FREExtension

Method details
Class Example

Package:: com.adobe.fre
Runtime version: AIR 3

The FREExtension interface defines the interface used by the AIR runtime to instantiate the Java code in a native extension.

Methods
Method	Description
void initialize()	Called by the runtime during extension initialization.
FREContext createContext( String contextType)	Creates an FREContext object.
void dispose()	Called by the runtime when the extension is destroyed.

Every native extension library must implement the FREExtension interface. The fully qualified name of the implementing class must be present in the <initializer> element of the extension descriptor file.

For example, if the extension Java code is packaged in a JAR file named ExampleExtension.jar and the class implementing FREExtension is com.example.ExampleExtension , then you would use the following extension descriptor entry:

<platform name="Android-ARM"> 
    <applicationDeployment> 
        <nativeLibrary>ExampleExtension.jar</nativeLibrary> 
        <initializer>com.example.ExampleExtension</initializer> 
    </applicationDeployment> 
</platform>

The <finalizer> element is not needed when using the Java extension interface.

Method details

createContext

FREContext createContext( String contextType )

Creates an FREContext object.

The AIR runtime calls the Java createContext() method after the extension invokes the ActionScript ExtensionContext.createExtensionContext() method. The runtime uses this context returned for subsequent method invocations.

This function typically uses the contextType parameter to choose the set of methods in the native implementation that the ActionScript side can call. Each context type corresponds to a different set of methods. Your extension can create a single context; multiple context instances that provide the same set of features, but with instance-specific state; or multiple context instances that provide different features.

Parameters:

contextType: A string identifying the type of the context. You define this string as required by your extension. The context type can indicate any agreed-to meaning between the ActionScript side and native side of the extension. If your extension has no use for context types, this value can be null . This value is a UTF-8 encoded string, terminated with the null character.

Returns:

FREContext: the extension context object.

Example:

The following example returns a context object based on the contextType parameter. If the contextType is the string, “TypeA”, the function returns a unique FREContext instance each time it is called. For other values of contextType , the function only creates a single FREContext instance and stores it in the private variable bContext .

    private FREContext bContext; 
    public FREContext createContext( String contextType ) { 
        FREContext theContext = null; 
        if( contextType == "TypeA" ) 
        { 
            theContext = new TypeAContext(); 
        } 
        else 
        { 
            if( bContext == null ) bContext = new TypeBContext(); 
            theContext = bContext; 
        } 
        return theContext; 
    }

dispose

void dispose()

Use the dispose() method to clean up any resources created by this FREExtension implementation. The AIR runtime calls this method when the associated ActionScript ExtensionContext object is disposed or becomes eligible for garbage collection.

initialize

void initialize()

Called by the AIR runtime during extension initialization.

Class Example

The following example illustrates a simple FREExtension example that creates a single FREContext object. The example also shows how to use the Android Log class to log informational messages to the Android system log (which you can view using the adb logcat command).

package com.example; 
 
import android.util.Log; 
import com.adobe.fre.FREContext; 
import com.adobe.fre.FREExtension; 
 
public class DataExchangeExtension implements FREExtension { 
 
    private static final String EXT_NAME = "DataExchangeExtension"; 
    private String tag = EXT_NAME + "ExtensionClass"; 
    private DataExchangeContext context; 
 
    public FREContext createContext(String arg0) { 
        Log.i(tag, "Creating context"); 
        if( context == null) context = new DataExchangeContext(); 
        return context; 
    } 
 
    public void dispose() { 
        Log.i(tag, "Disposing extension"); 
        // nothing to dispose for this example 
    } 
 
    public void initialize() { 
        Log.i(tag, "Initialize"); 
        // nothing to initialize for this example 
    } 
}