泽西岛:默认缓存控制为无缓存 [英] Jersey: Default Cache Control to no-cache

问题描述

在编写RESTful Web服务时，如果在客户端(当前是.NET胖客户端)上启用任何类型的缓存，就会遇到问题.默认情况下，Jersey不发送任何类型的缓存控制标头，因此客户端会自动缓存大多数页面(这似乎是有效的行为).

While writing a RESTful web service, I am encountering issues if I enable any sort of caching on my client (currently a .NET thick client). By default Jersey is not sending any sort of cache control header, so the client is caching most pages automatically (which seems to be valid behaviour).

我希望默认情况下，Jersey发送一个"no-cache"缓存控件，然后特别是响应将覆盖该缓存控件.

I would like to have Jersey by default send a cache control of "no-cache", and then in particular responses override the cache control.

有没有办法用泽西岛做到这一点?

Is there any way to do this with Jersey?

我发现RESTeasy可以使用@NoCache批注指定整个类的设置，但是我找不到与Jersey相似的东西.

I've found that RESTeasy has the ability to use the @NoCache annotation to specify the setting for the whole class, but I've not found anything similar with Jersey.

推荐答案

在Jersey中，使用ResourceFilterFactory很容易-您可以创建附加到方法的任何自定义注释来设置缓存控制设置.应用程序初始化时，将为每个发现的资源方法调用ResourceFilterFactories-在您的ResourceFilterFactory中，您可以检查该方法是否具有@CacheControlHeader批注(或任何您想调用的注解)-如果没有，只需返回添加"no-cache"的响应过滤器"作为指向响应的指令，否则应使用批注中的设置.这是如何执行此操作的示例:

This is easy with Jersey by using a ResourceFilterFactory - you can create any custom annotation you attach to your methods to set cache control settings. ResourceFilterFactories get called for each discovered resource method when the application initializes - in your ResourceFilterFactory you can check if the method has your @CacheControlHeader annotation (or whatever you want to call it) - if not, simply return response filter that adds "no-cache" directive to the response, otherwise it should use the settings from the annotation. Here is an example of how to do that:

public class CacheFilterFactory implements ResourceFilterFactory {
    private static final List<ResourceFilter> NO_CACHE_FILTER = Collections.<ResourceFilter>singletonList(new CacheResponseFilter("no-cache"));

    @Override
    public List<ResourceFilter> create(AbstractMethod am) {
        CacheControlHeader cch = am.getAnnotation(CacheControlHeader.class);
        if (cch == null) {
            return NO_CACHE_FILTER;
        } else {
            return Collections.<ResourceFilter>singletonList(new CacheResponseFilter(cch.value()));
        }
    }

    private static class CacheResponseFilter implements ResourceFilter, ContainerResponseFilter {
        private final String headerValue;

        CacheResponseFilter(String headerValue) {
            this.headerValue = headerValue;
        }

        @Override
        public ContainerRequestFilter getRequestFilter() {
            return null;
        }

        @Override
        public ContainerResponseFilter getResponseFilter() {
            return this;
        }

        @Override
        public ContainerResponse filter(ContainerRequest request, ContainerResponse response) {
            // attache Cache Control header to each response based on the annotation value
            response.getHttpHeaders().putSingle(HttpHeaders.CACHE_CONTROL, headerValue);
            return response;
        }
    }
}

注释看起来像这样:

@Retention(RetentionPolicy.RUNTIME)
@Target(ElementType.METHOD)
public @interface CacheControlHeader {
    String value();
}

通过在web.xml中的Jersey servlet定义中添加以下初始化参数，可以在您的应用程序中注册ResourceFilterFactory:

The ResourceFilterFactory can be registered in your application by adding the following init param to the definition of Jersey servlet in web.xml:

<init-param>
    <param-name>com.sun.jersey.spi.container.ResourceFilters</param-name>
    <param-value>package.name.CacheFilterFactory</param-value>
</init-param>

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