利用toast实现安卓按键测试，实现菜单键，返回键与音量加减键的显示，点击home键返回主页点击程序附带登陆界面，登录名跟密码可在login.java找到。-Andrews use toast to achieve key test to achieve the menu key, back key and volume keys subtraction display, click on the home button to return to home page click on the p