APP申请权限

写了一个Demo列出并播放本地的视频文件，但运行时发现/storage/emulated/0目录下面空空如也，没有任何目录和文件。颇费周折，才晓得是没有获取READ_EXTERNAL_STORAGE权限导致的。

原来从Android 6.0开始，APP不仅需要在AndroidManifest.xml声明其所需的permission，还需要在源码中显式申请权限(会弹出一个dialog，询问用户是否授予权限)，否则系统不予授权。

申请权限的示例源码如下：

private static final int CODE_FOR_READ_PERMISSION = 100;

/**
 * Beginning with Android 6.0 (API level 23), developers declare that your app
 * needs a permission by listing the permission in the app manifest, and then
 * requesting that the user approve each permission at runtime.
 */
private void requestReadPermission() {
    if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.M) {

        if (checkSelfPermission(Manifest.permission.READ_EXTERNAL_STORAGE) != PackageManager.PERMISSION_GRANTED) {
            requestPermissions(new String[]{Manifest.permission.READ_EXTERNAL_STORAGE}, CODE_FOR_READ_PERMISSION);
        }
    }
}

注意，CODE_FOR_READ_PERMISSION是一个本地定义的常量。

参考链接

• Request permissions at runtime appropriately (in Android 6.0+)
• Request App Permissions

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