Spring Boot 文件操做，上傳、瀏覽和刪除

視頻演示:
https://www.bilibili.com/video/BV1rv411B7fs/

一塊兒來完成如下步驟:

該工程演示Spring Boot如何上傳、展現和刪除文件

1. 頁面引擎採用Thymeleaf
2. 後端使用Spring Boot
3. 文件上傳使用Form提交方式(而不是Ajax方式或VUE先後端分離)

FileControlle.java

package com.deepincoding.fileuploadformpage;

import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.beans.factory.annotation.Value;
import org.springframework.core.io.Resource;
import org.springframework.core.io.UrlResource;
import org.springframework.http.HttpHeaders;
import org.springframework.http.ResponseEntity;
import org.springframework.stereotype.Controller;
import org.springframework.ui.Model;
import org.springframework.util.FileSystemUtils;
import org.springframework.util.StringUtils;
import org.springframework.web.bind.annotation.*;
import org.springframework.web.multipart.MultipartFile;
import org.springframework.web.servlet.mvc.method.annotation.MvcUriComponentsBuilder;

import java.io.IOException;
import java.net.MalformedURLException;
import java.nio.file.Files;
import java.nio.file.Path;
import java.nio.file.Paths;
import java.nio.file.StandardCopyOption;
import java.util.List;
import java.util.stream.Collectors;

@Controller
public class FileController {

    //上傳文件路徑
    @Value("${file.base.director}")
    private String fileBaseDirector;
    private Path fileBasePath;

    @Autowired
    private void createDirectories(){
        try {
            Files.createDirectories(Paths.get(fileBaseDirector));
        } catch (IOException e) {
            e.printStackTrace();
        }
        this.fileBasePath = Path.of(fileBaseDirector);
    }

    /**
     * 首頁
     * @return
     */
    @GetMapping("/")
    public String index(){
        return "index";
    }

    /**
     * 上傳頁面
     * @return
     */
    @GetMapping("/upload")
    public String upload(){
        return "upload";
    }

    /**
     * 獲取文件列表
     * @return
     * @throws IOException
     */
    @GetMapping("/files")
    public String files(Model model)  throws IOException {
        List<FileObject> filesAll = Files.walk(fileBasePath,1)
                .filter(path -> !path.equals(fileBasePath))
                .map(path -> {
                    String url = MvcUriComponentsBuilder.fromMethodName(FileController.class,"loadFile",path.getFileName().toString()).build().toString();
                    FileObject  fileObject = new FileObject(path.getFileName().toString(),url);
                    return fileObject;
                }).collect(Collectors.toList());
        model.addAttribute("files",filesAll);
        return "files";
    }

    /**
     * 刪除文件
     * @param fileName
     * @return
     */
    @GetMapping("/delete/{fileName}")
    public String deleteFile(@PathVariable String fileName){
        Path deletePath = fileBasePath.resolve(fileName);
        Boolean isDelete = Boolean.FALSE;
        try {
            isDelete = FileSystemUtils.deleteRecursively(deletePath);
        } catch (IOException e) {
            e.printStackTrace();
        }
        return "redirect:/files";
    }

    
    /**
     * 上傳文件事件
     * @param file
     * @return
     */
    @PostMapping("/upload")
    public String upload(@RequestParam("file") MultipartFile file){
        String fileName = StringUtils.cleanPath(file.getOriginalFilename());
        Path path = Path.of(fileBaseDirector + fileName);
        try {
            Files.copy(file.getInputStream(),path,StandardCopyOption.REPLACE_EXISTING);
        } catch (IOException e) {
            e.printStackTrace();
        }
        return "redirect:/files";
    }


}