Configuration (Java Channel Access 2.4.2 API)

All Known Implementing Classes:: AbstractConfiguration, DefaultConfiguration

public interface Configuration

Configuration is a interface encapsulating a configuration node used to retrieve configuration values.

This is a "read only" interface preventing applications from modifying their own configurations. Once it is created, the information never changes.

Data Model

The data model is a subset of XML's; a single-rooted hierarchical tree where each node can contain multiple attributes, and leaf nodes can also contain a value. Reflecting this, Configurations are usually built from an XML file by the DefaultConfigurationBuilder class, or directly by a SAX parser using a SAXConfigurationHandler or NamespacedSAXConfigurationHandler event handler.

Namespace support

Since version 4.1, each Configuration node has a namespace associated with it, in the form of a string, accessible through getNamespace(). If no namespace is present, getNamespace will return blank (""). See DefaultConfigurationBuilder for details on how XML namespaces are mapped to Configuration namespaces.

Example

As an example, consider two Configurations (with and without namespaces) built from this XML:

 <my-system version="1.3" xmlns:doc="http://myco.com/documentation">
   <doc:desc>This is a highly fictitious config file</doc:desc>
   <widget name="fooWidget" initOrder="1" threadsafe="true"/>
 </my-system>

If namespace support is enabled (eg through new DefaultConfigurationBuilder(true)), then the xmlns:doc element will not translate into a Configuration attribute, and the doc:desc element will become a Configuration node with name "desc" and namespace "http://myco.com/documentation". The widget element will have namespace "".

If namespace support is disabled (the default for DefaultConfigurationBuilder), the above XML will translate directly to Configuration nodes. The my-system node will have an attribute named "xmlns:doc", and a child called "doc:desc".

Assuming the Configuration object is named conf, here is how the data could be retrieved:

Code	No namespaces	With namespaces
`conf.getName()`	my-system
`conf.getAttributeNames().length`	2	1
`conf.getChildren().length`	2
`conf.getAttributeAsFloat("version")`	1.3
`conf.getChild("widget").getAttribute("name")`	fooWidget
`conf.getChild("widget") .getAttributeAsBoolean("threadsafe")`	`true`
`conf.getChild("widget").getLocation()`	file:///home/jeff/tmp/java/avalon/src/java/new.xconf:4:60
`conf.getChild("desc").getName()`	desc (see `getChild(String)`)	desc
`conf.getChild("doc:desc").getName()`	doc:desc	doc:desc (see `getChild(String)`)
`conf.getChild("desc").getValue()`	`ConfigurationException`	This is a highly fictitious config file
`conf.getChild("doc:desc").getValue()`	This is a highly fictitious config file	`ConfigurationException`
`conf.getChild("desc").getNamespace()`		http://myco.com/documentation"

Type-safe utility methods are provided for retrieving attribute and element values as String, int, long, float and boolean.

Miscellanea

Currently, the configuration tree can only be traversed one node at a time, eg., through getChild("foo") or getChildren(). In a future release, it may be possible to access child nodes with an XPath-like syntax.

Checking for the existence of an attribute can be done as follows:

String value = conf.getAttribute( "myAttribute", null );
 if ( null == value )
 {
   // Do the processing applicable if the attribute isn't present.
 }

Version:: 1.0
Author:: Federico Barbieri, Pierpaolo Fumagalli, Stefano Mazzocchi, Berin Loritsch, Peter Donald, Jeff Turner

Method Summary

All Methods Instance Methods Abstract Methods
Modifier and Type	Method and Description
`String`	`getAttribute(String paramName)` Return the value of specified attribute.
`String`	`getAttribute(String name, String defaultValue)` Returns the value of the attribute specified by its name as a `String`, or the default value if no attribute by that name exists or is empty.
`boolean`	`getAttributeAsBoolean(String paramName)` Return the `boolean` value of the specified parameter contained in this node.
`boolean`	`getAttributeAsBoolean(String name, boolean defaultValue)` Returns the value of the attribute specified by its name as a `boolean`, or the default value if no attribute by that name exists or is empty.
`float`	`getAttributeAsFloat(String paramName)` Return the `float` value of the specified parameter contained in this node.
`float`	`getAttributeAsFloat(String name, float defaultValue)` Returns the value of the attribute specified by its name as a `float`, or the default value if no attribute by that name exists or is empty.
`int`	`getAttributeAsInteger(String paramName)` Return the `int` value of the specified attribute contained in this node.
`int`	`getAttributeAsInteger(String name, int defaultValue)` Returns the value of the attribute specified by its name as a `int`, or the default value if no attribute by that name exists or is empty.
`long`	`getAttributeAsLong(String name)` Returns the value of the attribute specified by its name as a `long`.
`long`	`getAttributeAsLong(String name, long defaultValue)` Returns the value of the attribute specified by its name as a `long`, or the default value if no attribute by that name exists or is empty.
`String[]`	`getAttributeNames()` Return an array of all attribute names.
`Configuration`	`getChild(String child)` Return a new `Configuration` instance encapsulating the specified child node.
`Configuration`	`getChild(String child, boolean createNew)` Return a `Configuration` instance encapsulating the specified child node.
`Configuration[]`	`getChildren()` Return an `Array` of `Configuration` elements containing all node children.
`Configuration[]`	`getChildren(String name)` Return an `Array` of `Configuration` elements containing all node children with the specified name.
`String`	`getLocation()` Return a string describing location of Configuration.
`String`	`getName()` Return the name of the node.
`String`	`getNamespace()` Returns a string indicating which namespace this Configuration node belongs to.
`String`	`getValue()` Return the `String` value of the node.
`String`	`getValue(String defaultValue)` Returns the value of the configuration element as a `String`.
`boolean`	`getValueAsBoolean()` Return the `boolean` value of the node.
`boolean`	`getValueAsBoolean(boolean defaultValue)` Returns the value of the configuration element as a `boolean`.
`float`	`getValueAsFloat()` Return the `float` value of the node.
`float`	`getValueAsFloat(float defaultValue)` Returns the value of the configuration element as a `float`.
`int`	`getValueAsInteger()` Return the `int` value of the node.
`int`	`getValueAsInteger(int defaultValue)` Returns the value of the configuration element as an `int`.
`long`	`getValueAsLong()` Return the `long` value of the node.
`long`	`getValueAsLong(long defaultValue)` Returns the value of the configuration element as a `long`.

- Method Detail
  - getName
```
String getName()
```
    Return the name of the node.
    
    Returns:
    
    name of the Configuration node.
  - getLocation
```
String getLocation()
```
    Return a string describing location of Configuration. Location can be different for different mediums (ie "file:line" for normal XML files or "table:primary-key" for DB based configurations);
    
    Returns:
    
    a string describing location of Configuration
  - getNamespace
```
String getNamespace()
             throws ConfigurationException
```
    Returns a string indicating which namespace this Configuration node belongs to.
    What this returns is dependent on the configuration file and the Configuration builder. If the Configuration builder does not support namespaces, this method will return a blank string.
    
    In the case of DefaultConfigurationBuilder, the namespace will be the URI associated with the XML element. Eg.,:
```
 <foo xmlns:x="http://blah.com">
   <x:bar/>
 </foo>
 
```
    The namespace of foo will be "", and the namespace of bar will be "http://blah.com".
    Returns:
    
    a String identifying the namespace of this Configuration.
    
    Throws:
    
    ConfigurationException - if an error occurs
    
    Since:
    
    4.1
  - getChild
```
Configuration getChild(String child)
```
    Return a new Configuration instance encapsulating the specified child node.
    If no such child node exists, an empty Configuration will be returned, allowing constructs such as conf.getChild("foo").getChild("bar").getChild("baz").getValue("default");
    
    If you wish to get a null return when no element is present, use getChild("foo", false).
    
    Parameters:
    
    child - The name of the child node.
    
    Returns:
    
    Configuration
  - getChild
```
Configuration getChild(String child,
                       boolean createNew)
```
    Return a Configuration instance encapsulating the specified child node.
    
    Parameters:
    
    child - The name of the child node.
    
    createNew - If true, a new Configuration will be created and returned if the specified child does not exist. If false, null will be returned when the specified child doesn't exist.
    
    Returns:
    
    Configuration
  - getChildren
```
Configuration[] getChildren()
```
    Return an Array of Configuration elements containing all node children. The array order will reflect the order in the source config file.
    
    Returns:
    
    All child nodes
  - getChildren
```
Configuration[] getChildren(String name)
```
    Return an Array of Configuration elements containing all node children with the specified name. The array order will reflect the order in the source config file.
    
    Parameters:
    
    name - The name of the children to get.
    
    Returns:
    
    The child nodes with name name
  - getAttributeNames
```
String[] getAttributeNames()
```
    Return an array of all attribute names.
    The order of attributes in this array can not be relied on. As with XML, a Configuration's attributes are an unordered set. If your code relies on order, eg conf.getAttributeNames()[0], then it is liable to break if a different XML parser is used.
    
    Returns:
    
    a String[] value
  - getAttribute
```
String getAttribute(String paramName)
             throws ConfigurationException
```
    Return the value of specified attribute.
    
    Parameters:
    
    paramName - The name of the parameter you ask the value of.
    
    Returns:
    
    String value of attribute.
    
    Throws:
    
    ConfigurationException - If no attribute with that name exists.
  - getAttributeAsInteger
```
int getAttributeAsInteger(String paramName)
                   throws ConfigurationException
```
    Return the int value of the specified attribute contained in this node.
    
    Parameters:
    
    paramName - The name of the parameter you ask the value of.
    
    Returns:
    
    int value of attribute
    
    Throws:
    
    ConfigurationException - If no parameter with that name exists. or if conversion to int fails.
  - getAttributeAsLong
```
long getAttributeAsLong(String name)
                 throws ConfigurationException
```
    Returns the value of the attribute specified by its name as a long.
    
    Parameters:
    
    name - The name of the parameter you ask the value of.
    
    Returns:
    
    long value of attribute
    
    Throws:
    
    ConfigurationException - If no parameter with that name exists. or if conversion to long fails.
  - getAttributeAsFloat
```
float getAttributeAsFloat(String paramName)
                   throws ConfigurationException
```
    Return the float value of the specified parameter contained in this node.
    
    Parameters:
    
    paramName - The name of the parameter you ask the value of.
    
    Returns:
    
    float value of attribute
    
    Throws:
    
    ConfigurationException - If no parameter with that name exists. or if conversion to float fails.
  - getAttributeAsBoolean
```
boolean getAttributeAsBoolean(String paramName)
                       throws ConfigurationException
```
    Return the boolean value of the specified parameter contained in this node.
    
    Parameters:
    
    paramName - The name of the parameter you ask the value of.
    
    Returns:
    
    boolean value of attribute
    
    Throws:
    
    ConfigurationException - If no parameter with that name exists. or if conversion to boolean fails.
  - getValue
```
String getValue()
         throws ConfigurationException
```
    Return the String value of the node.
    
    Returns:
    
    the value of the node.
    
    Throws:
    
    ConfigurationException - if an error occurs
  - getValueAsInteger
```
int getValueAsInteger()
               throws ConfigurationException
```
    Return the int value of the node.
    
    Returns:
    
    the value of the node.
    
    Throws:
    
    ConfigurationException - If conversion to int fails.
  - getValueAsFloat
```
float getValueAsFloat()
               throws ConfigurationException
```
    Return the float value of the node.
    
    Returns:
    
    the value of the node.
    
    Throws:
    
    ConfigurationException - If conversion to float fails.
  - getValueAsBoolean
```
boolean getValueAsBoolean()
                   throws ConfigurationException
```
    Return the boolean value of the node.
    
    Returns:
    
    the value of the node.
    
    Throws:
    
    ConfigurationException - If conversion to boolean fails.
  - getValueAsLong
```
long getValueAsLong()
             throws ConfigurationException
```
    Return the long value of the node.
    
    Returns:
    
    the value of the node.
    
    Throws:
    
    ConfigurationException - If conversion to long fails.
  - getValue
```
String getValue(String defaultValue)
```
    Returns the value of the configuration element as a String. If the configuration value is not set, the default value will be used.
    
    Parameters:
    
    defaultValue - The default value desired.
    
    Returns:
    
    String value of the Configuration, or default if none specified.
  - getValueAsInteger
```
int getValueAsInteger(int defaultValue)
```
    Returns the value of the configuration element as an int. If the configuration value is not set, the default value will be used.
    
    Parameters:
    
    defaultValue - The default value desired.
    
    Returns:
    
    int value of the Configuration, or default if none specified.
  - getValueAsLong
```
long getValueAsLong(long defaultValue)
```
    Returns the value of the configuration element as a long. If the configuration value is not set, the default value will be used.
    
    Parameters:
    
    defaultValue - The default value desired.
    
    Returns:
    
    long value of the Configuration, or default if none specified.
  - getValueAsFloat
```
float getValueAsFloat(float defaultValue)
```
    Returns the value of the configuration element as a float. If the configuration value is not set, the default value will be used.
    
    Parameters:
    
    defaultValue - The default value desired.
    
    Returns:
    
    float value of the Configuration, or default if none specified.
  - getValueAsBoolean
```
boolean getValueAsBoolean(boolean defaultValue)
```
    Returns the value of the configuration element as a boolean. If the configuration value is not set, the default value will be used.
    
    Parameters:
    
    defaultValue - The default value desired.
    
    Returns:
    
    boolean value of the Configuration, or default if none specified.
  - getAttribute
```
String getAttribute(String name,
                    String defaultValue)
```
    Returns the value of the attribute specified by its name as a String, or the default value if no attribute by that name exists or is empty.
    
    Parameters:
    
    name - The name of the attribute you ask the value of.
    
    defaultValue - The default value desired.
    
    Returns:
    
    String value of attribute. It will return the default value if the named attribute does not exist, or if the value is not set.
  - getAttributeAsInteger
```
int getAttributeAsInteger(String name,
                          int defaultValue)
```
    Returns the value of the attribute specified by its name as a int, or the default value if no attribute by that name exists or is empty.
    
    Parameters:
    
    name - The name of the attribute you ask the value of.
    
    defaultValue - The default value desired.
    
    Returns:
    
    int value of attribute. It will return the default value if the named attribute does not exist, or if the value is not set.
  - getAttributeAsLong
```
long getAttributeAsLong(String name,
                        long defaultValue)
```
    Returns the value of the attribute specified by its name as a long, or the default value if no attribute by that name exists or is empty.
    
    Parameters:
    
    name - The name of the attribute you ask the value of.
    
    defaultValue - The default value desired.
    
    Returns:
    
    long value of attribute. It will return the default value if the named attribute does not exist, or if the value is not set.
  - getAttributeAsFloat
```
float getAttributeAsFloat(String name,
                          float defaultValue)
```
    Returns the value of the attribute specified by its name as a float, or the default value if no attribute by that name exists or is empty.
    
    Parameters:
    
    name - The name of the attribute you ask the value of.
    
    defaultValue - The default value desired.
    
    Returns:
    
    float value of attribute. It will return the default value if the named attribute does not exist, or if the value is not set.
  - getAttributeAsBoolean
```
boolean getAttributeAsBoolean(String name,
                              boolean defaultValue)
```
    Returns the value of the attribute specified by its name as a boolean, or the default value if no attribute by that name exists or is empty.
    
    Parameters:
    
    name - The name of the attribute you ask the value of.
    
    defaultValue - The default value desired.
    
    Returns:
    
    boolean value of attribute. It will return the default value if the named attribute does not exist, or if the value is not set.

Interface Configuration

Data Model

Namespace support

Example

Miscellanea

Method Summary

Method Detail

getName

getLocation

getNamespace

getChild

getChild

getChildren

getChildren

getAttributeNames

getAttribute

getAttributeAsInteger

getAttributeAsLong

getAttributeAsFloat

getAttributeAsBoolean

getValue

getValueAsInteger

getValueAsFloat

getValueAsBoolean

getValueAsLong