Package org.springframework.jdbc.object

Class SqlFunction<T>

java.lang.Object
org.springframework.jdbc.object.RdbmsOperation
org.springframework.jdbc.object.SqlOperation
org.springframework.jdbc.object.SqlQuery<T>
org.springframework.jdbc.object.MappingSqlQueryWithParameters<T>
org.springframework.jdbc.object.MappingSqlQuery<T>
org.springframework.jdbc.object.SqlFunction<T>
Type Parameters:
T - the result type
All Implemented Interfaces:
InitializingBean
public class SqlFunction<T> extends MappingSqlQuery<T>
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, Juergen Hoeller, Jean-Pierre Pawlak
See Also:

  • Constructor Details

    • SqlFunction

      public SqlFunction()
      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 Also:

    • SqlFunction

      public SqlFunction(DataSource ds, String sql)
      Create a new SqlFunction object with SQL, but without parameters. Must add parameters or settle with none.
      Parameters:
      ds - the DataSource to obtain connections from
      sql - the SQL to execute

    • SqlFunction

      public SqlFunction(DataSource ds, String sql, int[] types)
      Create a new SqlFunction object with SQL and parameters.
      Parameters:
      ds - the DataSource to obtain connections from
      sql - the SQL to execute
      types - the SQL types of the parameters, as defined in the java.sql.Types class
      See Also:

    • SqlFunction

      public SqlFunction(DataSource ds, String sql, int[] types, Class<T> resultType)
      Create a new SqlFunction object with SQL, parameters and a result type.
      Parameters:
      ds - the DataSource to obtain connections from
      sql - the SQL to execute
      types - the SQL types of the parameters, as defined in the java.sql.Types class
      resultType - the type that the result object is required to match
      See Also:

  • Method Details

    • setResultType

      public void setResultType(Class<T> 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.

    • mapRow

      @Nullable protected T mapRow(ResultSet rs, int rowNum) throws SQLException
      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.
      Specified by:
      mapRow in class MappingSqlQuery<T>
      Parameters:
      rs - the ResultSet we're working through
      rowNum - row number (from 0) we're up to
      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.

    • run

      public int run()
      Convenient method to run the function without arguments.
      Returns:
      the value of the function

    • run

      public int run(int parameter)
      Convenient method to run the function with a single int argument.
      Parameters:
      parameter - single int parameter
      Returns:
      the value of the function

    • run

      public int run(Object... parameters)
      Analogous to the SqlQuery.execute([]) method. This is a generic method to execute a query, taken a number of arguments.
      Parameters:
      parameters - array of parameters. These will be objects or object wrapper types for primitives.
      Returns:
      the value of the function

    • runGeneric

      @Nullable public Object runGeneric()
      Convenient method to run the function without arguments, returning the value as an object.
      Returns:
      the value of the function

    • runGeneric

      @Nullable public Object runGeneric(int parameter)
      Convenient method to run the function with a single int argument.
      Parameters:
      parameter - single int parameter
      Returns:
      the value of the function as an Object

    • runGeneric

      @Nullable public Object runGeneric(Object[] parameters)
      Analogous to the SqlQuery.findObject(Object[]) method. This is a generic method to execute a query, taken a number of arguments.
      Parameters:
      parameters - array of parameters. These will be objects or object wrapper types for primitives.
      Returns:
      the value of the function, as an Object
      See Also: