feat: 添加前后台状态变化监听

lib_base/src/main/java/com/quyunshuo/androidbaseframemvvm/base/app/ActivityLifecycleCallbacksImpl.kt

@@ -5,6 +5,7 @@ import android.app.Application
 import android.os.Bundle
 import android.util.Log
 import com.quyunshuo.androidbaseframemvvm.base.utils.ActivityStackManager
+import com.quyunshuo.androidbaseframemvvm.base.utils.ForegroundBackgroundHelper
 
 /**
  * Activity生命周期监听
@@ -23,6 +24,7 @@ class ActivityLifecycleCallbacksImpl : Application.ActivityLifecycleCallbacks {
 
     override fun onActivityStarted(activity: Activity) {
         Log.e(TAG, "${activity.javaClass.simpleName} --> onActivityStarted")
+        ForegroundBackgroundHelper.onActivityStarted()
     }
 
     override fun onActivityResumed(activity: Activity) {
@@ -35,6 +37,7 @@ class ActivityLifecycleCallbacksImpl : Application.ActivityLifecycleCallbacks {
 
     override fun onActivityStopped(activity: Activity) {
         Log.e(TAG, "${activity.javaClass.simpleName} --> onActivityStopped")
+        ForegroundBackgroundHelper.onActivityStopped()
     }
 
     override fun onActivitySaveInstanceState(activity: Activity, outState: Bundle) {

lib_base/src/main/java/com/quyunshuo/androidbaseframemvvm/base/utils/ForegroundBackgroundHelper.kt

@@ -0,0 +1,84 @@
+package com.quyunshuo.androidbaseframemvvm.base.utils
+
+/**
+ * 前后台切换帮助类，该类实现了前后台监听以及支持注册变化响应监听
+ *
+ * @see ForegroundBackgroundObserver
+ * @see ForegroundBackgroundSubject
+ *
+ * @author Qu Yunshuo
+ * @since 2023/5/31 14:22
+ */
+object ForegroundBackgroundHelper : ForegroundBackgroundSubject {
+
+    private var mActivityStartCount = 0
+
+    private var mIsForeground = false
+
+    private val mObservers = mutableListOf<ForegroundBackgroundObserver>()
+
+    fun onActivityStarted() {
+        mActivityStartCount++
+        if (mActivityStartCount == 1) {
+            mIsForeground = true
+            notifyObservers()
+        }
+    }
+
+    fun onActivityStopped() {
+        mActivityStartCount--
+        if (mActivityStartCount == 0) {
+            mIsForeground = false
+            notifyObservers()
+        }
+    }
+
+    /**
+     * 通知所有订阅者状态变化
+     */
+    override fun notifyObservers() {
+        mObservers.forEach {
+            it.foregroundBackgroundNotify(mIsForeground)
+        }
+    }
+
+    /**
+     * 添加订阅者
+     *
+     * @param observer ForegroundBackgroundObserver
+     */
+    override fun addObserve(observer: ForegroundBackgroundObserver) {
+        mObservers.add(observer)
+    }
+
+    /**
+     * 移除订阅者
+     *
+     * @param observer ForegroundBackgroundObserver
+     */
+    override fun removeObserver(observer: ForegroundBackgroundObserver) {
+        mObservers.remove(observer)
+    }
+}
+
+/**
+ * 订阅者需要实现的接口
+ *
+ * @author Qu Yunshuo
+ * @since 2023/5/31 14:23
+ */
+interface ForegroundBackgroundObserver {
+    fun foregroundBackgroundNotify(isForeground: Boolean)
+}
+
+/**
+ * 被观察者抽象主题
+ *
+ * @author Qu Yunshuo
+ * @since 2023/5/31 14:24
+ */
+interface ForegroundBackgroundSubject {
+    fun notifyObservers()
+    fun addObserve(observer: ForegroundBackgroundObserver)
+    fun removeObserver(observer: ForegroundBackgroundObserver)
+}