在web.xml中作如下配置:
用于处理静态资源(css、js、图片之类),启动后正常。但当修改了struts配置文件,并且struts.configuration.xml.reload=true时,再次加载静态资源时会出错如下错误:
java.lang.NullPointerException at org.apache.struts2.dispatcher.DefaultStaticContentLoader.findStaticResource(DefaultStaticContentLoader.java:164)
at org.apache.struts2.dispatcher.ng.ExecuteOperations.executeStaticResourceRequest(ExecuteOperations.java:62)
at org.apache.struts2.dispatcher.ng.filter.StrutsPrepareAndExecuteFilter.doFilter(StrutsPrepareAndExecuteFilter.java:86)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:235)
原因:重新加载配置文件时,静态资源的处理类DefaultStaticContentLoader的setHostConfig(HostConfig filterConfig)方法没调用,导致pathPrefixes为空。
解决方案:
1、继承StrutsPrepareOperations类,构造方法中传入参数FilterConfig。createActionContext方法中如果oldContext为空,则重新初始化静态资源配置。完整代码如下:
public class StrutsPrepareOperations extends PrepareOperations {
private ServletContext servletContext;
private Dispatcher dispatcher;
private FilterHostConfig config;
public StrutsPrepareOperations(ServletContext servletContext, Dispatcher dispatcher,
FilterConfig filterConfig) {
super(servletContext, dispatcher);
this.dispatcher = dispatcher;
this.servletContext = servletContext;
this.config = new FilterHostConfig(filterConfig);
}
// 重写doFilter,由于在struts配置文件重新加载后,静态资源有问题
/**
* Creates the action context and initializes the thread local
*/
public ActionContext createActionContext(HttpServletRequest request,
HttpServletResponse response) {
ActionContext ctx;
Integer counter = 1;
Integer oldCounter = (Integer) request.getAttribute(CLEANUP_RECURSION_COUNTER);
if (oldCounter != null) {
counter = oldCounter + 1;
}
ActionContext oldContext = ActionContext.getContext();
if (oldContext != null) {
// detected existing context, so we are probably in a forward
ctx = new ActionContext(new HashMap
} else {
ValueStack stack = dispatcher.getContainer().getInstance(ValueStackFactory.class)
.createValueStack();
stack.getContext().putAll(
dispatcher.createContextMap(request, response, null, servletContext));
ctx = new ActionContext(stack.getContext());
// add by zhaosf
StaticContentLoader staticResourceLoader = dispatcher.getContainer().getInstance(
StaticContentLoader.class);
staticResourceLoader.setHostConfig(config);
}
request.setAttribute(CLEANUP_RECURSION_COUNTER, counter);
ActionContext.setContext(ctx);
return ctx;
}
2、继承org.apache.struts2.dispatcher.ng.filter.StrutsPrepareAndExecuteFilter时,重写init方法,如下:
public class StrutsFilter extends StrutsPrepareAndExecuteFilter {
@Override
public void init(FilterConfig filterConfig) throws ServletException {
InitOperations init = new InitOperations();
try {
FilterHostConfig config = new FilterHostConfig(filterConfig);
init.initLogging(config);
Dispatcher dispatcher = init.initDispatcher(config);
init.initStaticContentLoader(config, dispatcher);
prepare = new StrutsPrepareOperations(filterConfig.getServletContext(), dispatcher,
filterConfig);
execute = new ExecuteOperations(filterConfig.getServletContext(), dispatcher);
this.excludedPatterns = init.buildExcludedPatternsList(dispatcher);
postInit(dispatcher, filterConfig);
} finally {
init.cleanup();
}
}