java实现web端文件上传与下载

今天药忘吃喽~ 2022-07-13 14:50 199阅读 0赞

在项目开发中经常会遇到文件的上传于下载功能,在此做详细的总结,以备不时之需~~

前端上传代码:

**注意: **accept属性值是用于默认点击上传显示的文件格式,并不能限制上传格式,如要限制,还是后台校验,在此不做赘述.

此处以pdf为例

accept 支持全部格式参考:[点此查看][Link 1]

后端代码:

上传:

MultipartHttpServletRequest multipartRequest = (MultipartHttpServletRequest) request;  
            CommonsMultipartFile applyFile = (CommonsMultipartFile) multipartRequest.getFile("file");  
                String versionId = sdf.format(now);//以当前时间为版本id--存在风险  
                String fileUrl = "";  
                if(applyFile != null){  
                    String fileName = applyFile.getOriginalFilename();  
                    if(fileName == null || "".equals(fileName)){  
                        return false;  
                    }  
                    System.out.println("文件名称:"+fileName);  
                    // 获取路径  
                    String applyPath = request.getSession().getServletContext()  
                            .getRealPath("/")+ "uploads/files/";  
      
                    // 创建文件目录  
                    File dirPath = new File(applyPath);  
                    if (!dirPath.exists()) {  
                        dirPath.mkdirs();  
                    }  
                      
                    String prefix = fileName.substring(fileName.lastIndexOf(".")+1);//获取文件后缀名  
                    String absFileUrl = applyPath + versionId +"."+prefix;//文件绝对路径  
                    fileUrl = "uploads/files/" + versionId +"."+prefix;//相对路径  
                    File uploadFile = new File(absFileUrl);  
                    System.out.println("上传后文件路径:"+absFileUrl);  
                    //上传  
                    FileCopyUtils.copy(applyFile.getBytes(), uploadFile);  
                }

下载:

public void download(HttpServletRequest request,HttpServletResponse response, String fileUrl, String fileName) {  
             java.io.BufferedInputStream bis = null;    
                java.io.BufferedOutputStream bos = null;    
                try {    
                    // 客户使用保存文件的对话框：    
                    fileUrl = new String(fileUrl.getBytes("utf-8"), "utf-8");    
                    response.setContentType("application/x-msdownload");    
                    response.setCharacterEncoding("utf-8");    
                    response.setHeader("Content-disposition", "attachment; filename="    
                            + fileName);    
                    // 通知客户文件的MIME类型：    
                    bis = new java.io.BufferedInputStream(new java.io.FileInputStream(    
                            (fileUrl)));    
                    bos = new java.io.BufferedOutputStream(response.getOutputStream());    
                    byte[] buff = new byte[2048];    
                    int bytesRead;    
                    int i = 0;    
            
                    while (-1 != (bytesRead = bis.read(buff, 0, buff.length))) {    
                        bos.write(buff, 0, bytesRead);    
                        i++;    
                    }    
                    bos.flush();    
                } catch (Exception e) {    
                    e.printStackTrace();    
                } finally {    
                    if (bis != null) {    
                        try {    
                            bis.close();    
                        } catch (IOException e) {    
                            // TODO Auto-generated catch block    
                            e.printStackTrace();    
                        }    
                        bis = null;    
                    }    
                    if (bos != null) {    
                        try {    
                            bos.close();    
                        } catch (IOException e) {    
                            // TODO Auto-generated catch block    
                            e.printStackTrace();    
                        }    
                        bos = null;    
                    }    
                }    
        }

[Link 1]: http://blog.csdn.net/mixika99/article/details/54408079