我们使用代码生成器的目的主要是提供开发效率，减少重复性的工作。在使用Springboot开发过程中，我们使用代码生成器把大概的模板生成出来，再根据自己的业务特征进行改动。这样就可以提高效率
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
```java
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。
```java
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 {
mathJaxContainer[0]}{
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 ({
mathJaxContainer[3]}columns)
## 排除父类字段
#if({
mathJaxContainer[4]}column.javaLowerAttrName))
#else
/**
* $column.column_comment
*/
@ApiModelProperty(value = "$column.column_comment")
private {
mathJaxContainer[5]}column.javaLowerAttrName;
#end
#end
}
mapper.java.vm
package {
mathJaxContainer[6]}{
moduleName}.mapper;
import com.baomidou.mybatisplus.core.mapper.BaseMapper;
import {
mathJaxContainer[7]}{
moduleName}.domain.entity.${
upperClassName}Entity;
import org.apache.ibatis.annotations.Mapper;
/**
* @author ${author}
* @date ${datetime}
*
* @description ${comment}
*/
@Mapper
public interface {
mathJaxContainer[8]}{
upperClassName}Entity> {
}
mapper.xml.vm
<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE mapper PUBLIC "-//mybatis.org//DTD Mapper 3.0//EN" "http://mybatis.org/dtd/mybatis-3-mapper.dtd">
<mapper namespace="${packageName}.${moduleName}.mapper.${upperClassName}Mapper">
<resultMap id="${lowerClassName}Map" type="${packageName}.${moduleName}.domain.${upperClassName}">
#foreach({
mathJaxContainer[12]}columns)
<result column="${column.column_name}" property="${column.javaLowerAttrName}"/>
#end
</resultMap>
</mapper>
service.java.vm
package {
mathJaxContainer[14]}{
moduleName}.service;
import com.baomidou.mybatisplus.core.metadata.IPage;
import com.baomidou.mybatisplus.extension.service.IService;
import {
mathJaxContainer[15]}{
moduleName}.domain.entity.${
upperClassName};
import com.didiplus.common.web.domain.PageDomain;
/**
* @author ${author}
* @date ${datetime}
*
* @description ${comment}
*/
public interface I{
mathJaxContainer[16]}{
upperClassName}Entity> {
/**
* 分页查询
* @param pageDomain
* @return
*/
IPage<${
upperClassName}Entity> page(PageDomain pageDomain);
}
serviceImpl.java.vm
package {
mathJaxContainer[17]}{
moduleName}.service.impl;
import com.didiplus.common.web.domain.PageDomain;
import com.baomidou.mybatisplus.extension.service.impl.ServiceImpl;
import {
mathJaxContainer[18]}{
moduleName}.domain.entity.${
upperClassName}Entity;
import {
mathJaxContainer[19]}{
moduleName}.mapper.${
upperClassName}Mapper;
import {
mathJaxContainer[20]}{
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 ${comment}
*/
@Service
public class {
mathJaxContainer[21]}{
upperClassName}Mapper, {
mathJaxContainer[22]}{
upperClassName}Service {
@Resource
{
mathJaxContainer[23]}{
lowerClassName}Mapper;
@Override
public IPage<${
upperClassName}Entity> page(PageDomain pageDomain) {
IPage<${
upperClassName}Entity> page = new Page<>(pageDomain.getPage(),pageDomain.getLimit());
return ${
lowerClassName}Mapper.selectPage(page,null);
}
}
controller.java.vm
package {
mathJaxContainer[24]}{
moduleName}.controller;
import com.baomidou.mybatisplus.core.metadata.IPage;
import com.baomidou.mybatisplus.extension.plugins.pagination.Page;
import {
mathJaxContainer[25]}{
moduleName}.domain.entity.${
upperClassName}Entity;
import {
mathJaxContainer[26]}{
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{
mathJaxContainer[28]}{
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${comment}")
@PostMapping
public String save(@Validated(ValidGroup.Crud.Create.class) @RequestBody {
mathJaxContainer[32]}{
lowerClassName}Entity) {
return {
mathJaxContainer[33]}{
lowerClassName}Entity)? "添加成功":"添加失败";
}
/**
* 修改${comment}
* @param ${lowerClassName}Entity ${comment}
* @return Result
*/
@ApiOperation(value = "修改${comment}", notes = "修改${comment}")
@PutMapping
public String updateById(@Validated(ValidGroup.Crud.Update.class) @RequestBody {
mathJaxContainer[36]}{
lowerClassName}Entity) {
return {
mathJaxContainer[37]}{
lowerClassName}Entity)? "修改成功":"修改失败";
}
/**
* 通过id删除${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”。
