如何優雅的處理Android 的OnActivityResult，RequestPermissions

序言

我們知道Android裏面啓動一個Activity For Result時，回調會回到原來這個Activity的OnActivityResult中，如果此時，你正在寫一個其他組件，而不能直接依賴這個Activity那是不是很尷尬？
還有當我們在寫一個圖片庫組件時，發現要請求權限，權限請求完後在進行操作，可是權限請求的回調依然在Activity中的onRequestPermissionsResult，那我們怎麼做呢？
今天介紹一個開源庫 ActivityResultPermission ，一個用於幫助OnActivityResult，PermissionRequest 解耦合的庫，不需要依賴Activity中的回調.

原理

解耦合Activity中的回調，有兩種方式

一種是啓動一個新的Activity來判斷權限，獲取ActivityForResult的結果. （可以參考RxAcitityResult,RxPermission的實現方式）
如下:

import android.app.Activity;
import android.content.ActivityNotFoundException;
import android.content.Intent;
import android.content.IntentSender;
import android.os.Bundle;

import io.reactivex.functions.Action;

public class HolderActivity extends Activity {
    private static Request request;
    private OnPreResult onPreResult;
    private OnResult onResult;
    private int resultCode;
    private int requestCode;
    private Intent data;
    private static int FAILED_REQUEST_CODE = -909;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);

        if (request == null) {
            finish();
            return;
        }

        onPreResult = request.onPreResult();
        onResult = request.onResult();

        if (savedInstanceState != null) return;

        if (request instanceof RequestIntentSender) {
            RequestIntentSender requestIntentSender = (RequestIntentSender) request;

            if (requestIntentSender.getOptions() == null) startIntentSender(requestIntentSender);
            else startIntentSenderWithOptions(requestIntentSender);
        } else {
            try {
                startActivityForResult(request.intent(), 0);
            } catch (ActivityNotFoundException e) {
                if (onResult != null) {
                    onResult.error(e);
                }
            }
        }
    }

    private void startIntentSender(RequestIntentSender requestIntentSender) {
        try {
            startIntentSenderForResult(requestIntentSender.getIntentSender(), 0,
                    requestIntentSender.getFillInIntent(), requestIntentSender.getFlagsMask(),
                    requestIntentSender.getFlagsValues(), requestIntentSender.getExtraFlags());
        } catch (IntentSender.SendIntentException exception) {
            exception.printStackTrace();
            onResult.response(FAILED_REQUEST_CODE, RESULT_CANCELED, null);
        }
    }

    private void startIntentSenderWithOptions(RequestIntentSender requestIntentSender) {
        try {
            startIntentSenderForResult(requestIntentSender.getIntentSender(), 0,
                    requestIntentSender.getFillInIntent(), requestIntentSender.getFlagsMask(),
                    requestIntentSender.getFlagsValues(), requestIntentSender.getExtraFlags(), requestIntentSender.getOptions());
        } catch (IntentSender.SendIntentException exception) {
            exception.printStackTrace();
            onResult.response(FAILED_REQUEST_CODE, RESULT_CANCELED, null);
        }
    }

    @Override
    protected void onActivityResult(int requestCode, int resultCode, Intent data) {
        super.onActivityResult(requestCode, resultCode, data);
        this.resultCode = resultCode;
        this.requestCode = requestCode;
        this.data = data;

        if (this.onPreResult != null) {
            this.onPreResult.response(requestCode, resultCode, data)
                    .doOnComplete(new Action() {
                        @Override
                        public void run() throws Exception {
                            finish();
                        }
                    })
                    .subscribe();
        } else {
            finish();
        }
    }

    @Override
    protected void onDestroy() {
        super.onDestroy();
        if (onResult != null)
            onResult.response(requestCode, resultCode, data);
    }

    static void setRequest(Request aRequest) {
        request = aRequest;
    }
}

一種是添加一個Fragment，在Fragment中獲取回調，進行解耦合.參考本文所提到庫的代碼如下

import android.app.Fragment;
import android.content.Intent;

import androidx.annotation.NonNull;

/**
 * author:DingDeGao
 * time:2019-07-16-14:30
 * function: ReplaceFragment
 */
public class ReplaceFragment extends Fragment {

    static final int ACTIVITY_REQUEST_CODE = 100;
    static final int PERMISSION_REQUEST_CODE = 101;


    private IHandle iHandle;

    public void setIHandle(IHandle iHandle) {
        this.iHandle = iHandle;
    }

    public IHandle getIHandle(){
        return iHandle;
    }

    @Override
    public void onActivityResult(int requestCode, int resultCode, Intent data) {
        super.onActivityResult(requestCode, resultCode, data);
        if (requestCode != ACTIVITY_REQUEST_CODE) return;
        if(iHandle != null){
            iHandle.onActivityResultHandle(resultCode,data);
        }
    }

    @Override
    public void onRequestPermissionsResult(int requestCode, @NonNull String[] permissions, @NonNull int[] grantResults) {
        super.onRequestPermissionsResult(requestCode, permissions, grantResults);
        if (requestCode != PERMISSION_REQUEST_CODE) return;
        if(iHandle != null){
            iHandle.onRequestPermissionsResultHandle(getActivity(),permissions,grantResults);
        }
    }
}

RxActivityResult，RxPermission採用都是前者，而此處採用了後者，使用Fragment.

與RxActivityResult和RxPermission有什麼不同？

不需要依賴RxJava，但也支持鏈式調用.
功能更豐富，兩者結合，使用更加方便，並支持部分國產Rom的權限判斷，跳轉權限設置頁面.
代碼量少，可以選擇拷貝代碼直接放入項目.（核心代碼不到 400行）
Fragment的方式佔用資源更少.

開始使用（minSdkVersion >= 14）

allprojects {
    repositories {
        ...
        maven { url 'https://jitpack.io' }
    }
}

dependencies {
	implementation 'com.github.DingProg:ActivityResultPermission:v0.0.1'
}

OnActivityResult

 Intent intent = new Intent(this, OnActivityResultActivity.class);
 //通過ActivityResultPermissionUtils 去啓動Activity，並註冊其回調
 ActivityResultPermissionUtils.startActivityForResult(this, intent).activityResult(new Listener.ResultListener() {
            @Override
        public void onResult(Intent data) {
            if (data != null) {
                String testStr = data.getStringExtra("test");
                Toast.makeText(MainActivity.this, "openActivity with result is:" + testStr, Toast.LENGTH_SHORT).show();
            }
        }

        @Override
        public void onCancel() {
            Toast.makeText(MainActivity.this, "openActivity with result cancel", Toast.LENGTH_SHORT).show();
        }
 });

Permissions處理

ActivityResultPermissionUtils.requestPermissions(this, Manifest.permission.CAMERA).permissions(new Listener.PermissionResultListener() {
        @Override
        public void permissionDenied(String permission, boolean rationale) {
            //rationale if true 僅僅點擊了禁止
            if(rationale){
                Toast.makeText(MainActivity.this, "Denied permission", Toast.LENGTH_SHORT).show();
            }else{
            //點擊禁止權限，並不允許在彈出
                  Toast.makeText(MainActivity.this, "Denied permission with ask never", Toast.LENGTH_SHORT).show();
                PermissionGoSettingsPageUtils.go(MainActivity.this);
            }
        }

        @Override
        public void permissionGranted() {
            releaseCamera();
            try{
                camera = Camera.open(0);
                camera.setPreviewDisplay(surfaceView.getHolder());
                camera.startPreview();
            }catch (Exception e){
                e.printStackTrace();
            }
        }
    });

如果對於一些非正常Rom（如oppo，vivo手機），可以調用PermissionUtils.checkSelfPermissionsWhitNoNoramal(context,permissions);

請求權限時，調用ActivityResultPermissionUtils.requestPermissions(this, permission).permissionsWithoutCheck();

關於更多請查看sample ActivityResultPermission

如何優雅的處理Android 的OnActivityResult，RequestPermissions