Java Reference
In-Depth Information
L ISTING 11.4 Continued
DownloadService ds = null;
ds = (DownloadService)Utilities.getService(“javax.jnlp.DownloadService”);
URL url = null;
try {
url = new URL(Utilities.getBasicService().getCodeBase(), resourceName);
} catch(IOException exc) {
System.out.println(“Creating URL: “+exc);
try {
ds.removeResource(url ,null);
System.out.println(“Resource “+url+” removed from JNLP cache.”);
} catch(IOException exc) {
System.out.println(“removing resource from JNLP cache: “+exc);
Persistence services are achieved through the use of a PersistenceService class that saves
FileContents objects given a URL as a key. The local file system works like a cache for this
data that is always thought of as being a copy of data stored on the server. The whole concept
is inspired by the cookies mechanism; the primary difference being that the space allowed on
the disk is bigger and more flexible.
The URL-keys work hierarchically. That is, common directories are shared by applications
sharing portions of their codebase.
For example, two applications having codebases can see each other application's data at loca-
tions and :
Therefore, common data can be organized following remote paths on a Web server.
Each single entry (a pair of a URL as a key and a FileContents as a value) can be tagged
regarding its relationship with the server-side data cache. Tags are represented as int s that can
be accessed via the accessory methods setTag() and getTag() . We can have three possible
states for data stored locally:
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