <!-- 生成实体类地址 -->
        <javaModelGenerator targetPackage="com.mybatisplus.mybatisplustest.dao.domain" targetProject="src/main/java"/>
        <!-- 生成mapper xml文件 -->
        <sqlMapGenerator targetPackage="mapper" targetProject="src/main/resources"/>
        <!-- 生成mapper xml对应Client-->
        <javaClientGenerator targetPackage="com.mybatisplus.mybatisplustest.dao.mapper" targetProject="src/main/java"
                             type="XMLMAPPER"/>
        <!-- 配置表信息 -->
        <table tableName="%">
            <!--mysql 配置-->
            <generatedKey column="id" sqlStatement="Mysql"/>
            <!--oracle 配置-->
            <!--<generatedKey column="id" sqlStatement="select SEQ_{1}.nextval from dual" identity="false" type="pre"/>-->
        </table>
    </context>
</generatorConfiguration>

需要修改其中的<classPathEntry>中的路径，<jdbcConnection>中的数据库配置，以及下面三个生成路径

然后找到该文件并运行，根据表生成文件

如果这里报错，根据报错信息查看是否配置文件有错误

生成的结构：

接下来整合MybatisPlus：

创建Service和Controller，不需要手写SQL语句

public interface UserInfoService {

    public List<UserInfo> getMusicInfo();
}

@Service
public class UserInfoServiceImpl implements UserInfoService {


    @Autowired
    private UserInfoMapper userInfoMapper;

    @Override
    public List<UserInfo> getMusicInfo() {
        List<UserInfo> userInfos = userInfoMapper.selectAll();
        return userInfos;
    }
}

@RestController
public class UserinfoController {

    @Autowired
    private UserInfoService userInfoService;

    @RequestMapping("/alluser")
    public List<UserInfo> getUserInfo() {
        List<UserInfo> musicInfo1 = userInfoService.getMusicInfo();
        return musicInfo1;
    }

}

在启动类上配置mapper

@SpringBootApplication
@MapperScan("com.mybatisplus.mybatisplustest.dao.mapper")
public class MybatisplustestApplication {

    public static void main(String[] args) {
        SpringApplication.run(MybatisplustestApplication.class, args);
    }
}

然后启动测试

注意：

//    Caused by: tk.mybatis.mapper.MapperException: id - 该字段@GeneratedValue配置只允许以下几种形式:
//            1.全部数据库通用的@GeneratedValue(generator="UUID")
//            2.useGeneratedKeys的@GeneratedValue(generator="JDBC")
//            3.类似mysql数据库的@GeneratedValue(strategy=GenerationType.IDENTITY[,generator="Mysql"])