【Android开发】EasyPermissions 请求权限

安卓6.0以后，开发应用的时候，仅在AndroidManifest.xml中申请权限已经不可以了，需要在代码中动态申请。

现在看一个google推出的机制：EasyPermissions

引入步骤：

1. 导入库文件：

dependencies {
    compile 'pub.devrel:easypermissions:1.0.1'
}

2. 实现 EasyPermissions.PermissionCallbacks

public class MainActivity extends AppCompatActivity implements EasyPermissions.PermissionCallbacks {

    String[] perms = {Manifest.permission.CAMERA, Manifest.permission.ACCESS_FINE_LOCATION};

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

        if (EasyPermissions.hasPermissions(this, perms)) {
            // Already have permission, do the thing
            // ...
        } else {
            // Do not have permissions, request them now
            EasyPermissions.requestPermissions(this, getString(R.string.camera_and_location_rationale),
                RC_CAMERA_AND_LOCATION, perms);
        }
    }

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

        // 将权限的处理交给EasyPermissions
        EasyPermissions.onRequestPermissionsResult(requestCode, permissions, grantResults, this);
    }

    @Override
    public void onPermissionsGranted(int requestCode, List<String> list) {
        // Some permissions have been granted
        // ...
    }

    @Override
    public void onPermissionsDenied(int requestCode, List<String> list) {
        // Some permissions have been denied
        // ...
    }
}

流程讲解：

1. 首先通过EasyPermissions.hasPermissions(this, perms)，查看是否已经获取了权限；
2. 如果没有授权，则通过 EasyPermissions.requestPermissions(.....)方法请求权限；
3. 处理请求的是onRequestPermissionsResult，它会将处理转交给EasyPermissions.onRequestPermissionsResult(.....);
4. 获取处理结果，如果授权，则执行onPermissionsGranted，未授权，则执行onPermissionsDenied；

Git地址请见：https://github.com/googlesamples/easypermissions#installation