java知识回顾

1读取properties文件获取Connection

	public static Connection getConn(String url,String user,String pwd)throws Exception{
		if(conn == null){
			URL[] urls = {new URL("file:mysql-connector-java-5.1.7-bin.jar")};
			URLClassLoader myClassLoader = new URLClassLoader(urls);
			Driver driver = (Driver)myClassLoader.loadClass("com.mysql.jdbc.Driver").newInstance();
			Properties properties = new Properties();
			properties.setProperty("user",user);
			properties.setProperty("password", pwd);
			conn = driver.connect("jdbc:mysql://localhost:3306/mysql",properties);
		}
		return conn;
	}

或者

	private static String jdbcDriver = "";
	
	private static String jdbcUrl = "";
	
	private static String jdbcUser = "";
	
	private static String jdbcPasswd = "";
	
	static {
		InputStream is = null;
		try {
			is = DBConn.class.getClassLoader().getResourceAsStream("database.properties");
			Properties p = new Properties();
			p.load(is);
			jdbcDriver = p.getProperty("jdbcDriver");
			jdbcUrl = p.getProperty("jdbcUrl");
			jdbcUser = p.getProperty("jdbcUser");
			jdbcPasswd = p.getProperty("jdbcPasswd");
		} catch (IOException e) {
			e.printStackTrace();
		} finally {
			if(is != null){
				try {
					is.close();
				} catch (IOException e) {
					e.printStackTrace();
				}
			}
		}
	}
	
	public static Connection getConn(){
		Connection  conn = null;
		try {
			Class.forName(jdbcDriver);
			conn = DriverManager.getConnection(jdbcUrl, jdbcUser, jdbcPasswd);
		} catch (ClassNotFoundException e) {
			e.printStackTrace();
		} catch (SQLException e) {
			e.printStackTrace();
		}
		return conn;
	}


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