servlets - @WebFilter 不同类型的不同初始化参数

Question

我正在将基于 Servlet 2.5 的 webapp 迁移到 Servlet 3.0，遇到了这个问题，我不知道如何将这些不同的过滤器映射压缩到一个 @WebFilter 注释中类。

过滤器:

<!-- Day is 12 hours, so if we update at night the new content will be fetched first     thing in the morning -->
<filter>
    <filter-name>CacheForDay</filter-name>
    <filter-class>x.web.client.filter.CacheHeaderFilter</filter-class>
    <init-param>
        <param-name>CacheTime</param-name>
        <param-value>43200</param-value>
    </init-param>
</filter>

<filter>
    <filter-name>CacheForWeek</filter-name>
    <filter-class>x.web.client.filter.CacheHeaderFilter</filter-class>
    <init-param>
        <param-name>CacheTime</param-name>
        <param-value>604800</param-value>
    </init-param>
</filter>

<filter>
    <filter-name>CacheForMonth</filter-name>
    <filter-class>x.web.client.filter.CacheHeaderFilter</filter-class>
    <init-param>
        <param-name>CacheTime</param-name>
        <param-value>18144000</param-value>
    </init-param>
</filter>

<filter>
    <filter-name>noCache</filter-name>
    <filter-class>x.web.client.filter.CacheHeaderFilter</filter-class>
    <init-param>
        <param-name>CacheTime</param-name>
        <param-value>0</param-value>
    </init-param>
</filter> 

过滤器映射:

<filter-mapping>
    <filter-name>CacheForDay</filter-name>
    <url-pattern>*.png</url-pattern>
  </filter-mapping>

  <filter-mapping>
    <filter-name>CacheForDay</filter-name>
    <url-pattern>*.gif</url-pattern>
  </filter-mapping>

  <filter-mapping>
    <filter-name>CacheForDay</filter-name>
    <url-pattern>*.js</url-pattern>
  </filter-mapping>

  <filter-mapping>
    <filter-name>CacheForDay</filter-name>
    <url-pattern>*.css</url-pattern>
  </filter-mapping>

  <filter-mapping>
    <filter-name>CacheForMonth</filter-name>
    <url-pattern>*.ico</url-pattern>
  </filter-mapping>

如何用 @WebFilter 替换它们？

Answer 1

用@WebFilter注解的单个类是不可能的。您将不得不:

• 继续使用 web.xml 方式；考虑到这种情况，这还不错。
• 在基类中实现逻辑并编写简单的扩展，并使用适当的 @WebFilter 进行注释。我认为这看起来不太好。

后者的例子:

public class BaseCacheFilter implements Filter
{
    public void doFilter(...) {
        ...implementation here...
    }
    ....
}

@WebFilter(
    urlPatterns={"*.png","*.gif",...},
    initParams=@WebInitParam(name="CacheTime",value="43200")
)
public class CacheForDay extends BaseCacheFilter
{ /* EMPTY */ }