public class ImgUtils {
    //保存文件到指定路径
    public static boolean saveImageToGallery(Context context, Bitmap bmp) {
        // 首先保存图片
        String storePath = Environment.getExternalStorageDirectory().getAbsolutePath() + File.separator + "dearxy";
        File appDir = new File(storePath);
        if (!appDir.exists()) {
            appDir.mkdir();
        }
        String fileName = System.currentTimeMillis() + ".jpg";
        File file = new File(appDir, fileName);
        try {
            FileOutputStream fos = new FileOutputStream(file);
            //通过io流的方式来压缩保存图片
            boolean isSuccess = bmp.compress(Bitmap.CompressFormat.JPEG, 60, fos);
            fos.flush();
            fos.close();

            //把文件插入到系统图库
            //MediaStore.Images.Media.insertImage(context.getContentResolver(), file.getAbsolutePath(), fileName, null);

            //保存图片后发送广播通知更新数据库
            Uri uri = Uri.fromFile(file);
            context.sendBroadcast(new Intent(Intent.ACTION_MEDIA_SCANNER_SCAN_FILE, uri));
            if (isSuccess) {
                return true;
            } else {
                return false;
            }
        } catch (IOException e) {
            e.printStackTrace();
        }
        return false;
    }
}

public class MainActivity extends AppCompatActivity implements EasyPermissions.PermissionCallbacks {

    private static final int REQUEST_CODE_SAVE_IMG = 10;
    private static final String TAG = "MainActivity";
    private Context mContext;

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

        mContext = this;
        findViewById(R.id.save_img_btn).setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                requestPermission();
            }
        });
    }

    /**
     * 请求读取sd卡的权限
     */
    private void requestPermission() {
        if (Build.VERSION.SDK_INT >= 23) {
            //读取sd卡的权限
            String[] mPermissionList = new String[]{Manifest.permission.READ_EXTERNAL_STORAGE, Manifest.permission.WRITE_EXTERNAL_STORAGE};
            if (EasyPermissions.hasPermissions(mContext, mPermissionList)) {
                //已经同意过
                saveImage();
            } else {
                //未同意过,或者说是拒绝了，再次申请权限
                EasyPermissions.requestPermissions(
                        this,  //上下文
                        "保存图片需要读取sd卡的权限", //提示文言
                        REQUEST_CODE_SAVE_IMG, //请求码
                        mPermissionList //权限列表
                );
            }
        } else {
            saveImage();
        }
    }


    //保存图片
    private void saveImage() {
        Bitmap bitmap = BitmapFactory.decodeResource(getResources(), R.mipmap.fj);
        boolean isSaveSuccess = ImgUtils.saveImageToGallery(mContext, bitmap);
        if (isSaveSuccess) {
            Toast.makeText(mContext, "保存图片成功", Toast.LENGTH_SHORT).show();
        } else {
            Toast.makeText(mContext, "保存图片失败，请稍后重试", Toast.LENGTH_SHORT).show();
        }
    }

    //授权结果，分发下去
    @Override
    public void onRequestPermissionsResult(int requestCode, String[] permissions, int[] grantResults) {
        super.onRequestPermissionsResult(requestCode, permissions, grantResults);
        // Forward results to EasyPermissions
        //跳转到onPermissionsGranted或者onPermissionsDenied去回调授权结果
        EasyPermissions.onRequestPermissionsResult(requestCode, permissions, grantResults, this);
    }


    //同意授权
    @Override
    public void onPermissionsGranted(int requestCode, List<String> list) {
        Log.i(TAG, "onPermissionsGranted:" + requestCode + ":" + list.size());
        saveImage();
    }

    //拒绝授权
    @Override
    public void onPermissionsDenied(int requestCode, List<String> perms) {
        Log.i(TAG, "onPermissionsDenied:" + requestCode + ":" + perms.size());
        if (EasyPermissions.somePermissionPermanentlyDenied(this, perms)) {
            //打开系统设置，手动授权
            new AppSettingsDialog.Builder(this).build().show();
        }
    }

    @Override
    protected void onActivityResult(int requestCode, int resultCode, Intent data) {
        super.onActivityResult(requestCode, resultCode, data);
        if (requestCode == AppSettingsDialog.DEFAULT_SETTINGS_REQ_CODE) {
            //拒绝授权后，从系统设置了授权后，返回APP进行相应的操作
            Log.i(TAG, "onPermissionsDenied:------>自定义设置授权后返回APP");
            saveImage();
        }
    }
}