Android6.0没有权限读取外部存储的问题

1.在AndroidManifest.xml加上：

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

package com.smarter.apkupdate;

import android.Manifest;
import android.app.Activity;
import android.content.pm.PackageManager;
import android.os.Build;
import android.support.annotation.NonNull;
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.util.Log;

public class MainActivity extends AppCompatActivity {


    public static  int PERMISSIONS_CODE=1;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);

        if(!isGrantExternalRW(MainActivity.this)){
            return;
        }
        Log.i("niewl","111");
        new UpdateManager(this).checkUpdate();


    }


    public void onRequestPermissionsResult(int requestCode, @NonNull String[] permissions, @NonNull int[] grantResults) {
        super.onRequestPermissionsResult(requestCode, permissions, grantResults);

        Log.i("niewl","222");

        if (requestCode == PERMISSIONS_CODE) {
            for (int i = 0; i < permissions.length; i++) {
                String permission = permissions[i];
                int grantResult = grantResults[i];

                if (permission.equals(Manifest.permission.READ_EXTERNAL_STORAGE)) {
                    if (grantResult == PackageManager.PERMISSION_GRANTED) {
                        //授权成功后的逻辑
                        new UpdateManager(this).checkUpdate();
                    } else {
                        requestPermissions(new String[]{Manifest.permission.READ_EXTERNAL_STORAGE}, PERMISSIONS_CODE);
                    }
                }
            }
        }
    }



    public static boolean isGrantExternalRW(Activity activity) {
        if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.M && activity.checkSelfPermission(
                Manifest.permission.WRITE_EXTERNAL_STORAGE) != PackageManager.PERMISSION_GRANTED) {

            activity.requestPermissions(new String[]{
                    Manifest.permission.READ_EXTERNAL_STORAGE,
                    Manifest.permission.WRITE_EXTERNAL_STORAGE
            }, 1);

            return false;
        }

        return true;
    }





}