mybatis的逆向工程和中文注解

取不到中文注释字段的时候，可以试试下面的方法

下面的配置均指的是Mybatis Generator 的配置文件(一般是叫generatorConfig.xml)的配置:

mysql

方法1:

<jdbcConnection driverClass="${driver}"
    connectionURL="{url}" userId="${username}" password="${password}">
    <!-- 针对mysql数据库 -->
    <property name="useInformationSchema" value="true"></property>
</jdbcConnection>

方法2

connectionURL="jdbc:mysql://127.0.0.1:3306/test?characterEncoding=UTF-8&useInformationSchema=true"

Oracle

<jdbcConnection driverClass="${driver}"
    connectionURL="{url}" userId="${username}" password="${password}">
    <!-- 针对oracle数据库 -->
    <property name="remarksReporting" value="true"></property>
</jdbcConnection>

详解

MBG访问数据库也是通过JDBC进行,而通过JDBC连接Oracle、Mysql(其它数据库暂不清楚)时,想获取到表及字段注释是需要额外设置一些连接属性的.一般大体上都是如下的代码(以Oracle为例):

我们先来看下MBG连接数据库的代码,可以在org.mybatis.generator.internal.JDBCConnectionFactory中找到:

    public JDBCConnectionFactory(JDBCConnectionConfiguration config) {
        super();
        userId = config.getUserId();
        password = config.getPassword();
        connectionURL = config.getConnectionURL();
        driverClass = config.getDriverClass();
        otherProperties = config.getProperties(); //注意此行
    }
    
    public Connection getConnection()
            throws SQLException {
        Driver driver = getDriver();

        Properties props = new Properties();

        if (stringHasValue(userId)) {
            props.setProperty("user", userId); //$NON-NLS-1$
        }

        if (stringHasValue(password)) {
            props.setProperty("password", password); //$NON-NLS-1$
        }

        props.putAll(otherProperties); //注意此行

        Connection conn = driver.connect(connectionURL, props);

        if (conn == null) {
            throw new SQLException(getString("RuntimeError.7")); //$NON-NLS-1$
        }

        return conn;
    }

通过上面代码(尤其是我加了注意此行注释的两行代码)我们可以看到,MBG在建立连接时,是把JDBCConnectionConfiguration中的所有properties给设置进去了.那么显然我们只需要找到在哪配置这些properties就行了.
JDBCConnectionConfiguration对应到XML配置里就是jdbcConnection节点.
再来看看官方的使用文档,官方文档关于jdbcConnection (点击查看) 一节中 <property>子元素的说明:

• <property> (0..N) Note: any properties specified here will be added to the properties of the JDBC driver.

那么在配置文件中我们如下改动即可:

<jdbcConnection driverClass="${driver}"
    connectionURL="{url}" userId="${username}" password="${password}">
    <!-- 针对oracle数据库 -->
    <property name="remarksReporting" value="true"></property>
</jdbcConnection>

由于MyBatis Generator自带了生成注释的功能,但是,是英文的而且生成的根本无法理解,所以可以通过,修改他的源码来实现生成中文的注释,具体方式有以下几种:

1) 自定义CommentGenerator
2) 修改源码
3) PluginAdapter插件的形式

这个例子通过自定义CommentGenerator来实现。

1.创建maven工程，修改pom.xml：

<?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.test</groupId>
    <artifactId>testgenerator</artifactId>
    <version>1.0-SNAPSHOT</version>

    <properties>
        <!--  依赖版本  -->
        <mapper.version>3.3.9</mapper.version>
        <mysql.version>5.1.10</mysql.version>
    </properties>

    <dependencies>
        <dependency>
            <groupId>junit</groupId>
            <artifactId>junit</artifactId>
            <version>3.8.1</version>
            <scope>test</scope>
        </dependency>
        <dependency>
            <groupId>tk.mybatis</groupId>
            <artifactId>mapper</artifactId>
            <version>${mapper.version}</version>
        </dependency>
        <dependency>
            <groupId>org.mybatis.generator</groupId>
            <artifactId>mybatis-generator-core</artifactId>
            <version>1.3.5</version>
        </dependency>
        <dependency>
            <groupId>org.mybatis.spring.boot</groupId>
            <artifactId>mybatis-spring-boot-starter</artifactId>
            <version>1.1.1</version>
        </dependency>
    </dependencies>

    <build>
        <plugins>
            <plugin>
                <groupId>org.mybatis.generator</groupId>
                <artifactId>mybatis-generator-maven-plugin</artifactId>
                <version>1.3.5</version>
                <configuration>
                    <configurationFile>${basedir}/src/main/resources/generatorConfig.xml</configurationFile>
                    <overwrite>true</overwrite>
                    <verbose>true</verbose>
                </configuration>
                <dependencies>
                    <dependency>
                        <groupId>mysql</groupId>
                        <artifactId>mysql-connector-java</artifactId>
                        <version>${mysql.version}</version>
                    </dependency>
                    <dependency>
                        <groupId>tk.mybatis</groupId>
                        <artifactId>mapper</artifactId>
                        <version>${mapper.version}</version>
                    </dependency>
                    <dependency>
                        <groupId>com.test</groupId>
                        <artifactId>testgenerator</artifactId>
                        <version>1.0-SNAPSHOT</version>
                    </dependency>
                </dependencies>
            </plugin>
        </plugins>
    </build>
</project>

在java目录里面增加MybatisCommentGenerator.java

import org.mybatis.generator.api.CommentGenerator;
import org.mybatis.generator.api.IntrospectedColumn;
import org.mybatis.generator.api.IntrospectedTable;
import org.mybatis.generator.api.dom.java.*;
import org.mybatis.generator.api.dom.xml.XmlElement;
import org.mybatis.generator.config.MergeConstants;
import org.mybatis.generator.config.PropertyRegistry;

import java.text.SimpleDateFormat;
import java.util.Date;
import java.util.Properties;

import static org.mybatis.generator.internal.util.StringUtility.isTrue;

/**
 * TODO
 *
 * @Author mx
 * @Date: 2019-04-09 11:32
 */
public class MybatisCommentGenerator implements CommentGenerator {
    private Properties properties;
    private Properties systemPro;
    private boolean suppressDate;
    private boolean suppressAllComments;
    private String currentDateStr;

    public MybatisCommentGenerator() {
        super();
        properties = new Properties();
        systemPro = System.getProperties();
        suppressDate = false;
        suppressAllComments = false;
        currentDateStr = (new SimpleDateFormat("yyyy-MM-dd")).format(new Date());
    }

    /**
     * Adds properties for this instance from any properties configured in the
     * CommentGenerator configuration.
     * <p>     * This method will be called before any of the other methods.
     *
     * @param properties All properties from the configuration
     */
    public void addConfigurationProperties(Properties properties) {
        this.properties.putAll(properties);

        suppressDate = isTrue(properties.getProperty(PropertyRegistry.COMMENT_GENERATOR_SUPPRESS_DATE));

        suppressAllComments = isTrue(properties.getProperty(PropertyRegistry.COMMENT_GENERATOR_SUPPRESS_ALL_COMMENTS));
    }

    /**
     * @param field              the field
     * @param introspectedTable  the introspected table
     * @param introspectedColumn
     */
    public void addFieldComment(Field field, IntrospectedTable introspectedTable, IntrospectedColumn introspectedColumn) {
        if (suppressAllComments) {
            return;
        }

        StringBuilder sb = new StringBuilder();
        field.addJavaDocLine("/**");
        sb.append(" * ");
        sb.append(introspectedColumn.getRemarks());
        field.addJavaDocLine(sb.toString());
        addJavadocTag(field, false);
        field.addJavaDocLine(" */");
    }

    /**
     * Adds the field comment.
     *
     * @param field             the field
     * @param introspectedTable
     */
    public void addFieldComment(Field field, IntrospectedTable introspectedTable) {
        if (suppressAllComments) {
            return;
        }

        StringBuilder sb = new StringBuilder();
        field.addJavaDocLine("/**");
        sb.append(" * ");
        sb.append(introspectedTable.getFullyQualifiedTable());
        field.addJavaDocLine(sb.toString());
        field.addJavaDocLine(" */");
    }

    public void addModelClassComment(TopLevelClass topLevelClass, IntrospectedTable introspectedTable) {
        if (suppressAllComments) {
            return;
        }
        StringBuilder sb = new StringBuilder();
        topLevelClass.addJavaDocLine("/**");
        sb.append(" * ");
        sb.append(introspectedTable.getRemarks());
        sb.append(" ");
        sb.append(introspectedTable.getTableType());
        sb.append(" ");
        sb.append(getDateString());
        topLevelClass.addJavaDocLine(sb.toString());
        topLevelClass.addJavaDocLine(" */");
    }

    /**
     * Adds the inner class comment.
     *
     * @param innerClass        the inner class
     * @param introspectedTable
     */
    public void addClassComment(InnerClass innerClass, IntrospectedTable introspectedTable) {
        if (suppressAllComments) {
            return;
        }
        StringBuilder sb = new StringBuilder();
        innerClass.addJavaDocLine("/**");
        sb.append(" * ");
        sb.append(introspectedTable.getFullyQualifiedTable());
        sb.append(" ");
        sb.append(getDateString());
        innerClass.addJavaDocLine(sb.toString());
        innerClass.addJavaDocLine(" */");
    }

    /**
     * Adds the inner class comment.
     *
     * @param innerClass        the inner class
     * @param introspectedTable the introspected table
     * @param markAsDoNotDelete
     */
    public void addClassComment(InnerClass innerClass, IntrospectedTable introspectedTable, boolean markAsDoNotDelete) {
        if (suppressAllComments) {
            return;
        }

        StringBuilder sb = new StringBuilder();

        innerClass.addJavaDocLine("/**");
        sb.append(" * ");
        sb.append(introspectedTable.getFullyQualifiedTable());
        innerClass.addJavaDocLine(sb.toString());

        sb.setLength(0);
        sb.append(" * @author ");
        sb.append(systemPro.getProperty("user.name"));
        sb.append(" ");
        sb.append(currentDateStr);

        addJavadocTag(innerClass, markAsDoNotDelete);

        innerClass.addJavaDocLine(" */");
    }

    /**
     * Adds the enum comment.
     *
     * @param innerEnum         the inner enum
     * @param introspectedTable
     */
    public void addEnumComment(InnerEnum innerEnum, IntrospectedTable introspectedTable) {
        if (suppressAllComments) {
            return;
        }

        StringBuilder sb = new StringBuilder();

        innerEnum.addJavaDocLine("/**");
        addJavadocTag(innerEnum, false);
        sb.append(" * ");
        sb.append(introspectedTable.getFullyQualifiedTable());
        innerEnum.addJavaDocLine(sb.toString());
        innerEnum.addJavaDocLine(" */");
    }

    /**
     * Adds the getter comment.
     *
     * @param method             the method
     * @param introspectedTable  the introspected table
     * @param introspectedColumn
     */
    public void addGetterComment(Method method, IntrospectedTable introspectedTable, IntrospectedColumn introspectedColumn) {
        if (suppressAllComments) {
            return;
        }

        method.addJavaDocLine("/**");

        StringBuilder sb = new StringBuilder();
        sb.append(" * ");
        sb.append(introspectedColumn.getRemarks());
        method.addJavaDocLine(sb.toString());

        sb.setLength(0);
        sb.append(" * @return ");
        sb.append(introspectedColumn.getActualColumnName());
        sb.append(" ");
        sb.append(introspectedColumn.getRemarks());
        method.addJavaDocLine(sb.toString());

        addJavadocTag(method, false);

        method.addJavaDocLine(" */");
    }

    /**
     * Adds the setter comment.
     *
     * @param method             the method
     * @param introspectedTable  the introspected table
     * @param introspectedColumn
     */
    public void addSetterComment(Method method, IntrospectedTable introspectedTable, IntrospectedColumn introspectedColumn) {
        if (suppressAllComments) {
            return;
        }

        method.addJavaDocLine("/**");
        StringBuilder sb = new StringBuilder();
        sb.append(" * ");
        sb.append(introspectedColumn.getRemarks());
        method.addJavaDocLine(sb.toString());

        Parameter parm = method.getParameters().get(0);
        sb.setLength(0);
        sb.append(" * @param ");
        sb.append(parm.getName());
        sb.append(" ");
        sb.append(introspectedColumn.getRemarks());
        method.addJavaDocLine(sb.toString());

        addJavadocTag(method, false);

        method.addJavaDocLine(" */");
    }

    /**
     * Adds the general method comment.
     *
     * @param method            the method
     * @param introspectedTable
     */
    public void addGeneralMethodComment(Method method, IntrospectedTable introspectedTable) {
        if (suppressAllComments) {
            return;
        }
        method.addJavaDocLine("/**");
//        addJavadocTag(method, false);
        StringBuilder sb = new StringBuilder();
        sb.append(" * ");
        sb.append(MergeConstants.NEW_ELEMENT_TAG);
        String s = method.getName();
        sb.append(' ');
        sb.append(s);
        method.addJavaDocLine(sb.toString());
        method.addJavaDocLine(" */");
    }

    public void addJavaFileComment(CompilationUnit compilationUnit) {

    }

    public void addComment(XmlElement xmlElement) {

    }

    public void addRootComment(XmlElement rootElement) {
    }

    protected void addJavadocTag(JavaElement javaElement, boolean markAsDoNotDelete) {
        javaElement.addJavaDocLine(" *");
        StringBuilder sb = new StringBuilder();
        sb.append(" * ");
        sb.append(MergeConstants.NEW_ELEMENT_TAG);
        if (markAsDoNotDelete) {
            sb.append(" do_not_delete_during_merge");
        }
        String s = getDateString();
        if (s != null) {
            sb.append(' ');
            sb.append(s);
        }
        javaElement.addJavaDocLine(sb.toString());
    }

    protected String getDateString() {
        String result = null;
        if (!suppressDate) {
            result = currentDateStr;
        }
        return result;
    }
}

在resources目录下面增加文件config.properties，generatorConfig.xml。

config.properties的内容：

# 数据库配置
jdbc.driverClass=com.mysql.jdbc.Driver
jdbc.url=jdbc:mysql://localhost:3306/wmbook
jdbc.user=root
jdbc.password=123456

# 通用Mapper固定配置
mapper.plugin=tk.mybatis.mapper.generator.MapperPlugin
mapper.Mapper=tk.mybatis.mapper.common.Mapper
mapper.forceAnnotation=true

# 生成文件保存位置
targetModelPackage=com.test.testgenerator.domain
targetXMLPackage=com.test.testgenerator.mapper.xml
targetMapperPackage=com.test.testgenerator.mapper
targetJavaProject=src/main/java
targetResourcesProject=src/main/java

generatorConfig.xml内容：

<?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="config.properties"/>

    <context id="Mysql" targetRuntime="MyBatis3" defaultModelType="flat">
        <property name="beginningDelimiter" value="`"/>
        <property name="endingDelimiter" value="`"/>

        <!--支持序列化-->
        <plugin type="org.mybatis.generator.plugins.SerializablePlugin"></plugin>

<!--        <commentGenerator>-->
<!--            &lt;!&ndash; 是否去除自动生成的注释 true：是 ： false:否 &ndash;&gt;-->
<!--            <property name="suppressAllComments" value="false"/>-->
<!--        </commentGenerator>-->

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

        <jdbcConnection driverClass="${jdbc.driverClass}"
                        connectionURL="${jdbc.url}"
                        userId="${jdbc.user}"
                        password="${jdbc.password}">
        </jdbcConnection>

        <javaModelGenerator targetPackage="${targetModelPackage}" targetProject="${targetJavaProject}">
            <!-- enableSubPackages:是否让schema作为包的后缀 -->
            <property name="enableSubPackages" value="false"/>
            <!-- 从数据库返回的值被清理前后的空格 -->
            <property name="trimStrings" value="true"/>
        </javaModelGenerator>

        <sqlMapGenerator targetPackage="${targetXMLPackage}" targetProject="${targetResourcesProject}">
            <!-- enableSubPackages:是否让schema作为包的后缀 -->
            <property name="enableSubPackages" value="false"/>
        </sqlMapGenerator>

        <javaClientGenerator targetPackage="${targetMapperPackage}" targetProject="${targetJavaProject}"
                             type="XMLMAPPER">
            <!-- enableSubPackages:是否让schema作为包的后缀 -->
            <property name="enableSubPackages" value="false"/>
        </javaClientGenerator>

        <!--全部表参与逆向工程-->
        <!--以下example为false，表示不会生成example类，否则将自动生成example类-->
        <table schema="" tableName="%">
        </table>

        <!--指定某些表参与逆向工程-->
        <!--<table tableName="user"-->
        <!--enableCountByExample="false"-->
        <!--enableUpdateByExample="false"-->
        <!--enableDeleteByExample="false"-->
        <!--enableSelectByExample="false"-->
        <!--selectByExampleQueryId="false">-->
        <!--</table>-->
    </context>
</generatorConfiguration>

创建完相关文件后的目录为：

生成方式一 

新建生成文件的类StartUp.java

public class StartUp {
    public static void main(String[] args) {
        try {
            List<String> warnings = new ArrayList<String>();
            boolean overwrite = true;
            ClassLoader classloader = Thread.currentThread().getContextClassLoader();
            InputStream is = classloader.getResourceAsStream("generatorConfig.xml");
            ConfigurationParser cp = new ConfigurationParser(warnings);
            Configuration config = cp.parseConfiguration(is);
            DefaultShellCallback callback = new DefaultShellCallback(overwrite);
            MyBatisGenerator myBatisGenerator = new MyBatisGenerator(config, callback, warnings);
            myBatisGenerator.generate(null);
        } catch (SQLException e) {
            e.printStackTrace();
        } catch (IOException e) {
            e.printStackTrace();
        } catch (InterruptedException e) {
            e.printStackTrace();
        } catch (InvalidConfigurationException e) {
            e.printStackTrace();
        } catch (XMLParserException e) {
            e.printStackTrace();
        }
    }
}

执行main方法就可以生成文件了。

如果需要让生成的实体和mapper继承其它对象和接口可以设置

        <javaModelGenerator targetPackage="${targetModelPackage}" targetProject="${targetJavaProject}">
            <!-- enableSubPackages:是否让schema作为包的后缀 -->
            <property name="enableSubPackages" value="false"/>
            <!-- 从数据库返回的值被清理前后的空格 -->
            <property name="trimStrings" value="true"/>
            <property name="rootClass" value="com.XXX.BaseEntity"/>
        </javaModelGenerator>

        <javaClientGenerator targetPackage="${targetMapperPackage}" targetProject="${targetJavaProject}"
                             type="XMLMAPPER">
            <!-- enableSubPackages:是否让schema作为包的后缀 -->
            <property name="enableSubPackages" value="true"/>
            <property name="rootInterface" value="com.XXX.BaseMapper"/>
        </javaClientGenerator>

如果还想自定义生成实体和mapper里面的内容，可以参考 让MyBatis Generator产生的Mapper更简洁

生成方式二

先安装maven项目，然后在配置文成通过执行maven插件执行程序生成文件

执行后生成的目录路径为：

在生成的实体文件中就有中文注释了：

生成方式三

使用IDEA的插件MyBatisCodeHelper等，也可以生成