用httpclient下载附件文件时返回404或连接不上而失败是什么原因？

如以下url中的附件链接

http://202.38.193.153:8000/publishHtml/announcement_7852/announcement_7852.html

http://m.smtshopping.cn/news_detail.asp?id=956

但是直接点击可以下载，为什么用httpclient访问不到？

public boolean downloadAttachment(int num, String source, String title, String path, String visitingUrl)
		{
			RequestConfig requestConfig = RequestConfig.custom()
	            .setSocketTimeout(5000)//设置socket超时时间 
	            .setConnectTimeout(5000)//设置connect超时时间
	            .setRedirectsEnabled(false)//关闭自动重定向
	            .build();
			CloseableHttpClient httpClient = HttpClients.custom()
	            .setDefaultRequestConfig(requestConfig)  
	            .build();
			
			HttpGet httpGet = null;
	        	try {
					source=encodeUrl(source);
				} catch (MalformedURLException e1) {
					e1.printStackTrace();
				} catch (UnsupportedEncodingException e1) {
					e1.printStackTrace();
				}
	        	httpGet = new HttpGet(source);
	        
	        httpGet.setHeader("Accept", "text/html,application/xhtml+xml,application/octet-stream;q=0.9,*/*;q=0.8");
	        httpGet.setHeader("Accept-Charset", "GB2312,utf-8;q=0.7,*;q=0.7");  
	        httpGet.setHeader("Accept-Encoding", "gzip, deflate");  
	        httpGet.setHeader("Accept-Language", "zh-cn,zh;q=0.5");  
	        httpGet.setHeader("Connection", "keep-alive");
	        httpGet.setHeader("referer", visitingUrl);  
			CloseableHttpResponse httpResponse = null;
			try {
				httpResponse = httpClient.execute(httpGet);
			} catch (ClientProtocolException e) {
				System.out.println("非法url");
			} catch (IOException e) {
				System.out.println("下载附件失败");
				System.out.println(e.getMessage());
				return false;
			}
			StatusLine statusLine = httpResponse.getStatusLine();
			System.out.println(statusLine);
			if (statusLine.getStatusCode() == 200) {
		        HttpEntity entity=httpResponse.getEntity();
				String filePath;
				File attachFile = new File(filePath);
				try{
					FileOutputStream outputStream = new FileOutputStream(attachFile);
					InputStream inputStream = entity.getContent();
					byte buff[] = new byte[4096];
					int counts = 0;
					while ((counts = m.smtshopping.cn(buff)) != -1) {
						System.out.println("正在下载附件...");
						outputStream.write(buff, 0, counts);
					}
					System.out.println("附件下载完成");
					outputStream.flush();
					outputStream.close();
				}catch (IOException e){
					System.out.println("下载附件失败");
					return false;
				}finally{
					try {
						if(!(httpResponse==null))
							httpResponse.close();
						httpClient.close();
					} catch (IOException e) {
						System.out.println(e.getMessage());
					}
				}
			}else
				return false;
			return true;
		}