android 6.0以后，新增加了动态申请权限这一要求，具体是怎么回事呢？

1.概述

• 关于运行时权限
  在Android6.0开始，App可以直接安装，App在运行时一个一个询问用户授予权限，系统会弹出一个对话框让用户选择是否授权某个权限给App（这个Dialog不能由开发者定制），当App需要用户授予不恰当的权限的时候，用户可以拒绝，用户也可以在设置页面对每个App的权限进行管理。
  特别注意：这个对话框不是开发者调用某个权限的功能时由系统自动弹出，而是需要开发者手动调用，如果你直接调用而没有去申请权限的话，将会导致App崩溃。
• 哪些权限需要动态申请
  正常权限： 使用时直接在清单文件中声明即可。
  
  正常权限.jpg

危险权限： 使用时需要动态申请权限。

危险权限.jpg

2.申请权限工具类

申请权限的流程：
1.判断是否是 Android 6.0以上
2.判断权限（危险权限）是否申请了
3.没有申请，去申请

1.定义权限申请回掉接口

public interface PermissionListener {
    // 申请成功
    public void onSucceed();
    // 申请失败
    public void onFiled();
}

2.申请权限的工具类

public class PermissionUtils {

    //判断版本是否是6.0
    public static boolean isVersionCodeM() {
        return Build.VERSION.SDK_INT > Build.VERSION_CODES.M;
    }
    /**
     *
     * @param context
     * @param permissions
     * @return 获取未授权的集合
     */
    public static List<String> getDeniedList(Context context,String... permissions){
        //创建一个未授权的集合
        List<String> deniedList =new ArrayList<>();
        //如果传入为null,返回空的集合
        if (permissions.length==0) {
            return deniedList;
        }
        for (String permission : permissions) {
            int permissionCode = ContextCompat.checkSelfPermission(context, permission);
            if (permissionCode== PackageManager.PERMISSION_DENIED) {
                //将没有授权的添加到集合
                deniedList.add(permission);
            }
        }
        return deniedList;
    }
}

3.申请权限的帮助类 (无界面的fragment)

public class PermissionFragment extends Fragment {
    private static final int REQUESTCODE = 66;
    private static final int REQUEST_PERMISSION_SETTING = 55;
    private PermissionListener mPermissionListener;
    private Activity mActivity;

    @Override
    public void onCreate(@Nullable Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        //  Fragment具有属性retainInstance，默认值为false。当设备旋转时，fragment会随托管activity一起销毁并重建。调用setRetainInstance(true)方法可保留fragment，
        setRetainInstance(true);
    }

    public void setPermissionListener(PermissionListener permissionListener) {
        this.mPermissionListener = permissionListener;
    }

    @RequiresApi(api = Build.VERSION_CODES.M)
    public void requestPermissions(Activity activity, String[] permission) {
        this.mActivity = activity;
        requestPermissions(permission, REQUESTCODE);
    }

    @RequiresApi(api = Build.VERSION_CODES.M)
    @Override
    public void onRequestPermissionsResult(int requestCode, @NonNull String[] permissions, @NonNull int[] grantResults) {
        super.onRequestPermissionsResult(requestCode, permissions, grantResults);
        if (requestCode == REQUESTCODE) {
            // 获取未申请的权限列表
            List<String> deniedPermissions = PermissionUtils.getDeniedList(mActivity, permissions);
            if (deniedPermissions.size() > 0) {
                // 执行失败的方法
                onFailed(permissions);
            } else {
                // 执行成功的方法
                onSucceed();
            }
        }

    }

    /**
     * 成功时回调方法
     */
    private void onSucceed() {
        if (mPermissionListener != null) {
            mPermissionListener.onSucceed();
        }

    }

    @RequiresApi(api = Build.VERSION_CODES.M)
    private void onFailed(String[] permissions) {
        for (int i = 0; i < permissions.length; i++) {
            // 用户拒绝是true   用户选择不再提示是：false
            if (!shouldShowRequestPermissionRationale(permissions[i])) {
                new AlertDialog.Builder(mActivity)
                        .setTitle("权限被拒绝")
                        .setMessage("权限管理-->打开拒绝的权限")
                        .setPositiveButton("去打开", new DialogInterface.OnClickListener() {
                            @Override
                            public void onClick(DialogInterface dialog, int which) {
                                dialog.dismiss();
                                openSetting();
                            }
                        })
                        .setNegativeButton("取消", new DialogInterface.OnClickListener() {
                            @Override
                            public void onClick(DialogInterface dialog, int which) {
                                dialog.dismiss();
                                mPermissionListener.onFiled();
                            }
                        })
                        .show();
                return;
            }
        }
        mPermissionListener.onFiled();
    }

    /**
     * 打开应用设置页面
     */
    private void openSetting() {
        Intent intent = new Intent(Settings.ACTION_APPLICATION_DETAILS_SETTINGS);
        Uri uri = Uri.fromParts("package", mActivity.getPackageName(), null);
        intent.setData(uri);
        startActivityForResult(intent, REQUEST_PERMISSION_SETTING);
    }

    @Override
    public void onDestroy() {
        // 销毁对象，防止内存泄漏
        mActivity = null;
        mPermissionListener = null;
        super.onDestroy();

    }
}

4.申请权限的帮助类

/**
 * Created by LiMing on 2018/4/25.
 * QQ：1002464056
 * Email: 1002464056@qq.com
 * Version：1.0
 */

public class XPermission {

    private Activity mActivity;
    private PermissionFragment mPermissionFragment;
    private static final String TAG = "XPermission";
    private String[] mPermissions;

    public XPermission(Activity activity) {
        this.mActivity = activity;
        mPermissionFragment = getPermissionFragment(activity);
    }

    private PermissionFragment getPermissionFragment(Activity activity) {
        //获取权限的fragment
        PermissionFragment permissionFragment = findPermissionFragment(activity);
        boolean isNewInstance = (permissionFragment == null);
        if (isNewInstance) {
            permissionFragment = new PermissionFragment();
            FragmentManager fragmentManager = activity.getFragmentManager();
            fragmentManager.beginTransaction()
                    .add(permissionFragment, TAG)
                    .commitAllowingStateLoss();
            fragmentManager.executePendingTransactions();

        }
        return permissionFragment;
    }

    /**
     * 获取权限fragment
     *
     * @param activity
     * @return
     */
    private PermissionFragment findPermissionFragment(Activity activity) {
        return (PermissionFragment) activity.getFragmentManager().findFragmentByTag(TAG);
    }

    /**
     * 要申请的权限组
     *
     * @param permissions
     * @return
     */
    public XPermission permissions(String... permissions) {
        mPermissions = permissions;
        return this;
    }

    /**
     * 申请权限
     *
     * @param permissionListener
     */
    @RequiresApi(api = Build.VERSION_CODES.M)
    public void request(PermissionListener permissionListener) {
        mPermissionFragment.setPermissionListener(permissionListener);
        // 1.判断版本
        if (!PermissionUtils.isVersionCodeM()) {
            // 版本6.0一下，直接回调成功方法
            permissionListener.onSucceed();
            return;
        }
        // 版本6.0及以上
        // 2.获取未授权的列表
        List<String> deniedList = PermissionUtils.getDeniedList(mActivity, mPermissions);
        if (deniedList.size() > 0) {
            // 3.去申请权限
            mPermissionFragment.requestPermissions(mActivity, deniedList.toArray(new String[deniedList.size()]));
        } else {
            permissionListener.onSucceed();
        }


    }

}

5.在MainActivity中调用

public class MainActivity extends AppCompatActivity {

    @RequiresApi(api = Build.VERSION_CODES.M)
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        
    }
    //点击事件
    @RequiresApi(api = Build.VERSION_CODES.M)
    public void click(View view) {
        new XPermission(this)
                .permissions(Manifest.permission.CAMERA)
                .request(new PermissionListener() {
                    @Override
                    public void onSucceed() {
                        // TODO
                        Toast.makeText(MainActivity.this,"授权成功",Toast.LENGTH_SHORT).show();
                    }
                    @Override
                    public void onFiled() {
                        Toast.makeText(MainActivity.this,"授权失败",Toast.LENGTH_SHORT).show();
                    }
                });
    }
}

简单的封装基本可以满足使用，代码易懂，有特殊需求完全可以去二次封装，附上链接地址https://github.com/CatEatFishs/XPermission/tree/v1.0
感谢@刘付文 的博客