在上篇文章中

https://blog.csdn.net/yanyf2016/article/details/102972195

生成的实体类没有数据库自己定义的注释，

根据网上找到的资料以及阅读Mybatis-generator源码，发现可以通过自定义注释生成器 CommentGenerator 接口的实现类来达到我们的目的。
通过阅读源码可以看到，代码生成注释是通过DefaultCommentGenerator类实现的，这个类继承了CommentGenerator接口，因此我们可以自己创建一个类继承CommentGenerator接口，然后重写里面相关方法就可以了（可以复制DefaultCommentGenerator中的代码过来，然后修改我们需要改动的方法）。

下面介绍实现过程。
1、自定义一个CommentGenerator接口的实现类，下面是我的自定义实现类代码

package com.generator;

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

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;

/**
 * 自定义实现 注释生成器 CommentGenerator 接口
 * 
 */
public class MyCommentGenerator implements CommentGenerator {

    private Properties properties;
    private Properties systemPro;
    private boolean suppressDate;
    private boolean suppressAllComments;
    private String nowTime;

    public MyCommentGenerator() {
        super();
        properties = new Properties();
        systemPro = System.getProperties();
        suppressDate = false;
        suppressAllComments = false;
        nowTime = (new SimpleDateFormat("yyyy-MM-dd HH:mm:ss")).format(new Date());
    }

    public void addJavaFileComment(CompilationUnit compilationUnit) {
        if (suppressAllComments) {
            return;
        }
        return;
    }

    /**
     * Adds a suitable comment to warn users that the element was generated, and
     * when it was generated.
     */
    public void addComment(XmlElement xmlElement) {
        return;
    }

    public void addRootComment(XmlElement rootElement) {
        // add no document level comments by default
        return;
    }

    public void addGeneralMethodAnnotation(Method method, IntrospectedTable introspectedTable, Set<FullyQualifiedJavaType> set) {

    }

    public void addGeneralMethodAnnotation(Method method, IntrospectedTable introspectedTable, IntrospectedColumn introspectedColumn, Set<FullyQualifiedJavaType> set) {

    }

    public void addFieldAnnotation(Field field, IntrospectedTable introspectedTable, Set<FullyQualifiedJavaType> set) {

    }

    public void addFieldAnnotation(Field field, IntrospectedTable introspectedTable, IntrospectedColumn introspectedColumn, Set<FullyQualifiedJavaType> set) {

    }

    public void addClassAnnotation(InnerClass innerClass, IntrospectedTable introspectedTable, Set<FullyQualifiedJavaType> set) {

    }

    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));
    }
    
    /**
     * 判断传入参数是否为true
     * @param property
     * @return
     */
    private boolean isTrue(String property) {
        if("true".equals(property)){
            return true;
        }
        return false;
    }

    /**
     * This method adds the custom javadoc tag for. You may do nothing if you do
     * not wish to include the Javadoc tag - however, if you do not include the
     * Javadoc tag then the Java merge capability of the eclipse plugin will
     * break.
     * 
     * @param javaElement
     *            the java element
     */
    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());
    }

    /**
     * This method returns a formated date string to include in the Javadoc tag
     * and XML comments. You may return null if you do not want the date in
     * these documentation elements.
     * 
     * @return a string representing the current timestamp, or null
     */
    protected String getDateString() {
        String result = null;
        if (!suppressDate) {
            result = nowTime;
        }
        return result;
    }

    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().replace("\n", " "));
        innerClass.addJavaDocLine(" */");
    }

    public void addEnumComment(InnerEnum innerEnum, IntrospectedTable introspectedTable) {
        if (suppressAllComments) {
            return;
        }
        StringBuilder sb = new StringBuilder();
        innerEnum.addJavaDocLine("/**");
        sb.append(" * ");
        sb.append(introspectedTable.getFullyQualifiedTable());
        innerEnum.addJavaDocLine(sb.toString().replace("\n", " "));
        innerEnum.addJavaDocLine(" */");
    }
    
    /**
     * 设置字段注释
     */
    public void addFieldComment(Field field, IntrospectedTable introspectedTable, IntrospectedColumn introspectedColumn) {
        if (suppressAllComments) {
            return;
        }
        StringBuilder sb = new StringBuilder();
        field.addJavaDocLine("/**");
        sb.append(" * ");
        sb.append(introspectedColumn.getRemarks() + " " + introspectedColumn.getActualColumnName());
        field.addJavaDocLine(sb.toString().replace("\n", " "));
        field.addJavaDocLine(" */");
    }

    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().replace("\n", " "));
        field.addJavaDocLine(" */");
    }

    public void addModelClassComment(TopLevelClass topLevelClass, IntrospectedTable introspectedTable) {

    }

    public void addGeneralMethodComment(Method method, IntrospectedTable introspectedTable) {
        if (suppressAllComments) {
            return;
        }
      method.addJavaDocLine("/**");
      addJavadocTag(method, false);
      method.addJavaDocLine(" */");
    }
    
    /**
     * 设置getter方法注释
     */
    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().replace("\n", " "));
        sb.setLength(0);
        
        //加入系统用户
        sb.append(" * @author ");
        sb.append(systemPro.getProperty("user.name"));
        method.addJavaDocLine(sb.toString().replace("\n", " "));
        sb.setLength(0);
        
        //是否加入时间戳
        if(suppressDate){
            sb.append(" * @date " + nowTime);
            method.addJavaDocLine(sb.toString().replace("\n", " "));
            sb.setLength(0);
        }
        
        sb.append(" * @return ");
        sb.append(introspectedColumn.getActualColumnName());
        sb.append(" ");
        sb.append(introspectedColumn.getRemarks());
        method.addJavaDocLine(sb.toString().replace("\n", " "));
        method.addJavaDocLine(" */");
    }
    
    /**
     * 设置setter方法注释
     */
    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().replace("\n", " "));
        sb.setLength(0);
        
        //加入系统用户
        sb.append(" * @author ");
        sb.append(systemPro.getProperty("user.name"));
        method.addJavaDocLine(sb.toString().replace("\n", " "));
        sb.setLength(0);
        
        //是否加入时间戳
        if(suppressDate){
            sb.append(" * @date " + nowTime);
            method.addJavaDocLine(sb.toString().replace("\n", " "));
            sb.setLength(0);
        }
        
        Parameter parm = method.getParameters().get(0);
        sb.append(" * @param ");
        sb.append(parm.getName());
        sb.append(" ");
        sb.append(introspectedColumn.getRemarks());
        method.addJavaDocLine(sb.toString().replace("\n", " "));
        method.addJavaDocLine(" */");
    }

    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().replace("\n", " "));
        sb.setLength(0);
        sb.append(" * @author ");
        sb.append(systemPro.getProperty("user.name"));
        sb.append(" ");
        sb.append(nowTime);
        innerClass.addJavaDocLine(" */");
    }
    
}

3.修改generatorConfig.xml，给commentGenerator元素设置type属性值为我们自定义类的全类名就可以了

<commentGenerator type="com.generator.MyCommentGenerator">
   <!-- 是否去除自动生成的注释 true：是 ： false:否 -->
   <property name="suppressAllComments" value="false" />
</commentGenerator>

最后，一般来说我们只需要实现实体类注释的方法就可以，如果觉得要实现CommentGenerator中所有的接口太麻烦的话，也可以让自定义实现类继承DefaultCommentGenerator类，然后重写与实体类属性、getter、setter注释相关的方法就可以了。