Android申请权限（相机权限和读写权限）

开发一个相机应用，需要申请三个权限：相机、读文件、写文件。

1、在AndroidManifest.xml中添加

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

2、新建一个Permission类

public class Permission {
    public static final int REQUEST_CODE = 5;
    //定义三个权限
    private static final String[] permission = new String[]{
            Manifest.permission.CAMERA,
            Manifest.permission.READ_EXTERNAL_STORAGE,
            Manifest.permission.WRITE_EXTERNAL_STORAGE,
    };
    //每个权限是否已授
    public static boolean isPermissionGranted(Activity activity){
        if(Build.VERSION.SDK_INT >= 23){
            for(int i = 0; i < permission.length;i++) {  
                int checkPermission = ContextCompat.checkSelfPermission(activity,permission[i]);
                /***
                 * checkPermission返回两个值
                 * 有权限: PackageManager.PERMISSION_GRANTED
                 * 无权限: PackageManager.PERMISSION_DENIED
                 */
                if(checkPermission != PackageManager.PERMISSION_GRANTED){
                    return false;
                }
            }
            return true;
        }else{
            return true;
        }
    }

    public static boolean checkPermission(Activity activity){
        if(isPermissionGranted(activity)) {
            return true;
        } else {
            //如果没有设置过权限许可，则弹出系统的授权窗口
            ActivityCompat.requestPermissions(activity,permission,REQUEST_CODE);
            return false;
        }
    }
}

3、在MainActivity中加入授权操作

@Override
    protected void onStart() {
        super.onStart();
        Permission.checkPermission(this);
    }

    @Override
    protected void onResume() {
        super.onResume();
        if(Permission.isPermissionGranted(this)) {
            Log.i("PERMISSION","请求权限成功");
        }
    }

初步授权成功

4、在MainActivity中处理授权失败结果，拒绝授权则退出应用

    @Override
    public void onRequestPermissionsResult(
            int requestCode, @NonNull String[] permissions, @NonNull int[] grantResults) {
        super.onRequestPermissionsResult(requestCode, permissions, grantResults);
        if (requestCode == Permission.REQUEST_CODE) {
            for (int grantResult : grantResults) {
                if (grantResult != PackageManager.PERMISSION_GRANTED) {
                    Log.e("Permission","授权失败！");
                    // 授权失败，退出应用
                    this.finish();
                    return;
                }
            }
        }
    }

效果图