Hi,
I am new to the Apache Felix platform, and I am using the examples provided
in the Apache Felix OSGi Tutorial page to learn how to write OSGi bundle.
Unfortunately, I run into a problem when trying to use the service provided
by
another bundle, and followings are the codes of the Activator.java.
-------------------------------------------------------------
/*
* Apache Felix OSGi tutorial.
**/
package tutorial.example3;
import java.io.BufferedReader;
import java.io.InputStreamReader;
import java.io.IOException;
import org.osgi.framework.BundleActivator;
import org.osgi.framework.BundleContext;
import org.osgi.framework.ServiceReference;
import tutorial.example2.service.DictionaryService;
public class Activator implements BundleActivator
{
public void start(BundleContext context) throws Exception
{
// Query for all service references matching any language.
ServiceReference[] refs = context.getServiceReferences(
DictionaryService.class.getName(), "(Language=*)");
if (refs != null)
{
try
{
System.out.println("Enter a blank line to exit.");
BufferedReader in = new BufferedReader(new
InputStreamReader(System.in));
String word = "";
// Loop endlessly.
while (true)
{
// Ask the user to enter a word.
System.out.print("Enter word: ");
word = in.readLine();
// If the user entered a blank line, then
// exit the loop.
if (word.length() == 0)
{
break;
}
// First, get a dictionary service and then check
// if the word is correct.
DictionaryService dictionary =
(DictionaryService) context.getService(refs[0]);
if (dictionary.checkWord(word))
{
System.out.println("Correct.");
}
else
{
System.out.println("Incorrect.");
}
// Unget the dictionary service.
context.ungetService(refs[0]);
}
} catch (IOException ex) { }
}
else
{
System.out.println("Couldn't find any dictionary service...");
}
}
public void stop(BundleContext context)
{
// NOTE: The service is automatically released.
}
}
-------------------------------------------------------------------------------------------
Two unchecked warnings were found when I used the javac command to
compile the code.
javac -Xlint:unchecked -d classes/ *.java
===================================================
Activator.java: warning: [unchecked] unchecked conversion
(DictionaryService) context.getService(refs[0]);
^
required: ServiceReference<S>
found: ServiceReference
where S is a type-variable:
S extends Object declared in method <S>getService(ServiceReference<S>)
Activator.java: warning: [unchecked] unchecked method invocation: method
getService in interface BundleContext is applied to given types
(DictionaryService) context.getService(refs[0]);
^
required: ServiceReference<S>
found: ServiceReference
where S is a type-variable:
S extends Object declared in method <S>getService(ServiceReference<S>)
2 warnings
===================================================
By checking the OSGi Service Platform Release 4 Core Specification Version
4.3,
the parameter fed to the getService method should be ServiceReference<S>.
However, the type of refs in the example is declared to be ServiceReference.
Could I cast the type of refs before feeding into the getService method?
Or there is a better solution to solve this problem?
Thanks.
Todd
