专门为小白准备的入门级mybatis-plus-generator代码自动生成器，提高开发效率。值得收藏

引入依赖

        <dependency>            <groupId>com.baomidou</groupId>            <artifactId>mybatis-plus-generator</artifactId>            <version>3.5.2</version>        </dependency>        <dependency>            <groupId>org.apache.velocity</groupId>            <artifactId>velocity-engine-core</artifactId>            <version>2.3</version>        </dependency>        <!--糊涂工具包-->        <!-- https://mvnrepository.com/artifact/cn.hutool/hutool-core -->        <dependency>            <groupId>cn.hutool</groupId>            <artifactId>hutool-core</artifactId>            <version>5.7.20</version>        </dependency>

MyBatisPlus提高高度封装好的代码生成器模块，只需要简单的几行代码就能实现。同时也可以根据自己的需求灵活的通过模板话的方式生成代码。下面我们分别通过这两种方式来了解一些。

简单的代码生成

package com.didiplus;import com.baomidou.mybatisplus.generator.FastAutoGenerator;import com.baomidou.mybatisplus.generator.config.OutputFile;import org.junit.jupiter.api.Test;import java.util.Collections;/** * Author: didiplus * Email: 972479352@qq.com * CreateTime: 2022/5/6 * Desc:快速生成 */public class FastAutoGeneratorTest {    @Test    public  void fastAutoGeneratorTest(){        String url="jdbc:mysql://127.0.0.1:3306/didiadmin?useUnicode=true&characterEncoding=utf8&zeroDateTimeBehavior=convertToNull&useSSL=true&serverTimezone=GMT%2B8&nullCatalogMeansCurrent=true";        FastAutoGenerator.create(url,"root","123456")                .globalConfig(builder -> {                    builder.author("didiplus") // 设置作者                            .enableSwagger() //开启 swagger 模式                            .outputDir("D://autocode");// 指定输出目录                })                .packageConfig(builder -> {                    builder.parent("com.didiplus.models") // 设置父包名                            .moduleName("sys") // 设置父包模块名                            .pathInfo(Collections.singletonMap(OutputFile.xml,"D://autocode/xml"));                })                .strategyConfig(builder -> {                    builder.addInclude("sys_dict_data") // 设置需要生成的表名                            .addTablePrefix("t_","c_") ; // 设置过滤表前缀                })                //  .templateEngine(new FreemarkerTemplateEngine()) 使用Freemarker引擎模板，默认的是Velocity引擎模板                .execute();    }}

运行以上代码，会自动的在D盘生成代码，但是，生成的代码只是最基本的模板。


以上生成的代码都是基于MybatisPlus代码生成默认模板去生成的。适合绝大多数场景。我们也可以根据自己的模板文件去生成代码的。

自定义模板生成代码

实现思路

• 从数据库中读取表的相关信息和表的相关字段
• 定义相对于的模板文件
• 组装模板属性

定义代码生成常量

这些常量主要用户后期在组装模板时，把数据库类型转换成Java数据类型需要用到的。

package com.didiplus.constant;/** * Author: didiplus * Email: 972479352@qq.com * CreateTime: 2022/5/6 * Desc:  码 生 成 通 用 常 量 */public class GenerateConstant {    /**     * 数据库字符串类型     */    public static final String[] COLUMN_TYPE_STR =  {"char", "varchar", "nvarchar", "varchar2", "tinytext", "text", "mediumtext", "longtext"};    /**     * 数据库时间类型     */    public static final String[] COLUMN_TYPE_TIME = {"datetime", "time", "date", "timestamp"};    /**     * 数据库数字类型     */    public static final String[] COLUMN_TYPE_NUMBER = {"tinyint", "smallint", "mediumint", "int", "number", "integer", "bit"};    /**     * 数据库bigint类型     */    public static final String[] COLUMN_TYPE_BIGINT = {"bigint"};    /**     * 数据库float类型     */    public static final String[] COLUMN_TYPE_FLOAT = {"float"};    /**     * 数据库double类型     */    public static final String[] COLUMN_TYPE_DOUBLE = {"double"};    /**     * 数据库decimal类型     */    public static final String[] COLUMN_TYPE_DECIMAL = {"decimal"};    /**     * 字符串类型     */    public static final String TYPE_STRING = "String";    /**     * 整型     */    public static final String TYPE_INTEGER = "Integer";    /**     * 长整型     */    public static final String TYPE_LONG = "Long";    /**     * 浮点型     */    public static final String TYPE_DOUBLE = "Double";    /**     * 高精度计算类型     */    public static final String TYPE_BIGDECIMAL = "BigDecimal";    /**     * 时间类型     */    public static final String TYPE_DATE = "Date";}

全局配置

    /**     * 全局配置     */    private GlobalConfig.Builder globalConfig() {        String projectPath = System.getProperty("user.dir");        return  new GlobalConfig.Builder()                .fileOverride() // 覆盖已生成文件                .disableOpenDir() // 禁止打开输出目录	默认值:true                .author("didiplus") //作者名                .outputDir(projectPath+"/src/main/resources/autocode") // 指定输出目录                .enableSwagger(); // 开启 swagger 模式	默认值:false    }

定义生成代码模板的路径

    /**     * 模板配置     */    private TemplateConfig.Builder templateConfig() {        return  new TemplateConfig.Builder()                .entity("/templates/vm/entity.java")                .mapper("/templates/vm/mapper.java")                .service("/templates/vm/service.java")                .serviceImpl("/templates/vm/serviceimpl.java")                .controller("/templates/vm/controller.java")                .xml("/templates/vm/mapper.xml");    }

以上的函数是声明代码生成根据这些模板去生成对应的模板。

定义各文件生成存储路径

    /**     * 包配置     */    private PackageConfig.Builder packageConfig() {        return  new PackageConfig.Builder()                .parent(packageName)                .moduleName(moduleName)                .entity("domain.entity")                .mapper("mapper")                .service("service")                .serviceImpl("service.impl")                .xml("mapper.xml")                .controller("controller");    }

数据源配置

    /**     * 数据源配置     */    private  static final DataSourceConfig DATA_SOURCE_CONFIG = new DataSourceConfig            .Builder("jdbc:mysql://127.0.0.1:3306/didiadmin?useUnicode=true&characterEncoding=utf8&zeroDateTimeBehavior=convertToNull&useSSL=true&serverTimezone=GMT%2B8&nullCatalogMeansCurrent=true","root","123456")            .build();

配置策略

    /**     * 策略配置     */    private StrategyConfig.Builder strategyConfig() {        return new StrategyConfig.Builder()                .addInclude(tableName);    }

组装模板属性

    /**     * 注入配置     */    private InjectionConfig.Builder injectionConfig(){        Map<String, Object> map = new HashMap<>();        setAttr(tableName, DATA_SOURCE_CONFIG, map);        return  new InjectionConfig.Builder().customMap(map);    }    /**     * 组装模板属性     *     * @param tableName        表名     * @param dataSourceConfig 数据源     * @param map              模板里面 自定义的属性     * @param  表前缀     */    private void setAttr(String tableName, DataSourceConfig dataSourceConfig, Map<String, Object> map ){        List<Map<String, Object>> columns = new ArrayList<>();        // 获取表信息sql        String tableSql = "select table_name , table_comment from information_schema.tables " +                "where table_schema = (select database()) and table_name = '" + tableName + "'";        // 获取字段信息sql        String columnSql = "select column_name , data_type , column_comment from information_schema.columns " +                "where table_name = '" + tableName + "' and table_schema = (select database()) and column_name != 'id_new'";        // 利用现有的dataSourceConfig来获取数据库连接，查询表字段及备注等信息        try(                Connection conn = dataSourceConfig.getConn();                PreparedStatement psTable = conn.prepareStatement(tableSql);                ResultSet rsTable = psTable.executeQuery();                PreparedStatement pscolumns= conn.prepareStatement(columnSql);                ResultSet rscolumns = pscolumns.executeQuery();        ){            if(rsTable.next()){                String table_name = rsTable.getString("table_name");                map.put("tableName",table_name);                map.put("comment",rsTable.getString("table_comment"));                // 类名 大驼峰                map.put("upperClassName", StrUtil.upperFirst(StrUtil.toCamelCase(table_name)));                // 对象名 小驼峰                map.put("lowerClassName",StrUtil.toCamelCase(table_name));            }            while (rscolumns.next()){                Map<String, Object> columnMap = new HashMap<>();                // 列名字、数据类型、java属性名字、java属性类型、备注                columnMap.put("column_name",rscolumns.getString("column_name"));                columnMap.put("data_type",rscolumns.getString("data_type"));                columnMap.put("javaLowerAttrName",StrUtil.toCamelCase(rscolumns.getString("column_name")));                columnMap.put("javaAttrType",columnTypeToJavaType(rscolumns.getString("data_type")));                columnMap.put("column_comment", rscolumns.getString("column_comment"));                columns.add(columnMap);            }        } catch (Exception e) {            log.info("----------sql执行出错");            e.printStackTrace();        }        map.put("columns",columns);        map.put("datetime", DateUtil.now());        map.put("packageName", packageName);        map.put("moduleName", moduleName);    }    /**     * 数据库类型转换为java类型     *     * @param columnType 数据库类型     * @return java类型     */    private String  columnTypeToJavaType(String columnType) {        if(StrUtil.isNotEmpty(columnType)){            if(Arrays.asList(GenerateConstant.COLUMN_TYPE_STR).contains(columnType)){                return GenerateConstant.TYPE_STRING;            }            if(Arrays.asList(GenerateConstant.COLUMN_TYPE_TIME).contains(columnType)){                return GenerateConstant.TYPE_DATE;            }            if (Arrays.asList(GenerateConstant.COLUMN_TYPE_NUMBER).contains(columnType)) {                return GenerateConstant.TYPE_INTEGER;            }            if (Arrays.asList(GenerateConstant.COLUMN_TYPE_BIGINT).contains(columnType)) {                return GenerateConstant.TYPE_LONG;            }            if (Arrays.asList(GenerateConstant.COLUMN_TYPE_FLOAT).contains(columnType)) {                return GenerateConstant.TYPE_DOUBLE;            }            if (Arrays.asList(GenerateConstant.COLUMN_TYPE_DOUBLE).contains(columnType)) {                return GenerateConstant.TYPE_DOUBLE;            }            if (Arrays.asList(GenerateConstant.COLUMN_TYPE_DECIMAL).contains(columnType)) {                return GenerateConstant.TYPE_BIGDECIMAL;            }        }        return  null;    }

定义对应的模板文件

在项目的资源文件夹templats中创建vm文件夹存放模板文件

entity.java.vm

package ${packageName}.${moduleName}.domain.entity;    #set($list=["createBy","createTime","createName", "updateBy", "updateName","updateTime", "deleteFlag"])import com.didiplus.common.base.BaseDomain;import lombok.Data;import io.swagger.annotations.ApiModel;import io.swagger.annotations.ApiModelProperty;import java.util.Date;import com.baomidou.mybatisplus.annotation.TableName;/** * @author ${author} * @date ${datetime} * * @description ${comment}(${upperClassName}实体类) */@Data@TableName("${tableName}")@ApiModel(value = "${comment}", description = "${comment}对象 ${lowerClassName}")public class ${upperClassName}Entity extends BaseDomain {    #foreach ($column in $columns)        ##    排除父类字段        #if($list.contains($column.javaLowerAttrName))        #else            /**             * $column.column_comment             */            @ApiModelProperty(value = "$column.column_comment")            private $column.javaAttrType $column.javaLowerAttrName;        #end    #end}

mapper.java.vm

package ${packageName}.${moduleName}.mapper;import com.baomidou.mybatisplus.core.mapper.BaseMapper;import ${packageName}.${moduleName}.domain.entity.${upperClassName}Entity;import org.apache.ibatis.annotations.Mapper;/** * @author ${author} * @date ${datetime} * * @description ${comment} */@Mapperpublic interface ${upperClassName}Mapper extends BaseMapper<${upperClassName}Entity> {}

mapper.xml.vm

<?xml version="1.0" encoding="UTF-8"?><!DOCTYPE mapper PUBLIC "-//mybatis.org//DTD Mapper 3.0//EN" "http://mybatis.org/dtd/mybatis-3-mapper.dtd"><mapper namespace="${packageName}.${moduleName}.mapper.${upperClassName}Mapper">    <resultMap id="${lowerClassName}Map" type="${packageName}.${moduleName}.domain.${upperClassName}">        #foreach($column in $columns)            <result column="${column.column_name}" property="${column.javaLowerAttrName}"/>        #end    </resultMap></mapper>

service.java.vm

package ${packageName}.${moduleName}.service;import com.baomidou.mybatisplus.core.metadata.IPage;import com.baomidou.mybatisplus.extension.service.IService;import ${packageName}.${moduleName}.domain.entity.${upperClassName};import com.didiplus.common.web.domain.PageDomain;/** * @author ${author} * @date ${datetime} * * @description ${comment} */public interface I${upperClassName}Service extends IService<${upperClassName}Entity> {    /**    * 分页查询    * @param pageDomain    * @return    */    IPage<${upperClassName}Entity> page(PageDomain pageDomain);}

serviceImpl.java.vm

package ${packageName}.${moduleName}.service.impl;import com.didiplus.common.web.domain.PageDomain;import com.baomidou.mybatisplus.extension.service.impl.ServiceImpl;import ${packageName}.${moduleName}.domain.entity.${upperClassName}Entity;import ${packageName}.${moduleName}.mapper.${upperClassName}Mapper;import ${packageName}.${moduleName}.service.I${upperClassName}Service;import org.springframework.stereotype.Service;import javax.annotation.Resource;import com.baomidou.mybatisplus.core.metadata.IPage;import com.baomidou.mybatisplus.extension.plugins.pagination.Page;/** * @author ${author} * @date ${datetime} * * @description ${comment} */@Servicepublic class ${upperClassName}ServiceImpl extends ServiceImpl<${upperClassName}Mapper, ${upperClassName}Entity> implements I${upperClassName}Service {        @Resource        ${upperClassName}Mapper ${lowerClassName}Mapper;        @Override        public IPage<${upperClassName}Entity> page(PageDomain pageDomain) {            IPage<${upperClassName}Entity> page = new Page<>(pageDomain.getPage(),pageDomain.getLimit());            return ${lowerClassName}Mapper.selectPage(page,null);        }}

controller.java.vm

package ${packageName}.${moduleName}.controller;import com.baomidou.mybatisplus.core.metadata.IPage;import com.baomidou.mybatisplus.extension.plugins.pagination.Page;import ${packageName}.${moduleName}.domain.entity.${upperClassName}Entity;import ${packageName}.${moduleName}.service.I${upperClassName}Service;import io.swagger.annotations.Api;import io.swagger.annotations.ApiOperation;import lombok.extern.slf4j.Slf4j;import com.didiplus.common.web.domain.PageDomain;import org.springframework.beans.factory.annotation.Autowired;import org.springframework.web.bind.annotation.*;import com.didiplus.common.base.ValidGroup;import javax.annotation.Resource;/** * @author ${author} * @date ${datetime} * * @description ${comment} */@Slf4j@RestController@RequestMapping("/${lowerClassName}")@Api(value = "${lowerClassName}", tags = "${comment}管理模块")public class ${upperClassName}Controller {    @Resource    private I${upperClassName}Service ${lowerClassName}Service;    /**     * 分页查询     * @param pageDomain 分页对象     * @param ${lowerClassName}Entity ${comment}     * @return IPage     */    @ApiOperation(value = "分页查询", notes = "分页查询")    @GetMapping("/page")    public IPage get${upperClassName}Page(@RequestBody PageDomain pageDomain) {        return ${lowerClassName}Service.page(pageDomain);    }    /**     * 新增${comment}     * @param ${lowerClassName}Entity ${comment}     * @return Result     */    @ApiOperation(value = "新增${comment}", notes = "新增${comment}")    @PostMapping    public String save(@Validated(ValidGroup.Crud.Create.class)  @RequestBody ${upperClassName}Entity ${lowerClassName}Entity) {        return  ${lowerClassName}Service.save(${lowerClassName}Entity)? "添加成功":"添加失败";    }    /**     * 修改${comment}     * @param ${lowerClassName}Entity ${comment}     * @return Result     */    @ApiOperation(value = "修改${comment}", notes = "修改${comment}")    @PutMapping    public String updateById(@Validated(ValidGroup.Crud.Update.class)  @RequestBody ${upperClassName}Entity ${lowerClassName}Entity) {        return  ${lowerClassName}Service.updateById(${lowerClassName}Entity)? "修改成功":"修改失败";    }    /**     * 通过id删除${comment}     * @param id id     * @return Result     */    @ApiOperation(value = "通过id删除${comment}", notes = "通过id删除${comment}")    @DeleteMapping("/{id}")    public String removeById(@PathVariable Integer id) {        return ${lowerClassName}Service.removeById(id)? "删除成功":"删除失败";    }}

定义启动类

    @Test    public  void  generatorCode(){        AutoGenerator generator = new AutoGenerator(DATA_SOURCE_CONFIG);        generator.strategy(strategyConfig().build());        generator.injection(injectionConfig().build());        generator.global(globalConfig().build());        generator.template(templateConfig().build());        generator.packageInfo(packageConfig().build());        generator.execute();    }

执行以上函数就可以自动生成代码了，如下图：
目前代码自动生成器只是一个脚本方式运行，后续我们会把它集成到页面上，通过图形界面的方式去操作。好了今天就分享到这里了，有什么问题欢迎留意。更多关注公众号“攻城狮成长日记”。