目前在app上通過記錄用戶操作（俗稱埋點(diǎn)），來分析用戶行為的做法，已經(jīng)成了app必不可少的一部分。有關(guān)app的埋點(diǎn)技術(shù)，也在發(fā)展中。正好最近項(xiàng)目組研發(fā)了一個(gè)埋點(diǎn)的sdk，所以把相關(guān)知識梳理下。
埋點(diǎn)方式
-
代碼埋點(diǎn)
這種方式主要是由程序猿們手動(dòng)在代碼中的回調(diào)事件里加上埋點(diǎn)代碼。優(yōu)點(diǎn)是高度定制，想怎么埋怎么埋，缺點(diǎn)是工作量大，而且易出錯(cuò)，難維護(hù)。
-
可視化埋點(diǎn)
這種埋點(diǎn)方式分為兩種，一是使用后臺界面配置需要埋點(diǎn)的位置，app下載配置文件，將需要埋點(diǎn)的事件上傳（代表MixPanel，百度，talkingdata等）。二是app把所有事件上傳，后臺自己選擇需要埋點(diǎn)的點(diǎn)（代表heap）。
兩種埋點(diǎn)方式各有優(yōu)劣，但是由于技術(shù)目前還在發(fā)展中，并沒有形成完全統(tǒng)一的理論以及方式，因此現(xiàn)在大多是這兩種方式并存。
參考文獻(xiàn)： http://blog.csdn.net/vshuang/article/details/60361314
MixPanel源碼分析－Android
下面是分析MixPanel的源碼，這應(yīng)該是唯一的開源的商業(yè)埋點(diǎn)實(shí)現(xiàn)（其他我沒找到），提供可視化埋點(diǎn)以及代碼埋點(diǎn)方式。開源地址：https://github.com/mixpanel ，我主要是研究Android的代碼。
本文的分析并不透徹，主要由于mixpanel的代碼比較復(fù)雜，很多是和服務(wù)器的交互，在不了解協(xié)議的情況下，我也是連蒙帶猜來看源碼的。想透徹分析的同學(xué)，可以在mixpanel的網(wǎng)站上注冊一個(gè)應(yīng)用，再在應(yīng)用里集成mixpanel的源碼，然后加日志或者debug來分析。由于時(shí)間有限，我并沒有這么做。請見諒。
首先是mixpanel的入口，MixPanelApi
該類中有大量的方法叫做Tweak，這個(gè)是用來做abtest的，在服務(wù)器上做相應(yīng)的配置，客戶端可以拉取配置實(shí)現(xiàn)不同的功能。本文不討論這個(gè)。
主要方法就是track，
/**
* Track an event.
*
* <p>Every call to track eventually results in a data point sent to Mixpanel. These data points
* are what are measured, counted, and broken down to create your Mixpanel reports. Events
* have a string name, and an optional set of name/value pairs that describe the properties of
* that event.
*
* @param eventName The name of the event to send
* @param properties A JSONObject containing the key value pairs of the properties to include in this event.
* Pass null if no extra properties exist.
*/
public void track(String eventName, JSONObject properties) {
track(eventName, properties, false);
}
我們通過不停跟蹤代碼發(fā)現(xiàn)，這個(gè)方法會把埋點(diǎn)的event，生成一個(gè)AnalyticsMessages.EventDescription對象，然后通過handler，發(fā)送到后臺線程中去處理，代碼如下
track(){
final AnalyticsMessages.EventDescription eventDescription =
new AnalyticsMessages.EventDescription(eventName, messageProps, mToken, isAutomaticEvent);
mMessages.eventsMessage(eventDescription);
}
// ...跳轉(zhuǎn)至eventsMessage
public void eventsMessage(final EventDescription eventDescription) {
final Message m = Message.obtain();
m.what = ENQUEUE_EVENTS;
m.obj = eventDescription;
mWorker.runMessage(m);
}
//消息處理
if (msg.what == ENQUEUE_EVENTS) {
final EventDescription eventDescription = (EventDescription) msg.obj;
try {
//省略部分代碼
returnCode = mDbAdapter.addJSON(message, token, MPDbAdapter.Table.EVENTS, eventDescription.isAutomatic());
} catch (final JSONException e) {
MPLog.e(LOGTAG, "Exception tracking event " + eventDescription.getEventName(), e);
}
}
可以看到，最終數(shù)據(jù)被存儲到了數(shù)據(jù)庫里，具體的數(shù)據(jù)庫表結(jié)構(gòu)大家可以自行看源碼，我就不研究哦了。
那數(shù)據(jù)什么時(shí)候上傳呢，主要是在activiyt的onPause之后上傳。
@Override
public void onActivityPaused(final Activity activity) {
mPaused = true;
if (check != null) {
mHandler.removeCallbacks(check);
}
mHandler.postDelayed(check = new Runnable(){
@Override
public void run() {
if (mIsForeground && mPaused) {
mIsForeground = false;
try {
double sessionLength = System.currentTimeMillis() - sStartSessionTime;
if (sessionLength >= mConfig.getMinimumSessionDuration() && sessionLength < mConfig.getSessionTimeoutDuration()) {
DecimalFormat df = new DecimalFormat("#.0");
String sessionLengthString = df.format((System.currentTimeMillis() - sStartSessionTime) / 1000);
JSONObject sessionProperties = new JSONObject();
sessionProperties.put(AutomaticEvents.SESSION_LENGTH, sessionLengthString);
mMpInstance.track(AutomaticEvents.SESSION, sessionProperties, true);
}
} catch (JSONException e) {
e.printStackTrace();
}
mMpInstance.flush(); ／／上傳
}
}
}, CHECK_DELAY);
}
用戶也可以通過MixPanelApi的flush方法上傳
public void flush() {
mMessages.postToServer(new AnalyticsMessages.FlushDescription(mToken));
}
這就是事件埋點(diǎn)的基本流程，當(dāng)然功能不止這些，還可以通過activity的生命周期，記錄頁面停留時(shí)長等，這些都是基于這個(gè)基本流程來處理的。
可視化埋點(diǎn)
? 我覺得埋點(diǎn)主要的難點(diǎn)就是在可視化埋點(diǎn)上，如何做到良好的用戶體驗(yàn)以及性能呢。我們一起來看看MixPanel是怎么做的。
首先看一下官網(wǎng)的介紹 https://mixpanel.com/autotrack/
通過視頻可以看到，網(wǎng)頁后臺可以找到我們所有可以埋點(diǎn)的區(qū)域，該區(qū)域會高亮＋邊框顯示出來，點(diǎn)擊該區(qū)域，就會顯示彈出一個(gè)對話框，就可以把這個(gè)區(qū)域射成一個(gè)埋點(diǎn)的位置。
這看起來是不是比代碼埋點(diǎn)好多啦。那服務(wù)器是怎么找到app中可以埋點(diǎn)的位置的呢。我們來看一下源碼，首先是連接上配置界面的地方，是通過websocket連接的，mixpanel繼承了大量websocket的實(shí)現(xiàn)，這里我們就不管他了，感興趣的同學(xué)可以去自己研究下websocket的開源實(shí)現(xiàn)。具體處理協(xié)議的地方是EditorClient這個(gè)類
private class EditorClient extends WebSocketClient {
public EditorClient(URI uri, int connectTimeout, Socket sslSocket) throws InterruptedException {
super(uri, new Draft_17(), null, connectTimeout);
setSocket(sslSocket);
}
@Override
public void onOpen(ServerHandshake handshakedata) {
MPLog.v(LOGTAG, "Websocket connected");
}
@Override
public void onMessage(String message) {
MPLog.v(LOGTAG, "Received message from editor:\n" + message);
try {
final JSONObject messageJson = new JSONObject(message);
final String type = messageJson.getString("type");
if (type.equals("device_info_request")) {
mService.sendDeviceInfo();
} else if (type.equals("snapshot_request")) {
mService.sendSnapshot(messageJson);
} else if (type.equals("change_request")) {
mService.performEdit(messageJson);
} else if (type.equals("event_binding_request")) {
mService.bindEvents(messageJson);
} else if (type.equals("clear_request")) {
mService.clearEdits(messageJson);
} else if (type.equals("tweak_request")) {
mService.setTweaks(messageJson);
}
} catch (final JSONException e) {
MPLog.e(LOGTAG, "Bad JSON received:" + message, e);
}
}
可以看到OnMessage的地方有這么幾個(gè)接口。這些都是后臺web頁面發(fā)過來的消息，然后app端執(zhí)行相應(yīng)的操作。
device_info_request 這個(gè)就不說了，顯然是獲取一些設(shè)備的信息。
snapshot_request 這個(gè)就是關(guān)鍵的地方，這里是app端將當(dāng)前展示的頁面的截圖，發(fā)送給后端，這樣后端就可以顯示出來了。我們通過代碼跟蹤，找到了實(shí)現(xiàn)在ViewCrawler里的sendSnapshot方法。
private void sendSnapshot(JSONObject message) {
final long startSnapshot = System.currentTimeMillis();
//...省略
try {
writer.write("{");
writer.write("\"type\": \"snapshot_response\",");
writer.write("\"payload\": {");
{
writer.write("\"activities\":");
writer.flush();
mSnapshot.snapshots(mEditState, out);
}
final long snapshotTime = System.currentTimeMillis() - startSnapshot;
writer.write(",\"snapshot_time_millis\": ");
writer.write(Long.toString(snapshotTime));
writer.write("}"); // } payload
writer.write("}"); // } whole message
} catch (final IOException e) {
MPLog.e(LOGTAG, "Can't write snapshot request to server", e);
} finally {
try {
writer.close();
} catch (final IOException e) {
MPLog.e(LOGTAG, "Can't close writer.", e);
}
}
}
關(guān)鍵代碼在ViewSnapShot里
/**
* Take a snapshot of each activity in liveActivities. The given UIThreadSet will be accessed
* on the main UI thread, and should contain a set with elements for every activity to be
* snapshotted. Given stream out will be written on the calling thread.
*/
public void snapshots(UIThreadSet<Activity> liveActivities, OutputStream out) throws IOException {
mRootViewFinder.findInActivities(liveActivities);
final FutureTask<List<RootViewInfo>> infoFuture = new FutureTask<List<RootViewInfo>>(mRootViewFinder);
mMainThreadHandler.post(infoFuture);
final OutputStreamWriter writer = new OutputStreamWriter(out);
List<RootViewInfo> infoList = Collections.<RootViewInfo>emptyList();
writer.write("[");
try {
infoList = infoFuture.get(1, TimeUnit.SECONDS);
} catch (final InterruptedException e) {
MPLog.d(LOGTAG, "Screenshot interrupted, no screenshot will be sent.", e);
} catch (final TimeoutException e) {
MPLog.i(LOGTAG, "Screenshot took more than 1 second to be scheduled and executed. No screenshot will be sent.", e);
} catch (final ExecutionException e) {
MPLog.e(LOGTAG, "Exception thrown during screenshot attempt", e);
}
RootViewInfo是一個(gè)Future，主要的方法是taskSnapShot
private void takeScreenshot(final RootViewInfo info) {
final View rootView = info.rootView;
Bitmap rawBitmap = null;
try {
final Method createSnapshot = View.class.getDeclaredMethod("createSnapshot", Bitmap.Config.class, Integer.TYPE, Boolean.TYPE);
createSnapshot.setAccessible(true);
rawBitmap = (Bitmap) createSnapshot.invoke(rootView, Bitmap.Config.RGB_565, Color.WHITE, false);
} catch (final NoSuchMethodException e) {
MPLog.v(LOGTAG, "Can't call createSnapshot, will use drawCache", e);
} catch (final IllegalArgumentException e) {
MPLog.d(LOGTAG, "Can't call createSnapshot with arguments", e);
} catch (final InvocationTargetException e) {
MPLog.e(LOGTAG, "Exception when calling createSnapshot", e);
} catch (final IllegalAccessException e) {
MPLog.e(LOGTAG, "Can't access createSnapshot, using drawCache", e);
} catch (final ClassCastException e) {
MPLog.e(LOGTAG, "createSnapshot didn't return a bitmap?", e);
}
Boolean originalCacheState = null;
try {
if (null == rawBitmap) {
originalCacheState = rootView.isDrawingCacheEnabled();
rootView.setDrawingCacheEnabled(true);
rootView.buildDrawingCache(true);
rawBitmap = rootView.getDrawingCache();
}
} catch (final RuntimeException e) {
MPLog.v(LOGTAG, "Can't take a bitmap snapshot of view " + rootView + ", skipping for now.", e);
}
float scale = 1.0f;
if (null != rawBitmap) {
final int rawDensity = rawBitmap.getDensity();
if (rawDensity != Bitmap.DENSITY_NONE) {
scale = ((float) mClientDensity) / rawDensity;
}
final int rawWidth = rawBitmap.getWidth();
final int rawHeight = rawBitmap.getHeight();
final int destWidth = (int) ((rawBitmap.getWidth() * scale) + 0.5);
final int destHeight = (int) ((rawBitmap.getHeight() * scale) + 0.5);
if (rawWidth > 0 && rawHeight > 0 && destWidth > 0 && destHeight > 0) {
mCachedBitmap.recreate(destWidth, destHeight, mClientDensity, rawBitmap);
}
}
if (null != originalCacheState && !originalCacheState) {
rootView.setDrawingCacheEnabled(false);
}
info.scale = scale;
info.screenshot = mCachedBitmap;
}
這里就知道了，首先通過反射view的createSnapshot方法，嘗試獲取view的截圖，如果沒有成功，則調(diào)用截屏的api，來獲取Drawingcache。獲取到之后，根據(jù)當(dāng)前手機(jī)屏幕的分辨率來縮放一次。保證跟手機(jī)的分辨率一致。再上傳給服務(wù)器，當(dāng)然這里只是屏幕的截圖，只根據(jù)截圖，是無法知道控件點(diǎn)擊位置的。然后又做了什么呢，我們繼續(xù)看代碼：
private void snapshotView(JsonWriter j, View view)
throws IOException {
final int viewId = view.getId();
final String viewIdName;
if (-1 == viewId) {
viewIdName = null;
} else {
viewIdName = mResourceIds.nameForId(viewId);
}
j.beginObject();
j.name("hashCode").value(view.hashCode());
j.name("id").value(viewId);
j.name("mp_id_name").value(viewIdName);
final CharSequence description = view.getContentDescription();
if (null == description) {
j.name("contentDescription").nullValue();
} else {
j.name("contentDescription").value(description.toString());
}
final Object tag = view.getTag();
if (null == tag) {
j.name("tag").nullValue();
} else if (tag instanceof CharSequence) {
j.name("tag").value(tag.toString());
}
j.name("top").value(view.getTop());
j.name("left").value(view.getLeft());
j.name("width").value(view.getWidth());
j.name("height").value(view.getHeight());
j.name("scrollX").value(view.getScrollX());
j.name("scrollY").value(view.getScrollY());
j.name("visibility").value(view.getVisibility());
float translationX = 0;
float translationY = 0;
if (Build.VERSION.SDK_INT >= 11) {
translationX = view.getTranslationX();
translationY = view.getTranslationY();
}
j.name("translationX").value(translationX);
j.name("translationY").value(translationY);
j.name("classes");
j.beginArray();
// ..省略部分
if (view instanceof ViewGroup) {
final ViewGroup group = (ViewGroup) view;
final int childCount = group.getChildCount();
for (int i = 0; i < childCount; i++) {
final View child = group.getChildAt(i);
// child can be null when views are getting disposed.
if (null != child) {
snapshotView(j, child);
}
}
}
}
這里就是關(guān)鍵，通過遍歷當(dāng)前view，將所有的view的信息，都傳給了后端，尤其是top，left，width，height這些信息，通過這些信息，后端就可以確定view的位置。這里我覺得是有優(yōu)化空間的，完全可以只上傳可以被埋點(diǎn)的view，例如button等，像一些純展示的無法點(diǎn)擊的view，其實(shí)沒必要上傳的。例如大部分textview。這樣增加了后端的負(fù)擔(dān)。
當(dāng)在后臺操作，選擇了一個(gè)點(diǎn)擊的view之后，app端就會收到event_binding_request消息，我們來看看如何處理這個(gè)消息的
final int size = mEditorEventBindings.size();
for (int i = 0; i < size; i++) {
final Pair<String, JSONObject> changeInfo = mEditorEventBindings.get(i);
try {
final ViewVisitor visitor = mProtocol.readEventBinding(changeInfo.second, mDynamicEventTracker);
newVisitors.add(new Pair<String, ViewVisitor>(changeInfo.first, visitor));
} catch (final EditProtocol.InapplicableInstructionsException e) {
MPLog.i(LOGTAG, e.getMessage());
} catch (final EditProtocol.BadInstructionsException e) {
MPLog.e(LOGTAG, "Bad editor event binding cannot be applied.", e);
}
}
首先調(diào)用readEventBinding讀取服務(wù)端發(fā)來的信息，然后將它存在一個(gè)ViewVisitor里，想找到具體的view，則需要識別view的一些基本的特征，之前的代碼已經(jīng)看到了，view的id，tag，contentdescription等特征，都已經(jīng)被上傳至服務(wù)器，這時(shí)服務(wù)器又會把它下發(fā)回來，放在path參數(shù)里。
// Package access FOR TESTING ONLY
/* package */ List<Pathfinder.PathElement> readPath(JSONArray pathDesc, ResourceIds idNameToId) throws JSONException {
final List<Pathfinder.PathElement> path = new ArrayList<Pathfinder.PathElement>();
for (int i = 0; i < pathDesc.length(); i++) {
final JSONObject targetView = pathDesc.getJSONObject(i);
final String prefixCode = JSONUtils.optionalStringKey(targetView, "prefix");
final String targetViewClass = JSONUtils.optionalStringKey(targetView, "view_class");
final int targetIndex = targetView.optInt("index", -1);
final String targetDescription = JSONUtils.optionalStringKey(targetView, "contentDescription");
final int targetExplicitId = targetView.optInt("id", -1);
final String targetIdName = JSONUtils.optionalStringKey(targetView, "mp_id_name");
final String targetTag = JSONUtils.optionalStringKey(targetView, "tag");
final int prefix;
if ("shortest".equals(prefixCode)) {
prefix = Pathfinder.PathElement.SHORTEST_PREFIX;
} else if (null == prefixCode) {
prefix = Pathfinder.PathElement.ZERO_LENGTH_PREFIX;
} else {
MPLog.w(LOGTAG, "Unrecognized prefix type \"" + prefixCode + "\". No views will be matched");
return NEVER_MATCH_PATH;
}
final int targetId;
final Integer targetIdOrNull = reconcileIds(targetExplicitId, targetIdName, idNameToId);
if (null == targetIdOrNull) {
return NEVER_MATCH_PATH;
} else {
targetId = targetIdOrNull.intValue();
}
path.add(new Pathfinder.PathElement(prefix, targetViewClass, targetIndex, targetId, targetDescription, targetTag));
}
return path;
}
通過這些參數(shù)，就可以找個(gè)那個(gè)view，繼而對view進(jìn)行監(jiān)聽，監(jiān)聽的方式就比較簡單了，用谷歌提供的Accessibility相關(guān)api就可以做到。
if ("click".equals(eventType)) {
return new ViewVisitor.AddAccessibilityEventVisitor(
path,
AccessibilityEvent.TYPE_VIEW_CLICKED,
eventName,
listener
);
} else if ("selected".equals(eventType)) {
return new ViewVisitor.AddAccessibilityEventVisitor(
path,
AccessibilityEvent.TYPE_VIEW_SELECTED,
eventName,
listener
);
} else if ("text_changed".equals(eventType)) {
return new ViewVisitor.AddTextChangeListener(path, eventName, listener);
} else if ("detected".equals(eventType)) {
return new ViewVisitor.ViewDetectorVisitor(path, eventName, listener);
} else {
throw new BadInstructionsException("Mixpanel can't track event type \"" + eventType + "\"");
}
而匹配view的規(guī)則也很簡單,就是對比class，id，contentDescription，tag四個(gè)元素
private boolean matches(PathElement matchElement, View subject) {
if (null != matchElement.viewClassName &&
!hasClassName(subject, matchElement.viewClassName)) {
return false;
}
if (-1 != matchElement.viewId && subject.getId() != matchElement.viewId) {
return false;
}
if (null != matchElement.contentDescription &&
!matchElement.contentDescription.equals(subject.getContentDescription())) {
return false;
}
final String matchTag = matchElement.tag;
if (null != matchElement.tag) {
final Object subjectTag = subject.getTag();
if (null == subjectTag || !matchTag.equals(subject.getTag().toString())) {
return false;
}
}
return true;
}
這樣，在每次app的activity的onresume方法里，都會去做這個(gè)尋找匹配的view的過程，具體看viewcrawler的onActivityResume方法
@Override //ViewCrawler.class
public void onActivityResumed(Activity activity) {
installConnectionSensor(activity);
mEditState.add(activity);
}
//通過一系列處理，最終調(diào)用了visit方法
/**
* Scans the View hierarchy below rootView, applying it's operation to each matching child view.
*/
public void visit(View rootView) {
Log.d(LOGTAG, mPath.get(0).toString());
mPathfinder.findTargetsInRoot(rootView, mPath, this);
}
這種做法的效率暫且不停，到這里我們的流程就分析完了。大致的流程就是
App端 上傳屏幕截圖和頁面布局信息－》服務(wù)端操作之后，下發(fā)需要埋點(diǎn)的viewpath －》 app端存儲這個(gè)path，并在每個(gè)activity的onResume都去執(zhí)行尋找path的任務(wù)－》注冊Accessibility監(jiān)聽，上傳相應(yīng)事件。
這樣就實(shí)現(xiàn)了可視化埋點(diǎn)，但是這種方式，應(yīng)該是用于已經(jīng)發(fā)布到線上的app的埋點(diǎn)，而且不同版本不通用。。。因?yàn)関iew的id等信息是會隨著版本變化的。如果這里有錯(cuò)誤，請大神指出。不勝感激，謝謝??！
