Tony Smith wrote:
I am runing tomcat 5.0 + postgresql. I set my
connection pool in server.xml as:
<Resource
name="jdbc/mysource"
type="javax.sql.DataSource"
password="xxxx"
driverClassName="org.postgresql.Driver"
maxIdle="100"
maxWait="5000"
validationQuery="select * from test"
For PostgreSQL (and MySQL, too), this is better done via "SELECT
version()", just an observation.
username="xxxx"
url="jdbc:postgresql://localhost:5432/mydb"
maxActive="100"/>
You can add parameters, like "removeAbandoned" to remove hanging
connections.
I call it from my servlet as:
public Connection getConnection(){
try{
Context initCtx = new InitialContext();
Context envCtx =
(Context)initCtx.lookup("java:comp/env");
DataSource ds =
(DataSource)envCtx.lookup("jdbc/mysource");
DatabaseManager.initDataSource(ds);
return ds.getConnection();
}catch(Exception e){
e.printStackTrace();
}
return null;
}
I use the connection as:
Connection connection = getConnection();
....//jdbc
//I did not call connection.close(). Should I?
YES! The Connection you get from this is a wrapper class, that will
actually return the connection to the pool, when you call "close()" on it.
Then, I can run my web app. But not for long. I got
the following exception after browse a few pages:
org.apache.tomcat.dbcp.dbcp.SQLNestedException: Cannot
get a connection, pool exhausted
Always close ResultSets, Statements and Connections - in that order.
This code will illustrate it for you:
PreparedStatement pstat = null;
ResultSet rs = null;
try {
pstat = conn.prepareStatement( "SELECT ..." );
pstat.setInt( 1, x );
...
rs = pstat.execute();
...
} catch (SQLException ex) {
...
} finally {
if (rs != null) {
try {
rs.close();
} catch (SQLException ex1) {}
}
if (pstat != null) {
try {
pstat.close();
} catch (SQLException ex1) {}
}
if (conn != null) {
try {
conn.close();
catch (SQLException ex1) {}
}
}
Nix.
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