/*
* Copyright 2002-2008 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 javax.sql.DataSource;
import org.springframework.dao.TypeMismatchDataAccessException;
import org.springframework.jdbc.core.SingleColumnRowMapper;
/**
* 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.
*
* <p>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.
*
* <p>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 <code>run</code> method
* repeatedly to execute the function. Subclasses are only supposed to add
* specialized <code>run</code> methods for specific parameter and return types.
*
* <p>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<T> extends MappingSqlQuery<T> {
private final SingleColumnRowMapper<T> rowMapper = new SingleColumnRowMapper<T>();
/**
* Constructor to allow use as a JavaBean.
* A DataSource, SQL and any parameters must be supplied before
* invoking the <code>compile</code> 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
* <code>java.sql.Types</code> 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
* <code>java.sql.Types</code> 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<T> resultType) {
setRowsExpected(1);
setDataSource(ds);
setSql(sql);
setTypes(types);
setResultType(resultType);
}
/**
* Specify the type that the result object is required to match.
* <p>If not specified, the result value will be exposed as
* returned by the JDBC driver.
*/
public void setResultType(Class<T> 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.
*/
@Override
protected T 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(new Object[0]);
}
/**
* 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[] {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 <code>SqlQuery.findObject(Object[])</code> 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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