Disabling browser cache JSF

问题

I'm getting a ViewExpiredException when I'm at my login page, it is not supposed to be. So I read a post (recommended by BalusC) on Filters. It might be that the page is loading from browser's cache and not from server. So I've implemented this code

@WebFilter(servletNames={"Faces Servlet"})
public class NoCacheFilter implements Filter {

    @Override
    public void doFilter(ServletRequest request, ServletResponse response, FilterChain chain) throws IOException, ServletException {
        HttpServletRequest httpReq = (HttpServletRequest) request;
        HttpServletResponse httpRes = (HttpServletResponse) response;

        if (!httpReq.getRequestURI().startsWith(httpReq.getContextPath() + ResourceHandler.RESOURCE_IDENTIFIER)) { // Skip JSF resources (CSS/JS/Images/etc)
            httpRes.setHeader("Cache-Control", "no-cache, no-store, must-revalidate"); // HTTP 1.1.
            httpRes.setHeader("Pragma", "no-cache"); // HTTP 1.0.
            httpRes.setDateHeader("Expires", 0); // Proxies.
        }

        chain.doFilter(request, response);
    }

    // ...

    @Override
    public void init(FilterConfig filterConfig) throws ServletException {
        throw new UnsupportedOperationException("Not supported yet.");
    }

    @Override
    public void destroy() {
        throw new UnsupportedOperationException("Not supported yet.");
    }
}

but when I try to test it I get the following error:

The module has not been deployed.
    at org.netbeans.modules.j2ee.deployment.devmodules.api.Deployment.deploy(Deployment.java:210)
    at org.netbeans.modules.j2ee.ant.Deploy.execute(Deploy.java:106)
    at org.apache.tools.ant.UnknownElement.execute(UnknownElement.java:291)
    at sun.reflect.GeneratedMethodAccessor193.invoke(Unknown Source)
    at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
    at java.lang.reflect.Method.invoke(Method.java:601)
    at org.apache.tools.ant.dispatch.DispatchUtils.execute(DispatchUtils.java:106)
    at org.apache.tools.ant.Task.perform(Task.java:348)
    at org.apache.tools.ant.Target.execute(Target.java:390)
    at org.apache.tools.ant.Target.performTasks(Target.java:411)
    at org.apache.tools.ant.Project.executeSortedTargets(Project.java:1399)
    at org.apache.tools.ant.Project.executeTarget(Project.java:1368)
    at org.apache.tools.ant.helper.DefaultExecutor.executeTargets(DefaultExecutor.java:41)
    at org.apache.tools.ant.Project.executeTargets(Project.java:1251)
    at org.apache.tools.ant.module.bridge.impl.BridgeImpl.run(BridgeImpl.java:284)
    at org.apache.tools.ant.module.run.TargetExecutor.run(TargetExecutor.java:539)
    at org.netbeans.core.execution.RunClassThread.run(RunClassThread.java:153)

回答1:

You're throwing an exception during filter's initialization (and destroy). So filter's initialization will completely fail and cause the webapp's startup to be blocked. Remove those lines. You shouldn't purposefully throw an exception in there.

@Override
public void init(FilterConfig filterConfig) throws ServletException {
    // NOOP.
}

@Override
public void destroy() {
    // NOOP.
}

Read the filter's javadoc to learn about what those methods are for.

See also:

• Our Servlet-Filters tag wiki page

来源：https://stackoverflow.com/questions/8259286/disabling-browser-cache-jsf