Javadoc Tag Specification

Entry Tag

The entry tag declares a context entry required by a component. The component is supplied the context entry via a context argument as part of the contextualization lifecycle stage. Context entries my declare a object type or array of object types. If the type is not declared java.lang.String is assumed. Context entries may also be declared as optional and/or volatile. The default behaviour is to assume that a context entry is required (not optional) is is non-volatile.

Attributes

Attribute	Required	Description
key	yes	The context entry lookup key.
alias	no	Declaration of an alternative name that the component may use to lookup the entry.
type	no	The classname of the context entry that the component may cast the component to. If not declared, java.lang.String is assumed.
volatile	no	A value of true or false - if true a new instance of the context entry value shall be created and retured to the component per request. If false (the default) a container context implementation may safely cache context entry values.
optional	no	Declares the context entry as optional in which case the supply of the context entry is at the discretion of a container.

Example

package org.apache.avalon.playground;

/**
 * Example of a component declaring a context entry dependencies.
 *
 * @avalon.component version="1.0" name="demo"
 */
public class Primary implements Contextualizable
{
   /**
    * @avalon.entry key="home" type="java.io.File" optional="true"
    * @avalon.entry key="time" type="java.util.Date" volatile="true"
    * @avalon.entry key="table" type="java.lang.Object[]"
    * @avalon.entry key="urn:avalon:name" alias="block.name"
    */
    public void contextualize( Context context ) 
      throws ContextException
    {
        String name = (String) context.get( "name" );
        Object[] array = (Object[]) context.get( "table" );
        try
        {
            File home = (File) context.get( "home" );
            ...
        }
        catch( ContextException ce )
        {
            // it's optional
        }
    }
}

Generated meta-info type descriptor:

<type>
  <info>
    <version>1.3.0</version>
    <name>primary-component</name>
  </info>
  <context>
    <entry key="home" type="java.io.File" optional="true"/>
    <entry key="time" type="java.util.Date" volatile="true"/>
    <entry key="table" type="java.lang.Object[]"/>
    <entry key="urn:avalon:name" alias="block.name">
  </context>
</type>