MyBatis Generator 代码生成工具

 本文完整代码已上传Github仓库：https://github.com/ouyangyewei/mybatis-codegen

1、MBG 的简介

 MyBatis Generator官网：MyBatis Generator Core – Introduction to MyBatis Generator

借助MyBatis Generator（MBG）工具，可以基于数据库表结构自动生成Bean/Mapper/Mapper XML代码，简化了大量重复繁琐的开发步骤，相关信息如下：

2、MGB 自定义插件

MGB支持自定义插件，比如：自动生成代码时带上表/表字段注释、分页、Lombok

2.1、注释插件

package com.github.codegen;

import org.apache.logging.log4j.util.Strings;
import org.mybatis.generator.api.IntrospectedColumn;
import org.mybatis.generator.api.IntrospectedTable;
import org.mybatis.generator.api.dom.java.Field;
import org.mybatis.generator.api.dom.java.TopLevelClass;
import org.mybatis.generator.internal.DefaultCommentGenerator;
import org.mybatis.generator.internal.util.StringUtility;

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

/**
 * 注释生成器
 * 

 *     根据元数据表的字段注释给JavaBean字段添加注释
 * 
 * @author ouyangyewei
 * @date 2021-09-01
 **/
public class CommentGenerator extends DefaultCommentGenerator {
    private boolean addRemarkComments = false;

    /**
     * 设置用户配置的参数
     * @param properties
     */
    @Override
    public void addConfigurationProperties(Properties properties) {
        super.addConfigurationProperties(properties);
        this.addRemarkComments = StringUtility.isTrue(properties.getProperty("addRemarkComments"));
    }

    /**
     * 根据表注释设置类文件注释
     * @param topLevelClass
     * @param introspectedTable
     */
    private static final SimpleDateFormat DATE_FORMAT = new SimpleDateFormat("yyyy-MM-dd");
    public void addModelClassComment(TopLevelClass topLevelClass, IntrospectedTable introspectedTable) {
        if (this.addRemarkComments) {
            topLevelClass.addJavaDocLine("/**");
            topLevelClass.addJavaDocLine(" * " + introspectedTable.getRemarks());
            topLevelClass.addJavaDocLine(" * @author MyBatis Generator");
            topLevelClass.addJavaDocLine(" * @date " + DATE_FORMAT.format(new Date()));
            topLevelClass.addJavaDocLine(" */");
        }
    }

    /**
     * 给字段添加注释
     * @param field
     * @param introspectedTable
     * @param introspectedColumn
     */
    @Override
    public void addFieldComment(Field field, IntrospectedTable introspectedTable, IntrospectedColumn introspectedColumn) {
        String remarks = introspectedColumn.getRemarks();
        // 根据参数和备注信息判断是否添加备注信息
        if (this.addRemarkComments && StringUtility.stringHasValue(remarks)) {
            // 数据库中特殊字符需要转义
            if (remarks.contains("\"")) {
                remarks = remarks.replace("\"","'");
            }
            // model的字段添加注解
            field.addJavaDocLine("/**" + Strings.LINE_SEPARATOR + "     * " + remarks + Strings.LINE_SEPARATOR + "     */");
        }
    }
}

2.2、分页插件

package com.github.codegen;

import org.mybatis.generator.api.IntrospectedTable;
import org.mybatis.generator.api.PluginAdapter;
import org.mybatis.generator.api.dom.java.*;
import org.mybatis.generator.api.dom.xml.Attribute;
import org.mybatis.generator.api.dom.xml.TextElement;
import org.mybatis.generator.api.dom.xml.XmlElement;

import java.util.List;

/**
 * Mybatis Page Limit Plugin
 * 

 *     用于为每个Example类添加offset和limit属性方法
 * 
 * @author ouyangyewei
 * @date 2021-08-31
 **/
public class LimitPlugin extends PluginAdapter {

    @Override
    public boolean validate(List list) {
        return true;
    }

    /**
     * 为每个Example类添加offset和rows属性已经set、get方法
     * @param topLevelClass
     * @param introspectedTable
     * @return
     */
    @Override
    public boolean modelExampleClassGenerated(TopLevelClass topLevelClass, IntrospectedTable introspectedTable) {
        PrimitiveTypeWrapper integerWrapper = FullyQualifiedJavaType.getIntInstance().getPrimitiveTypeWrapper();

        Field limit = new Field("limit", integerWrapper);
        limit.setVisibility(JavaVisibility.PRIVATE);
        topLevelClass.addField(limit);

        Method setLimit = new Method("setLimit");
        setLimit.setVisibility(JavaVisibility.PUBLIC);
        setLimit.addParameter(new Parameter(integerWrapper, "limit"));
        setLimit.addBodyLine("this.limit = limit;");
        topLevelClass.addMethod(setLimit);

        Method getLimit = new Method("getLimit");
        getLimit.setVisibility(JavaVisibility.PUBLIC);
        getLimit.setReturnType(integerWrapper);
        getLimit.addBodyLine("return limit;");
        topLevelClass.addMethod(getLimit);

        Field offset = new Field("offset", integerWrapper);
        offset.setVisibility(JavaVisibility.PRIVATE);
        topLevelClass.addField(offset);

        Method setOffset = new Method("setOffset");
        setOffset.setVisibility(JavaVisibility.PUBLIC);
        setOffset.addParameter(new Parameter(integerWrapper, "offset"));
        setOffset.addBodyLine("this.offset = offset;");
        topLevelClass.addMethod(setOffset);

        Method getOffset = new Method("getOffset");
        getOffset