What saved me 60% of my coding time? Use MBG

MyBatis Generator brief introduction

Business requirements are constantly changing , The structure of the database table is constantly modified , It's our destiny that we can't escape . A good workman does his work well , You must sharpen your tools first , It's time to sacrifice ：MyBatis Generator（ abbreviation ：MBG）, It's one for all versions MyBatis Automatic code generator for . It can automatically produce the corresponding entity class for the project according to the database table 、Mapper、DAO, Including simple CRUD Database operation ( establish 、 Inquire about 、 to update 、 Delete ). Free our hands , There's no need to do repetitive mechanical work . Save a lot of time , Don't have to work overtime , You can go on a date with sister paper .（ If you have to have a sister first ）

Create a MySQL surface

To facilitate the demonstration, create a MySQL surface , The table structure is relatively simple , It's a user information table ：

CREATE TABLE `user_info` (
  `id` bigint() NOT NULL AUTO_INCREMENT,
  `name` varchar() DEFAULT NULL,
  `age` int() DEFAULT NULL,
  `create_time` datetime DEFAULT NULL,
  PRIMARY KEY (`id`)
) ENGINE=InnoDB DEFAULT CHARSET=utf8;

Create a SpringBoot project

To use the IntelliJ IDEA For example , Create a SpringBoot project . Click on File->New->Projects…, choice Spring Initializr, Here's the picture ：

Click on Next, Input Group、Artifact Etc , Here's the picture ：

Click on Next, choice Web, And check the Spring Web, Here's the picture ：

Click on Next, Input Project name、Project location Etc , Here's the picture ：

Last , Click on Finish, One SpringBoot The project is created .

introduce MBG Of Maven plug-in unit

stay pom.xml Of plugins Add the following to the node ：

<plugin>
    <groupId>org.mybatis.generator</groupId>
    <artifactId>mybatis-generator-maven-plugin</artifactId>
    <version>1.4.0</version>
    <configuration>
        <overwrite>true</overwrite>
    </configuration>
    <dependencies>
        <dependency>
            <groupId>mysql</groupId>
            <artifactId>mysql-connector-java</artifactId>
            <version>${mysql.version}</version>
        </dependency>
    </dependencies>
</plugin>

To configure MBG Of Maven plug-in unit

stay resources Create a generatorConfig.xml file , It reads as follows ：

<?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>
    <!--defaultModelType Used to specify the style of the generated object ,flat Indicates that each table generates only one entity class , This entity class contains all the fields in the table .-->
    <context id="MySQLTables" targetRuntime="MyBatis3" defaultModelType="flat">
        <property name="javaFileEncoding" value="UTF-8"/>

        <!--  The generated entity class implements the serialization interface  -->
        <plugin type="org.mybatis.generator.plugins.SerializablePlugin"/>

        <commentGenerator>
            <property name="dateFormat" value="yyyy-MM-dd HH:mm:ss"/>
        </commentGenerator>

        <!-- Database connection information -->
        <jdbcConnection driverClass="${spring.datasource.driverClassName}"
                        connectionURL="${spring.datasource.url}"
                        userId="${spring.datasource.username}"
                        password="${spring.datasource.password}">
        </jdbcConnection>

        <!--  Configure the location of the generated entity class  -->
        <javaModelGenerator targetPackage="one.more.mybatisgenerator.model" targetProject="src/main/java">
            <!--  Is the setting setter In the method , Yes String Type field call trim() Method  -->
            <property name="trimStrings" value="true"/>
        </javaModelGenerator>

        <!--  Configure the interface location  -->
        <!-- type Set to ANNOTATEDMAPPER, Annotation based Mapper, There will be no corresponding xml File generation -->
        <javaClientGenerator targetPackage="one.more.mybatisgenerator.mapper" targetProject="src/main/java"
                             type="ANNOTATEDMAPPER">
        </javaClientGenerator>

        <!--  Configuration database table  -->
        <table tableName="user_info">
            <!-- In the generated insert Add on element useGeneratedKeys=”true” and keyProperty attribute -->
            <generatedKey column="id" sqlStatement="JDBC"/>
        </table>
    </context>
</generatorConfiguration>

The above is the configuration of the most basic introduction , In the actual development process is enough . If you have partners, you need more configuration functions , Official website （https://mybatis.org/generator/configreference/xmlconfig.html） see .

Automatic code generation

Here are the most exciting moments , One click automatic code generation . stay Maven Plug in toolbar , You can see mybatis-generator plug-in unit , Double click on generate Options can be , Here's the picture ：

After building successfully , You can see the generated code , Here's the picture ：

Verify automatically generated code

There is one more step before verification, don't miss it , Is to add... To the startup class MapperScan annotation , such as ：

@SpringBootApplication
@MapperScan("one.more.mybatisgenerator.mapper")
public class MybatisGeneratorDemoApplication {

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

}

The new data

Randomly generate one UserInfo Example , Insert into database ：

    public UserInfo add() {
        Random random = new Random(System.currentTimeMillis());
        UserInfo userInfo = new UserInfo();
        userInfo.setName("name" + random.nextInt());
        userInfo.setAge(random.nextInt());
        userInfo.setCreateTime(new Date());

        int rows = userInfoMapper.insert(userInfo);
        System.out.println("rows:" + rows);
        return userInfo;
    }

Query data

Query the database age Greater than a certain value user_info data ：

    public List<UserInfo> getGreaterThan(Integer age) {
        UserInfoExample example = new UserInfoExample();
        Criteria criteria = example.createCriteria();
        criteria.andAgeGreaterThan(age);
        return userInfoMapper.selectByExample(example);
    }

Complete sample source code

Complete sample source code can go to https://github.com/heihaozi/mybatis-generator-demo download .