/* | |
* 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 org.apache.openjpa.slice.policy; | |
import java.util.List; | |
import org.apache.openjpa.slice.DistributionPolicy; | |
import org.apache.openjpa.slice.PObject; | |
import org.apache.openjpa.slice.Person; | |
/** | |
* Exemplar {@link DistributionPolicy} that maintains closure and distributes | |
* based on attributes of the given instance. | |
* | |
* @author Pinaki Poddar | |
* | |
*/ | |
public class UserDistributionPolicy implements DistributionPolicy { | |
/** | |
* Distribute the given instance. | |
* Assumes that two configured slices are named as <em>One</em> and | |
* <em>Two</em>.<br> | |
* The policy is only implemented for PObject and Person i.e. two of three | |
* known classes. No policy is implemented for Address because Address is | |
* persisted always by cascade and hence Slice should assign automatically | |
* the same slice as its owner Person. | |
* | |
*/ | |
public String distribute(Object pc, List<String> slices, Object context) { | |
assertValidSlices(slices); | |
if (pc instanceof PObject) | |
return distribute((PObject)pc); | |
if (pc instanceof Person) { | |
return distribute((Person)pc); | |
} | |
throw new RuntimeException("No policy for " + pc.getClass()); | |
} | |
void assertValidSlices(List<String> slices) { | |
if (slices.contains("One") && slices.contains("Two")) | |
return; | |
throw new RuntimeException("This policy assumes two slices named " + | |
"One and Two. But configured slices are " + slices); | |
} | |
/** | |
* Distribute PObject based on odd-even value of its id. | |
*/ | |
String distribute(PObject pc) { | |
return (pc.getId()%2 == 0) ? "One" : "Two"; | |
} | |
/** | |
* Distribute Person based on first character of its name. | |
*/ | |
String distribute(Person pc) { | |
return (pc.getName().startsWith("A")) ? "One" : "Two"; | |
} | |
} |