Interface PortletPreferences

public interface PortletPreferences
The PortletPreferences interface allows the portlet to store configuration data. It is not the purpose of this interface to replace general purpose databases.

There are two different types of preferences:

  • modifiable preferences - these preferences can be changed by the portlet in any standard portlet mode (EDIT, HELP, VIEW). Per default every preference is modifiable.
  • read-only preferences - these preferences cannot be changed by the portlet in any standard portlet mode, but may be changed by administrative modes. Preferences are read-only, if the are defined in the deployment descriptor with read-only set to true, or if the portlet container restricts write access.

Changes are persisted when the store method is called. The store method can only be invoked within the scope of a processAction call. Changes that are not persisted are discarded when the processAction or render method ends.

  • Method Summary

    Modifier and Type
    Method
    Description
    Map
    getMap()
    Returns a Map of the preferences.
    Enumeration
    getNames()
    Returns all of the keys that have an associated value, or an empty Enumeration if no keys are available.
    String
    getValue(String key, String def)
    Returns the first String value associated with the specified key of this preference.
    String[]
    getValues(String key, String[] def)
    Returns the String array value associated with the specified key in this preference.
    boolean
    isReadOnly(String key)
    Returns true, if the value of this key cannot be modified by the user.
    void
    reset(String key)
    Resets or removes the value associated with the specified key.
    void
    setValue(String key, String value)
    Associates the specified String value with the specified key in this preference.
    void
    setValues(String key, String[] values)
    Associates the specified String array value with the specified key in this preference.
    void
    store()
    Commits all changes made to the preferences via the set methods in the persistent store.

  • Method Details

    • isReadOnly

      boolean isReadOnly(String key)
      Returns true, if the value of this key cannot be modified by the user.

      Modifiable preferences can be changed by the portlet in any standard portlet mode (EDIT, HELP, VIEW). Per default every preference is modifiable.

      Read-only preferences cannot be changed by the portlet in any standard portlet mode, but inside of custom modes it may be allowed changing them. Preferences are read-only, if they are defined in the deployment descriptor with read-only set to true, or if the portlet container restricts write access.

      Returns:
      false, if the value of this key can be changed, or if the key is not known
      Throws:
      IllegalArgumentException - if key is null.

    • getValue

      String getValue(String key, String def)
      Returns the first String value associated with the specified key of this preference. If there is one or more preference values associated with the given key it returns the first associated value. If there are no preference values associated with the given key, or the backing preference database is unavailable, it returns the given default value.
      Parameters:
      key - key for which the associated value is to be returned
      def - the value to be returned in the event that there is no value available associated with this key.
      Returns:
      the value associated with key, or def if no value is associated with key, or the backing store is inaccessible.
      Throws:
      IllegalArgumentException - if key is null. (A null value for def is permitted.)
      See Also:

    • getValues

      String[] getValues(String key, String[] def)
      Returns the String array value associated with the specified key in this preference.

      Returns the specified default if there is no value associated with the key, or if the backing store is inaccessible.

      If the implementation supports stored defaults and such a default exists and is accessible, it is used in favor of the specified default.

      Parameters:
      key - key for which associated value is to be returned.
      def - the value to be returned in the event that this preference node has no value associated with key or the associated value cannot be interpreted as a String array, or the backing store is inaccessible.
      Returns:
      the String array value associated with key, or def if the associated value does not exist.
      Throws:
      IllegalArgumentException - if key is null. (A null value for def is permitted.)
      See Also:

    • setValue

      void setValue(String key, String value) throws ReadOnlyException
      Associates the specified String value with the specified key in this preference.

      The key cannot be null, but null values for the value parameter are allowed.

      Parameters:
      key - key with which the specified value is to be associated.
      value - value to be associated with the specified key.
      Throws:
      ReadOnlyException - if this preference cannot be modified for this request
      IllegalArgumentException - if key is null, or key.length() or value.length are to long. The maximum length for key and value are implementation specific.
      See Also:

    • setValues

      void setValues(String key, String[] values) throws ReadOnlyException
      Associates the specified String array value with the specified key in this preference.

      The key cannot be null, but null values in the values parameter are allowed.

      Parameters:
      key - key with which the value is to be associated
      values - values to be associated with key
      Throws:
      IllegalArgumentException - if key is null, or key.length() is to long or value.size is to large. The maximum length for key and maximum size for value are implementation specific.
      ReadOnlyException - if this preference cannot be modified for this request
      See Also:

    • getNames

      Enumeration getNames()
      Returns all of the keys that have an associated value, or an empty Enumeration if no keys are available.
      Returns:
      an Enumeration of the keys that have an associated value, or an empty Enumeration if no keys are available.

    • getMap

      Map getMap()
      Returns a Map of the preferences.

      The values in the returned Map are from type String array (String[]).

      If no preferences exist this method returns an empty Map.

      Returns:
      an immutable Map containing preference names as keys and preference values as map values, or an empty Map if no preference exist. The keys in the preference map are of type String. The values in the preference map are of type String array (String[]).

    • reset

      void reset(String key) throws ReadOnlyException
      Resets or removes the value associated with the specified key.

      If this implementation supports stored defaults, and there is such a default for the specified preference, the given key will be reset to the stored default.

      If there is no default available the key will be removed.

      Parameters:
      key - to reset
      Throws:
      IllegalArgumentException - if key is null.
      ReadOnlyException - if this preference cannot be modified for this request

    • store

      void store() throws IOException, ValidatorException
      Commits all changes made to the preferences via the set methods in the persistent store.

      If this call returns succesfull, all changes are made persistent. If this call fails, no changes are made in the persistent store. This call is an atomic operation regardless of how many preference attributes have been modified.

      All changes made to preferences not followed by a call to the store method are discarded when the portlet finishes the processAction method.

      If a validator is defined for this preferences in the deployment descriptor, this validator is called before the actual store is performed to check wether the given preferences are vaild. If this check fails a ValidatorException is thrown.

      Throws:
      IOException - if changes cannot be written into the backend store
      ValidatorException - if the validation performed by the associated validator fails
      IllegalStateException - if this method is called inside a render call
      See Also: