从js到native的流程源码补充说明：
事件从js触发到native时，通过注入的对象[SystemExposedJsApi &@JavascriptInterface 注解标记的方法 ]
先初始化native，然后再去loadurl
1.注入native端xml文件中声明的 plugin【xml提供了后续扩展解耦plugin添加的入口】，解析xml并用全局map维护，指定onload为true的先行初始化，其他native端plugin 懒加载
... // CordovaActivity 的onCreate
ArrayList pluginEntity = (ArrayList)getIntent().getSerializableExtra("pluginEntity"); //第一次扩展插件的添加方式
//这里是corodva native插件的懒加载注入入口
loadConfig(pluginEntity);
...
// 加载xml中的native plugin入口
@SuppressWarnings("deprecation")
protected void loadConfig(ArrayList list) {
ConfigXmlParser parser = new ConfigXmlParser();
if (!CollectionUtils.isEmpty(list)) {
parser.setDynamicEntity(list);
}
parser.parse(this);
preferences = parser.getPreferences();
preferences.setPreferencesBundle(getIntent().getExtras());
launchUrl = parser.getLaunchUrl();
//xml 解析得到native xml中声明的 plugin 包装对象map 并在下面loadUrl的 init方法中传递到PluginManager中
pluginEntries = parser.getPluginEntries();
Config.parser = parser;
}
2.初始化webview的方法代理CordovaWebviewImpl以及 反射创建了SystemWebViewEngine[作为真正的webview和代理之间的bridge] ，SystemWebViewEngine 是Webview相关属性设置类
public void loadUrl(String url) {
if (appView == null) {
init();
}
// If keepRunning
this.keepRunning = preferences.getBoolean("KeepRunning", true);
appView.loadUrlIntoView(url, true);
}
//init方法调用到engine 的 init方法, 最后调用到 com.xxx.xxx.engine.SystemWebViewEngine#exposeJsInterface
private static void exposeJsInterface(WebView webView, CordovaBridge bridge) {
if ((Build.VERSION.SDK_INT < Build.VERSION_CODES.JELLY_BEAN_MR1)) {
LOG.i(TAG, "Disabled addJavascriptInterface() bridge since Android version is old.");
// Bug being that Java Strings do not get converted to JS strings automatically.
// This isn't hard to work-around on the JS side, but it's easier to just
// use the prompt bridge instead.
return;
}
SystemExposedJsApi exposedJsApi = new SystemExposedJsApi(bridge);
//webview注入native端 SystemExposedJsApi的对象 ，并以 _cordovaNative为名在js端使用
webView.addJavascriptInterface(exposedJsApi, "_cordovaNative");
}
// com.xxx.xxx.core.CordovaActivity#init 方法提供了子类重写init方法
protected void init() {
appView = makeWebView();
createViews();
if (!appView.isInitialized()) {
appView.init(cordovaInterface, pluginEntries, preferences);
}
cordovaInterface.onCordovaInit(appView.getPluginManager());
// Wire the hardware volume controls to control media if desired.
String volumePref = preferences.getString("DefaultVolumeStream", "");
if ("media".equals(volumePref.toLowerCase(Locale.ENGLISH))) {
setVolumeControlStream(AudioManager.STREAM_MUSIC);
}
}
// ContainerActivity#makeWebView
@Override
protected CordovaWebView makeWebView() {
mSystemWebView = new NormalWebView(this);
mEngine = new SystemWebViewEngine((NormalWebView)mSystemWebView);
mFlWeb.addView((NormalWebView)mSystemWebView);
mCordovaWebView = new CordovaWebViewImpl(mEngine);
mSystemWebView.resetUserAgent( " " + userAgent);
//这里抽象了 IWebview 【便于替换X5Webview等其他扩展WebView的实现】
mSystemWebView.resetWebViewClient(this, mEngine);
//同理在NormalWebview中注入了重写的WebViewClient和 WebChromeClient
mSystemWebView.resetWebChromeClient(this, mEngine);
return mCordovaWebView;
}
//证书校验调用入口
com.xxx.xxx.impl.RedirectSystemWebViewClient#onReceivedSslError
@Override
public void onReceivedSslError(WebView webView, SslErrorHandler handler, SslError sslError) {
// super.onReceivedSslError(webView, handler, sslError); 注释父类实现
//入口封装传入参数确定是否证书校验
if (isCheck()) {
//检验证书颁发机构以及证书的合法性 证书确实是发给指定域名的且为当前设备的根证书所信任
if (SSLChecker.chkMySSLCNCertOCFT(sslError.getCertificate())) {
handler.proceed(); // 如果证书一致，忽略错误
} else {
LogUtil.w("xxx", "onReceivedSslError" + "cancel" + sslError);
handler.cancel();
}
// }
} else {
handler.proceed();
}
if (client != null) {
client.onReceivedSslError();
}
LogUtil.w("xxx", "onReceivedSslError(NormalWebView.java:102)" );
}
});
3.初始化完成后，初始化js 部分 ….. 衔接部分
4.js调用native native响应并产生回调部分
// com.xxx.xxx.core.PluginManager#exec
public void exec(final String service, final String action, final String callbackId, final String rawArgs) {
//懒加载，根据协定传递指定key为service，初始化对应plugin【已初始化则直接取出】
CordovaPlugin plugin = getPlugin(service);
if (plugin == null) {
LOG.d(TAG, "exec() call to unknown plugin: " + service);
// PluginResult cr = new PluginResult(PluginResult.Status.CLASS_NOT_FOUND_EXCEPTION);
// app.sendPluginResult(cr, callbackId);
return;
}
//根据js端生成的callbackId 生成 native端的 CallbackContenxt对象，这个对象是native 回调js端，传递数据的起点
CallbackContext callbackContext = new CallbackContext(callbackId, app);
try {
long pluginStartTime = System.currentTimeMillis();
// 子plugin实现execute的返回值，action对应事件名,这里通过java多态找到CordovaPlugin的子实现类【即service映射的类】并execute
boolean wasValidAction = plugin.execute(action, rawArgs, callbackContext);
long duration = System.currentTimeMillis() - pluginStartTime;
//提示在主线程执行过长时间，建议使用线程池异步
if (duration > SLOW_EXEC_WARNING_THRESHOLD) {
LOG.w(TAG, "THREAD WARNING: exec() call to " + service + "." + action + " blocked the main thread for " + duration + "ms. Plugin should use CordovaInterface.getThreadPool().");
}//无效行为回调
if (!wasValidAction) {
PluginResult cr = new PluginResult(PluginResult.Status.INVALID_ACTION);
callbackContext.sendPluginResult(cr);
}
} catch (JSONException e) {
//异常回调
PluginResult cr = new PluginResult(PluginResult.Status.JSON_EXCEPTION);
callbackContext.sendPluginResult(cr);
} catch (Exception e) {
LOG.e(TAG, "Uncaught exception from plugin", e);
callbackContext.error(e.getMessage());
}
}
//任意CordovaPlugin子类完成事件触发即执行execute后，通过方法传递的 CallbackContext回调
...
public void success(JSONObject message) {
sendPluginResult(new PluginResult(PluginResult.Status.OK, message));
}
...//还有很多其他重载的success方法，可以兼容传递不同类型的数据类型，最终都会在PluginResult中完成封装，转换成最终传递到js的 payload string msg
public void sendPluginResult(PluginResult pluginResult) {
synchronized (this) {
if (finished) {
LOG.w(LOG_TAG, "Attempted to send a second callback for ID: " + callbackId + "\nResult was: " + pluginResult.getMessage());
return;
} else {
//如果执行过一次的事件 【finised 为 true】 下次不会再执行，如果keepcallback则可重复调用执行，回执到js端message process后也不会被移除全局的js callback数组【所以保持了两端的同步keepcallback能力】
finished = !pluginResult.getKeepCallback();
}
}
LogUtil.d("xxx", "sendPluginResult: "+callbackId+"-----"+pluginResult );
webView.sendPluginResult(pluginResult, callbackId);
}
//com.xxx.xxx.core.CordovaWebViewImpl#sendPluginResult
@Override
public void sendPluginResult(PluginResult cr, String callbackId) {
// nativeToJsMessageQueue native生成发送到js端的消息维护类
nativeToJsMessageQueue.addPluginResult(cr, callbackId);
}
public void addPluginResult(PluginResult result, String callbackId) {
if (callbackId == null) {
LogUtil.e(LOG_TAG, "Got plugin result with no callbackId", new Throwable());
return;
}
// Don't send anything if there is no result and there is no need to
// clear the callbacks.
boolean noResult = result.getStatus() == PluginResult.Status.NO_RESULT.ordinal();
boolean keepCallback = result.getKeepCallback();
if (noResult && keepCallback) {
return;
}
// 将PluginResult 和 callbackId 封装成 JsMessage对象 [ JsMessage 是 NativeToJsMessageQueue 的内部类，JsMessage用于生成协议规则message的类]
JsMessage message = new JsMessage(result, callbackId);
if (FORCE_ENCODE_USING_EVAL) {
StringBuilder sb = new StringBuilder(message.calculateEncodedLength() + 50);
message.encodeAsJsMessage(sb);
message = new JsMessage(sb.toString());
}
enqueueMessage(message);
}
private void enqueueMessage(JsMessage message) {
synchronized (this) {
if (activeBridgeMode == null) {
LOG.d(LOG_TAG, "Dropping Native->JS message due to disabled bridge");
return;
}
queue.add(message);
if (!paused) {
activeBridgeMode.onNativeToJsMessageAvailable(this);
}
}
}
@Override
public void onNativeToJsMessageAvailable(final NativeToJsMessageQueue queue) {
cordova.getActivity().runOnUiThread(new Runnable() {
public void run() {
//这里在发送信息到js端前，先处理
String js = queue.popAndEncodeAsJs();
if (js != null) {
//最后调用 webview 的 evaluateJavascript方法，将处理过的带协议规则的信息传递到js端
engine.evaluateJavascript(js, null);
}
}
});
}
}
//完成封装的api方法
public String popAndEncodeAsJs() {
synchronized (this) {
int length = queue.size();
if (length == 0) {
return null;
}
int totalPayloadLen = 0;
int numMessagesToSend = 0;
for (JsMessage message : queue) {
//计算长度
int messageSize = message.calculateEncodedLength() + 50; // overestimate.
//MAX_PAYLOAD_SIZE最大传递信息长度
if (numMessagesToSend > 0 && totalPayloadLen + messageSize > MAX_PAYLOAD_SIZE && MAX_PAYLOAD_SIZE > 0) {
break;
}
totalPayloadLen += messageSize;
numMessagesToSend += 1;
}
boolean willSendAllMessages = numMessagesToSend == queue.size();
StringBuilder sb = new StringBuilder(totalPayloadLen + (willSendAllMessages ? 0 : 100));
// Wrap each statement in a try/finally so that if one throws it does
// not affect the next.
for (int i = 0; i < numMessagesToSend; ++i) {
//从队列中取出第一条JsMessage对象并移除
JsMessage message = queue.removeFirst();
if (willSendAllMessages && (i + 1 == numMessagesToSend)) {
message.encodeAsJsMessage(sb);
} else {
sb.append("try{");
message.encodeAsJsMessage(sb);
sb.append("}finally{");
}
}
if (!willSendAllMessages) {
sb.append("window.setTimeout(function(){cordova.require('cordova/plugin/android/polling').pollOnce();},0);");
}
for (int i = willSendAllMessages ? 1 : 0; i < numMessagesToSend; ++i) {
sb.append('}');
}
String ret = sb.toString();
return ret;
}
}
// 转换成js能够执行的message【并包装回调js端的信息】
void encodeAsJsMessage(StringBuilder sb) {
if (pluginResult == null) {
sb.append(jsPayloadOrCallbackId);
} else {
int status = pluginResult.getStatus();
boolean success = (status == PluginResult.Status.OK.ordinal()) || (status == PluginResult.Status.NO_RESULT.ordinal());
// js端执行 cordova#callbackFromNative 该方法去处理包装的信息
sb.append("cordova.callbackFromNative('")
.append(jsPayloadOrCallbackId)
.append("',")
.append(success)
.append(",")
.append(status)
.append(",[");
switch (pluginResult.getMessageType()) {
case PluginResult.MESSAGE_TYPE_BINARYSTRING:
sb.append("atob('")
.append(pluginResult.getMessage())
.append("')");
break;
case PluginResult.MESSAGE_TYPE_ARRAYBUFFER:
sb.append("cordova.require('cordova/base64').toArrayBuffer('")
.append(pluginResult.getMessage())
.append("')");
break;
default:
sb.append(pluginResult.getMessage());
}
sb.append("],")
.append(pluginResult.getKeepCallback())
.append(");");
}
}
// cordova.callbackFromNative('XXXMessagePlugin1365781441',true,1,["{\"latitude\":31.181945,\"longitude\":121.365825}"],false
//com.xxx.xxx.core.CordovaPlugin#execute(java.lang.String, java.lang.String, com.xxx.xxx.core.CallbackContext)
public boolean execute(String action, String rawArgs, CallbackContext callbackContext) throws JSONException {
JSONArray args = new JSONArray(rawArgs);
return execute(action, args, callbackContext);
}
//com.xxx.xxx.core.CordovaPlugin#execute(java.lang.String, com.xxx.xxx.core.CordovaArgs, com.xxx.xxx.core.CallbackContext)
public boolean execute(String action, CordovaArgs args, CallbackContext callbackContext) throws JSONException {
mMCallbackContext = callbackContext;
return true;
}
//额外添加解耦插件添加方式，xml中声明即可，在androidmanifest合并后，sdk启动时通过appinfo读取mete-data信息
parseManifest(Context context) {
ArrayList pluginList = new ArrayList<>();
try {
ApplicationInfo appInfo = context.getPackageManager().getApplicationInfo(context.getPackageName(), PackageManager.GET_META_DATA);
if (appInfo.metaData!=null) {
for(String key : appInfo.metaData.keySet()) {
if(PLUGIN_MODULE_VALUE.equals(appInfo.metaData.get(key))) {
String service = key.substring(key.lastIndexOf('.')+1);
PluginEntry entry = new PluginEntry(service, key, false);
pluginList.add(entry);
}
}
}
} catch (PackageManager.NameNotFoundException e) {
e.printStackTrace();
}
return pluginList;
}