Hello my name is Claudio Veas Im very new in tomcat develop and I was trying
to use an interface to implement a cache. I make all the objects that I
wanted to keep in memory implement "cacheable" interface so I could insert
them into a Vector and then minimize the timing when looking for the same
information.
I dont have problems storing information in cache, and I dont have problems
when I try to retrieve directly to a variable declared "cacheable" but when
I try a direct cast the server shows me this error
type Informe de Excepción
mensaje
descripción El servidor encontró un error interno () que hizo que no pudiera
rellenar este requerimiento.
excepción
org.apache.jasper.JasperException: materias.materias
org.apache.jasper.servlet.JspServletWrapper
handleJspException(JspServletWrapper.java:510)
org.apache.jasper.servlet.JspServletWrapper.service(JspServletWrapper
java:393)
org.apache.jasper.servlet.JspServlet.serviceJspFile(JspServlet.java:314)
org.apache.jasper.servlet.JspServlet.service(JspServlet.java:264)
javax.servlet.http.HttpServlet.service(HttpServlet.java:802)
causa raíz
java.lang.ClassCastException: materias.materias
materia.experto_materias.getmaterias(experto_materias.java:54)
org.apache.jsp.buscatema_jsp._jspService(buscatema_jsp.java:88)
org.apache.jasper.runtime.HttpJspBase.service(HttpJspBase.java:97)
javax.servlet.http.HttpServlet.service(HttpServlet.java:802)
org.apache.jasper.servlet.JspServletWrapper.service(JspServletWrapper
java:332)
org.apache.jasper.servlet.JspServlet.serviceJspFile(JspServlet.java:314)
org.apache.jasper.servlet.JspServlet.service(JspServlet.java:264)
javax.servlet.http.HttpServlet.service(HttpServlet.java:802)
nota La traza completa de la causa de este error se encuentra en los
archivos de diario de Apache Tomcat/5.5.16.
Here are the interface and the classes
CACHEABLE
package interfaz_dbms;
public interface cacheable {
public int getId();
public int getTipo();
}
CACHE (some cache procedures )
public void agregar(cacheable obj){
Enumeration e=memoria.elements();
while(e.hasMoreElements()){
cacheable temp = (cacheable) e.nextElement();
if(obj.getId()==temp.getId()||obj.getTipo()==temp.getTipo()){
return;
}
}
memoria.addElement(obj);
}
MATERIAS (this procedures gets all the "materias" (subjects) that a profesor
teaches,
and i saves it in the cache object)
public static Vector getMateriaProf(int id){
Vector v=new Vector();
try{ String consulta ="SELECT m.id_materia,m.nombre,m.descripcion " +
" FROM materia m, mat_profe mp, profesor p " +
" WHERE m.id_materia = mp.id_materia " +
" AND p.id_profesor = mp.id_profesor " +
" AND p.id_profesor=" + String.valueOf(id);
ResultSet rs = conneccion.getconection().Consultar(consulta);
rs.next();
while(!(rs.isAfterLast())){
materias m=new materias(rs.getInt("id_materia"),rs.getString(
nombre"),rs.getString("descripcion"));
v.addElement(m);
if(cache.getReferencia().EstaEn(m)==null){
cache.getReferencia().agregar(m);
}
rs.next();
}
}
catch(SQLException e){
}
return v;
}
EXPERTO MATERIAS (in some other page I request one of the "materias" but
before going to the
database again I search for it in memory I retrieved into a cacheable object
and when I try the casting the error show up
)
public materias getmaterias(int id){
materias n = new materias();
interfaz_dbms.cacheable temp;
temp = interfaz_dbms.cache.getReferencia().Buscar(id,n.getTipo());
n = (materia.materias)temp;
if(temp==null){
n = materias.consultar(id);
}
return n;
}
I really hope I ve been clear enough and I hope you can help me out with
this problems.
Please excuse my english Im not very good at it
Thanks on advance
Claudio Veas
