Acegi의 JdbcDaoImpl 내 MappingSqlQuery 설명

MappingSqlQuery  is a reusable query in which concrete subclasses must implement the abstract mapRow(..)  method to convert each row of the supplied  ResultSet  into an object of the type specified. The following example shows a custom query that maps the data from the  t_actor  relation to an instance of the  Actor  class.

public class ActorMappingQuery extends MappingSqlQuery<Actor> {
        public ActorMappingQuery(DataSource ds) { 
                  super(ds, "select id,first_name, last_name from t_actor           where id = ?");
                  super.declareParameter(new SqlParameter("id",    Types.INTEGER)); 
                  compile();
 } 

@Override protected Actor mapRow(ResultSet rs, int rowNumber) throws SQLException { 
                  Actor actor = new Actor(); 
                  actor.setId(rs.getLong("id"));         
                  actor.setFirstName(rs.getString("first_name"));  
                  actor.setLastName(rs.getString("last_name")); 
                  return actor; 
} 
}

 
 
The class extends  MappingSqlQuery  parameterized with the  Actor  type. The constructor for this customer query takes the  DataSource  as the only parameter. In this constructor you call the constructor on the superclass with the  DataSource and the SQL that should be executed to retrieve the rows for this query. This SQL will be used to create a PreparedStatement  so it may contain place holders for any parameters to be passed in during execution.You must declare each parameter using the  declareParameter  method passing in an  SqlParameter . The  SqlParameter  takes a name and the JDBC type as defined in  java.sql.Types . After you define all parameters, you call the compile()  method so the statement can be prepared and later executed. This class is thread-safe after it is compiled, so as long as these instances are created when the DAO is initialized they can be kept as instance variables and be reused.

private ActorMappingQuery actorMappingQuery;

@Autowired public void setDataSource(DataSource dataSource) {        
          this.actorMappingQuery = new ActorMappingQuery(dataSource);
} 
public Customer getCustomer(Long id) {
           return actorMappingQuery.findObject(id); 
}

 
The method in this example retrieves the customer with the id that is passed in as the only parameter. Since we only want one object returned we simply call the convenience method  findObject with the id as parameter. If we had instead a query that returned a list of objects and took additional parameters then we would use one of the execute methods that takes an array of parameter values passed in as varargs.
 

public List<Actor> searchForActors(int age, String namePattern) {       
          List<Actor> actors = actorSearchMappingQuery.execute(age, namePattern);
          return actors; 
}