net.jini.config

Class AbstractConfiguration

java.lang.Object

net.jini.config.AbstractConfiguration

All Implemented Interfaces:

Configuration

Direct Known Subclasses:

ConfigurationFile, EmptyConfiguration

public abstract class AbstractConfiguration
extends Object
implements Configuration

A skeletal implementation of the Configuration interface, used to simplify writing implementations. This class checks the validity of arguments to the getEntry methods, checks that the result matches the requested type, and wraps exceptions other than Error or ConfigurationException in a ConfigurationException. Subclasses need to implement the getEntryInternal method, which supplies entry values, throws NoSuchEntryException if no matching entry is found, and performs any desired primitive conversions. The getEntryInternal method should return primitive values as instances of AbstractConfiguration.Primitive.

Since:

2.0

Author:

Sun Microsystems, Inc.

Implementation Specifics:

This implementation uses the Logger named net.jini.config to log information at the following logging levels:

net.jini.config

Level	Description
FAILED	problems getting entries, including getting entries that are not found
FINE	returning default values
FINER	getting existing entries

Nested Class Summary

Nested Classes

Modifier and Type	Class and Description
static class	AbstractConfiguration.Primitive<T> Represents the value of an entry with a primitive type.

Field Summary

Fields inherited from interface net.jini.config.Configuration

NO_DATA, NO_DEFAULT

Constructor Summary

Constructors

Modifier	Constructor and Description
protected	AbstractConfiguration() Creates an instance of this class.

Method Summary

Modifier and Type	Method and Description
<T> T	getEntry(String component, String name, Class<T> type) Returns an object of the specified type created using the information in the entry matching the specified component and name, which must be found, and supplying no data.
<T> T	getEntry(String component, String name, Class<T> type, Object defaultValue) Returns an object of the specified type created using the information in the entry matching the specified component and name, and supplying no data, returning the default value if no matching entry is found and the default value is not Configuration.NO_DEFAULT.
<T> T	getEntry(String component, String name, Class<T> type, Object defaultValue, Object data) Returns an object of the specified type created using the information in the entry matching the specified component and name, and using the specified data (unless it is Configuration.NO_DATA), returning the default value if no matching entry is found and the default value is not Configuration.NO_DEFAULT.
protected abstract <T> Object	getEntryInternal(String component, String name, Class<T> type, Object data) Returns an object created using the information in the entry matching the specified component and name, and the specified data, for the requested type.
protected static boolean	validIdentifier(String name) Checks if the argument is a valid Identifier, as defined in the Java(TM) Language Specification.
protected static boolean	validQualifiedIdentifier(String name) Checks if the argument is a valid QualifiedIdentifier, as defined in the Java Language Specification.

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Constructor Detail

AbstractConfiguration

protected AbstractConfiguration()

Creates an instance of this class.

Method Detail

getEntry

public <T> T getEntry(String component,
                      String name,
                      Class<T> type)
               throws ConfigurationException

Returns an object of the specified type created using the information in the entry matching the specified component and name, which must be found, and supplying no data. If type is a primitive type, then the result is returned as an instance of the associated wrapper class. Repeated calls with the same arguments may or may not return the identical object.

The default implementation checks that component, name, and type are not null; that component is a valid qualified identifier; and that name is a valid identifier. It returns the result of calling getEntryInternal with the specified arguments, as well as Configuration.NO_DEFAULT and Configuration.NO_DATA, converting results of type AbstractConfiguration.Primitive into the associated wrapper type. If the call throws an exception other than an Error or a ConfigurationException, it throws a ConfigurationException with the original exception as the cause.

Specified by:

getEntry in interface Configuration

Type Parameters:

T - Object returned.

Parameters:

component - the component being configured

name - the name of the entry for the component

type - the type of the object to be returned

Returns:

an object created using the information in the entry matching component and name

Throws:

NoSuchEntryException - if no matching entry is found

IllegalArgumentException - if component is not null and is not a valid QualifiedIdentifier, or if name is not null and is not a valid Identifier

NullPointerException - if any argument is null

ConfigurationException - if a matching entry is found but a problem occurs creating the object for the entry, or if type is a reference type and the result for the matching entry is not either null or an instance of type, or if type is a primitive type and the result is not an instance of the associated wrapper class. Any Error thrown while creating the object is propagated to the caller; it is not wrapped in a ConfigurationException.

See Also:

Configuration.getEntry(String, String, Class, Object)

getEntry

public <T> T getEntry(String component,
                      String name,
                      Class<T> type,
                      Object defaultValue)
               throws ConfigurationException

Returns an object of the specified type created using the information in the entry matching the specified component and name, and supplying no data, returning the default value if no matching entry is found and the default value is not Configuration.NO_DEFAULT. If type is a primitive type, then the result is returned as an instance of the associated wrapper class. Repeated calls with the same arguments may or may not return the identical object.

The default implementation checks that component, name, and type are not null; that component is a valid qualified identifier; that name is a valid identifier; and that defaultValue is of the right type. It returns the result of calling getEntryInternal with the specified arguments, as well as Configuration.NO_DATA, converting results of type AbstractConfiguration.Primitive into the associated wrapper type. If the call throws an exception other than an Error or a ConfigurationException, it throws a ConfigurationException with the original exception as the cause.

Specified by:

getEntry in interface Configuration

Parameters:

component - the component being configured

name - the name of the entry for the component

type - the type of the object to be returned

defaultValue - the object to return if no matching entry is found, or NO_DEFAULT to specify no default

Returns:

an object created using the information in the entry matching component and name, or defaultValue if no matching entry is found and defaultValue is not NO_DEFAULT

Throws:

NoSuchEntryException - if no matching entry is found and defaultValue is NO_DEFAULT

IllegalArgumentException - if component is not null and is not a valid QualifiedIdentifier; or if name is not null and is not a valid Identifier; or if type is a reference type and defaultValue is not NO_DEFAULT, null, or an instance of type; or if type is a primitive type and defaultValue is not NO_DEFAULT or an instance of the associated wrapper class

NullPointerException - if component, name, or type is null

ConfigurationException - if a matching entry is found but a problem occurs creating the object for the entry, or if type is a reference type and the result for the matching entry is not either null or an instance of type, or if type is a primitive type and the result is not an instance of the associated wrapper class. Any Error thrown while creating the object is propagated to the caller; it is not wrapped in a ConfigurationException.

See Also:

Configuration.getEntry(String, String, Class, Object, Object)

getEntry

public <T> T getEntry(String component,
                      String name,
                      Class<T> type,
                      Object defaultValue,
                      Object data)
               throws ConfigurationException

Returns an object of the specified type created using the information in the entry matching the specified component and name, and using the specified data (unless it is Configuration.NO_DATA), returning the default value if no matching entry is found and the default value is not Configuration.NO_DEFAULT. If type is a primitive type, then the result is returned as an instance of the associated wrapper class. Repeated calls with the same arguments may or may not return the identical object.

The default implementation checks that component, name, and type are not null; that component is a valid qualified identifier; that name is a valid identifier; and that defaultValue is of the right type. It returns the result of calling getEntryInternal with the specified arguments, converting results of type AbstractConfiguration.Primitive into the associated wrapper type. If the call throws an exception other than an Error or a ConfigurationException, it throws a ConfigurationException with the original exception as the cause.

Specified by:

getEntry in interface Configuration

Parameters:

component - the component being configured

name - the name of the entry for the component

type - the type of the object to be returned

defaultValue - the object to return if no matching entry is found, or NO_DEFAULT to specify no default

data - an object to use when computing the value of the entry, or NO_DATA to specify no data

Returns:

an object created using the information in the entry matching component and name, and using the value of data (unless it is NO_DATA), or defaultValue if no matching entry is found and defaultValue is not NO_DEFAULT

Throws:

NoSuchEntryException - if no matching entry is found and defaultValue is NO_DEFAULT

IllegalArgumentException - if component is not null and is not a valid QualifiedIdentifier; or if name is not null and is not a valid Identifier; or if type is a reference type and defaultValue is not NO_DEFAULT, null, or an instance of type; or if type is a primitive type and defaultValue is not NO_DEFAULT or an instance of the associated wrapper class

NullPointerException - if component, name, or type is null

ConfigurationException - if a matching entry is found but a problem occurs creating the object for the entry, or if type is a reference type and the result for the matching entry is not either null or an instance of type, or if type is a primitive type and the result is not an instance of the associated wrapper class. Any Error thrown while creating the object is propagated to the caller; it is not wrapped in a ConfigurationException.

getEntryInternal

protected abstract <T> Object getEntryInternal(String component,
                                               String name,
                                               Class<T> type,
                                               Object data)
                                        throws ConfigurationException

Returns an object created using the information in the entry matching the specified component and name, and the specified data, for the requested type. If the entry value is a primitive, then the object returned should be an instance of AbstractConfiguration.Primitive. Implementations may use type to perform conversions on primitive values, if desired, but are not required to check if the object is of the requested type. Repeated calls with the same arguments may or may not return the identical object.

The default implementations of the getEntry methods delegate to this method; implementations can rely on the fact that calls made to this method by those methods will have arguments that are not null and that have the correct syntax.

Type Parameters:

T -

Parameters:

component - the component being configured

name - the name of the entry for the component

type - the type of object requested

data - an object to use when computing the value of the entry, or Configuration.NO_DATA to specify no data

Returns:

an object created using the information in the entry matching component and name, and using the value of data (unless it is NO_DATA)

Throws:

NoSuchEntryException - if no matching entry is found

ConfigurationException - if a matching entry is found but a problem occurs creating the object for the entry

NullPointerException - if component, name, or type is null

See Also:

Configuration.getEntry

validIdentifier

protected static boolean validIdentifier(String name)

Checks if the argument is a valid Identifier, as defined in the Java(TM) Language Specification.

Parameters:

name - the name to check

Returns:

true if name is a valid Identifier, else false

validQualifiedIdentifier

protected static boolean validQualifiedIdentifier(String name)

Checks if the argument is a valid QualifiedIdentifier, as defined in the Java Language Specification.

Parameters:

name - the name to check

Returns:

true if name is a valid QualifiedIdentifier, else false