需求在 系统中 调用 A项目（11.aa.com）的 JS 去请求B项目(22.aa.com)的方法，上传图片，且返回 JSON 显示图片：

JS代码如下

$.ajaxFileUpload({
			url:'/uploadUserPic.html',secureuri:false,fileElementId:'userPic',dataType: 'json',data:{},success: function (data){
				$("#userPicUrl").attr("src",data.url);
				$("#avatar").val(data.url);
			},error: function (data,status,e)
			{
				alert(e);
			}
		}
	);

@ResponseBody
	@RequestMapping(method = RequestMethod.POST,value = "/uploadUserPic.html")
	public String saveUserPic(HttpServletRequest request,@RequestParam(value = "userPic",required = true) MultipartFile file)
			throws Exception {
		unpackCookie(request);
		String fileName = null;
		String realPath = com.joytrav.Constant.FILE_REAL_PATH
				+ com.joytrav.Constant.USER_UPLOAD_DIR;
		if (!file.isEmpty()) {
			String fileType = FileUtils.getFileType(file.getOriginalFilename());
			String name = RandomUtils.getRandomFileName();
			fileName = name + "." + fileType;
			byte[] bytes = file.getBytes();
			String newFileName = realPath + File.separator + fileName;
			FileOutputStream fos = new FileOutputStream(newFileName);

			fos.write(bytes); // 写入文件
			fos.close();
			File newFile = new File(newFileName);
			if (newFile.isFile()) {

				String url = "https://"+LinkConfigHolder.get().getFileDomain()+"/"
						+ USER_UPLOAD_URL + "/"
						+ fileName;
				return "{'url':'" + url + "'}";
			}
		}
		return null;
	}

如果是同顶级域名那么可以在B项目的Jsp中设置：

document.domain=obj.attr("aaa.com");

其中最好不要在input type="file"用 onchange,因为

.attr("src",data.url);

下面即可：

window.onload=function(){
	
	$("#photo1").on('change',function(){
		 uploadUserPicMore("photo1");
	})
	$("#photo2").on('change',function(){
		 uploadUserPicMore("photo2");
	})
	$("#photo3").on('change',function(){
		 uploadUserPicMore("photo3");
	})
	$("#photo4").on('change',function(){
		 uploadUserPicMore("photo4");
	});
	$("#userPic").on('change',function(){
		 uploadUserPicMore("userPic");
	});
}

function uploadUserPicMore(file){
	var id=file;
	$("#loading").ajaxStart(function(){
		$(this).show();
	}).ajaxComplete(function(){
		$(this).hide();
	});
	
	$.ajaxFileUpload(
		{
			url:'/uploadUserPic.html',fileElementId:id,success: function (data){
				$("#"+id+"-img").attr("src",data.url);
				$("#"+id+"-val").val(data.url);
			},e){
				alert(e);
			}
		}
	);
	return false;
}