通过配置文件能够减小我们的工作量，带来方便。

建立properties文件

1.首先是新建一个dbconfig.properties。然后添加如下代码：

driver=com.mysql.jdbc.Driver
dburl=jdbc:mysql://localhost:3306/jsp_dbb
user=root
password=
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读取飘柔properties文件

新建Properties类，让这个类的实例的load方法，读入配置文件的输入流。 
获取输入流是用的ConnectionFactory.class.getClassLoader().getResourceAsStream方法。 
最后用Properties实例的getProperties方法来获取相应的属性值。 
最后采用了单例设计模式，即是把类实例设为static，把构造方法设为private。通过一个静态方法getInstance返回实例。 
最后makeConnection方法封装了获取Connection的方法。 
具体代码如下：

public class ConnectionFactory {
    private static String driver;
    private static String dburl;
    private static String user;
    private static String password;
    public static ConnectionFactory factory = new ConnectionFactory();
    private Connection conn;
    static{
        Properties prop = new Properties();
        try {
            InputStream in = ConnectionFactory.class.getClassLoader().getResourceAsStream("dbconfig.properties");
            prop.load(in);
        } catch (Exception e) {
            System.out.println("========配置文件读取错误===========");
        }
        driver = prop.getProperty("driver");
        dburl = prop.getProperty("dburl");
        user = prop.getProperty("user");
        password = prop.getProperty("password");
        System.out.println(driver);
        System.out.println(dburl);
        System.out.println(user);
        System.out.println(password);
    }
    private ConnectionFactory(){

    }
    public static ConnectionFactory getInstance(){
        return factory;
    }
    public Connection makeConnection(){
        try {
            Class.forName(driver);  
            conn = (Connection) DriverManager.getConnection(dburl, user, password);

        } catch (Exception e) {
            e.printStackTrace();
        }
        return conn;
    }
}