This private class is the default resource handler +* used to load external resources that are referenced +* within a ScalableImage, namely within a SVG document in the case of SVG. +* The default resource handler will be used by the platform in the following cases: +* - if the MIDlet has not explicitly set its own handler to load external resources +* - if the resource handler specified by the MIDlet is not able to load the +* external resources (i.e. the MIDlet's SVGResourceHandle.getExternalResource() +* returns null).
+* @see javax.microedition.m2g.ExternalResourceHandler +*/ +public class M2GDefaultExternalResourceHandler implements ExternalResourceHandler +{ + + /* + * According to RFC 2396, the rules for determening the base URI can be summarized + * as follows (highest priority to lowest): + * 1.The base URI is embedded in the document's content. + * 2.The base URI is that of the encapsulating document. + * 3.The base URI is the URI used to retrieve the entity. + * 4.The base URI is defined by the context of the application + * + * Note that in the case of the M2GDefaultExternalResourceHandler 4. is not + * applicable. + */ + + //-------------------------------------------------- + // VARIABLES + //-------------------------------------------------- + private M2GUrlTokenizer iTokenizer = null; + + //-------------------------------------------------- + // METHODS + //-------------------------------------------------- + /** + * This constructor is used to create a default resource handler that can + * load resources from absolute URLs and from URLs that are relative + * to the aUrl. + * NOTE: This handler will not be allowed to load resources from the application's + * jar file. + * + * @param aUrl The already validated url used to load the svg document + */ + M2GDefaultExternalResourceHandler(String aUrl) + { + if (aUrl == null || aUrl.equals("")) + { + iTokenizer = new M2GUrlTokenizer(); + } + else + { + iTokenizer = new M2GUrlTokenizer(aUrl); + } + } + + /** + * This constructor is used to create a default resource handler that can + * load external resources from fully qualified URLs ONLY. Any relative URL + * will be considered to be a link to a resource within the application's jar file. + */ + M2GDefaultExternalResourceHandler() + { + this(null); + } + + /** + * This method is invoked when an external resource is required by the underlying implementation. + * When the request is completed by the implementation of this handler, a notification + * must be sent to the SVG engine through the requestCompleted() method ofScalableImage.
+ * To get a synchronous behaviour, requestCompleted() can be called in the implementation
+ * of requestResource. If called later, rendering the document before
+ * completing all the requests will just display the currently available content.
+ * Once the request is completed, the image will have to be redrawn to reflect the newly
+ * available data.
+ * For more details on required resources, please refer to the externalResourcesRequired
+ * attribute description in the SVG specification.
+ *
+ * @param image image that originated the external data request
+ * @param URL the an absolute or a relative URL for the external resource + drm mode
+ */
+ public void requestResource(ScalableImage aImage, String aUrl)
+ {
+ M2GConnectionProxy proxy = null;
+
+ /* IMPLEMENTATION NOTE:
+ * The default resource handler assumes that if there is an embedded base URL within the
+ * document then is upon the svg engine to provide the absolute URL.
+ * If the given URL is a relative URL then this handler will attempt to use as a base URL
+ * to retrieve the containing svg document. However, if the document's base
+ * URL is null then this handler will assume the given relative URL to be a file name
+ * within the application's jar file.
+ */
+ try
+ {
+ // NOTE: if exception is thrown during the resolveExternalResourceUrl() call then
+ // the requestCompleted should be called again with a null input stream.
+ proxy = M2GConnectionFactory.resolveExternalResourceUrl(iTokenizer, aUrl);
+ aImage.requestCompleted(aUrl, proxy.getInputStream());
+ }
+ catch (Exception e)
+ {
+ // e.printStackTrace();
+ // The requestCompleted() failed
+ try
+ {
+ aImage.requestCompleted(aUrl, null);
+ }
+ catch (Exception ee)
+ {
+ // ee.printStackTrace();
+ }
+ }
+ // Close streams
+ finally
+ {
+ try
+ {
+ if (proxy != null)
+ {
+ proxy.close();
+ }
+ }
+ catch (Exception e)
+ {
+ // e.printStackTrace();
+ }
+ }
+ }
+}
+
+