Hi, i have done a server web application that runs on tomcat.
The server handle more clients and since i have to access to db, i tried to
implement the connection pooling.
Since i had some problems with tomcat (crashes after some days telling thatthe
connection pool was full, or something like it), i wish to be sure i'm doing
the right things to use the connection pool.
Anyway, after reinstall of tomcat, it seems to work a lot better than before,
but i still wish to know if the way i do it has sense.
The configuration of context.xml file is:
<Context path="/SomeApp" docBase="SomeApp" debug="5" reloadable="true"
crossContext="true">
<Resource
name="jdbc/SomeAppDB"
auth="Container"
type="javax.sql.DataSource"
maxActive="300"
maxIdle="30"
maxWait="5000"
username="user"
password="pass"
driverClassName="com.mysql.jdbc.Driver"
url="jdbc:mysql://127.0.0.1:3306/db_db?autoReconnect=true"/>
</Context>
The setting in web.xml are:
...
<resource-ref>
<description>DB Connection</description>
<res-ref-name>jdbc/SomeAppDB</res-ref-name>
<res-type>javax.sql.DataSource</res-type>
<res-auth>Container</res-auth>
</resource-ref>
...
then i have a class with all methods that access to db, and it's like:
class Database {
private Connection getConnection() throws Exception {
// get context: provides the starting point for resolution of names
Context ctx = new InitialContext();
if (ctx == null) {
throw new Exception("No Context");
}
// retrieve datasource
DataSource ds = (DataSource) ctx.lookup("java:comp/env/jdbc/SomeAppDB");
if (ds == null) {
throw new Exception("No Datasource");
}
// return db connection
return ds.getConnection();
}
public Object getSomething() {
Connection con = null;
Statement stmt = null;
ResultSet rst = null;
try {
// get connection
con = getConnection();
if (con == null) {
throw new Exception("No Connection");
}
stmt = con.createStatement();
// perform query
rst = stmt.executeQuery("SELECT something FROM some_table WHERE id =
'1'");
if (rst.next()) {
return rst.getString("something");
}
else {
throw new Exception("No results");
}
}
catch (Exception e1) {
return null;
}
// close resources
finally {
try {
rst.close();
rst = null;
}
catch (Exception e2) {
}
try {
stmt.close();
stmt = null;
}
catch (Exception e3) {
}
try {
con.close();
con = null;
}
catch (Exception e4) {
}
}
return null;
}
public Object getSomeOtherThing() {
Connection con = null;
Statement stmt = null;
ResultSet rst = null;
try {
// get connection
con = getConnection();
if (con == null) {
throw new Exception("No Connection");
}
...
}
...
>From all other classes of the application, i just use:
(new Database()).getSomething();
to call the method that access to db that i need.
Is it the correct way to use the connection pooling?
Database class should be done in a different way? For example, methods inside
it, should be static so i don't need to create each time a Database object just
to call one?
Any suggestion about it is very appreciated. Thanks
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