mapfieldselector.java

lucene-2.4.0 是一个全文收索的工具包

package org.apache.lucene.document;

/**
 * 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.
 */

import java.util.HashMap;
import java.util.List;
import java.util.Map;

/**
 * A FieldSelector based on a Map of field names to FieldSelectorResults
 *
 */
public class MapFieldSelector implements FieldSelector {
    
    Map fieldSelections;
    
    /** Create a a MapFieldSelector
     * @param fieldSelections maps from field names (String) to FieldSelectorResults
     */
    public MapFieldSelector(Map fieldSelections) {
        this.fieldSelections = fieldSelections;
    }
    
    /** Create a a MapFieldSelector
     * @param fields fields to LOAD.  List of Strings.  All other fields are NO_LOAD.
     */
    public MapFieldSelector(List fields) {
        fieldSelections = new HashMap(fields.size()*5/3);
        for (int i=0; i<fields.size(); i++)
            fieldSelections.put(fields.get(i), FieldSelectorResult.LOAD);
    }
    
    /** Create a a MapFieldSelector
     * @param fields fields to LOAD.  All other fields are NO_LOAD.
     */
    public MapFieldSelector(String[] fields) {
        fieldSelections = new HashMap(fields.length*5/3);
        for (int i=0; i<fields.length; i++)
            fieldSelections.put(fields[i], FieldSelectorResult.LOAD);
    }
    
    /** Load field according to its associated value in fieldSelections
     * @param field a field name
     * @return the fieldSelections value that field maps to or NO_LOAD if none.
     */
    public FieldSelectorResult accept(String field) {
        FieldSelectorResult selection = (FieldSelectorResult) fieldSelections.get(field);
        return selection!=null ? selection : FieldSelectorResult.NO_LOAD;
    }
    
}