java如何发送httphead请求？
实现思路就是先定义请求头内容，之后进行请求头设置。；定义请求头；LinkedHashMap headers = new LinkedHashMap();；headers.put("Content-type","text/xml");；headers.put("Cache-Control", "no-cache");；headers.put("Connection", "close");；给HttpPost 设置请求头；
HttpPost httpPost = new HttpPost("地址");；if (headers != null) {；for (String key : headers.keySet()) {；httpPost.setHeader(key, headers.get(key));；}；}；备注：只需要在map中设置相应的请求头内容即可。根据实际需要修改即可
