/**
 * ClassName: PropertiesDemo 
 * @Description: Properties
 * properties可以用來做配置檔案
 * 
 * ResouceRundle 只讀
 * Properties 可讀可寫
 * @author cai
 * @date 2018年10月18日 
 */
public class PropertiesDemo {

	public static String version = "";
	public static String username = "";
	public static String password = "";
	
	//靜態程式碼塊，只會執行一次
	static {
		readConfig();
	}
	/**
	 * 
	 * @Description: 對屬性檔案操作
	 * @param @param version
	 * @param @param username
	 * @param @param password   
	 * @return void  
	 * @throws
	 */
	private static void  writerConfig(String version,String username,String password) {
		Properties p = new Properties();
		p.put("app.version", version);
		p.put("db.username", username);
		p.put("db.password", password);
		OutputStream out;
		try {
			out = new FileOutputStream("config.properties");
			p.store(out, "update config");
			out.close();
		} catch (FileNotFoundException e) {
			e.printStackTrace();
		} catch (IOException e) {
			e.printStackTrace();
		}
	}
	private static void readConfig() {
		Properties p = new Properties();
		InputStream inStream;
		try {
			inStream = new FileInputStream("config.properties");
			p.load(inStream);
			
			version = p.getProperty("app.version");
			username = p.getProperty("db.username");
			password = p.getProperty("db.password");
			
			inStream.close();
		} catch (FileNotFoundException e) {
			e.printStackTrace();
		} catch (IOException e) {
			e.printStackTrace();
		}
	}
	public static void main(String[] args) {
		writerConfig("2","cai","2222");
		//readConfig();   //此處呼叫可以用上面的靜態程式碼塊來代替
		System.out.println(version);
		System.out.println(username);
		System.out.println(password);
	}
}
 

#update config
#Fri Oct 19 11:58:34 CST 2018
db.password=2222
app.version=2
db.username=cai