org.springframework.jdbc.object
Class MappingSqlQueryWithParameters

java.lang.Object
  org.springframework.jdbc.object.RdbmsOperation
      org.springframework.jdbc.object.SqlOperation
          org.springframework.jdbc.object.SqlQuery
              org.springframework.jdbc.object.MappingSqlQueryWithParameters

All Implemented Interfaces:

InitializingBean

Direct Known Subclasses:

MappingSqlQuery

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.

Author:

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

logger

Constructor Summary

MappingSqlQueryWithParameters()
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, allowsUnusedParameters, checkCompiled, 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

MappingSqlQueryWithParameters

public MappingSqlQueryWithParameters()

Constructor to allow use as a JavaBean

MappingSqlQueryWithParameters

public MappingSqlQueryWithParameters(DataSource ds,
                                     String sql)

Convenient constructor with DataSource and SQL string.

Parameters:

ds - DataSource to use to get connections

sql - SQL to run

Method Detail

newResultReader

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

Parameters:

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)

mapRow

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.

Parameters:

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.

Returns:

an object of the result type

Throws:

SQLException - if there's an error extracting data. Subclasses can simply not catch SQLExceptions, relying on the framework to clean up.