//读取工程工程下面images文件夹的图片向浏览器输出
	public class ImageServlet_02 extends HttpServlet {
	 
		public void doGet(HttpServletRequest request, HttpServletResponse response)
				throws ServletException, IOException {
			//如果需要读取当前工程下面webroot的资源。那么建议使用servletContext读取去读取。
			//获取servletContext对象
			ServletContext context = this.getServletContext();
			//找到当前的文件资源, 返回的是文件的输入流.
			InputStream in = context.getResourceAsStream("/images/a.jpg"); // "/"代表了当前的工程根目录。 
			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);
		}
	 
	}