spring boot之http，頁面狀態跳轉與異常處理實戰

Http使用

　　http的使用主要是三個類:HttpServletRequest(向客戶端取數據),HttpServletResponse(向客戶端發數據),HttpSession(記錄瀏覽器和服務器的長期交互)。

HttpServletRequest

　　取出http的請求頭的參數和cookie數據：

 1     @RequestMapping(path= {"/request"})
 2     @ResponseBody
 3     public String request(HttpServletRequest request,
 4                                     HttpServletResponse response,
 5                                     HttpSession session) {
 6         StringBuilder sb = new StringBuilder();
 7         Enumeration<String> headerNames = request.getHeaderNames();
 8         while(headerNames.hasMoreElements()) {
 9             String name = headerNames.nextElement();
10             sb.append(name + " ::::::::::::::::::::::::::::: " + request.getHeader(name) + "<br/>");
11         }
12         for (Cookie cookie : request.getCookies()) {
13             sb.append("Cookie: ");
14             sb.append(cookie.getName());
15             sb.append(":");
16             sb.append(cookie.getValue());
17             sb.append("<br>");
18         }
19         return sb.toString();
20     }

 

　　顯示結果：

HttpServletResponse

　　添加cookie並在頁面上顯示：

 1     @RequestMapping(value= {"/response"})
 2     @ResponseBody
 3     public String response( @CookieValue(value = "cookieid", defaultValue = "cookieId") String cookieId,
 4                             @RequestParam(value = "key", defaultValue = "key") String key,
 5                             @RequestParam(value = "value", defaultValue = "value") String value,
 6                             HttpServletResponse response) {
 7         response.addCookie(new Cookie(key, value));
 8         //response.addHeader(key, value);
 9         return "cookievalue: " + cookieId;
10     }

 

 顯示結果：

　　備註：在url中把key寫入cookieid，顯示時，cookieid就會顯示value值，隨value的改變而改變。

301，302頁面跳轉與HttpSession

　　若訪問/redirect/301，就永久跳轉到/hello下(301)，不通過判斷。不然暫時性跳轉(302)。

 1 　　 //301永久性跳轉
 2     //302暫時性跳轉
 3     @RequestMapping(path = {"/redirect/{code}"})
 4     @ResponseBody
 5         public RedirectView redirect(@PathVariable("code") int code,
 6                                      HttpSession session) {
 7         RedirectView red = new RedirectView("/hello", true);
 8         if (code == 301)
 9             red.setStatusCode(HttpStatus.MOVED_PERMANENTLY);//301跳轉
10         //session，記錄瀏覽器和服務器長期的交互。
11         session.setAttribute("msg", "jump from redirect");
12         return red;
13     }

 

　　其次，/hello路徑：

 1     @RequestMapping(path = {"/hello"})
 2     @ResponseBody
 3     public String Hello_World(Model model,
 4                               HttpSession session) {
 5         model.addAttribute("aaa", "naive");
 6         model.addAttribute("l", "<br/>");
 7         List<String> ls = Arrays.asList(new String[] {"1","111", "2323a"});
 8         model.addAttribute("liststring", ls);
 9         model.addAttribute("user", new User("aw12"));
10         logger.info("yeah,finally i learn how to use logger");
11         //顯示session的msg信息。
12         return "session" + session.getAttribute("msg") + sss.show();
13     }

　　

異常及異常處理

　　當key的值不是admin時，拋出異常，在exception函數中處理異常。

 1 //異常
 2     @RequestMapping(path = {"/admin"})
 3     @ResponseBody
 4     public String error(@RequestParam(value = "key", required = false) String key) {
 5         if ("admin".equals(key))
 6             return "hello admin";
 7         throw new IllegalArgumentException("Key 錯誤");
 8     }
 9     //處理異常
10     @ExceptionHandler
11     @ResponseBody
12     public String exception(Exception e) {
13         return "error" + e.getMessage();
14     }

　　結果一，key=‘admin"時：

　　

　　結果二，key！="admin"時：