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/*
 * Copyright 2002-2005 the original author or authors.
 * 
 * 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 org.springframework.jdbc.object;

import java.sql.ResultSet;
import java.sql.SQLException;
import java.sql.Types;

import javax.sql.DataSource;

import org.springframework.dao.TypeMismatchDataAccessException;
import org.springframework.jdbc.core.SingleColumnRowMapper;
import org.springframework.jdbc.support.JdbcUtils;

/**
 * SQL "function" wrapper for a query that returns a single row of results. 
 * The default behavior is to return an int, but that can be overridden by 
 * using the constructor with an extra return type parameter.
 *
 * 

Intended to use to call SQL functions that return a single result using a * query like "select user()" or "select sysdate from dual". It is not intended * for calling more complex stored functions or for using a CallableStatement to * invoke a stored procedure or stored function. Use StoredProcedure or SqlCall * for this type of processing. * *

This is a concrete class, which there is often no need to subclass. * Code using this package can create an object of this type, declaring SQL * and parameters, and then invoke the appropriate run method * repeatedly to execute the function. Subclasses are only supposed to add * specialized run methods for specific parameter and return types. * *

Like all RdbmsOperation objects, SqlFunction objects are thread-safe. * * @author Rod Johnson * @author Juergen Hoeller * @author Jean-Pierre Pawlak * @see org.springframework.jdbc.object.StoredProcedure */ public class SqlFunction extends MappingSqlQuery { private final SingleColumnRowMapper rowMapper = new SingleColumnRowMapper(); /** * Constructor to allow use as a JavaBean. * A DataSource, SQL and any parameters must be supplied before * invoking the compile method and using this object. * @see #setDataSource * @see #setSql * @see #compile */ public SqlFunction() { setRowsExpected(1); } /** * Create a new SqlFunction object with SQL, but without parameters. * Must add parameters or settle with none. * @param ds DataSource to obtain connections from * @param sql SQL to execute */ public SqlFunction(DataSource ds, String sql) { setRowsExpected(1); setDataSource(ds); setSql(sql); } /** * Create a new SqlFunction object with SQL and parameters. * @param ds DataSource to obtain connections from * @param sql SQL to execute * @param types SQL types of the parameters, as defined in the * java.sql.Types class * @see java.sql.Types */ public SqlFunction(DataSource ds, String sql, int[] types) { setRowsExpected(1); setDataSource(ds); setSql(sql); setTypes(types); } /** * Create a new SqlFunction object with SQL, parameters and a result type. * @param ds DataSource to obtain connections from * @param sql SQL to execute * @param types SQL types of the parameters, as defined in the * java.sql.Types class * @param resultType the type that the result object is required to match * @see #setResultType(Class) * @see java.sql.Types */ public SqlFunction(DataSource ds, String sql, int[] types, Class resultType) { setRowsExpected(1); setDataSource(ds); setSql(sql); setTypes(types); setResultType(resultType); } /** * Specify the type that the result object is required to match. *

If not specified, the result value will be exposed as * returned by the JDBC driver. */ public void setResultType(Class resultType) { this.rowMapper.setRequiredType(resultType); } /** * This implementation of this method extracts a single value from the * single row returned by the function. If there are a different number * of rows returned, this is treated as an error. */ protected Object mapRow(ResultSet rs, int rowNum) throws SQLException { return this.rowMapper.mapRow(rs, rowNum); } /** * Convenient method to run the function without arguments. * @return the value of the function */ public int run() { return run(null); } /** * Convenient method to run the function with a single int argument. * @param parameter single int parameter * @return the value of the function */ public int run(int parameter) { return run(new Object[] {new Integer(parameter)}); } /** * Analogous to the SqlQuery.execute([]) method. This is a * generic method to execute a query, taken a number of arguments. * @param parameters array of parameters. These will be objects or * object wrapper types for primitives. * @return the value of the function */ public int run(Object[] parameters) { Object obj = super.findObject(parameters); if (!(obj instanceof Number)) { throw new TypeMismatchDataAccessException("Couldn't convert result object [" + obj + "] to int"); } return ((Number) obj).intValue(); } /** * Convenient method to run the function without arguments, * returning the value as an object. * @return the value of the function */ public Object runGeneric() { return findObject((Object[]) null); } /** * Convenient method to run the function with a single int argument. * @param parameter single int parameter * @return the value of the function as an Object */ public Object runGeneric(int parameter) { return findObject(parameter); } /** * Analogous to the SqlQuery.findObject(Object[]) method. * This is a generic method to execute a query, taken a number of arguments. * @param parameters array of parameters. These will be objects or * object wrapper types for primitives. * @return the value of the function, as an Object * @see #execute(Object[]) */ public Object runGeneric(Object[] parameters) { return findObject(parameters); } }





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