Hello Bo,
Thursday, March 15, 2001, 1:31:56 PM, you wrote:
BX> Andrey Myatlyuk wrote:
>> [...]
>> I have my StatesBean loaded by SystemClassLoader. OK.
>> MyServlet by WebAppLoader. Good.
>>
>> So when WebAppLoader reloads my servlet it should ask its parents
>> about loaded class. Ang guess what? StatesBean loaded already with
>> SystemClassLoader. What's wrong with it?
>>
>> Why do I get java.lang.NullPointerException in
>> _statesBean=
>> getServletContext().getAttribute(StatesBean.STATES_BEAN_NAME);
>>
>> after reloading servlets?
>>
>> --
>> Best regards,
>> Andrey mailto:[EMAIL PROTECTED]
BX> Hi :-)
BX> * is the following right?
BX> - StatesBean is your Helper class
BX> - STATES_BEAN_NAME is a "public static String" object in StatesBean
BX> if(the above is not right) return; //haha ^_^
* yes
* yes + final :)
continue...
BX> * is StatesBean.STATES_BEAN_NAME.hashCode() the same one
BX> before/after MyServlet reloading?
before:
hash code in state servlet=-24382515
hash code in name servlet=-24382515
hash code in city servlet=-24382515
after:
hash code in state servlet=-24382515
hash code in name servlet=-24382515
hash code in city servlet=-24382515
BX> * and I suggest you try the following:
BX> don't use StatesBean.STATES_BEAN_NAME as the "name" when you
BX> setAttribute(...): i.e. I suggest you try:
BX> - before reloading:
BX> getServletContext().setAttribute( "haha", new StatesBean() );
BX> - after reloading:
BX> Object o = getServletContext().getAttribute( "haha");
BX> try{
BX> if(o!=null) StatesBean sb=(StatesBean)o;
BX> }catch(Exception e){System.out.println(e);}
The same situation. ClassCastException
BX> * can you post the code of your StatesBean? and
BX> the version of TOMCAT? because I also want to
BX> know why :-)
package com.oneworldinc.flutrack.servlet;
import java.sql.*;
import java.util.*;
import javax.sql.*;
import org.apache.struts.action.*;
import javax.servlet.*;
import com.inet.tds.*;
/**
* Title:
* Description:
* Copyright: Oneworld Inc. (c) 2001
* Company:
* @author Andrey Myatlyuk
* @version 1.0
*/
public class StatesBean {
public static final String STATES_BEAN_NAME = "STATES_BEAN";
private String _db_driver;
private String _db_url;
private String _db_user;
private String _db_password;
private int _severityLevel;
private State[] _states;
private Connection _conn;
public void init(){
initDatabaseConnection();
_states=getStatesWithoutCities();
for(int a_i=0;a_i<_states.length;a_i++){
_states[a_i].cities=getCities(_states[a_i].stateID, _severityLevel);
}
}
public void update(){}
public void releaseResources(){
try{
if(_conn != null){
_conn.close();
}else{/* ignored */}
// to null all states
}catch(SQLException p_exc){
//
}
}
private void initDatabaseConnection(){
System.out.println("initDatabaseConnection()");
System.out.println("Driver="+_db_driver);
try{
Class.forName(_db_driver);
}catch(ClassNotFoundException p_exc){
System.out.println("Cannot load database driver");
}
System.out.println("Driver loaded...");
try{
_conn=DriverManager.getConnection(
_db_url,
_db_user,
_db_password
);
System.out.println("Connection established...");
}catch(SQLException p_exc){
System.out.println("Cannot get database connection");
}
}
private State[] getStatesWithoutCities(){
State[] a_states=new State[0];
try{
String a_sql=
"SELECT "+
"s.StateID,"+
"s.StateName,"+
"s.StateCode "+
"FROM "+
"States s";
PreparedStatement a_stmt=_conn.prepareStatement(a_sql);
ResultSet a_rs=a_stmt.executeQuery();
ArrayList a_list=new ArrayList(51);
while(a_rs.next()){
a_list.add(
new State(
a_rs.getInt(1),
a_rs.getString(2),
a_rs.getString(3)
)
);
}
int a_size=a_list.size();
a_states=new State[a_size];
for(int a_i=0;a_i<a_size;a_i++){
a_states[a_i]=(State)a_list.get(a_i);
}
}catch(SQLException p_exc){
System.out.println("cannot get empty states");
System.out.println("message="+p_exc.getMessage());
}
return a_states;
}
private City[] getCities(int p_stateID, int p_severityLevel){
City[] a_cities=new City[0];
String a_sql=
"SELECT "+
"hc.StateID,"+
"hc.City,"+
"hc.Severity,"+
"hc.NumberWeeks "+
"FROM "+
"HotCities hc "+
"WHERE "+
"hc.StateID=? AND "+
"hc.Severity>=? "+
"ORDER BY "+
"hc.City";
try{
PreparedStatement a_stmt=_conn.prepareStatement(a_sql);
a_stmt.setInt(1, p_stateID);
a_stmt.setInt(2, p_severityLevel);
ResultSet a_rs=a_stmt.executeQuery();
ArrayList a_list=new ArrayList(51);
while(a_rs.next()){
a_list.add(
new City(
a_rs.getInt(1),
a_rs.getString(2),
a_rs.getInt(3),
a_rs.getInt(4)
)
);
}
int a_size=a_list.size();
a_cities=new City[a_size];
for(int a_i=0;a_i<a_size;a_i++){
a_cities[a_i]=(City)a_list.get(a_i);
}
}catch(SQLException p_exc){
System.out.println("cannot get empty states");
System.out.println("message="+p_exc.getMessage());
}
return a_cities;
}
public State[] getStates(){
return _states;
}
public State getStateById(int p_id){
for(int a_i=0;a_i<_states.length;a_i++){
if(_states[a_i].stateID == p_id){
return _states[a_i];
}else{/* ignored */}
}
return null; // just for test - replace by StateNotFoundException
}
public void setDriver(String p_database_driver){
_db_driver = p_database_driver;
}
public void setDatabaseURL(String p_database_url){
_db_url = p_database_url;
}
public void setUser(String p_database_user){
_db_user = p_database_user;
}
public void setPassword(String p_database_password){
_db_password = p_database_password;
}
public void setSeverityLevel(int p_severityLevel){
_severityLevel=p_severityLevel;
}
}
BX> Bo
BX> Mar.15, 2001
--
Best regards,
Andrey mailto:[EMAIL PROTECTED]
