導致此問題的根代碼位於Spring MVC中,由WebContentGenerator調用。該類用作MVC/Webflow堆棧中幾個類的基類:WebContentInterceptor(MVC攔截器),AbstractController(MVC控制器),AbstractHandlerMethodAdapter(MVC HandlerAdapter),AnnotationMethodHadlerAdapter(MVC HandlerAdapter),FlowHandlerAdapter(Webflow HandlerAdapter),JsfFlowHandlerAdapter(Webflow + JSF HandlerAdapter)
CacheControl秒設置爲0調用preventCaching方法。因此,似乎該應用程序默認爲0
org.springframework.web.servlet.support.WebContentGenerator
protected final void preventCaching(HttpServletResponse response) {
response.setHeader(HEADER_PRAGMA, "no-cache");
if (this.useExpiresHeader) {
// HTTP 1.0 header
response.setDateHeader(HEADER_EXPIRES, 1L);
}
if (this.useCacheControlHeader) {
// HTTP 1.1 header: "no-cache" is the standard value,
// "no-store" is necessary to prevent caching on FireFox.
response.setHeader(HEADER_CACHE_CONTROL, "no-cache");
if (this.useCacheControlNoStore) {
response.addHeader(HEADER_CACHE_CONTROL, "no-store");
}
}
}
的設置,我發現,自從我使用JSF +的Webflow,該JsfFlowHandlerAdapter是首先處理服務器對流/視圖的請求。這就是爲什麼配置攔截器不起作用的原因,因爲JsfFlowHandlerAdapter此時已經設置了Cache-Control和其他HTTP Headers。事實證明,我已經擴展了JsfFlowHandlerAdapter來處理FlowExecutionRestorationFailureException(請參閱Sping Web Flow Preventing Back Button Use),所以我需要做的就是設置我想要的配置WebContentInterceptor(因爲配置屬於基類WebContentGenerator)。
定製JsfFlowHandlerAdapter
public class MyAppFlowHandlerAdapter extends org.springframework.faces.webflow.JsfFlowHandlerAdapter {
...
}
webmvc-config.xml中
<!-- Dispatches requests mapped to flows to FlowHandler implementations -->
<bean
class="com.myapp.MyAppFlowHandlerAdapter">
<property name="flowExecutor" ref="flowExecutor" />
<!-- Disable built in Cache-Control settings -->
<property name="cacheSeconds" value="-1" />
<property name="useExpiresHeader" value="false" />
<property name="useCacheControlHeader" value="false" />
<property name="useCacheControlNoStore" value="false" />
</bean>
<!-- Maps request paths to flows in the flowRegistry; e.g. a path of /hotels/booking
looks for a flow with id "hotels/booking" -->
<bean class="org.springframework.webflow.mvc.servlet.FlowHandlerMapping">
<!-- snip out unimportant -->
<property name="interceptors">
<list>
<ref bean="cacheControlInterceptor" />
</list>
</property>
</bean>
<bean id="cacheControlInterceptor"
class="com.myapp.CacheControlInterceptor">
CacheControlInterceptor(設置自己的HTTP標頭。該做的WebContentGenerator是最後所以不能@Override方法)
public class CacheControlInterceptor extends HandlerInterceptorAdapter {
@Override
public boolean preHandle(HttpServletRequest request, HttpServletResponse response, Object handler) throws Exception {
//Example below: set your Cache-Control, expires, pragma headers here
response.setHeader("Cache-Control", "private");
return true;
}
}