iReport Ultimate Guide - Nimsoft Library

iReport Ultimate GuideCode Example 11-9Interface JRQueryExecuterFactory provided by UR, continued* These parameters will be created as system-defined parameters for each* report/dataset having a query of this type.* The returned array should contain consecutive pairs of parameter* names and parameter classes* (e.g. {"Param1", String.class, "Param2", "List.class"}).* @return array of built-in parameter names and types associated* with this query type*/public Object[] getBuiltinParameters();/*** Creates a query executer.* This method is called at fill time for reports/datasets having a* query supported by* this factory.* @param dataset the dataset containing the query, fields, etc.* @param parameters map of value parameters (instances of* {@link JRValueParameter JRValueParameter})* indexed by name** @return a query executer* @throws JRException*/public JRQueryExecuter createQueryExecuter(JRDataset dataset, Map parameters) throws JRException;/*** Decides whether the query executers created by this factory support* a query parameter type.* This check is performed for all $P{..} parameters in the query.** @param className the value class name of the parameter* @return whether the parameter value type is supported*/public boolean supportsQueryParameterType(String className);}There are three methods to implement: getBuiltinParameters, createQueryExecuter, andsupportsQueryParameterType:• The first method returns an array containing names and types of built-in parameters that the query executer makesavailable. This feature is useful when the query is executed against some kind of session object or against a connection toan external entity, such as a database or a server.For example, the query executer factory for SQL provides the built-in parameter REPORT_CONNECTION, storing thejava.sql.Connection instance used to execute the query. This object can be used by subreports to execute their SQLqueries. Similarly, the query executer factory for HQL provides as a parameter the Hibernate session required to performthe query.• The second method (createQueryExecuter) is responsible for creating the query executer instance, making it possiblythe most important one of the three methods.212