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/*
* Licensed to the Apache Software Foundation (ASF) under one
* or more contributor license agreements. See the NOTICE file
* distributed with this work for additional information
* regarding copyright ownership. The ASF licenses this file
* to you under the Apache License, Version 2.0 (the
* "License"); you may not use this file except in compliance
* with the License. You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing,
* software distributed under the License is distributed on an
* "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
* KIND, either express or implied. See the License for the
* specific language governing permissions and limitations
* under the License.
*/
package calculator.dosgi;
import org.osgi.framework.BundleContext;
import org.osgi.framework.Constants;
import org.osgi.framework.Filter;
import org.osgi.framework.InvalidSyntaxException;
import org.osgi.util.tracker.ServiceTracker;
import calculator.dosgi.operations.AddService;
import calculator.dosgi.operations.DivideService;
import calculator.dosgi.operations.MultiplyService;
import calculator.dosgi.operations.SubtractService;
/**
* An implementation of the Calculator service.
*/
public class CalculatorServiceImpl implements CalculatorService {
// private AddService addService;
// private SubtractService subtractService;
// private MultiplyService multiplyService;
// private DivideService divideService;
private ServiceTracker tracker;
public CalculatorServiceImpl() {
super();
}
public CalculatorServiceImpl(BundleContext context) {
super();
Filter filter = null;
try {
filter = context.createFilter("(" + Constants.OBJECTCLASS + "=calculator.dosgi.operations.*)");
} catch (InvalidSyntaxException e) {
e.printStackTrace();
}
this.tracker = new ServiceTracker(context, filter, null);
tracker.open();
}
/*
* The following setters can be used for DS injection
*/
/*
public void setAddService(AddService addService) {
this.addService = addService;
}
public void setSubtractService(SubtractService subtractService) {
this.subtractService = subtractService;
}
public void setDivideService(DivideService divideService) {
this.divideService = divideService;
}
public void setMultiplyService(MultiplyService multiplyService) {
this.multiplyService = multiplyService;
}
*/
private <T> T getService(Class<T> cls) {
for (Object s : tracker.getServices()) {
if (cls.isInstance(s)) {
return cls.cast(s);
}
}
throw new IllegalStateException(cls.getSimpleName() + " is not available");
}
public double add(double n1, double n2) {
return getService(AddService.class).add(n1, n2);
}
public double subtract(double n1, double n2) {
return getService(SubtractService.class).subtract(n1, n2);
}
public double multiply(double n1, double n2) {
return getService(MultiplyService.class).multiply(n1, n2);
}
public double divide(double n1, double n2) {
return getService(DivideService.class).divide(n1, n2);
}
}
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