public void keyPressed(KeyEvent e) {
		if (e.getKeyCode() == KeyEvent.VK_ENTER ) {
			String str = tfTxt.getText().trim();//获取输入框的内容
			tfTxt.setText("");
			try {
				dos.writeUTF(str);//往流里写，发到服务器
				dos.flush();
			} catch (IOException e1) {
				e1.printStackTrace();
			}
		}
	}