文件上传：图片实例

实例：http://www.runoob.com/jsp/jsp-file-uploading.html

1.jsp

前端发送文件到后台，可以使用Form表单提交或者设置<input file onchang="checkImg(this.value)"/>，前者可以使用<button submit>，也可以使用<button οnclick="fun();">，fun（）中使用$.AjaxSubmit({...});。

<form method="post" action="/TomcatTest/UploadServlet" enctype="multipart/form-data">
    选择一个文件:
    <input type="file" name="uploadFile" />
    <br/><br/>
    <input type="submit" value="上传" />
</form>method="post" action="/TomcatTest/UploadServlet" enctype="multipart/form-data">
    选择一个文件:
    <input type="file" name="uploadFile" />
    <br/><br/>
    <input type="submit" value="上传" />
</form>

 

2.后台

 后台接收文件，使用InputStream和OutputStream将文件存储到相应位置。

1.接收

使用参数接收文件@RequestParam（value=“file”，required=“false”）MultipartFile file

2.设置路径和文件名

3.保存文件

项目路径获取，保存路径设置；判断路径是否存在，不存在则创建；

文件名获取，保存文件名设置；

InputStream和OutputStream建立，将文件输出保存到指定位置。

// 获得原始文件名  
        String fileName = file.getOriginalFilename();  
        System.out.println("原始文件名:" + fileName);  
        // 新文件名  
        String newFileName = UUID.randomUUID() + fileName;  //可自定
  
        // 获得项目的路径  
        ServletContext sc = request.getSession().getServletContext();  
        // 上传位置  
        String path = sc.getRealPath("/img") + "/"; // 设定文件保存的目录  
  
        File f = new File(path);  
        if (!f.exists())  
            f.mkdirs();  
        if (!file.isEmpty()) {  
            try {  
                FileOutputStream fos = new FileOutputStream(path + newFileName);  
                InputStream in = file.getInputStream();  
                int b = 0;  
                while ((b = in.read()) != -1) {  
                    fos.write(b);  
                }  
                fos.close();  
                in.close();  
            } catch (Exception e) {  
                e.printStackTrace();  
            }  
        }  
  
        System.out.println("上传图片到:" + path + newFileName);  
        // 保存文件地址，用于JSP页面回显  
        model.addAttribute("fileUrl", path + newFileName);  file.getOriginalFilename();  
        System.out.println("原始文件名:" + fileName);  
        // 新文件名  
        String newFileName = UUID.randomUUID() + fileName;  //可自定
  
        // 获得项目的路径  
        ServletContext sc = request.getSession().getServletContext();  
        // 上传位置  
        String path = sc.getRealPath("/img") + "/"; // 设定文件保存的目录  
  
        File f = new File(path);  
        if (!f.exists())  
            f.mkdirs();  
        if (!file.isEmpty()) {  
            try {  
                FileOutputStream fos = new FileOutputStream(path + newFileName);  
                InputStream in = file.getInputStream();  
                int b = 0;  
                while ((b = in.read()) != -1) {  
                    fos.write(b);  
                }  
                fos.close();  
                in.close();  
            } catch (Exception e) {  
                e.printStackTrace();  
            }  
        }  
  
        System.out.println("上传图片到:" + path + newFileName);  
        // 保存文件地址，用于JSP页面回显  
        model.addAttribute("fileUrl", path + newFileName); 

 

3.待测

http://blog.youkuaiyun.com/qian_ch/article/details/69258465 ：文件流上传，对象上传，文件下载

http://blog.youkuaiyun.com/evankaka/article/details/45826697/ ：文件上传，下载

https://www.cnblogs.com/fjsnail/p/3491033.html ：三种文件上传方式：Stream、Transto、Spring提供方法

1.

@RequestMapping("/onefile2")  
public String oneFileUpload2(HttpServletRequest request,  
        HttpServletResponse response) throws Exception {  
    CommonsMultipartResolver cmr = new CommonsMultipartResolver(request.getServletContext());  
    if (cmr.isMultipart(request)) {  
        MultipartHttpServletRequest mRequest = (MultipartHttpServletRequest) (request);  
        Iterator<String> files = mRequest.getFileNames();  
        while (files.hasNext()) {  
            MultipartFile mFile = mRequest.getFile(files.next());  
            if (mFile != null) {  
                String fileName = UUID.randomUUID()  
                        + mFile.getOriginalFilename();  
                String path = "d:/upload/" + fileName;  
  
                File localFile = new File(path);  
                mFile.transferTo(localFile);  
                request.setAttribute("fileUrl", path);  
            }  
        }  
    }  
    return "fileUpload";  
}  CommonsMultipartResolver cmr = new CommonsMultipartResolver(request.getServletContext());  
    if (cmr.isMultipart(request)) {  
        MultipartHttpServletRequest mRequest = (MultipartHttpServletRequest) (request);  
        Iterator<String> files = mRequest.getFileNames();  
        while (files.hasNext()) {  
            MultipartFile mFile = mRequest.getFile(files.next());  
            if (mFile != null) {  
                String fileName = UUID.randomUUID()  
                        + mFile.getOriginalFilename();  
                String path = "d:/upload/" + fileName;  
  
                File localFile = new File(path);  
                mFile.transferTo(localFile);  
                request.setAttribute("fileUrl", path);  
            }  
        }  
    }  
    return "fileUpload";  
} 

2.

//上传文件会自动绑定到MultipartFile中
     @RequestMapping(value="/upload",method=RequestMethod.POST)
     public String upload(HttpServletRequest request,
            @RequestParam("description") String description,
            @RequestParam("file") MultipartFile file) throws Exception {

        System.out.println(description);
        //如果文件不为空，写入上传路径
        if(!file.isEmpty()) {
            //上传文件路径
            String path = request.getServletContext().getRealPath("/images/");
            //上传文件名
            String filename = file.getOriginalFilename();
            File filepath = new File(path,filename);
            //判断路径是否存在，如果不存在就创建一个
            if (!filepath.getParentFile().exists()) { 
                filepath.getParentFile().mkdirs();
            }
            //将上传文件保存到一个目标文件当中
            file.transferTo(new File(path + File.separator + filename));
            return "success";
        } else {
            return "error";
        }

     }file.transferTo(new File(path + File.separator + filename));
            return "success";
        } else {
            return "error";
        }

     }