Interface Asset

  • All Known Implementing Classes:
    AbstractAsset, UrlAsset

    public interface Asset
    An Asset is any kind of resource that can be exposed to the client web browser. Although quite often an Asset is a resource in a web application's context folder, within Tapestry, Assets may also be resources on the classpath (i.e., packaged inside JARs). An Asset's toString() will return the URL for the resource (the same value as toClientURL()). Release introduced org.apache.tapestry5.Asset2, which extends this interface with an additional method. Release 5.7.0 merged Asset2 into Asset and Asset2 got removed.
    See Also:
    • Method Detail

      • toClientURL

        java.lang.String toClientURL()
        Returns a URL that can be passed, unchanged, to the client in order for it to access the resource. The same value is returned from toString(). Tapestry's built-in asset types (context and classpath) always incorporate a checksum as part of the path, and alternate implementations are encouraged to do so as well. In addition, Tapestry ensures that context and classpath assets have a far-future expires header (to ensure aggressive caching by the client). Note that starting in Tapestry 5.4, it is expected that Asset instances recognize when the underlying Resource's content has changed, and update the clientURL to reflect the new content's checksum. This wasn't an issue in earlier releases where the clientURL incorporated a version number. Finally, starting in 5.4, this value will often be variant: the exact URL returned will depend on whether the underlying resource content is compressable, whether the current Request supports compression.
        See Also:
        AssetSource, AssetPathConverter
      • isInvariant

        default boolean isInvariant()
        Returns true if the Asset is invariant (meaning that it returns the same value from toClientURL() at all times). Most Assets are invariant. Assets that are used as binding values will be cached more aggressively by Tapestry if they are invariant. This default implementation returns false
        true if invariant
        Since: (in Asset2), 5.7.0 (in Asset).
        See Also:
        AssetPathConverter.isInvariant(), Binding.isInvariant()