package test;
import com.alibaba.druid.pool.DruidDataSource;
import java.sql.Connection;import java.sql.SQLException;
public class JdbcConnectionPool {    private volatile static JdbcConnectionPool instance;
    private DruidDataSource dataSource;
    private JdbcConnectionPool(String url, String username, String password) {        dataSource = new DruidDataSource();        dataSource.setUrl(url);        dataSource.setUsername(username);        dataSource.setPassword(password);        dataSource.setMaxActive(5);        dataSource.setInitialSize(1);        dataSource.setMinIdle(1);    }
    public static JdbcConnectionPool getInstance(String url, String user, String password) {        if (instance == null) {            synchronized (JdbcConnectionPool.class) {                if (instance == null) {                    instance = new JdbcConnectionPool(url, user, password);                }            }        }        return instance;    }
    public Connection getConnection() throws SQLException {        return dataSource.getConnection();    }
}