文件上传

//1.确认该操作是否支持文件上传操作，enctype="multipart/form-data"

if(ServletFileUpload.isMultipartContent(request)){
    //2.创建磁盘工厂对象
    DiskFileItemFactory factory = new DiskFileItemFactory();
    //3.Servlet文件上传核心对象
    ServletFileUpload fileUpload = new ServletFileUpload(factory);
    //4.从request中读取数据
    List<FileItem> fileItems = fileUpload.parseRequest(request);

    for(FileItem item : fileItems){
        //5.当前表单是否是文件表单
        if(!item.isFormField()){
            //6.从临时存储文件的地方将内容写入到指定位置
            item.write(new File(this.getServletContext().getRealPath("upload"),item.getName()));
        }
    }