Can you believe it? It took me only two days to develop a management system

Preface ：
Because of the epidemic , The school informed that the summer vacation will be held in advance this semester , So the teacher announced the final homework to the public in advance , Develop a department store center supply chain management system according to the requirements , The development cycle is half a month , The title cannot be changed , Including early database design 、 System requirements document , In the later stage, it should be submitted in the form of text . Come here , Tell the truth , I'm in a panic ！！ That's why let's start from 0 To 1 Build a project by yourself , The key is to work in groups ！

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  This article was originally compiled by paidaxing

  Series column ： The project from 0 build

  This series of projects from the design to the realization of the source code are all open source, free to learn and use , Pursue the ideal together , Welcome to supervise the development of punch in ！

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  Difficulty analysis

​ Although, when I heard the news , I'm still shocked , After all, it is a complete management system , The function interface should not be too simple . And from the database design to the delivery of the whole system is completed by one person , The challenge effect will directly fill ！ But calm down and think , It's not that hard , The overall project process is ： Design ——> file ——> code ——> deliver . After the overall process is clarified , Start to realize from scratch step by step , I didn't expect the last step , I used it A day and a half Time for ！！ Later, it took half a day to optimize the overall project ！

  Project review

  Final effect demonstration ：

Technology selection ：

• SpringBoot
• Thymeleaf
•  Mybatis-Plus
•  MySQL
•  PageHelper
•  Lombok
•  Redis（ Later page optimization ）

  Project business process introduction

​ Login module 、 User module management and user role assignment , Management of news announcement module 、 Commodity module （ Including goods 、 Classification of goods 、 Order ） Management of 、 Management of role module ; Whether the front-end resource has permission to operate the resource , It uses thymeleaf Template syntax for judgment and identification, file upload and other basic functions .

  Project structures, ( Using a template engine )

1. First create Maven project

Introduce corresponding dependencies , Build the required file directory

2. To write yaml The configuration file

server:  port: 8080spring:  datasource:    driver-class-name: com.mysql.cj.jdbc.Driver    url: jdbc:mysql://localhost:3306/supplier?useUnicode=true&characterEncoding=utf8&serverTimezone=GMT%2B8    username: root    password: root  # thymeleaf  To configure   thymeleaf:    #  Turn off caching     cache: false    prefix: classpath:/templates/mybatis-plus:  mapper-locations: classpath*:/mapper/**/*.xml

3. The initial stage of the project is basically built

​ At the beginning of building a project , In order to make the system appear more standardized , I usually make the basic configuration and declaration in advance , The technologies involved in a project from the beginning and some basic configurations corresponding to these technologies , We should plan clearly in advance （ Personal habits ）. such as ： exception handling 、 Interceptor 、 filter 、 Constant classes, etc .

① exception handling

@ControllerAdvicepublic class ExceptionHandler {    private final org.slf4j.Logger logger = LoggerFactory.getLogger(this.getClass());    @org.springframework.web.bind.annotation.ExceptionHandler(Exception.class)    public ModelAndView exception(HttpServletRequest request, Exception e ) throws Exception {        logger.error("Request URL:{},Exception:{}",request.getRequestURL(),e);        if (AnnotationUtils.findAnnotation(e.getClass(), ResponseStatus.class )!= null){            throw e;        }        ModelAndView mv = new ModelAndView();        mv.addObject("url",request.getRequestURL());        mv.addObject("exception",e);        mv.setViewName("error/error");        return mv;    }}

② Interceptor

​ Interceptors are mainly used to process some resources , Similar to some resources that require users to log in before they can access , Some are not needed , such as ： The login function does not need to be blocked , The various management of users need to add interception operations , Only in this way can the security of the system be improved .

Login blocking

public class LoginInterceptor extends HandlerInterceptorAdapter {    @Override    public boolean preHandle(HttpServletRequest request, HttpServletResponse response, Object handler) throws Exception {        if (request.getSession().getAttribute("user") == null){            response.sendRedirect("/api");            return false;        }        return true;    }}

Resource release

@Configurationpublic class WebConfig extends WebMvcConfigurerAdapter {    @Override    public void addInterceptors(InterceptorRegistry registry) {        registry.addInterceptor(new LoginInterceptor())                .addPathPatterns("/api/**")                .excludePathPatterns("/api","/api/doLogin");    }}

4. To write Controller Front end controller code

First create a FileController class

① Jump to the page of file upload

// Jump to the page of file upload @RequestMapping("/file-upload")public String userList(){  return "file-upload";}

② Realize the function of file upload

@RequestMapping("/doAddForUser")public String doAdd(User user, @RequestParam("file") MultipartFile files, HttpServletRequest request) throws IOException {  //String path = null;  if (files != null && !files.isEmpty()){    String name = UUID.randomUUID().toString().replace("-","");    // Get the extension of the file     String ext = FilenameUtils.getExtension(files.getOriginalFilename());    // Set the path of file upload     String url =request.getSession().getServletContext().getRealPath("/upload/");    File file = new File(url);    if (!file.exists()){      file.mkdir();    }    // Test path     System.out.println(request.getServletPath()+ "/upload");    System.out.println(request.getContextPath() + "/upload/");    // Save the renamed file in an absolute path     files.transferTo(new File(url+"/"+name+"."+ext));    user.setAvatar(request.getContextPath() + "/upload/"+name+"."+ext);  }  user.setId(UUID.randomUUID().toString());  String salt = PasswordUtils.getSalt();  String password = user.getPassword();  String encode = PasswordUtils.encode(password, salt);  user.setSalt(salt) ;  user.setPassword(encode);  user.setCreateTime(new Date());  userService.save(user);  return "redirect:/api/users";}

notes ： How to upload multiple files? The changes are as follows ：

③ Realize multi file upload function

In this project, the multi file upload function is not realized

private void commons(Object obj, @RequestParam("file") CommonsMultipartFile[] files, HttpServletRequest request) throws IOException {    //String path = null;    for (int i = 0; i < files.length; i++) {        if (files[i] != null && !files[i].isEmpty()){            String name = UUID.randomUUID().toString().replace("-","");            // Get the extension of the file             String ext = FilenameUtils.getExtension(files[i].getOriginalFilename());            // Set the path of file upload             String url =request.getSession().getServletContext().getRealPath("/upload/");            File file = new File(url);            if (!file.exists()){                file.mkdir();            }            // Test path             System.out.println(request.getServletPath()+ "/upload");            System.out.println(request.getContextPath() + "/upload/");            // Save the renamed file in an absolute path             files[i].transferTo(new File(url+"/"+name+"."+ext));            if (i == 0){                obj.setUrl1(request.getContextPath() + "/upload/"+name+"."+ext);            }            if (i == 1){                obj.setUrl2(request.getContextPath() + "/upload/"+name+"."+ext);            }            if (i == 2){                obj.setUrl3(request.getContextPath() + "/upload/"+name+"."+ext);            }            if (i == 3){                obj.setUrl4(request.getContextPath() + "/upload/"+name+"."+ext);            }            if (i == 4){                obj.setUrl5(request.getContextPath() + "/upload/"+name+"."+ext);            }        }    }}

5. Project optimization

​ For items where the front and rear ends are not separated , Most use Page cache optimization , When the system suffers huge flow at a moment , When the first user accesses a page, the page data can be cached , such , Later, the pages visited by users are obtained from the cache , This reduces Operation on Database , Reduced the pressure on the database , So as to achieve optimal processing .

① Import dependence

<!--Redis--><dependency>  <groupId>org.springframework.boot</groupId>  <artifactId>spring-boot-starter-data-redis</artifactId></dependency><!--commons-pools2  Object pool dependency --><dependency>  <groupId>org.apache.commons</groupId>  <artifactId>commons-pool2</artifactId></dependency>

② yaml To configure

## Redis To configure   redis:    #  Server address     host: localhost    #  port     port: 6379    #  database     database: 0    #  Timeout time     connect-timeout: 10000ms    lettuce:      pool:        #  maximum connection         max-active: 8        #  Maximum connection blocking wait time   Default  -1        max-wait: 10000ms        #  Maximum free time   Default 8        max-idle: 200        #  Minimum free connection   Default 8        min-idle: 5

④ Redis Serialization

@Configurationpublic class RedisConfig {    @Bean    public RedisTemplate<String,Object>  redisTemplate(RedisConnectionFactory redisConnectionFactory){        RedisTemplate<String,Object> redisTemplate = new RedisTemplate<>();        //key serialize         redisTemplate.setKeySerializer(new StringRedisSerializer());        //value serialize         redisTemplate.setValueSerializer(new GenericJackson2JsonRedisSerializer());        //hash type key Serialization         redisTemplate.setHashKeySerializer(new StringRedisSerializer());        //hash type value Serialization         redisTemplate.setHashValueSerializer(new GenericJackson2JsonRedisSerializer());        redisTemplate.setConnectionFactory(redisConnectionFactory);        return redisTemplate;    }}

③ Optimize processing

    @Autowired    private NewsService newsService;    @Autowired    private RedisTemplate redisTemplate;    @Autowired    private ThymeleafViewResolver viewResolver;    @RequestMapping(value = "/news",produces = "text/html;charset=utf-8")    @ResponseBody    public String roles(Model model, @RequestParam(value = "pageNo",defaultValue = "1")Integer pageNo            , @RequestParam(value = "pageSize",defaultValue = "10")Integer pageSize            , HttpServletRequest request, HttpServletResponse response){				//Redis Get page , If it's not empty , Then go back to the page         ValueOperations valueOperations = redisTemplate.opsForValue();        String html = (String) valueOperations.get("news-list");        if (!StringUtils.isEmpty(html)){            return html;        }        PageHelper.startPage(pageNo,pageSize);        List<News> list = newsService.list();        PageInfo<News> pageInfo = new PageInfo<>(list);        model.addAttribute("news",list);        model.addAttribute("pageInfo",pageInfo);      	// If it is empty , Manual rendering , Deposit in Redis And in return         WebContext context = new WebContext(request, response, request.getServletContext(), request.getLocale(), model.asMap());        html = viewResolver.getTemplateEngine().process("news-list", context);        if (!StringUtils.isEmpty(html)){          	// Set the expiration time for the cache             valueOperations.set("news-list",html,60, TimeUnit.SECONDS);        }        return html;    }

④ Redis see

6. matters needing attention

1. Be careful @Controller and @RestController The difference between , This project uses the template to render the page , and @Controller Is used to respond to the page ; and @RestController It's used to return to Json

2. In the project optimization stage, you need to add notes on the method @ResponseBody, Because we cache the whole page , So convert the page into JSON For storage .
   

3. Inject Thymeleaf Parser , Will be specific The page is parsed into Json String to store
   

4. Will deposit Redis Data in plus expiration time , Because the data in the page should be consistent with the database , If the user sees the data tens of seconds or a minute ago, it is still barely acceptable .
   

At present, the code has been synchronized to Paidaxing department store center management system

If necessary, go to the warehouse and pick it up by yourself , Please don't be stingy with the three companies in your hands ！