出现sf ViewExpiredException错误如何避免，先来看一下RestoreViewPhase.java，在处理View的过程中有这样的一段代码：

196           if (isPostBack) {
197               facesContext.setProcessingEvents(false);
198               // try to restore the view
199               viewRoot = viewHandler.restoreView(facesContext, viewId);
200               if (viewRoot == null) {
201                   if (is11CompatEnabled(facesContext)) {
202                       // 1.1 -> create a new view and flag that the response should
203                       //        be immediately rendered
204                       if (LOGGER.isLoggable(Level.FINE)) {
205                           LOGGER.fine(“Postback: recreating a view for ” + viewId);
206                       }
207                       viewRoot = viewHandler.createView(facesContext, viewId);
208                       facesContext.renderResponse();
209
210                   } else {
211                       Object[] params = {viewId};
212                       throw new ViewExpiredException(
213                             MessageUtils.getExceptionMessageString(
214                                   MessageUtils.RESTORE_VIEW_ERROR_MESSAGE_ID,
215                                   params),
216                             viewId);
217                   }
218               }
219
220               facesContext.setViewRoot(viewRoot);
221               facesContext.setProcessingEvents(true);
222               if (LOGGER.isLoggable(Level.FINE)) {
223                   LOGGER.fine(“Postback: restored view for ” + viewId);
224               }
225           }

另外is11CompatEnabled如下：

307       private boolean is11CompatEnabled(FacesContext context) {
308
309           return (getWebConfig(context).isOptionEnabled(
310                 BooleanWebContextInitParameter.EnableRestoreView11Compatibility));
311
312       }

出现sf ViewExpiredException错误如何避免，可以在web.xml中设置如下：

<context-param>
<param-name>com.sun.faces.enableRestoreView11Compatibility</param-name>
<param-value>true</param-value>
</context-param>