分享myBatis-plus代码生成器的使用步骤以及以其为基础编写的在线crud代码生成器

1.pom文件中配置mybatis-plus-generator

使用代码生成器时需要先把pom文件中mybatis-plus依赖注释掉，并引入mybatis-plus-generaor依赖和模板引擎依赖，否则写生成器代码时候找不到对应的包

    <!--<dependency>
            <groupId>com.baomidou</groupId>
            <artifactId>mybatis-plus-boot-starter</artifactId>
            <version>3.3.1.tmp</version>
        </dependency>-->

        <dependency>
            <groupId>com.baomidou</groupId>
            <artifactId>mybatis-plus-generator</artifactId>
            <version>3.3.1.tmp</version>
        </dependency>
        <dependency>
            <groupId>org.apache.velocity</groupId>
            <artifactId>velocity-engine-core</artifactId>
            <version>2.2</version>
        </dependency>

2.编写代码生成器

直接复制官方示例代码的话需要修改代码中使用freemarker模板引擎的地方换成velocity，以下是修改后的代码

package com.lfy.springboot;

import com.baomidou.mybatisplus.core.toolkit.StringPool;
import com.baomidou.mybatisplus.generator.AutoGenerator;
import com.baomidou.mybatisplus.generator.InjectionConfig;
import com.baomidou.mybatisplus.generator.config.*;
import com.baomidou.mybatisplus.generator.config.po.TableInfo;
import com.baomidou.mybatisplus.generator.config.rules.NamingStrategy;
import com.baomidou.mybatisplus.generator.engine.VelocityTemplateEngine;

import java.util.ArrayList;
import java.util.List;

/**
 * @Author: 李丰翼
 * @DateTime: 2020/5/18 0018 19:21
 * @Description: TODO
 */
public class CodeGenerator {

    public static void main(String[] args) {
        // 代码生成器

        AutoGenerator mpg = new AutoGenerator();

        // 全局配置
        GlobalConfig gc = new GlobalConfig();
        String projectPath = System.getProperty("user.dir");
        
        gc.setOutputDir(projectPath + "/src/main/java");
        gc.setAuthor("lfy");
        gc.setOpen(false);
        gc.setMapperName("%sDao");
        gc.setXmlName("%sDao");
        gc.setSwagger2(true); //实体属性 Swagger2 注解
        gc.setFileOverride(true);
        gc.setBaseColumnList(true);
        gc.setBaseResultMap(true);
        mpg.setGlobalConfig(gc);

        // 数据源配置
        DataSourceConfig dsc = new DataSourceConfig();
        dsc.setUrl("jdbc:mysql://localhost:3306/wenjuan?useUnicode=true&characterEncoding=utf8&serverTimezone=GMT%2B8&useSSL=false");
        // dsc.setSchemaName("public");
        dsc.setDriverName("com.mysql.cj.jdbc.Driver");
        dsc.setUsername("root");
        dsc.setPassword("root");

        mpg.setDataSource(dsc);

        // 包配置
        PackageConfig pc = new PackageConfig();
        pc.setParent("com.lfy.springboot");
        pc.setMapper("dao");
        mpg.setPackageInfo(pc);

        // 自定义配置
        InjectionConfig cfg = new InjectionConfig() {
            @Override
            public void initMap() {
                // to do nothing
            }
        };

        // 如果模板引擎是 freemarker
        //String templatePath = "/templates/mapper.xml.ftl";
        // 如果模板引擎是 velocity
         String templatePath = "/templates/mapper.xml.vm";
        // 自定义输出配置
        List<FileOutConfig> focList = new ArrayList<>();
        // 自定义配置会被优先输出
        focList.add(new FileOutConfig(templatePath) {
            @Override
            public String outputFile(TableInfo tableInfo) {
                // 自定义输出文件名 ， 如果你 Entity 设置了前后缀、此处注意 xml 的名称会跟着发生变化！！
                return projectPath + "/src/main/resources/mapper/" +
                        tableInfo.getEntityName() + "Mapper" + StringPool.DOT_XML;
            }
        });

/*        cfg.setFileCreate(new IFileCreate() {
            @Override
            public boolean isCreate(ConfigBuilder configBuilder, FileType fileType, String filePath) {
                // 判断自定义文件夹是否需要创建
                checkDir("调用默认方法创建的目录，自定义目录用");
                if (fileType == FileType.MAPPER) {
                    // 已经生成 mapper 文件判断存在，不想重新生成返回 false
                    return !new File(filePath).exists();
                }
                // 允许生成模板文件
                return true;
            }
        });*/

        cfg.setFileOutConfigList(focList);
        mpg.setCfg(cfg);

        // 配置模板
        TemplateConfig templateConfig = new TemplateConfig();

        // 配置自定义输出模板
        //指定自定义模板路径，注意不要带上.ftl/.vm, 会根据使用的模板引擎自动识别
        // templateConfig.setEntity("templates/entity2.java");
        // templateConfig.setService();
        // templateConfig.setController();

        templateConfig.setXml(null);
        mpg.setTemplate(templateConfig);


        // 策略配置
        StrategyConfig strategy = new StrategyConfig();
        strategy.setNaming(NamingStrategy.underline_to_camel);
        strategy.setColumnNaming(NamingStrategy.underline_to_camel);
        strategy.setEntityLombokModel(true);
        strategy.setRestControllerStyle(true);
        // 写于父类中的公共字段
        strategy.setSuperEntityColumns("id");
        strategy.setControllerMappingHyphenStyle(true);
        strategy.setTablePrefix(pc.getModuleName() + "_");
        strategy.setRestControllerStyle(true);
        strategy.setSuperControllerClass("com.lfy.springboot.controller.BaseController");



        mpg.setStrategy(strategy);
        mpg.setTemplateEngine(new VelocityTemplateEngine());

        mpg.execute();
    }

}

3.编写xml模板

创建mapper.xml.vm放在templates目录下，这里只写了mapper.xml的模板，其他的部分也可以自定义模板文件
可以参考https://blog.csdn.net/kanglong129/article/details/98362009

<?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="${package.Mapper}.${table.mapperName}">

    #if(${enableCache})
           <cache type="org.mybatis.caches.ehcache.LoggingEhcache"/>

    #end
    #if(${baseResultMap})
        <resultMap id="BaseResultMap" type="${package.Entity}.${entity}">
        #foreach($field in ${table.fields})
            #if(${field.keyFlag})##生成主键排在第一位
               <id column="${field.name}" property="${field.propertyName}" />
            #end
        #end
        #foreach($field in ${table.commonFields})##生成公共字段
               <result column="${field.name}" property="${field.propertyName}" />
        #end
        #foreach($field in ${table.fields})
            #if(!${field.keyFlag})##生成普通字段
                <result column="${field.name}" property="${field.propertyName}" />
            #end
        #end
        </resultMap>
    #end
        <sql id="Base_Table_Name">
            ${table.name}
        </sql>
        <sql id="Base_Column_List">
#foreach($field in ${table.commonFields})
   #if(${field.name} == ${field.propertyName})${field.name}#else${field.name} AS ${field.propertyName}#end,
#end
        ${table.fieldNames}
        </sql>
</mapper>

mapper模板中可以使用的属性可以参考源码中com.baomidou.mybatisplus.generator.config.po.TableInfo中的属性

/*
 * Copyright (c) 2011-2020, baomidou (jobob@qq.com).
 * <p>
 * Licensed under the Apache License, Version 2.0 (the "License"); you may not
 * use this file except in compliance with the License. You may obtain a copy of
 * the License at
 * <p>
 * https://www.apache.org/licenses/LICENSE-2.0
 * <p>
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
 * WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
 * License for the specific language governing permissions and limitations under
 * the License.
 */
package com.baomidou.mybatisplus.generator.config.po;

import java.util.HashSet;
import java.util.List;
import java.util.Set;
import java.util.stream.IntStream;

import com.baomidou.mybatisplus.core.toolkit.CollectionUtils;
import com.baomidou.mybatisplus.core.toolkit.StringUtils;
import com.baomidou.mybatisplus.generator.config.StrategyConfig;
import com.baomidou.mybatisplus.generator.config.rules.NamingStrategy;

import lombok.Data;
import lombok.experimental.Accessors;

/**
 * 表信息，关联到当前字段信息
 *
 * @author YangHu
 * @since 2016/8/30
 */
@Data
@Accessors(chain = true)
public class TableInfo {

    private final Set<String> importPackages = new HashSet<>();
    private boolean convert;
    private String name;
    private String comment;
    private String entityName;
    private String mapperName;
    private String xmlName;
    private String serviceName;
    private String serviceImplName;
    private String controllerName;
    private List<TableField> fields;
    /**
     * 公共字段
     */
    private List<TableField> commonFields;
    private String fieldNames;

    public TableInfo setConvert(boolean convert) {
        this.convert = convert;
        return this;
    }

    protected TableInfo setConvert(StrategyConfig strategyConfig) {
        if (strategyConfig.containsTablePrefix(name) || strategyConfig.isEntityTableFieldAnnotationEnable()) {
            // 包含前缀
            this.convert = true;
        } else if (strategyConfig.isCapitalModeNaming(name)) {
            // 包含
            this.convert = false;
        } else {
            // 转换字段
            if (NamingStrategy.underline_to_camel == strategyConfig.getColumnNaming()) {
                // 包含大写处理
                if (StringUtils.containsUpperCase(name)) {
                    this.convert = true;
                }
            } else if (!entityName.equalsIgnoreCase(name)) {
                this.convert = true;
            }
        }
        return this;
    }

    public String getEntityPath() {
        return entityName.substring(0, 1).toLowerCase() + entityName.substring(1);
    }

    public TableInfo setEntityName(StrategyConfig strategyConfig, String entityName) {
        this.entityName = entityName;
        this.setConvert(strategyConfig);
        return this;
    }

    public TableInfo setFields(List<TableField> fields) {
        if (CollectionUtils.isNotEmpty(fields)) {
            this.fields = fields;
            // 收集导入包信息
            for (TableField field : fields) {
                if (null != field.getColumnType() && null != field.getColumnType().getPkg()) {
                    importPackages.add(field.getColumnType().getPkg());
                }
                if (field.isKeyFlag()) {
                    // 主键
                    if (field.isConvert() || field.isKeyIdentityFlag()) {
                        importPackages.add(com.baomidou.mybatisplus.annotation.TableId.class.getCanonicalName());
                    }
                    // 自增
                    if (field.isKeyIdentityFlag()) {
                        importPackages.add(com.baomidou.mybatisplus.annotation.IdType.class.getCanonicalName());
                    }
                } else if (field.isConvert()) {
                    // 普通字段
                    importPackages.add(com.baomidou.mybatisplus.annotation.TableField.class.getCanonicalName());
                }
                if (null != field.getFill()) {
                    // 填充字段
                    importPackages.add(com.baomidou.mybatisplus.annotation.TableField.class.getCanonicalName());
                    importPackages.add(com.baomidou.mybatisplus.annotation.FieldFill.class.getCanonicalName());
                }
            }
        }
        return this;
    }

    public TableInfo setImportPackages(String pkg) {
        importPackages.add(pkg);
        return this;
    }

    /**
     * 逻辑删除
     */
    public boolean isLogicDelete(String logicDeletePropertyName) {
        return fields.parallelStream().anyMatch(tf -> tf.getName().equals(logicDeletePropertyName));
    }

    /**
     * 转换filed实体为 xml mapper 中的 base column 字符串信息
     */
    public String getFieldNames() {
        if (StringUtils.isBlank(fieldNames)
            && CollectionUtils.isNotEmpty(fields)) {
            StringBuilder names = new StringBuilder();
            IntStream.range(0, fields.size()).forEach(i -> {
                TableField fd = fields.get(i);
                if (i == fields.size() - 1) {
                    names.append(fd.getName());
                } else {
                    names.append(fd.getName()).append(", ");
                }
            });
            fieldNames = names.toString();
        }
        return fieldNames;
    }
}