<!DOCTYPE html>
<html lang="en" xmlns:th="http://www.thymeleaf.org">
<head>
    <meta charset="UTF-8">
    <title>upload</title>
</head>
<body bgcolor="#CED3FE">
<img src="images/1.GIF"/>
<hr/>
<div style="text-align: center">
    <h1>注冊用戶~</h1>
    <form action="#" th:action="@{/upload}" method="post" enctype="multipart/form-data">
        用戶名:<input type="text" style="width:150px" name="name"/><br/><br/>
        電　郵:<input type="text" style="width:150px" name="email"/><br/><br/>
        年　齡:<input type="text" style="width:150px" name="age"/><br/><br/>
        職　位:<input type="text" style="width:150px" name="job"/><br/><br/>
        頭　像:<input type="file" style="width:150px" name="header"><br/><br/>
        寵　物:<input type="file" style="width:150px" name="photos" multiple><br/><br/>
        <input type="submit" value="注冊"/>
        <input type="reset" value="重新填寫"/>
    </form>
</div>
<hr/>
</body>
</html>

2.創(chuàng)建src\main\java\com\llp\springboot\controller\UploadController.java

@Slf4j
@Controller
public class UploadController {
    //處理轉(zhuǎn)發(fā)到用戶注冊-可以完成文件上傳頁面
    @GetMapping("/upload.html")
    public String uploadPage() {
        return "upload";// 視圖解析,轉(zhuǎn)發(fā)到templates/upload.html
    }
    @PostMapping("/upload")
    @ResponseBody
    public String upload(@RequestParam("name") String name,
                         @RequestParam("email") String email,
                         @RequestParam("age") Integer age,
                         @RequestParam("job") String job,
                         @RequestParam("header") MultipartFile header,
                         @RequestParam("photos") MultipartFile[] photos) throws IOException {
        log.info("name:{},email:{},age:{},job:{},header.size:{},photos.length:{}",name,email,age,job,header.getSize(),photos.length);
        //1.獲取源文件名稱
        String originalFilename = header.getOriginalFilename();
        // /E:/IdeaProjects/springboot-sysuser/target/classes/
        String path = ResourceUtils.getURL("classpath:").getPath();
        System.out.println(path);
        File file = new File(path+"static/images/upload/");
        if(!file.exists()){
            file.mkdirs();
        }
        header.transferTo(new File(path+"static/images/upload/"+originalFilename));
        return "注冊用戶成功/文件上傳成功";
    }
}

3.引出兩個(gè)問題

1.文件覆蓋問題

上面的示例中實(shí)現(xiàn)了文件的上傳，但當(dāng)兩個(gè)不同的文件文件名相同時(shí)會(huì)存在文件覆蓋的問題，如何解決呢？

@PostMapping("/upload")
@ResponseBody
public String upload(@RequestParam("name") String name,
                     @RequestParam("email") String email,
                     @RequestParam("age") Integer age,
                     @RequestParam("job") String job,
                     @RequestParam("header") MultipartFile header,
                     @RequestParam("photos") MultipartFile[] photos) throws IOException {
    log.info("name:{},email:{},age:{},job:{},header.size:{},photos.length:{}",name,email,age,job,header.getSize(),photos.length);
    //1.獲取源文件名稱
    String originalFilename = header.getOriginalFilename();
    originalFilename = UUID.randomUUID().toString().replaceAll("-","")+System.nanoTime()+originalFilename;
    //2.獲取文件上傳的路徑
    // /E:/IdeaProjects/springboot-sysuser/target/classes/
    String path = ResourceUtils.getURL("classpath:").getPath();
    System.out.println(path);
    //3.動(dòng)態(tài)的創(chuàng)建文件上傳目錄
    File file = new File(path+"static/images/upload/");
    if(!file.exists()){
        file.mkdirs();
    }
    //4.將文件傳輸?shù)侥繕?biāo)目錄
    header.transferTo(new File(path+"static/images/upload/"+originalFilename));
    return "注冊用戶成功/文件上傳成功";
}

originalFilename = UUID.randomUUID().toString().replaceAll("-","")+System.nanoTime()+originalFilename;，實(shí)現(xiàn)思路就是給上傳的文件重新指定一個(gè)不重復(fù)的文件名

2.將文件都上傳到一個(gè)目錄下，當(dāng)上傳文件很多時(shí)，會(huì)造成訪問文件速度變慢

解決思路：將文件上傳到不同目錄比如一天上傳的文件，統(tǒng)一放到一個(gè)文件夾年/月/日, 比如 2022/11/11 目錄

public class WebUtils {
    //定義一個(gè)文件上傳的路徑
    public static String  UPLOAD_FILE_DIRECTORY = "static/images/upload/";
    //編寫方法，生成一個(gè)目錄-根據(jù)當(dāng)前日期 年/月/日
    public static String getUploadFileDirectory() {
        return UPLOAD_FILE_DIRECTORY + new SimpleDateFormat("yyyy/MM/dd").format(new Date());
    }
}

@PostMapping("/upload")
@ResponseBody
public String upload(@RequestParam("name") String name,
                     @RequestParam("email") String email,
                     @RequestParam("age") Integer age,
                     @RequestParam("job") String job,
                     @RequestParam("header") MultipartFile header,
                     @RequestParam("photos") MultipartFile[] photos) throws IOException {
    //輸出獲取到的信息
    log.info("上傳的信息 name={} email={} age={} job={} header={} photos={} ",
            name, email, age, job, header.getSize(), photos.length);
    //得到類路徑(運(yùn)行的時(shí)候)
    String path = ResourceUtils.getURL("classpath:").getPath();
    //log.info("path={}", path);
    //動(dòng)態(tài)創(chuàng)建指定目錄
    File file = new File(path + WebUtils.getUploadFileDirectory());
    if (!file.exists()) {//如果目錄不存在，我們就創(chuàng)建, 在java io
        file.mkdirs();
    }
    if (!header.isEmpty()) {//處理頭像
        //獲取上傳文件的名字
        String originalFilename = header.getOriginalFilename();
        String fileName = UUID.randomUUID().toString() + "_" + System.currentTimeMillis() + "_" + originalFilename;
        //保存到動(dòng)態(tài)創(chuàng)建的目錄
        header.transferTo(new File(file.getAbsolutePath() + "/" + fileName));
    }
    //處理多個(gè)文件
    if (photos.length > 0) {
        for (MultipartFile photo : photos) {//遍歷
            if (!photo.isEmpty()) {
                String originalFilename = photo.getOriginalFilename();
                String fileName = UUID.randomUUID().toString() + "_" + System.currentTimeMillis() + "_" + originalFilename;
                //保存到動(dòng)態(tài)創(chuàng)建的目錄
                photo.transferTo(new File(file.getAbsolutePath() + "/" + fileName));
            }
        }
    }
    return "注冊用戶成功/文件上傳成功";
}