這節課我們實現一個功能，我們把連線mysql要用到的資訊放在properties配置檔案裡，讓Dbc載入這個檔案讀取配置資訊給我們返回一個Connection物件

實現:

package com.tool;



import java.io.*;

import java.sql.Connection;

import java.sql.DriverManager;

import java.sql.SQLException;

import java.util.Properties;



//Database Connection，負責連線資料庫，返回一個Connection物件

 
public class Dbc {



    //不允許呼叫構造器

    private Dbc(){}



    private static Properties properties;



    private static InputStream inputStream;



    public static Connection getConnection(String driver,String url,String user
 
, String password) throws ClassNotFoundException, SQLException {

        Class.forName(driver);

        return DriverManager.getConnection(url,user,password);

    }



    public static Connection 
 
getConnection(String propertiesPath) throws IOException, SQLException, ClassNotFoundException {

        File file = new File(propertiesPath);

        if (file.getName().endsWith(".properties") && file.exists())

        {

            inputStream = new FileInputStream(file);

            properties = new Properties();

            properties.load(inputStream);



            String driver = properties.getProperty("driver");

            String url = properties.getProperty("url");

            String user = properties.getProperty("user");

            String password = properties.getProperty("password");



            return getConnection(driver,url,user,password);

        }

        else

        {

            throw new FileNotFoundException("cannot find file " + file.getAbsolutePath());

        }

    }

}

測試:

public static void main(String[] args) throws SQLException, ClassNotFoundException, IOException {

    Connection conn = Dbc.getConnection("src/com/resource/dbc.properties");



    //測試下連線是否真的可用

    Statement statement = conn.createStatement();

    String sql = "select * from tbl_employee where id = 1";

    ResultSet resultSet = statement.executeQuery(sql);

    resultSet.next();

    System.out.println(resultSet.getInt(1));

    System.out.println(resultSet.getString(2));

    //連線確實可用

}

結果:

1

xiaoye