血的教训 关于6.0的读取权限问题

本来做的头像设置的功能好好的（读取sd文件），可是当运行在华为5C（6.0）上时，马丹，不可行。

String path = Environment.getExternalStorageDirectory().getPath()+ "/head.png";
if(!path.equals("")){
Bitmap b = BitmapFactory.decodeFile(path);
if (b != null){
find_img_head.setImageBitmap(b);
}
}

报的这个错！

E/BitmapFactory: Unable to decode stream: java.io.FileNotFoundException: /storage/emulated/0/head.png: open failed: EACCES (Permission denied)

打印这个方法检测能否读取：

File sd = Environment.getExternalStorageDirectory();
boolean can_write = sd.canWrite();
Log.e("tag","can_write:"+can_write);

当然是false。

可是我权限都加了呀  

<uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE"/>
<uses-permission android:name="android.permission.MOUNT_UNMOUNT_FILESYSTEMS"/>

最后才知道在6.0不光要在mainfest中加上上面两个权限，还要在Activity中加上权限，调用这个方法即可。

private static final int REQUEST_EXTERNAL_STORAGE = 1;
private static String[] PERMISSIONS_STORAGE = {
Manifest.permission.READ_EXTERNAL_STORAGE,
Manifest.permission.WRITE_EXTERNAL_STORAGE};

public static void verifyStoragePermissions(Activity activity) {
// Check if we have write permission
int permission = ActivityCompat.checkSelfPermission(activity,
Manifest.permission.WRITE_EXTERNAL_STORAGE);

if (permission != PackageManager.PERMISSION_GRANTED) {
// We don't have permission so prompt the user
ActivityCompat.requestPermissions(activity, PERMISSIONS_STORAGE,
REQUEST_EXTERNAL_STORAGE);
}
}

2016.7.6添加6.0定位的权限：

private static final int REQUEST_EXTERNAL_STORAGE = 1;
private static String[] PERMISSIONS_STORAGE = {
Manifest.permission.ACCESS_COARSE_LOCATION,
Manifest.permission.ACCESS_FINE_LOCATION,
Manifest.permission.ACCESS_WIFI_STATE,
Manifest.permission.ACCESS_NETWORK_STATE,
Manifest.permission.CHANGE_WIFI_STATE,
Manifest.permission.READ_PHONE_STATE,
Manifest.permission.WRITE_EXTERNAL_STORAGE,
Manifest.permission.INTERNET,
Manifest.permission.MOUNT_UNMOUNT_FILESYSTEMS};

public static void verifyStoragePermissions(Activity activity) {
// Check if we have write permission
int permission = ActivityCompat.checkSelfPermission(activity,
Manifest.permission.ACCESS_FINE_LOCATION);

if (permission != PackageManager.PERMISSION_GRANTED) {
// We don't have permission so prompt the user
ActivityCompat.requestPermissions(activity, PERMISSIONS_STORAGE,
REQUEST_EXTERNAL_STORAGE);
}
}