Android动态申请SDcard权限

Android6.0后必须使用动态申请SDcard权限，否则会抛出"java.io.FileNotFoundException"异常。

try {
    //检测是否有写的权限
    int permission = ActivityCompat.checkSelfPermission(this,
            "android.permission.WRITE_EXTERNAL_STORAGE");
    if (permission != PackageManager.PERMISSION_GRANTED) {
        // 没有写的权限，去申请写的权限，会弹出对话框
        ActivityCompat.requestPermissions(this,
                new String[]{Manifest.permission.WRITE_EXTERNAL_STORAGE}, 1);
    }
} catch (Exception e) {
    e.printStackTrace();
}