Class KeyedHandler<K>

java.lang.Object
org.apache.commons.dbutils.handlers.AbstractKeyedHandler<K,Map<String,Object>>
org.apache.commons.dbutils.handlers.KeyedHandler<K>
Type Parameters:
K - The type of the key
All Implemented Interfaces:
ResultSetHandler<Map<K,Map<String,Object>>>

public class KeyedHandler<K> extends AbstractKeyedHandler<K,Map<String,Object>>

ResultSetHandler implementation that returns a Map of Maps. ResultSet rows are converted into Maps which are then stored in a Map under the given key.

If you had a Person table with a primary key column called ID, you could retrieve rows from the table like this:

 ResultSetHandler h = new KeyedHandler("id");
 Map found = (Map) queryRunner.query("select id, name, age from person", h);
 Map jane = (Map) found.get(new Long(1)); // jane's id is 1
 String janesName = (String) jane.get("name");
 Integer janesAge = (Integer) jane.get("age");
 
Note that the "id" passed to KeyedHandler and "name" and "age" passed to the returned Map's get() method can be in any case. The data types returned for name and age are dependent upon how your JDBC driver converts SQL column types from the Person table into Java types. </p>

This class is thread safe.

Since:
DbUtils 1.1
See Also:
  • Field Details

    • convert

      protected final RowProcessor convert
      The RowProcessor implementation to use when converting rows into Objects.
    • columnIndex

      protected final int columnIndex
      The column index to retrieve key values from. Defaults to 1.
    • columnName

      protected final String columnName
      The column name to retrieve key values from. Either columnName or columnIndex will be used but never both.
  • Constructor Details

    • KeyedHandler

      public KeyedHandler()
      Creates a new instance of KeyedHandler. The value of the first column of each row will be a key in the Map.
    • KeyedHandler

      public KeyedHandler(RowProcessor convert)
      Creates a new instance of KeyedHandler. The value of the first column of each row will be a key in the Map.
      Parameters:
      convert - The RowProcessor implementation to use when converting rows into Maps
    • KeyedHandler

      public KeyedHandler(int columnIndex)
      Creates a new instance of KeyedHandler.
      Parameters:
      columnIndex - The values to use as keys in the Map are retrieved from the column at this index.
    • KeyedHandler

      public KeyedHandler(String columnName)
      Creates a new instance of KeyedHandler.
      Parameters:
      columnName - The values to use as keys in the Map are retrieved from the column with this name.
    • KeyedHandler

      private KeyedHandler(RowProcessor convert, int columnIndex, String columnName)
      Private Helper
      Parameters:
      convert - The RowProcessor implementation to use when converting rows into Maps
      columnIndex - The values to use as keys in the Map are retrieved from the column at this index.
      columnName - The values to use as keys in the Map are retrieved from the column with this name.
  • Method Details

    • createKey

      protected K createKey(ResultSet rs) throws SQLException
      This factory method is called by handle() to retrieve the key value from the current ResultSet row. This implementation returns ResultSet.getObject() for the configured key column name or index.
      Specified by:
      createKey in class AbstractKeyedHandler<K,Map<String,Object>>
      Parameters:
      rs - ResultSet to create a key from
      Returns:
      Object from the configured key column name/index
      Throws:
      SQLException - if a database access error occurs
      ClassCastException - if the class datatype does not match the column type
    • createRow

      protected Map<String,Object> createRow(ResultSet rs) throws SQLException
      This factory method is called by handle() to store the current ResultSet row in some object. This implementation returns a Map with case insensitive column names as keys. Calls to map.get("COL") and map.get("col") return the same value.
      Specified by:
      createRow in class AbstractKeyedHandler<K,Map<String,Object>>
      Parameters:
      rs - ResultSet to create a row from
      Returns:
      Object typed Map containing column names to values
      Throws:
      SQLException - if a database access error occurs