一、简介
最近刚入职一个新团队，还没来得及熟悉业务，甲方爸爸就要求项目要在2个月内完成开发并上线！
本想着往后推迟1个月在交付，但是甲方爸爸不同意，只能赶鸭子上架了！
然后根据业务需求，设计出了大概30多张表，如果这30多张表，全靠开发人员手写 crud，开发所需的时间肯定会大大的延长，甚至可能直接会影响交付时间！
于是就想着，能不能通过代码生成器一键搞定全部的 crud？
本来计划是用mybatis-plus的，但是生成的代码，根据现有的框架标准，很多代码也需要自己改，有些地方还不如自己手写用的舒服，因此就决定手写一套代码生成器！
很多新手会觉得代码生成器很个高深的东西。其实不然，一点都不高深，当你看完本文的时候，你会完全掌握代码生成器的逻辑，甚至可以根据自己的项目情况，进行深度定制。
废话也不多说了，直接代码撸上！
二、实现思路
下面我就以SpringBoot项目为例，数据持久化操作采用Mybatis，数据库采用Mysql，编写一个自动生成增、删、改、查等基础功能的代码生成器，内容包括controller、service、dao、entity、dto、vo等信息。
实现思路如下：
- 第一步：获取表字段名称、类型、表注释等信息
- 第二步：基于 freemarker 模板引擎，编写相应的模板
- 第三步：根据对应的模板，生成相应的 java 代码
2.1、获取表结构
首先我们创建一张test_db表，脚本如下：
CREATE TABLE test_db (
id bigint(20) unsigned NOT NULL COMMENT '主键ID',
name varchar(50) COLLATE utf8mb4_unicode_ci NOT NULL DEFAULT '' COMMENT '名称',
is_delete tinyint(4) NOT NULL DEFAULT '0' COMMENT '是否删除 1：已删除；0：未删除',
create_time datetime NOT NULL DEFAULT CURRENT_TIMESTAMP COMMENT '创建时间',
update_time datetime NOT NULL DEFAULT CURRENT_TIMESTAMP ON UPDATE CURRENT_TIMESTAMP COMMENT '更新时间',
PRIMARY KEY (id),
KEY idx_create_time (create_time) USING BTREE
) ENGINE=InnoDB DEFAULT CHARSET=utf8mb4 COLLATE=utf8mb4_unicode_ci COMMENT='测试表';
表创建完成之后，基于test_db表，我们查询对应的表结果字段名称、类型、备注信息，这些信息收集将用于后续进行代码生成器所使用！
# 获取对应表结构
SELECT column_name, data_type, column_comment FROM information_schema.columns WHERE table_schema = 'yjgj_base' AND table_name = 'test_db'
同时，获取对应表注释，用于生成备注信息！
# 获取对应表注释
SELECT TABLE_COMMENT FROM INFORMATION_SCHEMA.TABLES WHERE table_schema = 'yjgj_base' AND table_name = 'test_db'
2.2、编写模板
- 编写
mapper模板，涵盖新增、修改、删除、查询等信息
<?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="${daoPackageName}.${daoName}">
<!--BaseResultMap-->
<resultMap id="BaseResultMap" type="${entityPackageName}.${entityName}">
<#list columns as pro>
<#if pro.proName == primaryId>
<id column="${primaryId}" property="${primaryId}" jdbcType="${pro.fieldType}"/>
<#else>
<result column="${pro.fieldName}" property="${pro.proName}" jdbcType="${pro.fieldType}"/>
</#if>
</#list>
</resultMap>
<!--Base_Column_List-->
<sql id="Base_Column_List">
<#list columns as pro>
<#if pro_index == 0>${pro.fieldName}<#else>,${pro.fieldName}</#if>
</#list>
</sql>
<!--批量插入-->
<insert id="insertList" parameterType="java.util.List">
insert into ${tableName} (
<#list columns as pro>
<#if pro_index == 0>${pro.fieldName},<#elseif pro_index == 1>${pro.fieldName}<#else>,${pro.fieldName}</#if>
</#list>
)
values
<foreach collection ="list" item="obj" separator =",">
<trim prefix=" (" suffix=")" suffixOverrides=",">
<#list columns as pro>
${r"#{obj." + pro.proName + r"}"},
</#list>
</trim>
</foreach >
</insert>
<!--按需新增-->
<insert id="insertPrimaryKeySelective" parameterType="${entityPackageName}.${entityName}">
insert into ${tableName}
<trim prefix="(" suffix=")" suffixOverrides=",">
<#list columns as pro>
<if test="${pro.proName} != null">
${pro.fieldName},
</if>
</#list>
</trim>
<trim prefix="values (" suffix=")" suffixOverrides=",">
<#list columns as pro>
<if test="${pro.proName} != null">
${r"#{" + pro.proName + r",jdbcType=" + pro.fieldType +r"}"},
</if>
</#list>
</trim>
</insert>
<!-- 按需修改-->
<update id="updatePrimaryKeySelective" parameterType="${entityPackageName}.${entityName}">
update ${tableName}
<set>
<#list columns as pro>
<#if pro.fieldName != primaryId && pro.fieldName != primaryId>
<if test="${pro.proName} != null">
${pro.fieldName} = ${r"#{" + pro.proName + r",jdbcType=" + pro.fieldType +r"}"},
</if>
</#if>
</#list>
</set>
where ${primaryId} = ${r"#{" + "${primaryId}" + r",jdbcType=BIGINT}"}
</update>
<!-- 按需批量修改-->
<update id="updateBatchByIds" parameterType="java.util.List">
update ${tableName}
<trim prefix="set" suffixOverrides=",">
<#list columns as pro>
<#if pro.fieldName != primaryId && pro.fieldName != primaryId>
<trim prefix="${pro.fieldName}=case" suffix="end,">
<foreach collection="list" item="obj" index="index">
<if test="obj.${pro.proName} != null">
when id = ${r"#{" + "obj.id" + r"}"}
then ${r"#{obj." + pro.proName + r",jdbcType=" + pro.fieldType +r"}"}
</if>
</foreach>
</trim>
</#if>
</#list>
</trim>
where
<foreach collection="list" separator="or" item="obj" index="index" >
id = ${r"#{" + "obj.id" + r"}"}
</foreach>
</update>
<!-- 删除-->
<delete id="deleteByPrimaryKey" parameterType="java.lang.Long">
delete from ${tableName}
where ${primaryId} = ${r"#{" + "${primaryId}" + r",jdbcType=BIGINT}"}
</delete>
<!-- 查询详情 -->
<select id="selectByPrimaryKey" resultMap="BaseResultMap" parameterType="java.lang.Long">
select
<include refid="Base_Column_List"/>
from ${tableName}
where ${primaryId} = ${r"#{" + "${primaryId}" + r",jdbcType=BIGINT}"}
</select>
<!-- 按需查询 -->
<select id="selectByPrimaryKeySelective" resultMap="BaseResultMap" parameterType="${entityPackageName}.${entityName}">
select
<include refid="Base_Column_List"/>
from ${tableName}
</select>
<!-- 批量查询-->
<select id="selectByIds" resultMap="BaseResultMap" parameterType="java.util.List">
select
<include refid="Base_Column_List"/>
from ${tableName}
<where>
<if test="ids != null">
and ${primaryId} in
<foreach item="item" index="index" collection="ids" open="(" separator="," close=")">
${r"#{" + "item" + r"}"}
</foreach>
</if>
</where>
</select>
<!-- 根据条件查询 -->
<select id="selectByMap" resultMap="BaseResultMap" parameterType="java.util.Map">
select
<include refid="Base_Column_List"/>
from ${tableName}
</select>
<!-- 查询${entityName}总和 -->
<select id="countPage" resultType="int" parameterType="${dtoPackageName}.${dtoName}">
select count(${primaryId})
from ${tableName}
</select>
<!-- 查询${entityName}列表 -->
<select id="selectPage" resultMap="BaseResultMap" parameterType="${dtoPackageName}.${dtoName}">
select
<include refid="Base_Column_List"/>
from ${tableName}
limit ${r"#{" + "start,jdbcType=INTEGER" + r"}"},${r"#{" + "end,jdbcType=INTEGER" + r"}"}
</select>
</mapper>
- 编写
dao数据访问模板
package ${daoPackageName};
import com.example.generator.core.BaseMapper;
import java.util.List;
import ${entityPackageName}.${entityName};
import ${dtoPackageName}.${dtoName};
/**
*
* @ClassName: ${daoName}
* @Description: 数据访问接口
* @author ${authorName}
* @date ${currentTime}
*
*/
public interface ${daoName} extends BaseMapper<${entityName}>{
int countPage(${dtoName} ${dtoName?uncap_first});
List<${entityName}> selectPage(${dtoName} ${dtoName?uncap_first});
}
- 编写
service服务接口模板
package ${servicePackageName};
import com.example.generator.core.BaseService;
import com.example.generator.common.Pager;
import ${voPackageName}.${voName};
import ${dtoPackageName}.${dtoName};
import ${entityPackageName}.${entityName};
/**
*
* @ClassName: ${serviceName}
* @Description: ${entityName}业务访问接口
* @author ${authorName}
* @date ${currentTime}
*
*/
public interface ${serviceName} extends BaseService<${entityName}> {
/**
* 分页列表查询
* @param request
*/
Pager<${voName}> getPage(${dtoName} request);
}
- 编写
serviceImpl服务实现类模板
package ${serviceImplPackageName};
import com.example.generator.common.Pager;
import com.example.generator.core.BaseServiceImpl;
import com.example.generator.test.service.TestEntityService;
import org.springframework.beans.BeanUtils;
import org.springframework.stereotype.Service;
import org.springframework.util.CollectionUtils;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import java.util.ArrayList;
import java.util.List;
import ${daoPackageName}.${daoName};
import ${entityPackageName}.${entityName};
import ${dtoPackageName}.${dtoName};
import ${voPackageName}.${voName};
@Service
public class ${serviceImplName} extends BaseServiceImpl<${daoName}, ${entityName}> implements ${serviceName} {
private static final Logger log = LoggerFactory.getLogger(${serviceImplName}.class);
/**
* 分页列表查询
* @param request
*/
public Pager<${voName}> getPage(${dtoName} request) {
List<${voName}> resultList = new ArrayList();
int count = super.baseMapper.countPage(request);
List<${entityName}> dbList = count > 0 ? super.baseMapper.selectPage(request) : new ArrayList<>();
if(!CollectionUtils.isEmpty(dbList)){
dbList.forEach(source->{
${voName} target = new ${voName}();
BeanUtils.copyProperties(source, target);
resultList.add(target);
});
}
return new Pager(request.getCurrPage(), request.getPageSize(), count, resultList);
}
}
- 编写
controller控制层模板
package ${controllerPackageName};
import com.example.generator.common.IdRequest;
import com.example.generator.common.Pager;
import org.springframework.beans.BeanUtils;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.web.bind.annotation.PostMapping;
import org.springframework.web.bind.annotation.RequestBody;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RestController;
import java.util.Objects;
import ${servicePackageName}.${serviceName};
import ${entityPackageName}.${entityName};
import ${dtoPackageName}.${dtoName};
import ${voPackageName}.${voName};
/**
*
* @ClassName: ${controllerName}
* @Description: 外部访问接口
* @author ${authorName}
* @date ${currentTime}
*
*/
@RestController
@RequestMapping("/${entityName?uncap_first}")
public class ${controllerName} {
@Autowired
private ${serviceName} ${serviceName?uncap_first};
/**
* 分页列表查询
* @param request
*/
@PostMapping(value = "/getPage")
public Pager<${voName}> getPage(@RequestBody ${dtoName} request){
return ${serviceName?uncap_first}.getPage(request);
}
/**
* 查询详情
* @param request
*/
@PostMapping(value = "/getDetail")
public ${voName} getDetail(@RequestBody IdRequest request){
${entityName} source = ${serviceName?uncap_first}.selectById(request.getId());
if(Objects.nonNull(source)){
${voName} result = new ${voName}();
BeanUtils.copyProperties(source, result);
return result;
}
return null;
}
/**
* 新增操作
* @param request
*/
@PostMapping(value = "/save")
public void save(${dtoName} request){
${entityName} entity = new ${entityName}();
BeanUtils.copyProperties(request, entity);
${serviceName?uncap_first}.insert(entity);
}
/**
* 编辑操作
* @param request
*/
@PostMapping(value = "/edit")
public void edit(${dtoName} request){
${entityName} entity = new ${entityName}();
BeanUtils.copyProperties(request, entity);
${serviceName?uncap_first}.updateById(entity);
}
/**
* 删除操作
* @param request
*/
@PostMapping(value = "/delete")
public void delete(IdRequest request){
${serviceName?uncap_first}.deleteById(request.getId());
}
}
- 编写
entity实体类模板
package ${entityPackageName};
import java.io.Serializable;
import java.math.BigDecimal;
import java.util.Date;
/**
*
* @ClassName: ${entityName}
* @Description: ${tableDes!}实体类
* @author ${authorName}
* @date ${currentTime}
*
*/
public class ${entityName} implements Serializable {
private static final long serialVersionUID = 1L;
<#--属性遍历-->
<#list columns as pro>
<#--<#if pro.proName != primaryId
&& pro.proName != 'remarks'
&& pro.proName != 'createBy'
&& pro.proName != 'createDate'
&& pro.proName != 'updateBy'
&& pro.proName != 'updateDate'
&& pro.proName != 'delFlag'
&& pro.proName != 'currentUser'
&& pro.proName != 'page'
&& pro.proName != 'sqlMap'
&& pro.proName != 'isNewRecord'
></#if>-->
/**
* ${pro.proDes!}
*/
private ${pro.proType} ${pro.proName};
</#list>
<#--属性get||set方法-->
<#list columns as pro>
public ${pro.proType} get${pro.proName?cap_first}() {
return this.${pro.proName};
}
public ${entityName} set${pro.proName?cap_first}(${pro.proType} ${pro.proName}) {
this.${pro.proName} = ${pro.proName};
return this;
}
</#list>
}
- 编写
dto实体类模板
package ${dtoPackageName};
import com.example.generator.core.BaseDTO;
import java.io.Serializable;
/**
* @ClassName: ${dtoName}
* @Description: 请求实体类
* @author ${authorName}
* @date ${currentTime}
*
*/
public class ${dtoName} extends BaseDTO {
}
- 编写
vo视图实体类模板
package ${voPackageName};
import java.io.Serializable;
/**
* @ClassName: ${voName}
* @Description: 返回视图实体类
* @author ${authorName}
* @date ${currentTime}
*
*/
public class ${voName} implements Serializable {
private static final long serialVersionUID = 1L;
}
可能细心的网友已经看到了，在模板中我们用到了BaseMapper、BaseService、BaseServiceImpl等等服务类。
之所以有这三个类，是因为在模板中，我们有大量的相同的方法名包括逻辑也相似，除了所在实体类不一样意以外，其他都一样，因此我们可以借助泛型类来将这些服务抽成公共的部分。
BaseMapper，主要负责将dao层的公共方法抽出来
package com.example.generator.core;
import org.apache.ibatis.annotations.Param;
import java.io.Serializable;
import java.util.List;
import java.util.Map;
/**
* @author pzblog
* @Description
* @since 2020-11-11
*/
public interface BaseMapper<T> {
/**
* 批量插入
* @param list
* @return
*/
int insertList(@Param("list") List<T> list);
/**
* 按需插入一条记录
* @param entity
* @return
*/
int insertPrimaryKeySelective(T entity);
/**
* 按需修改一条记录（通过主键ID）
* @return
*/
int updatePrimaryKeySelective(T entity);
/**
* 批量按需修改记录（通过主键ID）
* @param list
* @return
*/
int updateBatchByIds(@Param("list") List<T> list);
/**
* 根据ID删除
* @param id 主键ID
* @return
*/
int deleteByPrimaryKey(Serializable id);
/**
* 根据ID查询
* @param id 主键ID
* @return
*/
T selectByPrimaryKey(Serializable id);
/**
* 按需查询
* @param entity
* @return
*/
List<T> selectByPrimaryKeySelective(T entity);
/**
* 批量查询
* @param ids 主键ID集合
* @return
*/
List<T> selectByIds(@Param("ids") List<? extends Serializable> ids);
/**
* 查询（根据 columnMap 条件）
* @param columnMap 表字段 map 对象
* @return
*/
List<T> selectByMap(Map<String, Object> columnMap);
}
BaseService，主要负责将service层的公共方法抽出来
package com.example.generator.core;
import java.io.Serializable;
import java.util.List;
import java.util.Map;
/**
* @author pzblog
* @Description 服务类
* @since 2020-11-11
*/
public interface BaseService<T> {
/**
* 新增
* @param entity
* @return boolean
*/
boolean insert(T entity);
/**
* 批量新增
* @param list
* @return boolean
*/
boolean insertList(List<T> list);
/**
* 通过ID修改记录（如果想全部更新，只需保证字段都不为NULL）
* @param entity
* @return boolean
*/
boolean updateById(T entity);
/**
* 通过ID批量修改记录（如果想全部更新，只需保证字段都不为NULL）
* @param list
* @return boolean
*/
boolean updateBatchByIds(List<T> list);
/**
* 根据ID删除
* @param id 主键ID
* @return boolean
*/
boolean deleteById(Serializable id);
/**
* 根据ID查询
* @param id 主键ID
* @return
*/
T selectById(Serializable id);
/**
* 按需查询
* @param entity
* @return
*/
List<T> selectByPrimaryKeySelective(T entity);
/**
* 批量查询
* @param ids
* @return
*/
List<T> selectByIds(List<? extends Serializable> ids);
/**
* 根据条件查询
* @param columnMap
* @return
*/
List<T> selectByMap(Map<String, Object> columnMap);
}
BaseServiceImpl，service层的公共方法具体实现类
package com.example.generator.core;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.transaction.annotation.Transactional;
import java.io.Serializable;
import java.util.List;
import java.util.Map;
/**
* @author pzblog
* @Description 实现类（ 泛型说明：M 是 mapper 对象，T 是实体）
* @since 2020-11-11
*/
public abstract class BaseServiceImpl<M extends BaseMapper<T>, T> implements BaseService<T>{
@Autowired
protected M baseMapper;
/**
* 新增
* @param entity
* @return boolean
*/
@Override
@Transactional(rollbackFor = {Exception.class})
public boolean insert(T entity){
return returnBool(baseMapper.insertPrimaryKeySelective(entity));
}
/**
* 批量新增
* @param list
* @return boolean
*/
@Override
@Transactional(rollbackFor = {Exception.class})
public boolean insertList(List<T> list){
return returnBool(baseMapper.insertList(list));
}
/**
* 通过ID修改记录（如果想全部更新，只需保证字段都不为NULL）
* @param entity
* @return boolean
*/
@Override
@Transactional(rollbackFor = {Exception.class})
public boolean updateById(T entity){
return returnBool(baseMapper.updatePrimaryKeySelective(entity));
}
/**
* 通过ID批量修改记录（如果想全部更新，只需保证字段都不为NULL）
* @param list
* @return boolean
*/
@Override
@Transactional(rollbackFor = {Exception.class})
public boolean updateBatchByIds(List<T> list){
return returnBool(baseMapper.updateBatchByIds(list));
}
/**
* 根据ID删除
* @param id 主键ID
* @return boolean
*/
@Override
@Transactional(rollbackFor = {Exception.class})
public boolean deleteById(Serializable id){
return returnBool(baseMapper.deleteByPrimaryKey(id));
}
/**
* 根据ID查询
* @param id 主键ID
* @return
*/
@Override
public T selectById(Serializable id){
return baseMapper.selectByPrimaryKey(id);
}
/**
* 按需查询
* @param entity
* @return
*/
@Override
public List<T> selectByPrimaryKeySelective(T entity){
return baseMapper.selectByPrimaryKeySelective(entity);
}
/**
* 批量查询
* @param ids
* @return
*/
@Override
public List<T> selectByIds(List<? extends Serializable> ids){
return baseMapper.selectByIds(ids);
}
/**
* 根据条件查询
* @param columnMap
* @return
*/
@Override
public List<T> selectByMap(Map<String, Object> columnMap){
return baseMapper.selectByMap(columnMap);
}
/**
* 判断数据库操作是否成功
* @param result 数据库操作返回影响条数
* @return boolean
*/
protected boolean returnBool(Integer result) {
return null != result && result >= 1;
}
}
在此，还封装来其他的类，例如 dto 公共类BaseDTO，分页类Pager，还有 id 请求类IdRequest。
BaseDTO公共类
public class BaseDTO implements Serializable {
/**
* 请求token
*/
private String token;
/**
* 当前页数
*/
private Integer currPage = 1;
/**
* 每页记录数
*/
private Integer pageSize = 20;
/**
* 分页参数（第几行）
*/
private Integer start;
/**
* 分页参数（行数）
*/
private Integer end;
/**
* 登录人ID
*/
private String loginUserId;
/**
* 登录人名称
*/
private String loginUserName;
public String getToken() {
return token;
}
public BaseDTO setToken(String token) {
this.token = token;
return this;
}
public Integer getCurrPage() {
return currPage;
}
public BaseDTO setCurrPage(Integer currPage) {
this.currPage = currPage;
return this;
}
public Integer getPageSize() {
return pageSize;
}
public BaseDTO setPageSize(Integer pageSize) {
this.pageSize = pageSize;
return this;
}
public Integer getStart() {
if (this.currPage != null && this.currPage > 0) {
start = (currPage - 1) * getPageSize();
return start;
}
return start == null ? 0 : start;
}
public BaseDTO setStart(Integer start) {
this.start = start;
return this;
}
public Integer getEnd() {
return getPageSize();
}
public BaseDTO setEnd(Integer end) {
this.end = end;
return this;
}
public String getLoginUserId() {
return loginUserId;
}
public BaseDTO setLoginUserId(String loginUserId) {
this.loginUserId = loginUserId;
return this;
}
public String getLoginUserName() {
return loginUserName;
}
public BaseDTO setLoginUserName(String loginUserName) {
this.loginUserName = loginUserName;
return this;
}
}
Pager分页类
public class Pager<T extends Serializable> implements Serializable {
private static final long serialVersionUID = -6557244954523041805L;
/**
* 当前页数
*/
private int currPage;
/**
* 每页记录数
*/
private int pageSize;
/**
* 总页数
*/
private int totalPage;
/**
* 总记录数
*/
private int totalCount;
/**
* 列表数据
*/
private List<T> list;
public Pager(int currPage, int pageSize) {
this.currPage = currPage;
this.pageSize = pageSize;
}
public Pager(int currPage, int pageSize, int totalCount, List<T> list) {
this.currPage = currPage;
this.pageSize = pageSize;
this.totalPage = (int) Math.ceil((double) totalCount / pageSize);;
this.totalCount = totalCount;
this.list = list;
}
public int getCurrPage() {
return currPage;
}
public Pager setCurrPage(int currPage) {
this.currPage = currPage;
return this;
}
public int getPageSize() {
return pageSize;
}
public Pager setPageSize(int pageSize) {
this.pageSize = pageSize;
return this;
}
public int getTotalPage() {
return totalPage;
}
public Pager setTotalPage(int totalPage) {
this.totalPage = totalPage;
return this;
}
public int getTotalCount() {
return totalCount;
}
public Pager setTotalCount(int totalCount) {
this.totalCount = totalCount;
return this;
}
public List<T> getList() {
return list;
}
public Pager setList(List<T> list) {
this.list = list;
return this;
}
}
IdRequest公共请求类
public class IdRequest extends BaseDTO {
private Long id;
public Long getId() {
return id;
}
public IdRequest setId(Long id) {
this.id = id;
return this;
}
}
2.3、编写代码生成器
前两部分主要介绍的是如何获取对应的表结构，以及代码器运行之前的准备工作。
其实代码生成器，很简单，其实就是一个main方法，没有想象中的那么复杂。
处理思路也很简单，过程如下：
- 1、定义基本变量，例如包名路径、模块名、表名、转换后的实体类、以及数据库连接配置，我们可以将其写入配置文件
- 2、读取配置文件，封装对应的模板中定义的变量
- 3、根据对应的模板文件和变量，生成对应的java文件
2.3.1、创建配置文件，定义变量
小编我用的是application.properties配置文件来定义变量，这个没啥规定，你也可以自定义文件名，内容如下：
#包前缀
packageNamePre=com.example.generator
#模块名称
moduleName=test
#表
tableName=test_db
#实体类名称
entityName=TestEntity
#主键ID
primaryId=id
#作者
authorName=pzblog
#数据库名称
databaseName=yjgj_base
#数据库服务器IP地址
ipName=127.0.0.1
#数据库服务器端口
portName=3306
#用户名
userName=root
#密码
passWord=123456
#文件输出路径，支持自定义输出路径，如果为空，默认取当前工程的src/main/java路径
outUrl=
2.3.2、根据模板生成对应的java代码
- 首先，读取配置文件变量
public class SystemConstant {
private static Properties properties = new Properties();
static {
try {
// 加载上传文件设置参数：配置文件
properties.load(SystemConstant.class.getClassLoader().getResourceAsStream("application.properties"));
} catch (IOException e) {
e.printStackTrace();
}
}
public static final String tableName = properties.getProperty("tableName");
public static final String entityName = properties.getProperty("entityName");
public static final String packageNamePre = properties.getProperty("packageNamePre");
public static final String outUrl = properties.getProperty("outUrl");
public static final String databaseName = properties.getProperty("databaseName");
public static final String ipName = properties.getProperty("ipName");
public static final String portName = properties.getProperty("portName");
public static final String userName = properties.getProperty("userName");
public static final String passWord = properties.getProperty("passWord");
public static final String authorName = properties.getProperty("authorName");
public static final String primaryId = properties.getProperty("primaryId");
public static final String moduleName = properties.getProperty("moduleName");
}
- 然后，封装对应的模板中定义的变量
public class CodeService {
public void generate(Map<String, Object> templateData) {
//包前缀
String packagePreAndModuleName = getPackagePreAndModuleName(templateData);
//支持对应实体插入在前面，需要带上%s
templateData.put("entityPackageName", String.format(packagePreAndModuleName + ".entity",
templateData.get("entityName").toString().toLowerCase()));
templateData.put("dtoPackageName", String.format(packagePreAndModuleName + ".dto",
templateData.get("entityName").toString().toLowerCase()));
templateData.put("voPackageName", String.format(packagePreAndModuleName + ".vo",
templateData.get("entityName").toString().toLowerCase()));
templateData.put("daoPackageName", String.format(packagePreAndModuleName + ".dao",
templateData.get("entityName").toString().toLowerCase()));
templateData.put("mapperPackageName", packagePreAndModuleName + ".mapper");
templateData.put("servicePackageName", String.format(packagePreAndModuleName + ".service",
templateData.get("entityName").toString().toLowerCase()));
templateData.put("serviceImplPackageName", String.format(packagePreAndModuleName + ".service.impl",
templateData.get("entityName").toString().toLowerCase()));
templateData.put("controllerPackageName", String.format(packagePreAndModuleName + ".web",
templateData.get("entityName").toString().toLowerCase()));
templateData.put("apiTestPackageName", String.format(packagePreAndModuleName + ".junit",
templateData.get("entityName").toString().toLowerCase()));
templateData.put("currentTime", new SimpleDateFormat("yyyy-MM-dd").format(new Date()));
//======================生成文件配置======================
try {
// 生成Entity
String entityName = String.format("%s", templateData.get("entityName").toString());
generateFile("entity.ftl", templateData, templateData.get("entityPackageName").toString(), entityName+".java");
// 生成dto
String dtoName = String.format("%sDTO", templateData.get("entityName").toString());
templateData.put("dtoName", dtoName);
generateFile("dto.ftl", templateData, templateData.get("dtoPackageName").toString(),
dtoName + ".java");
// 生成VO
String voName = String.format("%sVO", templateData.get("entityName").toString());
templateData.put("voName", voName);
generateFile("vo.ftl", templateData, templateData.get("voPackageName").toString(),
voName + ".java");
// 生成DAO
String daoName = String.format("%sDao", templateData.get("entityName").toString());
templateData.put("daoName", daoName);
generateFile("dao.ftl", templateData, templateData.get("daoPackageName").toString(),
daoName + ".java");
// 生成Mapper
String mapperName = String.format("%sMapper", templateData.get("entityName").toString());
generateFile("mapper.ftl", templateData, templateData.get("mapperPackageName").toString(),
mapperName+".xml");
// 生成Service
String serviceName = String.format("%sService", templateData.get("entityName").toString());
templateData.put("serviceName", serviceName);
generateFile("service.ftl", templateData, templateData.get("servicePackageName").toString(),
serviceName + ".java");
// 生成ServiceImpl
String serviceImplName = String.format("%sServiceImpl", templateData.get("entityName").toString());
templateData.put("serviceImplName", serviceImplName);
generateFile("serviceImpl.ftl", templateData, templateData.get("serviceImplPackageName").toString(),
serviceImplName + ".java");
// 生成Controller
String controllerName = String.format("%sController", templateData.get("entityName").toString());
templateData.put("controllerName", controllerName);
generateFile("controller.ftl", templateData, templateData.get("controllerPackageName").toString(),
controllerName + ".java");
// // 生成junit测试类
// String apiTestName = String.format("%sApiTest", templateData.get("entityName").toString());
// templateData.put("apiTestName", apiTestName);
// generateFile("test.ftl", templateData, templateData.get("apiTestPackageName").toString(),
// apiTestName + ".java");
} catch (Exception e) {
e.printStackTrace();
}
}
/**
* 生成文件
* @param templateName 模板名称
* @param templateData 参数名
* @param packageName 包名
* @param fileName 文件名
*/
public void generateFile(String templateName, Map<String, Object> templateData, String packageName, String fileName) {
templateData.put("fileName", fileName);
DaseService dbService = new DaseService(templateData);
// 获取数据库参数
if("entity.ftl".equals(templateName) || "mapper.ftl".equals(templateName)){
dbService.getAllColumns(templateData);
}
try {
// 默认生成文件的路径
FreeMakerUtil freeMakerUtil = new FreeMakerUtil();
freeMakerUtil.generateFile(templateName, templateData, packageName, fileName);
} catch (Exception e) {
e.printStackTrace();
}
}
/**
* 封装包名前缀
* @return
*/
private String getPackagePreAndModuleName(Map<String, Object> templateData){
String packageNamePre = templateData.get("packageNamePre").toString();
String moduleName = templateData.get("moduleName").toString();
if(StringUtils.isNotBlank(moduleName)){
return packageNamePre + "." + moduleName;
}
return packageNamePre;
}
}
- 接着，获取模板文件，并生成相应的模板文件
public class FreeMakerUtil {
/**
* 根据Freemark模板，生成文件
* @param templateName:模板名
* @param root：数据原型
* @throws Exception
*/
public void generateFile(String templateName, Map<String, Object> root, String packageName, String fileName) throws Exception {
FileOutputStream fos=null;
Writer out =null;
try {
// 通过一个文件输出流，就可以写到相应的文件中，此处用的是绝对路径
String entityName = (String) root.get("entityName");
String fileFullName = String.format(fileName, entityName);
packageName = String.format(packageName, entityName.toLowerCase());
String fileStylePackageName = packageName.replaceAll("\\.", "/");
File file = new File(root.get("outUrl").toString() + "/" + fileStylePackageName + "/" + fileFullName);
if (!file.getParentFile().exists()) {
file.getParentFile().mkdirs();
}
file.createNewFile();
Template template = getTemplate(templateName);
fos = new FileOutputStream(file);
out = new OutputStreamWriter(fos);
template.process(root, out);
out.flush();
} catch (Exception e) {
e.printStackTrace();
} finally {
try {
if (fos != null){
fos.close();
}
if(out != null){
out.close();
}
} catch (IOException e) {
e.printStackTrace();
}
}
}
/**
*
* 获取模板文件
*
* @param name
* @return
*/
public Template getTemplate(String name) {
try {
Configuration cfg = new Configuration(Configuration.VERSION_2_3_23);
cfg.setClassForTemplateLoading(this.getClass(), "/ftl");
Template template = cfg.getTemplate(name);
return template;
} catch (IOException e) {
e.printStackTrace();
}
return null;
}
}
- 最后，我们编写一个
main方法，看看运行之后的效果
public class GeneratorMain {
public static void main(String[] args) {
System.out.println("生成代码start......");
//获取页面或者配置文件的参数
Map<String, Object> templateData = new HashMap<String, Object>();
templateData.put("tableName", SystemConstant.tableName);
System.out.println("表名=="+ SystemConstant.tableName);
templateData.put("entityName", SystemConstant.entityName);
System.out.println("实体类名称=="+ SystemConstant.entityName);
templateData.put("packageNamePre", SystemConstant.packageNamePre);
System.out.println("包名前缀=="+ SystemConstant.packageNamePre);
//支持自定义输出路径
if(StringUtils.isNotBlank(SystemConstant.outUrl)){
templateData.put("outUrl", SystemConstant.outUrl);
} else {
String path = GeneratorMain.class.getClassLoader().getResource("").getPath() + "../../src/main/java";
templateData.put("outUrl", path);
}
System.out.println("生成文件路径为=="+ templateData.get("outUrl"));
templateData.put("authorName", SystemConstant.authorName);
System.out.println("以后代码出问题找=="+ SystemConstant.authorName);
templateData.put("databaseName", SystemConstant.databaseName);
templateData.put("ipName", SystemConstant.ipName);
templateData.put("portName", SystemConstant.portName);
templateData.put("userName", SystemConstant.userName);
templateData.put("passWord", SystemConstant.passWord);
//主键ID
templateData.put("primaryId", SystemConstant.primaryId);
//模块名称
templateData.put("moduleName", SystemConstant.moduleName);
CodeService dataService = new CodeService();
try {
//生成代码文件
dataService.generate(templateData);
} catch (Exception e) {
e.printStackTrace();
}
System.out.println("生成代码end......");
}
}
结果如下：
- 生成的 Controller 层代码如下
/**
*
* @ClassName: TestEntityController
* @Description: 外部访问接口
* @author pzblog
* @date 2020-11-16
*
*/
@RestController
@RequestMapping("/testEntity")
public class TestEntityController {
@Autowired
private TestEntityService testEntityService;
/**
* 分页列表查询
* @param request
*/
@PostMapping(value = "/getPage")
public Pager<TestEntityVO> getPage(@RequestBody TestEntityDTO request){
return testEntityService.getPage(request);
}
/**
* 查询详情
* @param request
*/
@PostMapping(value = "/getDetail")
public TestEntityVO getDetail(@RequestBody IdRequest request){
TestEntity source = testEntityService.selectById(request.getId());
if(Objects.nonNull(source)){
TestEntityVO result = new TestEntityVO();
BeanUtils.copyProperties(source, result);
return result;
}
return null;
}
/**
* 新增操作
* @param request
*/
@PostMapping(value = "/save")
public void save(TestEntityDTO request){
TestEntity entity = new TestEntity();
BeanUtils.copyProperties(request, entity);
testEntityService.insert(entity);
}
/**
* 编辑操作
* @param request
*/
@PostMapping(value = "/edit")
public void edit(TestEntityDTO request){
TestEntity entity = new TestEntity();
BeanUtils.copyProperties(request, entity);
testEntityService.updateById(entity);
}
/**
* 删除操作
* @param request
*/
@PostMapping(value = "/delete")
public void delete(IdRequest request){
testEntityService.deleteById(request.getId());
}
}
至此，一张单表的90%的基础工作量全部开发完毕！
三、总结
代码生成器，在实际的项目开发中应用非常的广，本文主要以freemaker模板引擎为基础，开发的一套全自动代码生成器，一张单表的CRUD，只需要5秒钟就可以完成！
最后多说一句，如果你是项目中的核心开发，那么掌握代码生成器的规则，对项目开发效率的提升会有非常直观的帮助！
如果想要获取源代码，关注下方公众号，并回复【cccc4】即可获取！