java上传文件

上传文件

1.上传文件原理

2.使用fileupload的jar包代码实现

String tempPath = this.getServletContext().getRealPath("temp");
        DiskFileItemFactory factory=new DiskFileItemFactory(1024*1024,new File(tempPath));
        
        ServletFileUpload upload=new ServletFileUpload(factory);
        upload.setHeaderEncoding("utf-8");
        try {
            @SuppressWarnings("unchecked")
            List<FileItem> items = upload.parseRequest(request);
            if(items!=null){
                for (FileItem fileItem : items) {
                    if(fileItem.isFormField()){
                        String fieldName = fileItem.getFieldName();
                        String value = fileItem.getString("utf-8");
                        System.out.println(fieldName+"----->"+value);
                    }else{
                        String fileName = fileItem.getName();
                        InputStream in = fileItem.getInputStream();
                        StringBuilder filePath=new StringBuilder(this.getServletContext().getRealPath("upload"));
                        filePath.append("/").append(new Date().getTime()).append(fileName.substring(fileName.lastIndexOf(".")));
                        OutputStream out=new FileOutputStream(filePath.toString());
                        byte[] b=new byte[1024];
                        int len=0;
                        while((len=in.read(b))!=-1){
                            out.write(b, 0, len);
                        }
                        out.close();
                        in.close();
                        fileItem.delete();
                    }
                }
            }
        } catch (FileUploadException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        }