JDBC：四步完成MySQL數據庫的連接

->首先,將MySQL的jar包引入

->然后創建一個.properties的文件(例:connection.properties),在該文件中寫入如下代碼:

jdbc.driver.class = com.mysql.jdbc.Driver
jdbc.connection.url = jdbc:mysql://服務器地址:端口號/數據庫名?useUnicode=true&characterEncoding=UTF-8
jdbc.connection.username = MySQL數據庫名稱
jdbc.connection.password = MySQL數據庫密碼

注: ?useUnicode=true&characterEncoding=UTF-8 這段代碼的作用是防止出現中文亂碼

->然后創建一個解析connection.properties的類(ConfigManager.class),這里涉及到一個單例模式:

省略相關包的導入...

public class ConfigManager {
    private Properties properties = null;
    private static ConfigManager configManager = null;

    //構造方法
    private ConfigManager() {
        InputStream inputstream = null;
        try {
            inputstream = ConfigManager.class.getClassLoader().getResourceAsStream("connection.properties");
            properties = new Properties();
            properties.load(inputstream);
        } catch (IOException e) {
            e.printStackTrace();
        } finally {
            try {
                inputstream.close();
            } catch (IOException e) {
                e.printStackTrace();
            }
        }
    }

    //獲得實例(單例)
    public static ConfigManager getInstance() {
        if (configManager == null) {
            configManager = new ConfigManager();
        }
        return configManager;
    }

    //獲得配置的值
    public String getPropertyValue(String key) {
        return properties.getProperty(key);
    }
}

->最后完成數據庫連接,代碼如下:

省略相關包的導入...

public class Base {

    public Connection connection = null;
    
    //jdbc數據庫連接
    public Connection jdbcGetConnection() {
        String driver = ConfigManager.getInstance().getPropertyValue("jdbc.driver.class");
        String url = ConfigManager.getInstance().getPropertyValue("jdbc.connection.url");
        String username = ConfigManager.getInstance().getPropertyValue("jdbc.connection.username");
        String password = ConfigManager.getInstance().getPropertyValue("jdbc.connection.password");
        try {
            Class.forName(driver);
            connection = DriverManager.getConnection(url, username, password);
        } catch (Exception e) {
            e.printStackTrace();
        }        
        return connection;
    }
}