JDBC连接

package com.fastech.utils;

import java.io.IOException;
import java.io.InputStream;
import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.SQLException;
import java.util.Properties;

import org.apache.log4j.Logger;

public class ConnectJDBC {
    private static Logger log = Logger.getLogger(ConnectJDBC.class);
    private Connection conn = null;

    public static ConnectJDBC getInstance() {
        return SingletonClassInstance.instance;
    }
    private static class SingletonClassInstance {
        private static final ConnectJDBC instance = new ConnectJDBC();
    }
    /**
     * 获取数据库连接
     * @return
     * @throws SQLException 
     */
    public  Connection getConnection() throws SQLException {
        if (null ==conn || conn.isClosed()) {
            Properties prop = new Properties(); 
            InputStream ips = Thread.currentThread().getContextClassLoader().getResourceAsStream("jdbc.properties"); 
            try {
                prop.load(ips);
            } catch (IOException e) {
                
            } 
            String driver = prop.getProperty("jdbc.driverClassName");
            String user = prop.getProperty("jdbc.username");
            String pass = prop.getProperty("jdbc.password");
            String url = prop.getProperty("jdbc.url");
            log.info(driver+","+user+","+pass+","+url);
            try {
                Class.forName(driver).newInstance();
                conn = DriverManager.getConnection(url, user, pass);
                if (null != conn) {
                    return conn;
                }
            } catch (ClassNotFoundException e) {
                e.printStackTrace();
            } catch (SQLException e) {
                e.printStackTrace();
            } catch (InstantiationException e) {
                // TODO Auto-generated catch block
                e.printStackTrace();
            } catch (IllegalAccessException e) {
                // TODO Auto-generated catch block
                e.printStackTrace();
            }
        }else{
            return conn;
        }
        return null;
    }
    public void close() {
        if (conn != null) {
            try {
                conn.close();
                log.info("Close SQL Success.");
            } catch (SQLException e) {
                e.printStackTrace();
                log.error("Close SQL failed!");
            }
            conn = null;
        }
    }
}