Multiple JdbcTemplate instances or not?

Question

From what I understand, both DataSource and JdbcTemplates are threadsafe, so you can configure a single instance of a JdbcTempla

Answer 1

so it should be spilt two situations:

We don’t change JdbcTemplate properties in DAO, we can define as below:

NOTE: Most of time we don’t change the JdbcTemplate properties, because it is not necessary.

We change JdbcTemplate properties in DAO, we should be extends JdbcDaoSupport.

State:
•   fetchSize: If this variable is set to a non-zero value, it will be used for setting the fetchSize property on statements used for query processing(JDBC Driver default)
•   maxRows: If this variable is set to a non-zero value, it will be used for setting the maxRows property on statements used for query processing(JDBC Driver default)
•   queryTimeout: If this variable is set to a non-zero value, it will be used for setting the queryTimeout property on statements used for query processing.(JDBC Driver default)
•   skipResultsProcessing: If this variable is set to true then all results checking will be bypassed for any callable statement processing.  This can be used to avoid a bug in some older Oracle JDBC drivers like 10.1.0.2.(false)
•   skipUndeclaredResults: If this variable is set to true then all results from a stored procedure call that don't have a corresponding SqlOutParameter declaration will be bypassed. All other results processing will be take place unless the variable {@code skipResultsProcessing} is set to {@code true}(false)
•   resultsMapCaseInsensitive: If this variable is set to true then execution of a CallableStatement will return the results in a Map that uses case insensitive names for the parameters if Commons Collections is available on the classpath.(false)

1. JdbcDaoSupport

   public abstract class JdbcDaoSupport extends DaoSupport {

   private JdbcTemplate jdbcTemplate;
   
   
   /**
    * Set the JDBC DataSource to be used by this DAO.
    */
   public final void setDataSource(DataSource dataSource) {
       if (this.jdbcTemplate == null || dataSource != this.jdbcTemplate.getDataSource()) {
           this.jdbcTemplate = createJdbcTemplate(dataSource);
           initTemplateConfig();
       }
   }
   

summary: I don’t think spring give the practice in guide is the best.