文件的上传和下载-优快云博客

本文介绍了一个使用Java实现的Web应用中文件上传和下载的功能。通过MultipartFile接口处理文件上传，利用HttpServletRequest获取服务器真实路径并保存文件。下载功能则通过ResponseEntity返回文件的字节流，设置响应头信息实现。

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上传.jsp

<%@ page contentType="text/html;charset=UTF-8" language="java" %>
<html>
<body>
<h2>Hello World!</h2>
<a href="user/getjson">getjson</a>
<a href="user/getjson2">getjson2</a>
<form action="toupload" method="post" enctype="multipart/form-data" >
    username:<input type="text" name="username"><br>
    file:<input type="file" name="myfile"><br>
    <input type="submit" value="保存">
</form>
</body>
</html>

下载.jsp

<body>

<a href="down?fname=${filename}">下载</a>
   <img src="uploadimage/${filename}">
</body>

web.java


@Controller
public class JsonController {
    @RequestMapping("/toupload")
    public String upload( MultipartFile myfile,
                          String username,
                         HttpServletRequest request){

        String path=request.getRealPath("uploadimage");
        System.out.println("path="+path);
        try {
            myfile.transferTo(new File(path+"/"+myfile.getOriginalFilename()));//复制
        } catch (IOException e) {
            e.printStackTrace();
        }
        request.setAttribute("filename",myfile.getOriginalFilename());
        return "success";
    }

    @RequestMapping("/down")
    public ResponseEntity<byte[]> down(String fname,HttpServletRequest request){

        //下载的文件
        String path=request.getRealPath("/uploadimage");
        File f=new File(path+"/"+fname);
        ResponseEntity<byte[]> rsp= null;
        try {
            //设置响应的头信息
            HttpHeaders httpHeaders=new HttpHeaders();
            httpHeaders.setContentType(MediaType.APPLICATION_OCTET_STREAM);//响应的信息类型
            httpHeaders.setContentDispositionFormData("attachment", URLEncoder.encode(fname,"utf-8"));

            rsp = new ResponseEntity<byte[]>(FileUtils.readFileToByteArray(f),httpHeaders, HttpStatus.CREATED);
        } catch (IOException e) {
            e.printStackTrace();
        }
        return rsp;
    }
    }