Class MappingSqlQueryWithParameters

  extended byorg.springframework.jdbc.object.RdbmsOperation
      extended byorg.springframework.jdbc.object.SqlOperation
          extended byorg.springframework.jdbc.object.SqlQuery
              extended byorg.springframework.jdbc.object.MappingSqlQueryWithParameters
All Implemented Interfaces:
Direct Known Subclasses:

public abstract class MappingSqlQueryWithParameters
extends SqlQuery

Reusable RDBMS query in which concrete subclasses must implement the abstract mapRow(ResultSet, int) method to map each row of the JDBC ResultSet into an object.

Such manual mapping is usually preferable to "automatic" mapping using reflection, which can become complex in non-trivial cases. For example, the present class allows different objects to be used for different rows (for example, if a subclass is indicated). It allows computed fields to be set. And there's no need for ResultSet columns to have the same names as bean properties. The Pareto Principle in action: going the extra mile to automate the extraction process makes the framework much more complex and delivers little real benefit.

Subclasses can be constructed providing SQL, parameter types and a DataSource. SQL will often vary between subclasses.

Rod Johnson, Thomas Risberg, Jean-Pierre Pawlak
See Also:
MappingSqlQuery, SqlQuery

Nested Class Summary
protected  class MappingSqlQueryWithParameters.ResultReaderImpl
          Implementation of ResultReader that calls the enclosing class's mapRow() method for each row.
Field Summary
Fields inherited from class org.springframework.jdbc.object.RdbmsOperation
Constructor Summary
          Constructor to allow use as a JavaBean
MappingSqlQueryWithParameters(DataSource ds, String sql)
          Convenient constructor with DataSource and SQL string.
Method Summary
protected abstract  Object mapRow(ResultSet rs, int rowNum, Object[] parameters, Map context)
          Subclasses must implement this method to convert each row of the ResultSet into an object of the result type.
protected  ResultReader newResultReader(int rowsExpected, Object[] parameters, Map context)
          Implementation of protected abstract method.
Methods inherited from class org.springframework.jdbc.object.SqlQuery
execute, execute, execute, execute, execute, execute, execute, execute, execute, execute, execute, execute, findObject, findObject, findObject, findObject, findObject, findObject, findObject, findObject, findObject, findObject, getRowsExpected, setRowsExpected
Methods inherited from class org.springframework.jdbc.object.SqlOperation
compileInternal, newPreparedStatementCreator, newPreparedStatementSetter, onCompileInternal
Methods inherited from class org.springframework.jdbc.object.RdbmsOperation
afterPropertiesSet, compile, declareParameter, getDeclaredParameters, getGeneratedKeysColumnNames, getJdbcTemplate, getResultSetType, getSql, isCompiled, isReturnGeneratedKeys, isUpdatableResults, setDataSource, setFetchSize, setGeneratedKeysColumnNames, setJdbcTemplate, setMaxRows, setResultSetType, setReturnGeneratedKeys, setSql, setTypes, setUpdatableResults, supportsLobParameters, validateParameters
Methods inherited from class java.lang.Object
clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Constructor Detail


public MappingSqlQueryWithParameters()
Constructor to allow use as a JavaBean


public MappingSqlQueryWithParameters(DataSource ds,
                                     String sql)
Convenient constructor with DataSource and SQL string.

ds - DataSource to use to get connections
sql - SQL to run
Method Detail


protected ResultReader newResultReader(int rowsExpected,
                                       Object[] parameters,
                                       Map context)
Implementation of protected abstract method. This invokes the subclass's implementation of the mapRow() method.

Specified by:
newResultReader in class SqlQuery
rowsExpected - If 0, we don't know how many rows to expect. This parameter can be ignored, but may help some implementations choose the most efficient Collection type: e.g. ArrayList instead of LinkedList for large result sets.
parameters - parameters to the execute() method, in case subclass is interested. May be null if there were no parameters.
See Also:
SqlQuery.execute(java.lang.Object[], java.util.Map)


protected abstract Object mapRow(ResultSet rs,
                                 int rowNum,
                                 Object[] parameters,
                                 Map context)
                          throws SQLException
Subclasses must implement this method to convert each row of the ResultSet into an object of the result type.

rs - ResultSet we're working through
rowNum - row number (from 0) we're up to
parameters - to the query (passed to the execute() method). Subclasses are rarely interested in these. It can be null if there are no parameters.
context - passed to the execute() method. It can be null if no contextual information is need.
an object of the result type
SQLException - if there's an error extracting data. Subclasses can simply not catch SQLExceptions, relying on the framework to clean up.

Copyright (C) 2003-2004 The Spring Framework Project.