Source :https://www.cnblogs.com/homejim/p/9782403.html
In the use of mybatis In the process , When handwriting JavaBean and XML When I write more and more , More and more agree to make mistakes . This repetitive work , We certainly don't want to do so much .

not so bad , mybatis Provides us with powerful code generation --MybatisGenerator.

Through simple configuration , We can generate various types of entity classes , Mapper Interface , MapperXML file , Example Object etc. . Through these generated files , We can easily add, delete, modify and query a single table .

The following tools use IDEA

1 Create a code generator

1.1 establish Maven project

1.1.1 Select new project from the menu

File | New | Project

1.1.2 Choose the one on the left Maven

Because we're just creating a normal project , Click here Next that will do .

1.1.3 Input GroupId and ArtifactId

• In my project ,

GroupId fill com.homejim.mybatis

ArtifactId fill mybatis-generator

Click on Next.

1.1.4 Finish

Go through the above steps , An ordinary Maven The project is created .

1.2 To configure generator.xml

The name doesn't matter , Just follow the one below pom.xml The correspondence in the document is good .

<?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>
    <!--  Local database driver jar Full path of package  -->
    <classPathEntry location="C:\Users\\Administrator\\.m2\repository\\mysql\\mysql-connector-java\\8.0.12\\mysql-connector-java-8.0.12.jar"/>
    <context id="context" targetRuntime="MyBatis3">
        <commentGenerator>
            <property name="suppressAllComments" value="false"/>
            <property name="suppressDate" value="true"/>
        </commentGenerator>
        <!--  Database configuration  -->
        <jdbcConnection
                driverClass="com.mysql.jdbc.Driver"
                connectionURL="jdbc:mysql://localhost:3306/mybatis"
                userId="root"
                password="jim777"/>
        <javaTypeResolver>
            <property name="forceBigDecimals" value="false"/>
        </javaTypeResolver>
        <!--  Where entity classes are generated  -->
        <javaModelGenerator
                targetPackage="com.homejim.mybatis.entity"
                targetProject=".\src\main\java">
            <property name="enableSubPackages" value="false"/>
            <property name="trimStrings" value="true"/>
        </javaModelGenerator>
        <!-- *Mapper.xml  The location of the file   sqlMapGenerator-->
        <sqlMapGenerator
                targetPackage="mybatis/mapper"
                targetProject=".\src\main\resources">
            <property name="enableSubPackages" value="false"/>
        </sqlMapGenerator>
        <!-- Mapper  Location of interface files  -->
        <javaClientGenerator type="XMLMAPPER"
                             targetPackage="com.homejim.mybatis.mapper"
                             targetProject=".\src\main\java">
            <property name="enableSubPackages" value="false"/>
        </javaClientGenerator>
        <!--  Configuration of related tables  -->
        <table tableName="blog" />
    </context>
</generatorConfiguration>

Something needs to be changed ：

1. Local database driver jar Full path of package （ It has to be changed ）.

2. Database configuration （ It has to be changed ）

3. Configuration of related tables （ It has to be changed ）

4. Location of entity class generation and storage .

5. MapperXML The location where the generated files are stored .

6. Mapper Where the interface is stored .

If you don't know how to change , Please look at the back Configuration details .

1.3 To configure pom.xml

Add something to the original .

<?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.homejim.mybatis</groupId>
    <artifactId>mybatis-generator</artifactId>
    <version>1.0-SNAPSHOT</version>
    <!-- Add... To the original   That's it -->
    <build>
        <finalName>mybatis-generator</finalName>
        <plugins>
            <plugin>
                <groupId>org.mybatis.generator</groupId>
                <artifactId>mybatis-generator-maven-plugin</artifactId>
                <version>1.3.7</version>
                <configuration>
                   <!-- Notice here ,  The file matches the file above -->
                   <configurationFile>src/main/resources/generator.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>1.3.7</version>
                    </dependency>
                </dependencies>
            </plugin>
        </plugins>
    </build>
    <!-- To this end -->
</project>

It should be noted that configurationFile The document in refers to generator.xml. So the path is the relative path of the file , The name is the same as the file .

Here we are , mybatis-generator You can use it .

1.4 Use and test

1.4.1 open Maven Projects View

stay IDEA On , open ：

View | Tools | Windwos | Maven Projects

Maven Project window

1.4.2 Maven Projects Middle double click mybatis-generator

On the right, you can see Maven Projects 了 . find mybatis-generator plug-in unit .

mybatis-generator | Plugins | mybatis-generator | mybatis-generator

Running plug-ins

1.4.3 Double-click on the run

After correct operation , The generated code , The following structure is obtained

2 XML Configuration details

It's not cool just to use it as simple as above . Then we can change generator.xml Configuration file to generate the configuration .

2.1 first

Official documents for reference .

Good English ： Official website .

Chinese translation ： Translated website

2.2 It's not on the official website

2.2.1 property label

The tag is only used to specify the attributes of elements in the official website , As for how to use it, there is no detailed explanation .

2.2.1.1 Separator related

<property name="autoDelimitKeywords" value="true"/>
<property name="beginningDelimiter" value="`"/>
<property name="endingDelimiter" value="`"/>

The above configuration corresponds to mysql, When the fields in the database are the same as the keywords in the database , You'll use the separator .

For example, our data column is delete, According to the above configuration , Where it appears , It becomes delete.

2.2.1.2 code

The default is to use the encoding of the current system environment , Can be configured as GBK or UTF-8.

<property name="javaFileEncoding" value="UTF-8"/>

I think the project is UTF-8, If you specify a build GBK, Then automatically generated Chinese is garbled code .

2.2.1.3 format

<!-- Format generated  Java  Code -->
<property name="javaFormatter" value="org.mybatis.generator.api.dom.DefaultJavaFormatter"/>
<!-- Format generated  XML-->
<property name="xmlFormatter" value="org.mybatis.generator.api.dom.DefaultXmlFormatter"/>

These are obviously customizable .

2.2.2 plugins label

plugins Tags are used to extend or modify code generated by code generators .

In the generated XML in , It's not **** This label's . This tag is configured for caching .

If we want to generate this tag , Then you can. plugins To configure .

<plugin type="org.mybatis.generator.plugins.CachePlugin" >
            <property name="cache_eviction" value="LRU"/>
</plugin>

cache

Like what you want to generate JavaBean It can be realized by itself Serializable Interface .

<plugin type="org.mybatis.generator.plugins.SerializablePlugin" />

Serialization interface implementation

You can also customize plug-ins .

These plug-ins are very useful , I feel that I can open an article to explain .

2.2.3 commentGenerator label

Look at the name , It's used to generate comments .

The default configuration ：

    <commentGenerator >
        <property name="suppressAllComments" value="false"/>
        <property name="suppressDate" value="false"/>
        <property name="addRemarkComments" value="false"/>
    </commentGenerator>

suppressAllComments： Prevent comments from being generated , The default value is false.

suppressDate: Prevent generated comments from including timestamps , The default is false.

addRemarkComments: Add database comments to comments , The default is false.

And then there's us Can pass type Attribute specifies our custom annotation implementation class , Generate annotations we want . Custom implementation classes need to implement org.mybatis.generator.api.CommentGenerator.

 Recommended reading 
 Code comparison tool , I'll use this 6 individual 
 Share my favorite 5 A free online  SQL Database environment , It's so convenient ！
Spring Boot A combination of three moves , Hand in hand to teach you to play elegant back-end interface 
MySQL 5.7 vs 8.0, You choose the one ？ Net friend ： I'm going to stay where I am ~

Last , I recommend you an interesting and interesting official account ： The guy who wrote the code ,7 Old programmers teach you to write bug, reply interview | resources Send you a complete set of Development Notes There's a surprise