Coverage Report - org.apache.commons.dbutils.handlers.KeyedHandler
 
Classes in this File Line Coverage Branch Coverage Complexity
KeyedHandler
0%
0/20
0%
0/4
1.222
 
 1  
 /*
 2  
  * Licensed to the Apache Software Foundation (ASF) under one or more
 3  
  * contributor license agreements.  See the NOTICE file distributed with
 4  
  * this work for additional information regarding copyright ownership.
 5  
  * The ASF licenses this file to You under the Apache License, Version 2.0
 6  
  * (the "License"); you may not use this file except in compliance with
 7  
  * the License.  You may obtain a copy of the License at
 8  
  *
 9  
  *      http://www.apache.org/licenses/LICENSE-2.0
 10  
  *
 11  
  * Unless required by applicable law or agreed to in writing, software
 12  
  * distributed under the License is distributed on an "AS IS" BASIS,
 13  
  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 14  
  * See the License for the specific language governing permissions and
 15  
  * limitations under the License.
 16  
  */
 17  
 package org.apache.commons.dbutils.handlers;
 18  
 
 19  
 import java.sql.ResultSet;
 20  
 import java.sql.SQLException;
 21  
 import java.util.HashMap;
 22  
 import java.util.Map;
 23  
 
 24  
 import org.apache.commons.dbutils.ResultSetHandler;
 25  
 import org.apache.commons.dbutils.RowProcessor;
 26  
 
 27  
 /**
 28  
  * <p>
 29  
  * <code>ResultSetHandler</code> implementation that returns a Map of Maps.
 30  
  * <code>ResultSet</code> rows are converted into Maps which are then stored
 31  
  * in a Map under the given key.  Although this implementation uses Maps to 
 32  
  * store row contents, subclasses are encouraged to override the 
 33  
  * <code>createRow()</code> method to convert the rows into any kind of object.
 34  
  * </p>
 35  
  * <p>
 36  
  * If you had a Person table with a primary key column called ID, you could 
 37  
  * retrieve rows from the table like this:
 38  
  * <pre>
 39  
  * ResultSetHandler h = new KeyedHandler("id");
 40  
  * Map found = (Map) queryRunner.query("select id, name, age from person", h);
 41  
  * Map jane = (Map) found.get(new Long(1)); // jane's id is 1
 42  
  * String janesName = (String) jane.get("name");
 43  
  * Integer janesAge = (Integer) jane.get("age");
 44  
  * </pre>
 45  
  * Note that the "id" passed to KeyedHandler and "name" and "age" passed to the
 46  
  * returned Map's get() method can be in any case.  The data types returned for
 47  
  * name and age are dependent upon how your JDBC driver converts SQL column 
 48  
  * types from the Person table into Java types.  
 49  
  * </p>
 50  
  * <p>
 51  
  * To avoid these type issues you could subclass KeyedHandler and override 
 52  
  * <code>createRow()</code> to store rows in Java bean instances (ie. a
 53  
  * Person class).
 54  
  * </p>
 55  
  * <p>This class is thread safe.</p>
 56  
  * 
 57  
  * @see org.apache.commons.dbutils.ResultSetHandler
 58  
  * @since DbUtils 1.1
 59  
  */
 60  
 public class KeyedHandler implements ResultSetHandler {
 61  
 
 62  
     /**
 63  
      * The RowProcessor implementation to use when converting rows
 64  
      * into Objects.
 65  
      */
 66  
     protected final RowProcessor convert;
 67  
 
 68  
     /**
 69  
      * The column index to retrieve key values from.  Defaults to 1.
 70  
      */
 71  
     protected final int columnIndex;
 72  
 
 73  
     /**
 74  
      * The column name to retrieve key values from.  Either columnName or 
 75  
      * columnIndex will be used but never both.
 76  
      */
 77  
     protected final String columnName;
 78  
 
 79  
     /** 
 80  
      * Creates a new instance of KeyedHandler.  The value of the first column 
 81  
      * of each row will be a key in the Map.
 82  
      */
 83  
     public KeyedHandler() {
 84  0
         this(ArrayHandler.ROW_PROCESSOR, 1, null);
 85  0
     }
 86  
 
 87  
     /**
 88  
      * Creates a new instance of KeyedHandler.  The value of the first column 
 89  
      * of each row will be a key in the Map.
 90  
      *
 91  
      * @param convert The <code>RowProcessor</code> implementation
 92  
      * to use when converting rows into Maps
 93  
      */
 94  
     public KeyedHandler(RowProcessor convert) {
 95  0
         this(convert, 1, null);
 96  0
     }
 97  
 
 98  
     /** 
 99  
      * Creates a new instance of KeyedHandler.
 100  
      * 
 101  
      * @param columnIndex The values to use as keys in the Map are 
 102  
      * retrieved from the column at this index.
 103  
      */
 104  
     public KeyedHandler(int columnIndex) {
 105  0
         this(ArrayHandler.ROW_PROCESSOR, columnIndex, null);
 106  0
     }
 107  
 
 108  
     /** 
 109  
      * Creates a new instance of KeyedHandler.
 110  
      * 
 111  
      * @param columnName The values to use as keys in the Map are 
 112  
      * retrieved from the column with this name.
 113  
      */
 114  
     public KeyedHandler(String columnName) {
 115  0
         this(ArrayHandler.ROW_PROCESSOR, 1, columnName);
 116  0
     }
 117  
 
 118  
     // Helper
 119  
     private KeyedHandler(RowProcessor convert, int columnIndex,
 120  
             String columnName) {
 121  0
         super();
 122  0
         this.convert = convert;
 123  0
         this.columnIndex = columnIndex;
 124  0
         this.columnName = columnName;
 125  0
     }
 126  
 
 127  
     /**
 128  
      * Convert each row's columns into a Map and store then 
 129  
      * in a <code>Map</code> under <code>ResultSet.getObject(key)</code> key.
 130  
      * 
 131  
      * @return A <code>Map</code> of Maps, never <code>null</code>. 
 132  
      * @throws SQLException if a database access error occurs
 133  
      * @see org.apache.commons.dbutils.ResultSetHandler#handle(java.sql.ResultSet)
 134  
      */
 135  
     public Object handle(ResultSet rs) throws SQLException {
 136  0
         Map result = createMap();
 137  0
         while (rs.next()) {
 138  0
             result.put(createKey(rs), createRow(rs));
 139  
         }
 140  0
         return result;
 141  
     }
 142  
 
 143  
     /**
 144  
      * This factory method is called by <code>handle()</code> to create the Map
 145  
      * to store records in.  This implementation returns a <code>HashMap</code>
 146  
      * instance.
 147  
      *
 148  
      * @return Map to store records in
 149  
      */
 150  
     protected Map createMap() {
 151  0
         return new HashMap();
 152  
     }
 153  
 
 154  
     /**
 155  
      * This factory method is called by <code>handle()</code> to retrieve the
 156  
      * key value from the current <code>ResultSet</code> row.  This 
 157  
      * implementation returns <code>ResultSet.getObject()</code> for the 
 158  
      * configured key column name or index. 
 159  
      * @param rs ResultSet to create a key from
 160  
      * @return Object from the configured key column name/index
 161  
      * @throws SQLException if a database access error occurs
 162  
      */
 163  
     protected Object createKey(ResultSet rs) throws SQLException {
 164  0
         return (columnName == null) ? rs.getObject(columnIndex) : rs
 165  
                 .getObject(columnName);
 166  
     }
 167  
 
 168  
     /**
 169  
      * This factory method is called by <code>handle()</code> to store the
 170  
      * current <code>ResultSet</code> row in some object. This 
 171  
      * implementation returns a <code>Map</code> with case insensitive column
 172  
      * names as keys.  Calls to <code>map.get("COL")</code> and 
 173  
      * <code>map.get("col")</code> return the same value.
 174  
      * @param rs ResultSet to create a row from
 175  
      * @return Object typed Map containing column names to values
 176  
      * @throws SQLException if a database access error occurs
 177  
      */
 178  
     protected Object createRow(ResultSet rs) throws SQLException {
 179  0
         return this.convert.toMap(rs);
 180  
     }
 181  
 
 182  
 }