Activity管理

前言

你是否有如下需求：

• finish所有Activity，然后start一个新的Activity
• 想某些Activity不被finish，其它的Activity都被销毁
• 判断当前app是否处于前台
• 获取当前栈顶Activity

如果有的话，那么恭喜你，找到宝了！

Kotlin版本

import android.app.Activity
import android.app.Application
import android.os.Bundle
import androidx.annotation.NonNull
import androidx.collection.arrayMapOf

/**
 *    author : A Lonely Cat
 *    github : https://github.com/anjiemo
 *    gitee  : https://gitee.com/anjiemo
 *    time   : 2021/6/18
 *    desc   : Activity 管理类
 */
object ActivityManager : Application.ActivityLifecycleCallbacks {

    private lateinit var mApplication: Application

    private val mActivityTaskMap = arrayMapOf<String, Activity>()

    // 最后可见 Activity 对象的 TAG
    private var mLastVisibleTag: String? = null

    // 最后不可见 Activity 对象的 TAG
    private var mLastInvisibleTag: String? = null

    /**
     * 初始化，仅第一次有效
     */
    fun init(application: Application) {
        if (::mApplication.isInitialized.not()) {
            mApplication = application
            application.registerActivityLifecycleCallbacks(this)
        }
    }

    /**
     * 获取 Application 对象
     */
    fun getApplication() = mApplication

    /**
     * 最后一个可见的Activity和最后一个不可见的Activity不是同一个（换言之：是同一个 Activity，app则未处于前台），或栈顶 Activity不为null，则app处于前台
     *
     */
    fun appIsForeground() =
        ((mLastVisibleTag == mLastInvisibleTag).not() || getStackTopActivity() != null)

    /**
     * 获取在栈顶的 Activity
     */
    fun getStackTopActivity() = mActivityTaskMap[mLastVisibleTag]

    /**
     * 销毁所有 Activity
     */
    fun finishAllActivities() {
        finishAllActivities(null)
    }

    /**
     * 销毁除了参数列表中以外的所有 Activity
     */
    fun finishAllActivities(vararg clazzArray: Class<out Activity>?) {
        val keys: Array<String> = mActivityTaskMap.keys.toTypedArray()
        for (key in keys) {
            val activity: Activity? = mActivityTaskMap[key]
            activity ?: continue
            if (activity.isFinishing.not()) {
                var isWhitelistActivity = false
                for (clazz in clazzArray) {
                    if (activity.javaClass == clazz) {
                        isWhitelistActivity = true
                    }
                }
                // 如果不是白名单上面的 Activity 就销毁掉
                if (!isWhitelistActivity) {
                    activity.finish()
                    mActivityTaskMap.remove(key)
                }
            }
        }
    }

    override fun onActivityCreated(activity: Activity, savedInstanceState: Bundle?) {
        setLastVisibleTag(activity)
        mActivityTaskMap[mLastVisibleTag] = activity
    }

    override fun onActivityStarted(activity: Activity) {
        setLastVisibleTag(activity)
    }

    override fun onActivityResumed(activity: Activity) {
        setLastVisibleTag(activity)
    }

    override fun onActivityPaused(activity: Activity) {
        setLastInvisibleTag(activity)
    }

    override fun onActivityStopped(activity: Activity) {
        setLastInvisibleTag(activity)
    }

    override fun onActivitySaveInstanceState(activity: Activity, outState: Bundle) {}

    override fun onActivityDestroyed(activity: Activity) {
        val objectTag = getObjectTag(activity)
        mActivityTaskMap.remove(objectTag)
        if (objectTag == mLastVisibleTag) {
            // 清除当前标记
            mLastVisibleTag = null
        }
    }

    private fun setLastInvisibleTag(activity: Activity) {
        mLastInvisibleTag = getObjectTag(activity)
    }

    private fun setLastVisibleTag(activity: Activity) {
        mLastVisibleTag = getObjectTag(activity)
    }

    /**
     * 对象所在的包名 + 对象的内存地址
     */
    private fun getObjectTag(@NonNull any: Any): String =
        any::class.java.name + Integer.toHexString(any.hashCode())
}

Java版本

/**
 *    author : Android 轮子哥
 *    github : https://github.com/getActivity/AndroidProject
 *    time   : 2018/11/18
 *    desc   : Activity 管理类
 */
public final class ActivityManager implements Application.ActivityLifecycleCallbacks {

    private static volatile ActivityManager sInstance;

    private final ArrayMap<String, Activity> mActivitySet = new ArrayMap<>();

    /** 当前应用上下文对象 */
    private Application mApplication;
    /** 最后一个可见的 Activity 对象标记 */
    private String mLastVisibleTag;
    /** 最后一个不可见的 Activity 对象标记 */
    private String mLastInvisibleTag;


    private ActivityManager() {}

    public static ActivityManager getInstance() {
        // 加入双重校验锁
        if(sInstance == null) {
            synchronized (ActivityManager.class) {
                if(sInstance == null){
                    sInstance = new ActivityManager();
                }
            }
        }
        return sInstance;
    }

    public void init(Application application) {
        mApplication = application;
        application.registerActivityLifecycleCallbacks(this);
    }

    /**
     * 获取 Application 对象
     */
    public Application getApplication() {
        return mApplication;
    }

    /**
     * 获取栈顶的 Activity
     */
    public Activity getTopActivity() {
        return mActivitySet.get(mLastVisibleTag);
    }

    /**
     * 判断当前应用是否处于前台状态
     *
     * @return appIsForeground
     */
    public Boolean appIsForeground() {
        // 最后一个可见的Activity和最后一个不可见的Activity是同一个，则app未处于前台
        if (mLastVisibleTag.equals(mLastInvisibleTag)) {
            return false;
        }
        return getTopActivity() != null;
    }

    /**
     * 销毁所有的 Activity
     */
    public void finishAllActivities() {
        finishAllActivities((Class<? extends Activity>) null);
    }

    /**
     * 销毁所有的 Activity，除这些 Class 之外的 Activity
     */
    @SafeVarargs
    public final void finishAllActivities(Class<? extends Activity>... classArray) {
        String[] keys = mActivitySet.keySet().toArray(new String[]{});
        for (String key : keys) {
            Activity activity = mActivitySet.get(key);
            if (activity != null && !activity.isFinishing()) {
                boolean whiteClazz = false;
                if (classArray != null) {
                    for (Class<? extends Activity> clazz : classArray) {
                        if (activity.getClass() == clazz) {
                            whiteClazz = true;
                        }
                    }
                }
                // 如果不是白名单上面的 Activity 就销毁掉
                if (!whiteClazz) {
                    activity.finish();
                    mActivitySet.remove(key);
                }
            }
        }
    }

    /**
     * 获取一个对象的独立无二的标记
     */
    private static String getObjectTag(Object object) {
        // 对象所在的包名 + 对象的内存地址
        return object.getClass().getName() + Integer.toHexString(object.hashCode());
    }

    @Override
    public void onActivityCreated(@NonNull Activity activity, @Nullable Bundle savedInstanceState) {
        mLastVisibleTag = getObjectTag(activity);
        mActivitySet.put(getObjectTag(activity), activity);
    }

    @Override
    public void onActivityStarted(@NonNull Activity activity) {
        mLastVisibleTag = getObjectTag(activity);
    }

    @Override
    public void onActivityResumed(@NonNull Activity activity) {
        mLastVisibleTag = getObjectTag(activity);
    }

    @Override
    public void onActivityPaused(@NonNull Activity activity) {
        mLastInvisibleTag = getObjectTag(activity);
    }

    @Override
    public void onActivityStopped(@NonNull Activity activity) {
        mLastInvisibleTag = getObjectTag(activity);
    }

    @Override
    public void onActivitySaveInstanceState(@NonNull Activity activity, @NonNull Bundle outState) {}

    @Override
    public void onActivityDestroyed(@NonNull Activity activity) {
        mActivitySet.remove(getObjectTag(activity));
        if (getObjectTag(activity).equals(mLastVisibleTag)) {
            // 清除当前标记
            mLastVisibleTag = null;
        }
    }
}

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