Spring自定義MVC

541732025發表於2014-03-25
SpringMVC
由於struts等開源MVC框架有漏洞，可以考慮自己實現一套輕量級的MVC框架
自定義一個Dispatcher，實現spring的ApplicationContextAware介面

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  1. public class AjaxDispatcher implements ApplicationContextAware {
  2.     //兩個最重要的容器，分別儲存請求path對應的method，以及請求path對應的bean。為了以後反射呼叫method.invoke(bean)
  3.     private static Map<String, Method> ajaxName2Method = new ConcurrentHashMap<String, Method>();
  4.     private static Map<String, Object> ajaxName2Bean = new ConcurrentHashMap<String, Object>();
  5.     ...
  6.     
  7.     @override
  8.     public void setApplicationContext(ApplicationContext ctx) throws BeansException {
  9.         Map<String, Object> map = ctx.getBeansWithAnnotation(AjaxClass.class);//要求每個Ajax類在宣告時會加上@AjaxClass，AjaxClass為自定義annotation
  10.         Collection<Object> beans = map.values();
  11.         for (Object bean : beans) {
  12.             logger.info(\"Inspecting AjaxClass: \" + bean.getClass());
  13.             registerAjaxClass(bean.getClass(), bean);
  14.         }
  15.     }

  17.     public static void registerAjaxClass(Class beanClass, Object bean) {
  18.         String prefix = ((AjaxClass) beanClass.getAnnotation(AjaxClass.class)).prefix();
  19.         if (prefix == null) {
  20.             prefix = \"\";
  21.         }
  22.         //將Ajax類的每個方法註冊到ajaxName2Method容器中
  23.         Method[] ms = beanClass.getMethods();
  24.         for (int j = 0; j < ms.length; j++) {
  25.             Method m = ms[j];
  26.         //跟AjaxClass一樣，Ajax類中的每個method也會宣告為AjaxMethod（自定義annotation，其中有path屬性）
  27.             AjaxMethod ajaxMethod = m.getAnnotation(AjaxMethod.class);
  28.             if (ajaxMethod != null) {
  29.                 String path = ajaxMethod.path();
  30.                 if (path == null || path.trim().equals(\"\")) {
  31.                     path = m.getName();
  32.                 }
  33.                 String fullPath = prefix + path;
  34.                 ajaxName2Method.put(fullPath, ms[j]);
  35.                 logger.info(\"Registering ajax method at path: \" + fullPath);
  36.                 ajaxName2Bean.put(fullPath, bean);
  37.             }
  38.         }
  39.     }

  41.     //業務邏輯呼叫，每一個請求都會呼叫該方法（web.xml中配置相應的servlet，servlet中呼叫該方法）
  42.     public static String dispatch(Map<String, String> req) throws Exception {
  43.         ObjectMapper mapper = new ObjectMapper();
  44.         String path = req.get(KEY_PATH);
  45.         Object ins = ajaxName2Bean.get(path);
  46.         Method m = ajaxName2Method.get(path);
  47.         if (m == null) {
  48.             logger.error(\"No matching method found for path: \" + path);
  49.             return METHOD_ERROR_RESPONSE;
  50.         }
  51.         Class<?>[] paramClasses = m.getParameterTypes();
  52.         Object[] paramValues = null;
  53.         if (null != paramClasses && 1 == paramClasses.length) {
  54.             paramValues = new Object[paramClasses.length];
  55.             try {
  56.                 paramValues[0] = Long.parseLong(req.get(KEY_USERID));
  57.             } catch (NumberFormatException e) {
  58.                 logger.error(\"userid incorrect\" + req.get(KEY_USERID), e);
  59.                 return PARAM_ERROR_RESPONSE;
  60.             }


  63.         } else if (null != paramClasses && 2 <= paramClasses.length) {
  64.             paramValues = new Object[paramClasses.length];
  65.             try {
  66.                 paramValues[0] = Long.parseLong(req.get(KEY_USERID));
  67.             } catch (NumberFormatException e) {
  68.                 logger.error(\"userid incorrect\" + req.get(KEY_USERID), e);
  69.                 return PARAM_ERROR_RESPONSE;
  70.             }


  73.             try {
  74.                 paramValues[1] = mapper.readValue(req.get(KEY_PARAM), paramClasses[1]);
  75.             } catch (Exception e) {
  76.                 logger.error(\"Can not deserialize json param \" + req.get(KEY_PARAM) + \" to class \" + paramClasses[1], e);
  77.                 return PARAM_ERROR_RESPONSE;
  78.             }
  79.         }

  81.         try {
  82.             Object result = m.invoke(ins, paramValues);
  83.             if (result instanceof String) {
  84.                 return (String) result;
  85.             } else {
  86.                 StringWriter buf = new StringWriter();
  87.                 mapper.writeValue(buf, result);
  88.                 return buf.toString();
  89.             }
  90.         } catch (Throwable e) {
  91.             logger.error(\"Exception occured when invoke Ajax Method, path=\" + path, e);
  92.             return DEFAULT_ERROR_RESPONSE;
  93.         }
  94.     }
  95. }

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