Example #2: MysqlConnectionPool

package see613.core.db;

import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.SQLException;
import java.util.LinkedList;
import java.util.Queue;

import see613.core.log.ILog;

public class MysqlConnectionPool implements IConnectionPool {
    private Queue<Connection> pool = new LinkedList<Connection>();
    private ILog log;
    private String address;
    private String login;
    private String pass;
    public int connectTimeout = 3;


    public Connection get() throws Exception {
        synchronized (pool) {
            Connection connect;

            while (true) {
                connect = pool.poll();

                if ( connect == null ) {
                    break;
                }

                if ( isValid(connect) ) {
                    return connect;
                }
            }
        }

        return create();
    }

    public void add(Connection connect) {
        synchronized (pool) {
            pool.add(connect);
        }
    }

    private Connection create() throws Exception {
        Connection connect = null;

        try {
            Class.forName("com.mysql.jdbc.Driver");
            connect = DriverManager.getConnection( "jdbc:mysql://"+ getAddress(), getLogin(), getPass() );

            getLog().notice("new mysql connection: "+ getAddress() );

        } catch (Exception e) {
            close(connect);
            connect = null;
            throw e;
        }
        return connect;
    }

    public void close(Connection connect) throws Exception {
        if (connect != null) {
            connect.close();
        }
    }

    private Boolean isValid(Connection connect) throws SQLException {
        try {
            return connect.isValid( connectTimeout );

        } catch (SQLException e) {
            throw e;
        }
    }

    public void setLog(ILog value) {
        log = value;
    }

    private ILog getLog() {
        if ( log == null ) {
            throw new NullPointerException("log is null");
        }
        return log;
    }

    public void setAddress(String value) {
        address = value;
    }

    private String getAddress() {
        if ( address == null ) {
            throw new NullPointerException("address is null");
        }
        return address;
    }

    public void setLogin(String value) {
        login = value;
    }

    private String getLogin() {
        if ( login == null ) {
            throw new NullPointerException("login is null");
        }
        return login;
    }

    public void setPass(String value) {
        pass = value;
    }

    private String getPass() {
        if ( pass == null ) {
            throw new NullPointerException("pass is null");
        }
        return pass;
    }

}