Struts2与Ajax的整合

整合:

导入jar包

sturts2-json-plugin-2.1.8.1.jar

说明:

在该jar包中有struts-plugin.xml文件

　　　　<struts>
                  <package name="json-default" extends="struts-default">
                       <result-types>
                          <result-type name="json" class="org.apache.struts2.json.JSONResult"/>
                        </result-types>
                        <interceptors>
                          <interceptor name="json" class="org.apache.struts2.json.JSONInterceptor"/>
                        </interceptors>
                  </package>
             </struts>

从上述配置中可以看到
    *  有一个package"json-default",有一个自定义的结果集，该结果集处理哪些数据应该返回客户端
    *  在struts的配置文件中：
         所有的package应该继承json-default,result的类型应该是"json",result没有文本值
    *  在action中，所有的get方法，例如
               getXxx  将会已这样的形式返回{xxx:'aaa'}
    *  针对struts2与ajax结合，无论采用$.post还是$.ajax都捕获不到服务器产生的错误，这点struts2内部设计的不是很好
        但是$.ajax捕获错误在servlet能做到。因为
        所以所有的struts2的错误都会走该模板页面
    *  如果在action中，一个get方法返回的不是数据，而且是一个对象，比如返回一个service
       这个时候只需要在该方法上加@JSON(serialize=false)就可以忽略该方法

public void serviceAction(HttpServletRequest request, HttpServletResponse response, ServletContext context,
                              ActionMapping mapping) throws ServletException {

        Map<String, Object> extraContext = createContextMap(request, response, mapping, context);

        // If there was a previous value stack, then create a new copy and pass it in to be used by the new Action
        ValueStack stack = (ValueStack) request.getAttribute(ServletActionContext.STRUTS_VALUESTACK_KEY);
        boolean nullStack = stack == null;
        if (nullStack) {
            ActionContext ctx = ActionContext.getContext();
            if (ctx != null) {
                stack = ctx.getValueStack();
            }
        }
        if (stack != null) {
            extraContext.put(ActionContext.VALUE_STACK, valueStackFactory.createValueStack(stack));
        }

        String timerKey = "Handling request from Dispatcher";
        try {
            UtilTimerStack.push(timerKey);
            String namespace = mapping.getNamespace();
　　　　String name = mapping.getName();
            String method = mapping.getMethod();

            Configuration config = configurationManager.getConfiguration();
            ActionProxy proxy = config.getContainer().getInstance(ActionProxyFactory.class).createActionProxy(
                    namespace, name, method, extraContext, true, false);

            request.setAttribute(ServletActionContext.STRUTS_VALUESTACK_KEY, proxy.getInvocation().getStack());

            // if the ActionMapping says to go straight to a result, do it!
            if (mapping.getResult() != null) {
                Result result = mapping.getResult();
                result.execute(proxy.getInvocation());
            } else {
                proxy.execute();
            }

            // If there was a previous value stack then set it back onto the request
            if (!nullStack) {
                request.setAttribute(ServletActionContext.STRUTS_VALUESTACK_KEY, stack);
            }
        } catch (ConfigurationException e) {
         // WW-2874 Only log error if in devMode
         if(devMode) {
                String reqStr = request.getRequestURI();
                if (request.getQueryString() != null) {
                    reqStr = reqStr + "?" + request.getQueryString();
                }
                LOG.error("Could not find action or result\n" + reqStr, e);
            }
         else {
                    if (LOG.isWarnEnabled()) {
          LOG.warn("Could not find action or result", e);
                    }
         }
            sendError(request, response, context, HttpServletResponse.SC_NOT_FOUND, e);//产生错误的模板页面，并返回到客户端
        } catch (Exception e) {
            sendError(request, response, context, HttpServletResponse.SC_INTERNAL_SERVER_ERROR, e);//产生错误的模板页面，并返回到客户端
        } finally {
            UtilTimerStack.pop(timerKey);
        }
    }