Android動態權限管理框架PermissionsDispatcher使用介紹

對於動態權限，大家應該都不陌生了，在Android6.0版本加入了動態權限的概念，在Android 6.0之前申明權限只需要在AndroidManifest清單中註冊相應權限就可以；Android 6.0以上系統就需要根據權限的等級（普通權限和危險權限）進行權限註冊，如果是普通權限還是依照之前的處理方式直接在AndroidManifest清單中註冊即可，但是危險權限不僅需要在AndroidManifest清單中註冊且還需要在使用時動態申請；
權限分級清單見
https://yilanjingwang.blog.csdn.net/article/details/102992896

其實現在主流權限管理框架有三個，分別爲PermissionsDispatcher、RxPermissions（基於RxJava）和easypermissions（谷歌出品，必是XX）；但是我比較推薦使用PermissionsDispatcher（因爲它使用起來更簡單，尤其是配合插件使用）。

添加依賴：
java：

dependencies {
  implementation "org.permissionsdispatcher:permissionsdispatcher:${latest.version}"
  annotationProcessor "org.permissionsdispatcher:permissionsdispatcher-processor:${latest.version}"
}

With Kotlin(advance with the times):

apply plugin: 'kotlin-kapt'

dependencies {
  implementation "org.permissionsdispatcher:permissionsdispatcher:${latest.version}"
  kapt "org.permissionsdispatcher:permissionsdispatcher-processor:${latest.version}"
}

另外如果還沒用AndroidX的請用3.x的版本。

安裝PermissionsDispatcher插件

install之後restart（如果找不到位置，請自行百度……）

使用插件的方式很簡單，在activity/fragment中右鍵
Usage with Kotlin

Here’s a minimum example, in which you register a MainActivity which requires Manifest.permission.CAMERA.
0. Prepare AndroidManifest

Add the following line to AndroidManifest.xml:

1. Attach annotations

PermissionsDispatcher introduces only a few annotations, keeping its general API concise:

NOTE: Annotated methods must not be private.

Annotation	Required	Description
@RuntimePermissions	✓	Register an Activity or Fragment to handle permissions
@NeedsPermission	✓	Annotate a method which performs the action that requires one or more permissions
@OnShowRationale		Annotate a method which explains why the permissions are needed. It passes in a PermissionRequest object which can be used to continue or abort the current permission request upon user input. If you don’t specify any argument for the method compiler will generate process${NeedsPermissionMethodName}ProcessRequest and cancel${NeedsPermissionMethodName}ProcessRequest. You can use those methods in place of PermissionRequest(ex: with DialogFragment)
@OnPermissionDenied		Annotate a method which is invoked if the user doesn’t grant the permissions
@OnNeverAskAgain		Annotate a method which is invoked if the user chose to have the device “never ask again” about a permission

@RuntimePermissions
class MainActivity : AppCompatActivity(), View.OnClickListener {

    @NeedsPermission(Manifest.permission.CAMERA)
    fun showCamera() {
        supportFragmentManager.beginTransaction()
                .replace(R.id.sample_content_fragment, CameraPreviewFragment.newInstance())
                .addToBackStack("camera")
                .commitAllowingStateLoss()
    }

    @OnShowRationale(Manifest.permission.CAMERA)
    fun showRationaleForCamera(request: PermissionRequest) {
        showRationaleDialog(R.string.permission_camera_rationale, request)
    }

    @OnPermissionDenied(Manifest.permission.CAMERA)
    fun onCameraDenied() {
        Toast.makeText(this, R.string.permission_camera_denied, Toast.LENGTH_SHORT).show()
    }

    @OnNeverAskAgain(Manifest.permission.CAMERA)
    fun onCameraNeverAskAgain() {
        Toast.makeText(this, R.string.permission_camera_never_askagain, Toast.LENGTH_SHORT).show()
    }
}

2. Delegate to generated functions

Now generated functions become much more concise and intuitive than Java version!

 override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)
        setContentView(R.layout.activity_main)
        findViewById(R.id.button_camera).setOnClickListener {
            // NOTE: delegate the permission handling to generated function
            showCameraWithPermissionCheck()
        }
    }

    override fun onRequestPermissionsResult(requestCode: Int, permissions: Array<String>, grantResults: IntArray) {
        super.onRequestPermissionsResult(requestCode, permissions, grantResults)
        // NOTE: delegate the permission handling to generated function
        onRequestPermissionsResult(requestCode, grantResults)
    }

Usage with Java

Here’s a minimum example, in which you register a MainActivity which requires Manifest.permission.CAMERA.
0. Prepare AndroidManifest

Add the following line to AndroidManifest.xml:

1. Attach annotations

PermissionsDispatcher introduces only a few annotations, keeping its general API concise:

NOTE: Annotated methods must not be private.

Annotation	Required	Description
@RuntimePermissions	✓	Register an Activity or Fragment to handle permissions
@NeedsPermission	✓	Annotate a method which performs the action that requires one or more permissions
@OnShowRationale		Annotate a method which explains why the permissions are needed. It passes in a PermissionRequest object which can be used to continue or abort the current permission request upon user input. If you don’t specify any argument for the method compiler will generate process${NeedsPermissionMethodName}ProcessRequest and cancel${NeedsPermissionMethodName}ProcessRequest. You can use those methods in place of PermissionRequest(ex: with DialogFragment)
@OnPermissionDenied		Annotate a method which is invoked if the user doesn’t grant the permissions
@OnNeverAskAgain		Annotate a method which is invoked if the user chose to have the device “never ask again” about a permission

@RuntimePermissions
public class MainActivity extends AppCompatActivity {

    @NeedsPermission(Manifest.permission.CAMERA)
    void showCamera() {
        getSupportFragmentManager().beginTransaction()
                .replace(R.id.sample_content_fragment, CameraPreviewFragment.newInstance())
                .addToBackStack("camera")
                .commitAllowingStateLoss();
    }

    @OnShowRationale(Manifest.permission.CAMERA)
    void showRationaleForCamera(final PermissionRequest request) {
        new AlertDialog.Builder(this)
            .setMessage(R.string.permission_camera_rationale)
            .setPositiveButton(R.string.button_allow, (dialog, button) -> request.proceed())
            .setNegativeButton(R.string.button_deny, (dialog, button) -> request.cancel())
            .show();
    }

    @OnPermissionDenied(Manifest.permission.CAMERA)
    void showDeniedForCamera() {
        Toast.makeText(this, R.string.permission_camera_denied, Toast.LENGTH_SHORT).show();
    }

    @OnNeverAskAgain(Manifest.permission.CAMERA)
    void showNeverAskForCamera() {
        Toast.makeText(this, R.string.permission_camera_neverask, Toast.LENGTH_SHORT).show();
    }
}

2. Delegate to generated class

Upon compilation, PermissionsDispatcher generates a class for MainActivityPermissionsDispatcher([Activity Name] + PermissionsDispatcher), which you can use to safely access these permission-protected methods.

The only step you have to do is delegating the work to this helper class:

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);
    findViewById(R.id.button_camera).setOnClickListener(v -> {
      // NOTE: delegate the permission handling to generated method
      MainActivityPermissionsDispatcher.showCameraWithPermissionCheck(this);
    });
}

@Override
public void onRequestPermissionsResult(int requestCode, @NonNull String[] permissions, @NonNull int[] grantResults) {
    super.onRequestPermissionsResult(requestCode, permissions, grantResults);
    // NOTE: delegate the permission handling to generated method
    MainActivityPermissionsDispatcher.onRequestPermissionsResult(this, requestCode, grantResults);
}