0. 前言

一般的Android應(yīng)用只是對(duì)Crash進(jìn)行捕捉旭旭。而Sunzxyong大神的Recovery框架，能做到對(duì)Crash進(jìn)行捕捉并自動(dòng)恢復(fù)玉转。大大地提高APP的用戶體驗(yàn)芍耘。

本文意在分析Recovery框架的三個(gè)關(guān)鍵點(diǎn)，讓大家了解其實(shí)現(xiàn)原理队寇。

Github地址：https://github.com/Sunzxyong/Recovery

1. 捕獲異常

通過(guò)實(shí)現(xiàn)并注冊(cè)接口 Thread.UncaughtExceptionHandler，處理沒(méi)有被try-catch捕獲的異常章姓。

public class MyCrashHandler implements Thread.UncaughtExceptionHandler {

    @Override
    public void uncaughtException(Thread t, Throwable e) {
        // 處理異常：打印異常信息佳遣，恢復(fù)Activity棧
    }

    // 在外部調(diào)用，注冊(cè)異常捕捉
    public static void register() {
        Thread.setDefaultUncaughtExceptionHandler(new MyCrashHandler());
    }
}

2. 維護(hù)私有的Activity棧

通過(guò)在Application里調(diào)用registerActivityLifecycleCallbacks()進(jìn)行注冊(cè)凡伊，監(jiān)聽(tīng)Activity的創(chuàng)建和銷毀零渐，自己維護(hù)一個(gè)Activity的棧。使用要求：API 14+

public class RecoveryActivityLifecycleCallback implements Application.ActivityLifecycleCallbacks {

    @Override
    public void onActivityCreated(final Activity activity, Bundle savedInstanceState) {
    }

    @Override
    public void onActivityStarted(final Activity activity) {
        .... 省略一些判斷 .....

        Window window = activity.getWindow();
        if (window != null) {
            View decorView = window.getDecorView();
            if (decorView == null)
                return;
            decorView.post(new Runnable() {
                @Override
                public void run() {
                     // Activity進(jìn)棧
                    RecoveryStore.getInstance().putActivity(activity);
                    Object o = activity.getIntent().clone();
                    RecoveryStore.getInstance().setIntent((Intent) o);
                }
            });
        }
    }

    @Override
    public void onActivityResumed(Activity activity) {
    }

    @Override
    public void onActivityPaused(Activity activity) {
    }

    @Override
    public void onActivityStopped(Activity activity) {
    }

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

    }

    @Override
    public void onActivityDestroyed(Activity activity) {
        // Activity出棧
        RecoveryStore.getInstance().removeActivity(activity);
    }

}

注冊(cè)全局的Activity監(jiān)聽(tīng)

((Application) mContext).registerActivityLifecycleCallbacks(new RecoveryActivityLifecycleCallback());

3. 恢復(fù)Activity棧

崩潰時(shí)系忙，通過(guò)startActivities()來(lái)啟動(dòng)多個(gè)Activity诵盼，從而恢復(fù)Activity棧

    private void recoverActivityStack() {
        ArrayList<Intent> intents = getRecoveryIntents();
        if (intents != null && !intents.isEmpty()) {
            ArrayList<Intent> availableIntents = new ArrayList<>();
            for (Intent tmp : intents) {
                if (tmp != null && RecoveryUtil.isIntentAvailable(this, tmp)) {
                    tmp.setExtrasClassLoader(getClassLoader());
                    availableIntents.add(tmp);
                }
            }
            if (!availableIntents.isEmpty()) {
                availableIntents.get(0).addFlags(Intent.FLAG_ACTIVITY_NEW_TASK | Intent.FLAG_ACTIVITY_CLEAR_TASK);
                availableIntents.get(availableIntents.size() - 1).putExtra(RECOVERY_MODE_ACTIVE, true);
                startActivities(availableIntents.toArray(new Intent[availableIntents.size()]));
                overridePendingTransition(0, 0);
                finish();
                return;
            }
        }
        restart();
    }

4. 存在的問(wèn)題

在多進(jìn)程并共用同一個(gè)任務(wù)棧的APP中，因?yàn)槊總€(gè)進(jìn)程內(nèi)存都是獨(dú)立的银还，無(wú)法把不同進(jìn)程的Activity放到同一個(gè)List里风宁。所以在恢復(fù)Activity任務(wù)棧時(shí)會(huì)出現(xiàn)問(wèn)題。

解決方法：對(duì)Activty棧使用本地文件來(lái)保存蛹疯，實(shí)現(xiàn)跨進(jìn)程共享戒财。