CacheFilter

CacheFilter is a Java Servlet filter that allows you to enable browser caching for requested resources.

Filter parameters

Option	Required	Default	Description
static	No	false	Defines whether a component is a static asset or not. Conditional requests(1) are not required for static components.
private	No	false	Cache directive to control where the response may be cached. false indicates that the response MAY be cached by any cache. true indicates that the response is intended for a single user and MUST NOT be cached by a shared cache, a private (non-shared) cache MAY cache the response.
expirationTime	Yes	--	Cache directive to set an expiration time, in seconds, relative to the current date.

⁽¹⁾ If a component is already in the browser's cache and is being re-requested, the browser will pass the Last-Modified date in the request header. This is called a conditional GET request and if the component has not been modified, the server will return a 304 Not Modified response.

Sample configuration

Declare the filter in your web descriptor file web.xml:

<filter>
    <filter-name>imagesCache</filter-name>
    <filter-class>com.samaxes.filter.CacheFilter</filter-class>
    <init-param>
        <param-name>static</param-name>
        <param-value>true</param-value>
    </init-param>
    <init-param>
        <param-name>expirationTime</param-name>
        <param-value>2592000</param-value>
    </init-param>
</filter>

<filter>
    <filter-name>cssCache</filter-name>
    <filter-class>com.samaxes.filter.CacheFilter</filter-class>
    <init-param>
        <param-name>expirationTime</param-name>
        <param-value>604800</param-value>
    </init-param>
</filter>

<filter>
    <filter-name>jsCache</filter-name>
    <filter-class>com.samaxes.filter.CacheFilter</filter-class>
    <init-param>
        <param-name>private</param-name>
        <param-value>true</param-value>
    </init-param>
    <init-param>
        <param-name>expirationTime</param-name>
        <param-value>216000</param-value>
    </init-param>
</filter>

Map the filter to serve your static resources:

<filter-mapping>
    <filter-name>imagesCache</filter-name>
    <url-pattern>/img/*</url-pattern>
</filter-mapping>

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

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