002登录验证码及校验+AOP+代理设计模式

一. 登录验证码及校验

@WebServlet("/demo")
public class DemoServlet extends HttpServlet {
	@Override
	protected void service(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
		//输出文字流
		//PrintWriter out = resp.getWriter();
		//获取响应流
		ServletOutputStream os = resp.getOutputStream();
		InputStream is = new FileInputStream(new File(getServletContext().getRealPath("images"),"a.png"));
		int index = -1;
		while((index=is.read())!=-1){
			os.write(index);
		}
	}
}@WebServlet("/demo")
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