HttpClient发送get请求带参数实例

1.前端from表达提交参数，所要下载的文件路径为其他系统数据，因此，本地后台需要写个请求去得到数据，直接上代码
前端请求参数：

var jsonParam = {
		title : title,
		partPath : partPath,
		modelId : modelId,
		exportTemplate : exportTemplate,
		officeCode : officeCode,
        orderNo : orderNo,
		currentUserId : currentUserId,
		newTitle : newTitle,
		exportFileType : exportFileType,
		
		fileType : fileType
	};
	var form = document.createElement("form");
	form.setAttribute("method", "get");
	form.setAttribute("action", "/uploadFile/getLuoHuoPaperDownLoad.do");
	var hiddenField = document.createElement("input");
	hiddenField.setAttribute("type", "hidden");
	hiddenField.setAttribute("name", "param");
	hiddenField.setAttribute("value", JSON.stringify(jsonParam));
	form.appendChild(hiddenField);
	document.body.appendChild(form);
	form.submit();

后端代码展示，转译字符格式是参数的形式，此处参数不认String类型，所以得先转化，转化后因为是GET请求，则直接拼接到HttpGet 里面的url后面，url为动态的的获取，根据项目需要本地自行截取转化。如url不变，可以直接写死。execute发送之后获取到的是文件流，则直接输出，自己设置文件名。这样，文件流就输出到文件里啦。

   /*
	 * 获取落货纸打印数据
	 */
	@RequestMapping(value = "getLuoHuoPaperDownLoad.do", method = RequestMethod.GET)
	@ResponseBody
	public ResponseEntity getLuoHuoPaperDownLoad(HttpServletRequest request, HttpServletResponse httpResponse) throws Exception {
		ResponseEntity re = new ResponseEntity();
	HttpClient client = HttpClients.createDefault(); 

		//转译字符格式
	List<BasicNameValuePair> list = new ArrayList<>();
	BasicNameValuePair bn= new BasicNameValuePair("param",request.getParameter("param"));
	list.add(bn);
	String paramsStr = EntityUtils.toString(new UrlEncodedFormEntity(list, "UTF-8"));

	//获取文件名
	String jsonResult = request.getParameter("param");
	JSONObject jsonObject = new JSONObject(jsonResult);
	String orderNo = jsonObject.getString("orderNo");

	String url = Config.get("url.llnQuery");
		if (!StringUtils.isBlank(url)) {
			url = url.substring(0, url.length()-17);

		}
	HttpGet get = new HttpGet(url+"/servlet/EcExportTemplateServlet?"+paramsStr)；		
	HttpResponse responsecfs;
	responsecfs = client.execute(get);
	HttpEntity output = responsecfs.getEntity();
	
	httpResponse.setHeader("Pragma", "public");
	httpResponse.setHeader("Expires", "0");
	httpResponse.setHeader("Cache-Control",
			"must-revalidate, post-check=0, pre-check=0");
	httpResponse.setHeader("Content-Type", "application/force-download");
	httpResponse.setHeader("Content-Disposition", "attachment;filename="+orderNo+".xls");
	httpResponse.setContentType("text/html; charset=utf-8");
	OutputStream outPut1 = httpResponse.getOutputStream();
	output.writeTo(outPut1);
	outPut1.flush();
	outPut1.close();
	return re;
}	

记住，最后一定要关闭，这里重点只是将连接获取文件流，一般还得写上捕获异常，finally里面关闭文件流，一定得关闭，不然一致打开会造成服务器压力。