org.vader.apm.dao.util.MapExtractor.java Source code

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Here is the source code for org.vader.apm.dao.util.MapExtractor.java

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/*
 * Copyright 2014. Vadim Baranov
 *
 *    Licensed 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.vader.apm.dao.util;

import org.apache.commons.lang3.Validate;
import org.springframework.jdbc.core.RowCallbackHandler;
import org.springframework.jdbc.core.RowMapper;
import org.vader.apm.domain.ApmDbObject;

import java.sql.ResultSet;
import java.sql.SQLException;
import java.util.HashMap;
import java.util.Map;

/**
 * @author Vadim Baranov
 * @param <K> key type
 * @param <V> value type
 */
public class MapExtractor<K, V> implements RowCallbackHandler {
    private final RowMapper<K> keyMapper;
    private final RowMapper<V> valueMapper;

    private int rowNum;
    private Map<Long, K> loadedKeys = new HashMap<>();
    private Map<Long, V> loadedValues = new HashMap<>();

    private final Map<K, V> result = new HashMap<>();

    /**
     * Constructor.
     *
     * @param keyMapper key mapper
     * @param valueMapper value mapper
     */
    public MapExtractor(RowMapper<K> keyMapper, RowMapper<V> valueMapper) {
        Validate.notNull(keyMapper, "key mapper must be not null");
        Validate.notNull(valueMapper, "value mapper must be not null");
        this.keyMapper = keyMapper;
        this.valueMapper = valueMapper;
    }

    /**
     * Constructor.
     *
     * @param keyColumn key column name
     * @param keyClazz key type
     * @param valueMapper value mapper
     */
    public MapExtractor(String keyColumn, Class<K> keyClazz, RowMapper<V> valueMapper) {
        Validate.notBlank(keyColumn, "key column name must be not blank");
        Validate.notNull(keyClazz, "key class must be not null");
        Validate.notNull(valueMapper, "value mapper must be not null");
        this.keyMapper = new PrimitiveRowMapper<>(keyColumn, keyClazz);
        this.valueMapper = valueMapper;
    }

    /**
     * Constructor.
     *
     * @param keyColumn key column name
     * @param keyClazz key type
     * @param valueColumn value column name
     * @param valueClazz value type
     */
    public MapExtractor(String keyColumn, Class<K> keyClazz, String valueColumn, Class<V> valueClazz) {
        Validate.notBlank(keyColumn, "key column name must be not blank");
        Validate.notNull(keyClazz, "key class must be not null");
        Validate.notBlank(valueColumn, "value column name must be not blank");
        Validate.notNull(valueClazz, "value class must be not null");
        this.keyMapper = new PrimitiveRowMapper<>(keyColumn, keyClazz);
        this.valueMapper = new PrimitiveRowMapper<>(valueColumn, valueClazz);
    }

    /**
     * Constructor.
     *
     * @param keyMapper key mapper
     * @param valueColumn value column name
     * @param valueClazz value type
     */
    public MapExtractor(RowMapper<K> keyMapper, String valueColumn, Class<V> valueClazz) {
        Validate.notNull(keyMapper, "key mapper must be not null");
        Validate.notBlank(valueColumn, "value column name must be not blank");
        Validate.notNull(valueClazz, "value class must be not null");
        this.keyMapper = keyMapper;
        this.valueMapper = new PrimitiveRowMapper<>(valueColumn, valueClazz);
    }

    @Override
    public void processRow(ResultSet rs) throws SQLException {
        K key = keyMapper.mapRow(rs, rowNum);
        if (key instanceof ApmDbObject) {
            final ApmDbObject dbObject = (ApmDbObject) key;
            if (loadedKeys.containsKey(dbObject.getId())) {
                key = loadedKeys.get(dbObject.getId());
            } else {
                loadedKeys.put(dbObject.getId(), key);
            }
        }
        V value = valueMapper.mapRow(rs, rowNum++);
        if (value instanceof ApmDbObject) {
            final ApmDbObject dbObject = (ApmDbObject) value;
            if (loadedValues.containsKey(dbObject.getId())) {
                value = loadedValues.get(dbObject.getId());
            } else {
                loadedValues.put(dbObject.getId(), value);
            }
        }
        result.put(key, value);
    }

    public Map<K, V> getResult() {
        return result;
    }

    /**
     * Primitive row mapper.
     */
    private static class PrimitiveRowMapper<T> implements RowMapper<T> {
        private final String column;
        private final Class<T> clazz;

        /**
         * Constructor.
         *
         * @param column column name
         * @param clazz column type
         */
        private PrimitiveRowMapper(String column, Class<T> clazz) {
            this.column = column;
            this.clazz = clazz;
        }

        @Override
        public T mapRow(ResultSet rs, int rowNum) throws SQLException {
            return clazz.cast(rs.getObject(column));
        }
    }
}