resultloader.java

本套系统采用了业界当前最为流行的beanAction组件

/*
 *  Copyright 2004 Clinton Begin
 *
 *  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 com.ibatis.sqlmap.engine.mapping.result.loader;

import com.ibatis.sqlmap.engine.impl.ExtendedSqlMapClient;
import com.ibatis.sqlmap.engine.type.DomCollectionTypeMarker;

import java.sql.SQLException;
import java.util.Collection;
import java.util.HashSet;
import java.util.List;
import java.util.Set;

/**
 * Class to load results into objects
 */
public class ResultLoader {

  private ResultLoader() {
  }

  /**
   * Loads a result lazily
   *
   * @param client          - the client creating the object
   * @param statementName   - the name of the statement to be used
   * @param parameterObject - the parameters for the statement
   * @param targetType      - the target type of the result
   * @return the loaded result
   * @throws SQLException
   */
  public static Object loadResult(ExtendedSqlMapClient client, String statementName, Object parameterObject, Class targetType)
      throws SQLException {
    Object value = null;


    if (client.isLazyLoadingEnabled()) {
      if (client.isEnhancementEnabled()) {
        EnhancedLazyResultLoader lazy = new EnhancedLazyResultLoader(client, statementName, parameterObject, targetType);
        value = lazy.loadResult();
      } else {
        LazyResultLoader lazy = new LazyResultLoader(client, statementName, parameterObject, targetType);
        value = lazy.loadResult();
      }
    } else {
      value = getResult(client, statementName, parameterObject, targetType);
    }

    return value;
  }

  protected static Object getResult(ExtendedSqlMapClient client, String statementName, Object parameterObject, Class targetType) throws SQLException {
    Object value = null;
    if (DomCollectionTypeMarker.class.isAssignableFrom(targetType)) {
      value = client.queryForList(statementName, parameterObject);
    } else if (Set.class.isAssignableFrom(targetType)) {
      value = new HashSet(client.queryForList(statementName, parameterObject));
    } else if (Collection.class.isAssignableFrom(targetType)) {
      value = client.queryForList(statementName, parameterObject);
    } else if (targetType.isArray()) {
      List list = client.queryForList(statementName, parameterObject);
      value = listToArray(list, targetType.getComponentType());
    } else {
      value = client.queryForObject(statementName, parameterObject);
    }
    return value;
  }


  private static Object[] listToArray(List list, Class type) {
    Object array = java.lang.reflect.Array.newInstance(type, list.size());
    array = list.toArray((Object[]) array);
    return (Object[]) array;
  }

}