Android 开发基本知识备忘

一、程序常用权限

 

 

android.permission.INTERNET

允许程序联网，非常常用(Allows applications to open network sockets)

 

 

android.permission.ACCESS_COARSE_LOCATION

允许一个程序访问CellID或WiFi热点来获取粗略的位置(Allows an application to access coarse (e.g., Cell-ID, WiFi) location)

 

android.permission.ACCESS_FINE_LOCATION

允许一个程序访问精良位置(如GPS) (Allows an application to access fine (e.g., GPS) location)

 

android.permission.ACCESS_NETWORK_STATE

允许程序访问有关GSM网络信息(Allows applications to access information about networks)

 

android.permission.ACCESS_WIFI_STATE

允许程序访问Wi-Fi网络状态信息(Allows applications to access information about Wi-Fi networks)

 

 

android.permission.CHANGE_WIFI_STATE

允许程序改变Wi-Fi连接状态(Allows applications to change Wi-Fi connectivity state)

 

 

android.permission.CHANGE_NETWORK_STATE

允许程序改变网络连接状态(Allows applications to change network connectivity state)

 

 

 

android.permission.CAMERA

请求访问使用照相设备(Required to be able to access the camera device. )

 

 

android.permission.VIBRATE

允许访问振动设备(Allows access to the vibrator)

 

 

二、检查SD卡是否存在，并取出绝对路径：

 

 

String rootPath = null;if(Environment.getExternalStorageState().equals(android.os.Environment.MEDIA_MOUNTED)){rootPath = Environment.getExternalStorageDirectory().getAbsolutePath();} 

 

 

三、创建文件夹

/* * @see 创建一个绝对路径目录 * @param 绝对路径 * @return 是否创建成功 */public boolean createFolder(String fullpath){try {File path = new File(fullpath);if(!path.exists()){path.mkdir();}return true;} catch (Exception e) {// TODO: handle exceptionLog.w("apkdev", "FileManager.createFolder: "+"Please Check path " + fullpath);return false;}} 

 

四、这里讲下如何禁止横屏和竖屏切换

在某些游戏中我们可能需要禁止横屏和竖屏切换，只要在

AndroidManifest.xml 里面加入这一行 android :screenOrientation="landscape "（landscape 是横向，portrait 是纵向）。

在android中每次屏幕的切换动会重启Activity，所以应该在Activity销毁前保存当前活动的状态，在Activity再次Create的时候载入配置。在activity加上android:configChanges="keyboardHidden|orientation"属性,就不会重启activity.而是去调用onConfigurationChanged(Configuration newConfig). 这样就可以在这个方法里调整显示方式. 

 

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