Thread: problem in connetting using reflection
Hi all,
I am trying to connect to postgresql from a JAVA program.
Previously I used this code:
---------------------------------------------------------------
String classe ="org.postgresql.jdbc3.Jdbc3ConnectionPool";
org.postgresql.jdbc3.Jdbc3ConnectionPool pg;
pg = Class.forName(classe).newInstance();
pg.setServerName(prop.getProperty(serverName));
pg.setPortNumber((new
Integer(prop.getProperty(serverPortNumber)).intValue());
pg.setDatabaseName(prop.getProperty(databaseName));
pg.setUser(login);
pg.setPassword(password);
---------------------------------------------------------------
I then had to change the application in order to use a generic
DataSource (postgresql, oracle, mysql) and noticed that these classes
have different behaviours:
postgreSQL does not have a callable getUrl(), oracle call it getURL,
oracle need a call to getDriverType(), mySQL use setPortNumber(Integer)
instead of setPortNumber(int).
So I tried to use the java reflection to inspect the
org.postgresql.jdbc3.Jdbc3ConnectionPool class (or other classes) and
call all required methods.
The problem is that, when I use this way (a source is attached) I always
get the error:
Exception in thread "main" org.postgresql.util.PSQLException: La
proprietà ``user'' è mancante. E` obbligatoria.
at
org.postgresql.jdbc1.AbstractJdbc1Connection.openConnection(AbstractJdbc1Connection.java:130)
at org.postgresql.Driver.connect(Driver.java:138)
at java.sql.DriverManager.getConnection(DriverManager.java:538)
at java.sql.DriverManager.getConnection(DriverManager.java:188)
at
org.postgresql.jdbc2.optional.BaseDataSource.getConnection(BaseDataSource.java:68)
at
org.postgresql.jdbc2.optional.BaseDataSource.getConnection(BaseDataSource.java:51)
at
org.postgresql.jdbc3.Jdbc3ConnectionPool.getPooledConnection(Jdbc3ConnectionPool.java:39)
at dao.jdbc.JDBCMemberDAO.<init>(JDBCMemberDAO.java:29)
at dao.JDBCDAOFactory.getMemberDAO(JDBCDAOFactory.java:197)
at test.TestMemberDAO.main(TestMemberDAO.java:34)
that is, in english, "The ``user'' property is missing while it is
mandatory."
Of course the 'setUser()' method is called but it doesn't work.
Do you have any idea about this problem?
I thank you very much,
Giuseppe
Attachment
On Sun, 11 Apr 2004, Giuseppe Sacco wrote: > [I want to use reflection to configure a datasource] > > Exception in thread "main" org.postgresql.util.PSQLException: La > propriet� ``user'' � mancante. E` obbligatoria. > at > org.postgresql.jdbc1.AbstractJdbc1Connection.openConnection(AbstractJdbc1Connection.java:130) > at org.postgresql.Driver.connect(Driver.java:138) > at java.sql.DriverManager.getConnection(DriverManager.java:538) > at java.sql.DriverManager.getConnection(DriverManager.java:188) > at > org.postgresql.jdbc2.optional.BaseDataSource.getConnection(BaseDataSource.java:68) > at > org.postgresql.jdbc2.optional.BaseDataSource.getConnection(BaseDataSource.java:51) > at > org.postgresql.jdbc3.Jdbc3ConnectionPool.getPooledConnection(Jdbc3ConnectionPool.java:39) > at dao.jdbc.JDBCMemberDAO.<init>(JDBCMemberDAO.java:29) > at dao.JDBCDAOFactory.getMemberDAO(JDBCDAOFactory.java:197) > at test.TestMemberDAO.main(TestMemberDAO.java:34) > > > that is, in english, "The ``user'' property is missing while it is > mandatory." > You haven't included the code that is actually mentioned in the stacktrace. You'll need to either provide the rest of the code in question or even better a simpler example of the problem you are seeing. Kris Jurka
Kris Jurka wrote:
>
> On Sun, 11 Apr 2004, Giuseppe Sacco wrote:
>>[... my error code..]
> You haven't included the code that is actually mentioned in the
> stacktrace. You'll need to either provide the rest of the code in
> question or even better a simpler example of the problem you are seeing.
>
> Kris Jurka
You are right. Today I made a smaller script, that is attached, and
found my error :-)
Now it works with PostgreSQL, Oracle and mySQL.
Thanks,
Giuseppe
import java.util.Properties;
import java.io.*;
import javax.sql.*;
import java.sql.*;
public class JDBCDAOFactory
{
static final String datasourceclassname = "org.postgresql.jdbc3.Jdbc3ConnectionPool";
static final String dbservername = "localhost";
static final String dbserverportnumber = "5432";
static final String dbname = "database";
/*
* It should work with
#
# Oracle
#
#db.dataSourceClassName=oracle.jdbc.pool.OracleConnectionPoolDataSource
#db.servername=localhost
#db.serverportnumber=1521
#
# PostgreSQL
#
db.dataSourceClassName=org.postgresql.jdbc3.Jdbc3ConnectionPool
db.servername=localhost
db.serverportnumber=5432
#
# mySQL
#
#db.dataSourceClassName=gwe.sql.gweMysqlConnectionPoolDataSource
#db.servername=localhost
#db.serverportnumber=3306
*
*/
static private ConnectionPoolDataSource connectionPoolDataSource;
public static void main(String[] args) throws Exception {
connectToPg("myuser","mypassword");
/*
* Now we are supposed to be connected, so create a statement and execute it
*/
doQuery();
}
static void doQuery() throws Exception {
PooledConnection pooledConn = connectionPoolDataSource.getPooledConnection();
Statement stmt = pooledConn.getConnection().createStatement();
ResultSet rs;
rs = stmt.executeQuery("SELECT CURRENT_DATE");
stmt.close();
}
static void connectToPg(String login, String password) throws Exception {
Class classe = Class.forName(datasourceclassname);
Object conDS = classe.newInstance();
java.lang.reflect.Method metodo;
Class argomenti[] = new Class[1];
String args[] = new String[1];
argomenti[0] = String.class;
metodo = classe.getMethod("setServerName", argomenti);
args[0] = dbservername;
metodo.invoke(conDS, args);
if (dbserverportnumber != null) {
Integer iargs[] = new Integer[1];
iargs[0] = new Integer(dbserverportnumber);
try {
argomenti[0] = Class.forName("java.lang.Integer");
metodo = classe.getMethod("setPortNumber", argomenti);
metodo.invoke(conDS, iargs);
}
catch (Exception e) { /* this only works in mySQL driver */ }
try {
argomenti[0] = int.class;
metodo = classe.getMethod("setPortNumber", argomenti);
metodo.invoke(conDS, iargs);
}
catch (Exception e) { /* this work on all other drivers */ }
}
argomenti[0] = String.class;
metodo = classe.getMethod("setDatabaseName", argomenti);
args[0] = dbname;
metodo.invoke(conDS, args);
try {
argomenti[0] = String.class;
metodo = classe.getMethod("setDriverType", argomenti);
args[0] = "thin";
metodo.invoke(conDS, args);
}
catch (Exception e) { /* funziona solo con oracle e fallisce con gli altri */ }
argomenti[0] = String.class;
metodo = classe.getMethod("setUser", argomenti);
args[0] = login;
metodo.invoke(conDS, args);
argomenti[0] = String.class;
metodo = classe.getMethod("setPassword", argomenti);
args[0] = password;
metodo.invoke(conDS, args);
try {
metodo = classe.getMethod("getURL", null);
args[0] = (String)(metodo.invoke(conDS, null));
}
catch (Exception e) {
try {
metodo = classe.getMethod("getUrl", null);
args[0] = (String)(metodo.invoke(conDS, null));
}
catch (Exception ee) {
args[0] = null;
}
}
if (args[0] != null)
System.err.println("getUrl() = " + args[0]);
connectionPoolDataSource = (ConnectionPoolDataSource)conDS;
}
}
Giuseppe Sacco wrote: > So I tried to use the java reflection to inspect the > org.postgresql.jdbc3.Jdbc3ConnectionPool class (or other classes) and > call all required methods. > > The problem is that, when I use this way (a source is attached) I always > get the error: > that is, in english, "The ``user'' property is missing while it is > mandatory." > > Of course the 'setUser()' method is called but it doesn't work. > > Do you have any idea about this problem? We use exactly the same technique (set properties by reflection on the DataSource) and it works fine, so the concept is ok; the problem lies in your implementation. Perhaps you are setting the username to an empty string? -O