cookie記錄用戶名

login

public void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
			//設置編碼
		response.setContentType("text/html;charset=utf-8");
		request.setCharacterEncoding("utf-8");
		PrintWriter out = response.getWriter();//服務器到瀏覽器寫出    
		
		//用servlet寫登錄頁面  
		out.print("<form action='"+request.getContextPath()+"/servlet/doLogin' method=''>");
		out.print("用戶名：<input type='text' name='username'><br/>");
		out.print("密碼：<input type='password' name='password'><br/>");
		
		out.print("<input type='checkbox' name='remember'>記住用戶名<br/>");	//remember 記住密碼
		out.print("<input type='submit' value='登錄'>");
		
		out.print("</form>");
		
	}

dologin

public void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
		response.setContentType("text/html;charset=utf-8");
		request.setCharacterEncoding("utf-8");
		PrintWriter out = response.getWriter();//服務器到瀏覽器寫出
		
		//1.獲取前端數據
		String username = request.getParameter("username");
		String password = request.getParameter("password");
		
		//2.處理業務邏輯
		if("admin".equals(username)&&"123456".equals(password)){
			out.print("登錄成功");
		}else{
			//3.分發轉向
			out.print("登錄失敗");     // 2秒後 重定向路徑    動態獲取項目名
			response.setHeader("refresh", "2;url="+request.getContextPath()+"/servlet/login");
		}
		
		
	}

login

public void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
			//設置編碼
		response.setContentType("text/html;charset=utf-8");
		request.setCharacterEncoding("utf-8");
		PrintWriter out = response.getWriter();//服務器到瀏覽器寫出    		
		//+++
		String username="";
		String checked="";
		Cookie[] cookies=request.getCookies();
		for(int i=0;cookies!=null&&i<cookies.length;i++){
			if("username".equals(cookies[i].getName())){  //getname   
			 username = cookies[i].getValue();   //  getvalue   (name,value)
			checked="checked='checked'";
			}
		}
			
		//用servlet寫登錄頁面  
		out.print("<form action='"+request.getContextPath()+"/servlet/doLogin' method=''>");
		out.print("用戶名：<input type='text' name='username' value='"+username+"'><br/>");
		out.print("密碼：<input type='password' name='password'><br/>");
		
		out.print("<input type='checkbox' name='remember' value='"+checked+"'>記住用戶名<br/>");	//remember 記住密碼
		out.print("<input type='submit' value='登錄'>");
		
		out.print("</form>");
		
	}

dologin

public void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
		response.setContentType("text/html;charset=utf-8");
		request.setCharacterEncoding("utf-8");
		PrintWriter out = response.getWriter();//服務器到瀏覽器寫出
		
		//1.獲取前端數據
		String username = request.getParameter("username");
		String password = request.getParameter("password");
		
		//++1
		String remember=request.getParameter("remember");
		//++2 創建一個cookie
		Cookie cookie=new Cookie("username",username);
		

		//2.處理業務邏輯
		if("admin".equals(username)&&"123456".equals(password)){
			//登陸成功後選擇是否記錄用戶名
			if(remember!=null){   //checkbox 不打√  null
				//記住用戶名
				cookie.setMaxAge(Integer.MAX_VALUE); //設置cookie保存時間
				
			}else{
				cookie.setMaxAge(0);  //清除cookie
				//回寫到客戶端
				response.addCookie(cookie);
			}
			out.print("登錄成功");
		}else{
			//3.分發轉向
			out.print("登錄失敗");     // 2秒後 重定向路徑    動態獲取項目名
			response.setHeader("refresh", "2;url="+request.getContextPath()+"/servlet/login");
		}
		
		
	}