//讀取工程工程下面images資料夾的圖片向瀏覽器輸出
	public class ImageServlet_02 extends HttpServlet {
	 
		public void doGet(HttpServletRequest request, HttpServletResponse response)
				throws ServletException, IOException {
			//如果需要讀取當前工程下面webroot的資源。那麼建議使用servletContext讀取去讀取。
			//獲取servletContext物件
			ServletContext context = this.getServletContext();
			//找到當前的檔案資源, 返回的是檔案的輸入流.
			InputStream in = context.getResourceAsStream("/images/a.jpg"); // "/"代表了當前的工程根目錄。 
			byte[] buf = new byte[1024];
			int length = 0; 
			
			OutputStream out = response.getOutputStream();
			while((length =in.read(buf))!=-1){
				out.write(buf,0,length);
			}
			in.close();
		}
		public void doPost(HttpServletRequest request, HttpServletResponse response)
				throws ServletException, IOException {
			doGet(request, response);
		}
	 
	}