org.apache.openjpa.kernel.AbstractPCResultObjectProvider Maven / Gradle / Ivy
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* Licensed to the Apache Software Foundation (ASF) under one
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* distributed with this work for additional information
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* 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.kernel;
import org.apache.openjpa.lib.rop.ResultObjectProvider;
import org.apache.openjpa.meta.ClassMetaData;
import org.apache.openjpa.meta.MetaDataRepository;
import org.apache.openjpa.util.ObjectNotFoundException;
import org.apache.openjpa.util.StoreException;
/**
* Abstract implementation of {@link PCResultObjectProvider}
* that implements {@link ResultObjectProvider#getResultObject}
* by assembling the necessary information about the object to be loaded.
*
* @author Patrick Linskey
*/
public abstract class AbstractPCResultObjectProvider
implements PCResultObjectProvider {
/**
* The {@link StoreContext} that this result object
* provider will load objects into.
*/
protected final StoreContext ctx;
/**
* Create a new provider for loading PC objects from the input
* into ctx.
*/
public AbstractPCResultObjectProvider(StoreContext ctx) {
this.ctx = ctx;
}
/**
* Return the context this provider was constructed with.
*/
public StoreContext getContext() {
return ctx;
}
public void initialize(OpenJPAStateManager sm, PCState state,
FetchConfiguration fetch)
throws Exception {
sm.initialize(getPCType(), state);
load(sm, fetch);
}
public Object getResultObject()
throws Exception {
Class type = getPCType();
MetaDataRepository repos = ctx.getConfiguration().
getMetaDataRepositoryInstance();
ClassMetaData meta = repos.getMetaData
(type, ctx.getClassLoader(), true);
Object oid = getObjectId(meta);
Object res = ctx.find(oid, null, null, this, 0);
if (res == null)
throw new ObjectNotFoundException(oid);
return res;
}
/**
* Implement this method to extract the object id value from the
* current record of the input.
*/
protected abstract Object getObjectId(ClassMetaData meta)
throws Exception;
/**
* Implement this method to extract the type of the pc stored
* in the current record of the input.
*/
protected abstract Class getPCType()
throws Exception;
/**
* Load data from the current input record into the given state
* manager. Remember to call {@link OpenJPAStateManager#setVersion} to set
* the optimistic versioning information, if it has any.
*/
protected abstract void load(OpenJPAStateManager sm,
FetchConfiguration fetch)
throws Exception;
/**
* Override if desired. Does nothing by default.
*/
public void open()
throws Exception {
}
/**
* Override if desired. Returns false by default.
*
* @see ResultObjectProvider#supportsRandomAccess
*/
public boolean supportsRandomAccess() {
return false;
}
/**
* Implement this method to advance the input.
*
* @see ResultObjectProvider#next
*/
public abstract boolean next()
throws Exception;
/**
* Override if desired. Throws an exception by default.
*
* @see ResultObjectProvider#absolute
*/
public boolean absolute(int pos)
throws Exception {
throw new UnsupportedOperationException();
}
/**
* Override if desired. Returns {@link Integer#MAX_VALUE} by default.
*
* @see ResultObjectProvider#size
*/
public int size()
throws Exception {
return Integer.MAX_VALUE;
}
/**
* Override if desired. Throws an exception by default.
*
* @see ResultObjectProvider#reset
*/
public void reset()
throws Exception {
throw new UnsupportedOperationException();
}
/**
* Override if desired. Does nothing by default.
*
* @see ResultObjectProvider#close
*/
public void close()
throws Exception {
}
/**
* Throws a {@link StoreException} by default.
*/
public void handleCheckedException(Exception e) {
throw new StoreException (e);
}
}