Package ucar.util.prefs

Class XMLStore

java.lang.Object
ucar.util.prefs.XMLStore
public class XMLStore extends Object
This implements an XML-based backing store for PreferencesExt. XMLStores can be chained together to provide independent collections of "stored defaults", eg store1 -> store2 -> store3. In this case, a call to getXXX( key) first looks in store1, and if not found, then in store2, etc. A call to putXXX(key, value) first checks to see if the (key, value) pair already exists in any of the chained stores; if not, then it is added to store1. Normally, only store1 would be changed and saved.

A chain of stored defaults might look like: 

 try {
   XMLStore store3 = XMLStore.createFromResource("/auxdata/system.xml", null);
   XMLStore store2 = XMLStore.createFromFile("/usr/local/metapps/GDV/site.xml", store3);
   XMLStore store1 = XMLStore.createFromFile("/home/username/.GDV/user.xml", store2);
   PreferencesExt prefs = store1.getPreferences();
 } catch (IOException e) {
   System.out.println("XMLStore Creation failed " + e);
 }
If you plan to call Preferences.userRoot(), you must explicilty set it, eg: 
 PreferencesExt.setUserRoot(prefs);

Before exiting the application, in order to save changes, you must call: 

 try {
   store1.save();
 } catch (IOException e) {
   System.out.println("XMLStore Save failed " + e);
 }
See Also:

  • Constructor Details

    • XMLStore

      public XMLStore()

  • Method Details

    • createFromFile

      public static XMLStore createFromFile(String fileName, XMLStore storedDefaults) throws IOException
      Create an XMLStore reading from the specified filename.
      Parameters:
      fileName - The XMLStore is stored in this files.
      storedDefaults - This contains the "stored defaults", or null if none.
      Returns:
      new XMLStore object
      Throws:
      IOException - on error

    • createFromInputStream

      public static XMLStore createFromInputStream(InputStream is1, InputStream is2, XMLStore storedDefaults) throws IOException
      Create an XMLStore reading from an input stream. Because of some peculiariteis, you must open the input stream wtice, and pass both in.
      Parameters:
      is1 - the first copy of the input stream.
      is2 - the second copy of the input stream.
      storedDefaults - This contains the "stored defaults", or null if none.
      Returns:
      new XMLStore object
      Throws:
      IOException - on error

    • createFromResource

      public static XMLStore createFromResource(String resourceName, XMLStore storedDefaults) throws IOException
      Create a read-only XMLStore reading from the specified resource, opened as a Resource stream using the XMLStore ClassLoader. This allows you to find files that are in jar files on the application CLASSPATH.
      Parameters:
      resourceName - The XMLStore is stored in this resource. By convention it has .xml suffix.
      storedDefaults - This contains the "stored defaults", or null if none.
      Returns:
      new XMLStore object
      Throws:
      IOException - if Resource not found or error reading it

    • makeStandardFilename

      public static String makeStandardFilename(String appName, String storeName)
      Convenience routine for creating an XMLStore file in a standard place.

      Initialize:

      1. $user.home = System.getProperty("user.home"), if not exist, use "."
      2. create directory "$(user_home)/appName/" , if not exist, create it
      3. return "$(user_home)/appName/storeName" for use in createFromFile()
      Parameters:
      appName - application name
      storeName - store name
      Returns:
      standard file name

    • getPreferences

      public PreferencesExt getPreferences()
      Get the root Preferences node. All manipulation is done through it.

    • save

      public void save() throws IOException
      Save the current state of the Preferences tree to disk, using the original filename. The XMLStore must have been constructed from a writeable XML file.
      Throws:
      IOException - on read error

    • save

      public void save(OutputStream out) throws IOException
      Save the current state of the Preferences tree to the given OutputStream.
      Throws:
      IOException