com.appeligo.search.util.ChunkedResults.java Source code

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Here is the source code for com.appeligo.search.util.ChunkedResults.java

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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 com.appeligo.search.util;

import java.util.List;

import org.hibernate.Query;

public class ChunkedResults<T> {

    private Query query;
    private int chunkSize;
    private List<T> list;
    private int nextChunkStart;
    private int pos;

    public ChunkedResults(Query query) {
        this(query, 1000);
    }

    public ChunkedResults(Query query, int chunkSize) {
        this.query = query;
        this.chunkSize = chunkSize;
        query.setMaxResults(chunkSize);
        beforeFirst();
    }

    public void beforeFirst() {
        if (nextChunkStart != chunkSize) {
            list = null;
            nextChunkStart = 0;
        }
        //query.setFirstResult(0);
        //pos = 0;
    }

    @SuppressWarnings("unchecked")
    public boolean next() {
        if (list != null) {
            if (pos >= list.size()) {
                list = null;
            }
        }
        if (list == null) {
            query.setFirstResult(nextChunkStart);
            list = query.list();
            nextChunkStart += chunkSize;
            pos = 0;
        } else {
            pos++;
        }
        if (pos >= list.size()) {
            return false;
        }
        return true;
    }

    public T get() {
        if (list == null || pos >= list.size()) {
            return null;
        } else {
            return list.get(pos);
        }
    }
}