少年击剑更吹箫，剑气箫心一例消。这篇文章主要讲述干掉RxJava系列--1. 手写权限请求替代RxPermission相关的知识，希望能为你提供帮助。
起因

• 最近在对公司项目做APK包体积优化, 其中少不了对一些不必要的三方库的移除，在此过程中发现项目中居然有一系列的Rx相关库，Rxjava,RxBus,RxPermission，于是心中起了一丝杀意。
• 当然RxJava还是相当强大的，基于事件流的链式调用，进行耗时任务，线程切换，是一个很好的异步操作库，毕竟我上一个系列文章才写过探索Android开源框架 - 3. RxJava使用及源码解析，如果想更深入的了解RxJava的话可以看一下，不过随着现在kotlin的普及，其协程和Flow基本也可以替代RxJava，所以准备尝试移除RxJava及其相关的一系列库，毕竟还是可以减少不小的包体积的。
• 那么先拿RxPermission开刀吧。 RxPermission的简单使用
  
• 先来介绍一下RxPermission的使用吧，毕竟背靠RxJava这颗大树，它还是使得我们的运行时权限请求变得简洁了很多的；

  //1. build.gradle中添加依赖 allprojects repositories ... mavenurl https://jitpack.io

  
  

dependencies
implementation com.github.tbruyelle:rxpermissions:0.12

//注意:最新版rxpermission需要配合RxJava3使用
implementation io.reactivex.rxjava3:rxjava:3.0.4
implementation io.reactivex.rxjava3:rxandroid:3.0.0
//2.调用
//所有权限统一结果
new RxPermissions(this)
.request(Manifest.permission.READ_EXTERNAL_STORAGE, Manifest.permission.CALL_PHONE, Manifest.permission.CAMERA)
.subscribe(accept ->
if (accept)
LjyLogUtil.d(" 允许了权限申请" );
else
LjyLogUtil.d(" 拒绝了权限申请" );

);
//将权限申请结果逐一返回
new RxPermissions(this)
.requestEach(Manifest.permission.READ_EXTERNAL_STORAGE, Manifest.permission.CALL_PHONE, Manifest.permission.CAMERA)
.subscribe(permission ->
// will emit 2 Permission objects
LjyLogUtil.d(permission.toString());
if (permission.granted)
// permission.name is granted !
LjyLogUtil.d(" 允许了权限申请:" + permission.name);
else if (permission.shouldShowRequestPermissionRationale)
// Denied permission without ask never again
LjyLogUtil.d(" 取消了权限申请:" + permission.name);
else
// Denied permission with ask never again
// Need to go to the settings
LjyLogUtil.d(" 权限被拒绝，将导致APP无法正常使用，请前往设置中修改:" + permission.name);

);

- 如上，使用了RxPermissions就可以将权限请求和结果回调放到一个链式代码中了，而且支持 所有权限统一返回结果（request） 和 将权限申请结果逐一返回（requestEach）， - 其主要原理是：新建RxPermissions类的时候，框架会悄悄的新建一个RxPermissionsFragment类，也就是说框架在内部封装了一个没有界面的fragment，这样做的好处是请求权限的回调可以在Fragment中实现，不需要用户再去调用onRequestPermissionsResult，再结合RxJava的各种操作符，使用起来就会非常方便。 ### 简单的封装 - 之前也自己封装过一个权限请求的工具类，代码如下

public class LjyPermissionUtil
private PermissionResultListener permissionResultListener;

private LjyPermissionUtil() public static LjyPermissionUtil getInstance() return PermissionUtilHolder.instancePermissionUtil; private static class PermissionUtilHolder private static final LjyPermissionUtil instancePermissionUtil = new LjyPermissionUtil(); /** * 判断当前应用是否有指定权限，运行时权限的检测 */ public boolean hasPermissions(Context context, String[] permissions) if (permissions == null || permissions.length == 0) return true; boolean ifSdk = Build.VERSION.SDK_INT > = Build.VERSION_CODES.JELLY_BEAN; for (String permission : permissions) if (ifSdk & & !hasPermission(context, permission)) return false; return true; private boolean hasPermission(Context context, String permission) return ActivityCompat.checkSelfPermission(context, permission) == PackageManager.PERMISSION_GRANTED; /** * 动态申请指定权限，配合hasPermission使用,注意在使用的activity中调用onRequestPermissionsResult权限申请结果的回调 * * @param activity * @param permissions * @param requestCode */ public void requestPermission(final Activity activity, final String[] permissions, final int requestCode, final PermissionResultListener permissionResultListener) this.permissionResultListener = permissionResultListener; ActivityCompat.requestPermissions(activity, permissions, requestCode); /** * 申请权限的结果回调，需要在Activity的onRequestPermissionsResult中调用 * * @param grantResults */ public void onPermissionResult(Activity activity, final int requestCode, String[] permissions, int[] grantResults) boolean hasPermission = true; List< String> deniedList = new ArrayList< > (); List< String> cancelList = new ArrayList< > (); for (int i = 0; i < grantResults.length; i++) boolean isAllow = grantResults[i] == PackageManager.PERMISSION_GRANTED; hasPermission & = isAllow; if (!isAllow) if (Build.VERSION.SDK_INT < Build.VERSION_CODES.M || !activity.shouldShowRequestPermissionRationale(permissions[i])) deniedList.add(permissions[i]); else cancelList.add(permissions[i]); if (permissionResultListener != null) if (hasPermission) permissionResultListener.onSuccess(requestCode); else if (deniedList.size() > 0) permissionResultListener.onDenied(deniedList); if (cancelList.size() > 0) permissionResultListener.onCancel(cancelList); /** * 权限申请结果的回调接口 */ public interface PermissionResultListener /** * 申请成功 */ void onSuccess(final int requestCode); /** * 拒绝的权限集合(不在弹框提醒) */ void onDenied(@NonNull List< String> deniedList); /** * 取消的权限集合 */ void onCancel(@NonNull List< String> cancelList);

- 使用如下

//baseActivity的onRequestPermissionsResult中
open class BaseActivity : AppCompatActivity()
override fun onRequestPermissionsResult(requestCode: Int, permissions: Array< out String> , grantResults: IntArray)
if (grantResults.isNotEmpty())
LjyPermissionUtil.getInstance().onPermissionResult(this, requestCode, permissions, grantResults)



class PermissionActivity : BaseActivity()
override fun onCreate(savedInstanceState: Bundle?)
super.onCreate(savedInstanceState)
setContentView(R.layout.activity_permission)

fun onBtnClick(view: View) when (view.id) //原生获取运行时权限 R.id.button_perm_1 -> requestPermission()private fun requestPermission() val permissions = arrayOf(Manifest.permission.READ_EXTERNAL_STORAGE, Manifest.permission.CALL_PHONE, Manifest.permission.CAMERA) if (LjyPermissionUtil.getInstance().hasPermissions(this@PermissionActivity, permissions)) printFileName() else val mRequestCode=1002 LjyPermissionUtil.getInstance().requestPermission( this@PermissionActivity, permissions, mRequestCode, object : LjyPermissionUtil.PermissionResultListener override fun onSuccess(requestCode: Int) if (requestCode == mRequestCode) printFileName()override fun onDenied(deniedList: MutableList< String> ) LjyToastUtil.toast(this@PermissionActivity, "权限被拒绝，将导致APP无法正常使用，请前往设置中修改") for (it in deniedList) LjyLogUtil.d("deniedList:$it")override fun onCancel(cancelList: MutableList< String> ) LjyToastUtil.toast(this@PermissionActivity, "取消了权限申请") for (it in cancelList) LjyLogUtil.d("failList:$it"))private fun printFileName() LjyLogUtil.d("操作文件...")

- 倒也勉强能用，但是不够优雅, 一个是入侵了基类BaseActivity，另外写出来的代码看起来也比较繁琐，那么就来参考RxPermission重写一下吧 ### 创建PermissionUtil - 这次我们用kotlin来实现，这样就可以借助其各种语法糖使得代码写起来更优雅一些， #### kotlin单例 - 既然是工具类，那么先来搞个单例吧, 关于kotlin的一些特性和单例的实现方式，以后有时间会单独出一篇文章汇总一下；

class PermissionUtil private constructor() : Serializable //构造器私有化

private fun readResolve(): Any //防止单例对象在反序列化时重新生成对象 return instancecompanion object @JvmStatic //使用lazy属性代理，并指定LazyThreadSafetyMode为SYNCHRONIZED模式保证线程安全 val instance: PermissionUtil by lazy(LazyThreadSafetyMode.SYNCHRONIZED)PermissionUtil()

#### 封装PermissionFragment - 创建一个请求结果的数据类

data class Permission(
var name: String?,
var granted: Boolean,
var shouldShowRequestPermissionRationale: Boolean
)

- 然后我们也来封装一个没有界面的fragment，用来实现真正的权限请求，避免用户再去调用onRequestPermissionsResult，也就不用像上面那样入侵BaseActivity了

class PermissionFragment : Fragment()
private val PERMISSIONS_REQUEST_CODE = 520
var permissions: Array< String> ? = null
var callBack: ((Boolean) -> Unit)? = null

fun removeFragment() val fragmentTransaction: FragmentTransaction = parentFragmentManager.beginTransaction() fragmentTransaction.remove(this).commit()@TargetApi(Build.VERSION_CODES.M) fun requestPermissions(permissions: Array< String?> ) requestPermissions( permissions, PERMISSIONS_REQUEST_CODE )@TargetApi(Build.VERSION_CODES.M) override fun onRequestPermissionsResult( requestCode: Int, permissions: Array< out String> , grantResults: IntArray ) super.onRequestPermissionsResult(requestCode, permissions, grantResults)

#### 使用registerForActivityResult - 如上代码，我们发现requestPermissions和onRequestPermissionsResult已经过时了，点进去看看，提示要有registerForActivityResult替换，代码如下

class PermissionFragment : Fragment()
private lateinit var requestMultiplePermissionsLauncher:
ActivityResultLauncher< Array< String> >
var permissions: Array< String> ? = null
var callBack: ((Boolean) -> Unit)? = null

fun removeFragment() val fragmentTransaction: FragmentTransaction = parentFragmentManager.beginTransaction() fragmentTransaction.remove(this).commit()override fun onAttach(context: Context) super.onAttach(context) requestMultiplePermissionsLauncher = registerForActivityResult(ActivityResultContracts.RequestMultiplePermissions())it -> //通过的权限 val grantedList = it.filterValuesit .mapNotNullit.key //是否所有权限都通过 val allGranted = grantedList.size == it.size val list = (it - grantedList.toSet()).mapit.key //未通过的权限 val deniedList = list.filter ActivityCompat.shouldShowRequestPermissionRationale( requireActivity(), it )//拒绝并且点了“不再询问”权限 val alwaysDeniedList = list - deniedList.toSet() callBack?.invoke(allGranted) removeFragment()if (permissions?.isNotEmpty() == true) requestMultiplePermissionsLauncher.launch(permissions)

#### 使用Flow - 上面基本已经实现了权限请求，不过还可以使用kotlin的flow来进一步优化一下

class PermissionFragment : Fragment()
private lateinit var requestMultiplePermissionsLauncher:
ActivityResultLauncher< Array< String> >
var permissions: Array< String> ? = null
var accept: ((Boolean) -> Unit)? = null
var permissionResult: ((Permission) -> Unit)? = null
var denied: ((String) -> Unit)? = null
var alwaysDenied: ((String) -> Unit)? = null

fun removeFragment() val fragmentTransaction: FragmentTransaction = parentFragmentManager.beginTransaction() fragmentTransaction.remove(this).commit()override fun onAttach(context: Context) super.onAttach(context) requestMultiplePermissionsLauncher = registerForActivityResult(ActivityResultContracts.RequestMultiplePermissions())it -> lifecycleScope.launch //是否所有权限都通过 val allGranted = it.iterator() .asFlow() .flowOn(Dispatchers.Main) .mapit.value .reducea, b -> a & & baccept?.invoke(allGranted) it.iterator() .asFlow() .flowOn(Dispatchers.Main) .onEachentry -> log("所有权限:" + entry.key) permissionResult?.invoke( Permission( entry.key, entry.value, ActivityCompat.shouldShowRequestPermissionRationale( requireActivity(), entry.key ) ) ).filter!it.value .onEachentry -> log("拒绝的权限:" + entry.key) denied?.invoke(entry.key).filter !ActivityCompat.shouldShowRequestPermissionRationale( requireActivity(), it.key ).onEachentry -> log("拒绝并且点了“不再询问”的权限:" + entry.key) alwaysDenied?.invoke(entry.key).collect() if (isAdded) removeFragment()if (permissions?.isNotEmpty() == true) requestMultiplePermissionsLauncher.launch(permissions)

#### 实现PermissionUtil - 已经有了PermissionFragment，接下来就是在PermissionUtil中使用了

class PermissionUtil private constructor() : Serializable

private fun readResolve(): Any return instancecompanion object @JvmStatic val instance: PermissionUtil by lazy(LazyThreadSafetyMode.SYNCHRONIZED)PermissionUtil()

val permissionFragment: PermissionFragment = PermissionFragment()
/**

• 所有权限统一返回结果
  */
  fun permissionsRequest(
  activity: FragmentActivity,
  permissions: Array< String> ,
  accept: (allGranted: Boolean) -> Unit
  )
  permissionFragment.permissions = permissions
  permissionFragment.accept = accept
  val fragmentTransaction = activity.supportFragmentManager.beginTransaction()
  fragmentTransaction.add(permissionFragment, " permissionFragment@LJY" ).commit()
  
  /**
  
• 所有权限统一返回结果 & & getTopActivity
  */
  fun permissionsRequest(permissions: Array< String> , accept: (allGranted: Boolean) -> Unit)
  val context: Activity = ApplicationUtil.instance.getTopActivity()
  ?: throw java.lang.NullPointerException(" Top Activity is Null!" )
  permissionsRequest(context as FragmentActivity, permissions, accept)
  
  /**
  
• 将权限申请结果逐一返回
  */
  fun permissionsRequestEach(
  activity: FragmentActivity,
  permissions: Array< String> ,
  permissionResult: (Permission) -> Unit
  )
  permissionFragment.permissions = permissions
  permissionFragment.permissionResult = permissionResult
  val fragmentTransaction = activity.supportFragmentManager.beginTransaction()
  fragmentTransaction.add(permissionFragment, " permissionFragment@LJY" ).commit()
  
  /**
  
• 将权限申请结果逐一返回 & & getTopActivity
  */
  fun permissionsRequestEach(permissions: Array< String> , permissionResult: (Permission) -> Unit)
  val context: Activity = ApplicationUtil.instance.getTopActivity()
  ?: throw java.lang.NullPointerException(" Top Activity is Null!" )
  permissionsRequestEach(context as FragmentActivity, permissions, permissionResult)
  
  

  #### 使用 PermissionUtil

  
  //所有权限统一返回结果
  permissionsRequest(
  arrayOf(
  Manifest.permission.CAMERA,
  Manifest.permission.SEND_SMS,
  Manifest.permission.CALL_PHONE,
  Manifest.permission.READ_EXTERNAL_STORAGE,
  Manifest.permission.WRITE_EXTERNAL_STORAGE,
  )
  )
  if (it)
  todoSomething()
  else
  Toast.makeText(this, " 我们需要相应的权限，请允许权限申请" , Toast.LENGTH_LONG).show()
  
  
  

【干掉RxJava系列--1. 手写权限请求替代RxPermission】//将权限申请结果逐一返回
permissionsRequestEach(
arrayOf(
Manifest.permission.CAMERA,
Manifest.permission.SEND_SMS,
Manifest.permission.CALL_PHONE,
Manifest.permission.READ_EXTERNAL_STORAGE,
Manifest.permission.WRITE_EXTERNAL_STORAGE,
)
)
when
it.granted ->
// permission.name is granted !
log(" Activity.允许了权限申请:" + it.name);

it.shouldShowRequestPermissionRationale ->
// Denied permission without ask never again
log(" Activity.取消了权限申请:" + it.name);

else ->
// Denied permission with ask never again
// Need to go to the settings
log(" Activity.拒绝并且点了“不再询问”的权限:" + it.name);

- 到此简单的权限请求就封装好了，不过如果用到线上的话还是需要进一步完善的；### 我是今阳，如果想要进阶和了解更多的干货，欢迎关注微信公众号 “今阳说” 接收我的最新文章

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