springboot成神之——mybatis和mybatis-generator

• 项目结构
• 依赖
• generator配置文件
• properties配置
• 生成文件
• 使用Example

本文讲解如何在spring-boot中使用mybatis和mybatis-generator自动生成文件

项目结构

依赖

<dependency>
    <groupId>mysql</groupId>
    <artifactId>mysql-connector-java</artifactId>
    <version>8.0.12</version>
    <scope>runtime</scope>
</dependency>

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


<build>
    <plugins>
        <plugin>
            <groupId>org.mybatis.generator</groupId>
            <artifactId>mybatis-generator-maven-plugin</artifactId>
            <version>1.3.7</version>

            <executions>
                <execution>
                <id>Generate MyBatis Artifacts</id>
                <!-- 允许maven打包自动执行generator操作 -->
                <goals>
                    <goal>generate</goal>
                </goals>
                </execution>
            </executions>

            <configuration>
                <!--允许移动生成的文件 -->
                <verbose>true</verbose>
                <!-- 是否覆盖 -->
                <!-- <overwrite>true</overwrite> -->
                <!-- 自动生成的配置 -->
                <configurationFile>src/main/resources/MBG.xml</configurationFile>
            </configuration>

            <dependencies>
                <dependency>
                    <groupId>mysql</groupId>
                    <artifactId>mysql-connector-java</artifactId>
                    <version>8.0.12</version>
                </dependency>
            </dependencies>
        </plugin>
    </plugins>
</build>

generator配置文件

MBG.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.properties"></properties>

  <context id="MYSQLTables" targetRuntime="MyBatis3">
    <jdbcConnection driverClass="${spring.datasource.driver-class-name}"
        connectionURL="${spring.datasource.url}"
        userId="${spring.datasource.username}"
        password="${spring.datasource.password}">
        <property name="nullCatalogMeansCurrent" value="true" />
    </jdbcConnection>

    <javaTypeResolver >
      <property name="forceBigDecimals" value="false" />
    </javaTypeResolver>

    <javaModelGenerator targetPackage="com.springlearn.learn.model" targetProject="src/main/java">
      <property name="enableSubPackages" value="true" />
      <property name="trimStrings" value="true" />
    </javaModelGenerator>

    <sqlMapGenerator targetPackage="com.springlearn.learn.mapper"  targetProject="src/main/resources">
      <property name="enableSubPackages" value="true" />
    </sqlMapGenerator>

    <javaClientGenerator type="XMLMAPPER" targetPackage="com.springlearn.learn.DAO"  targetProject="src/main/java">
      <property name="enableSubPackages" value="true" />
    </javaClientGenerator>

    <table tableName="test" domainObjectName="User" ></table>

  </context>
</generatorConfiguration>

properties配置

# ===============================
# DATABASE
# ===============================

spring.datasource.url=jdbc:mysql://localhost:3306/mydb?useUnicode=true&characterEncoding=UTF-8&serverTimezone=GMT&zeroDateTimeBehavior=CONVERT_TO_NULL&allowMultiQueries=true&useSSL=false&allowPublicKeyRetrieval=true
spring.datasource.username=root
spring.datasource.password=123
spring.datasource.driver-class-name=com.mysql.cj.jdbc.Driver

server.tomcat.uri-encoding=UTF-8
server.port=20001

mybatis.mapper-locations=classpath:com/springlearn/learn/mapper/*.xml
mybatis.configuration.cache-enabled=true

生成文件

运行mvn mybatis-generator:generate

即可生成 model文件，mapper xml文件，dao接口文件

dao接口没有添加@Mapper注释，需要手动添加

使用Example

在生成的model文件中有一个Example文件，这个文件是方便生成where字句的

基本使用demo如下

@RestController
public class TestController {
    @Autowired
    SqlSession sqlSession;

    @ResponseBody
    @RequestMapping(value = "/test", method = RequestMethod.GET)
    public List<User> Test3(HttpServletRequest request, @RequestParam("id") Integer id){
        
        UserMapper mapper = sqlSession.getMapper(UserMapper.class);
        // User result = mapper.selectByPrimaryKey(id); 使用生成的方法访问数据库

        UserExample example = new UserExample();  
        example.setDistinct(true);
        example.or().andAgeBetween(20, 30);   // 使用Example自动生成where字句
        List<User> result = mapper.selectByExample(example);

        return result;
    }

}