客戶端、H5註冊
客戶端
在BridgeWebView的初始化方法中,添加了自定義的BridgeWebViewClient,在onPageFinished方法中,去加載WebViewJavascriptBridge.js文件(在assets目錄下):
@Override
public void onPageFinished(WebView view, String url) {
super.onPageFinished(view, url);
if (BridgeWebView.toLoadJs != null) {
BridgeUtil.webViewLoadLocalJs(view, BridgeWebView.toLoadJs);
}
...
}
BridgeUtil # webViewLoadLocalJs:
public static void webViewLoadLocalJs(WebView view, String path){
String jsContent = assetFile2Str(view.getContext(), path);
view.loadUrl("javascript:" + jsContent);
}
H5
var doc = document;
_createQueueReadyIframe(doc);
var readyEvent = doc.createEvent('Events');
readyEvent.initEvent('WebViewJavascriptBridgeReady');
readyEvent.bridge = WebViewJavascriptBridge;
doc.dispatchEvent(readyEvent);
H5端在使用的時候需要檢測是否初始化完畢:
if(window.WebViewJavascriptBridge) {
return callback(WebViewJavascriptBridge);
} else {
document.addEventListener(
'WebViewJavascriptBridgeReady',
function() {
return callback(WebViewJavascriptBridge);
},
false
);
}
Native調用JS
jsBridgeWebview.callHandler(String handlerName, String data, CallBackFunction callBack);
public interface CallBackFunction {
public void onCallBack(String data);
}
callHandler方法中調用doSend方法(參數:方法名; 數據; 回調):
private void doSend(String handlerName, String data, CallBackFunction responseCallback) {
Message m = new Message();
if (!TextUtils.isEmpty(data)) {
m.setData(data);
}
if (responseCallback != null) {
String callbackStr = String.format(BridgeUtil.CALLBACK_ID_FORMAT, ++uniqueId + (BridgeUtil.UNDERLINE_STR + SystemClock.currentThreadTimeMillis()));
responseCallbacks.put(callbackStr, responseCallback);
m.setCallbackId(callbackStr);
}
if (!TextUtils.isEmpty(handlerName)) {
m.setHandlerName(handlerName);
}
queueMessage(m);
}
doSend方法中,將參數封裝到Message對象中(注意這個Message不是Android SDK中的Message,是該開源庫自己封裝的Message);
方法名和數據判空後放入Message對象,單獨看下回調:
生成每個callBack唯一對應的id(其實就是一個固定格式的字符串,用於存儲在Map中的key值):
String callbackStr = String.format(BridgeUtil.CALLBACK_ID_FORMAT, ++uniqueId + (BridgeUtil.UNDERLINE_STR + SystemClock.currentThreadTimeMillis()));
格式:"JAVA_CB_%s" + uniqueId + "_" + 當前時間毫秒值;uniqueId:一個自增的int類型值,默認值爲0;
然後將其放入消息隊列中(List<Message>):
private void queueMessage(Message m) {
if (startupMessage != null) {
startupMessage.add(m);
} else {
dispatchMessage(m);
}
}
走到這裏會看到,startupMessage在直接聲明的時候就初始化了,怎麼會爲空?翻到BridgeWebViewClient類中的onPageFinished方法:
@Override
public void onPageFinished(WebView view, String url) {
...
if (webView.getStartupMessage() != null) {
for (Message m : webView.getStartupMessage()) {
webView.dispatchMessage(m);
}
webView.setStartupMessage(null);
}
}
這裏可以看到,webview內容加載完之後,會遍歷這個startupMessage隊列,去調用BridgeWebView中的dispatchMessage方法,將Message作爲參數,並且將startupMessage隊列置爲null;
dispatchMessage方法:
void dispatchMessage(Message m) {
String messageJson = m.toJson();
//escape special characters for json string
messageJson = messageJson.replaceAll("(\\\\)([^utrn])", "\\\\\\\\$1$2");
messageJson = messageJson.replaceAll("(?<=[^\\\\])(\")", "\\\\\"");
String javascriptCommand = String.format(BridgeUtil.JS_HANDLE_MESSAGE_FROM_JAVA, messageJson);
if (Thread.currentThread() == Looper.getMainLooper().getThread()) {
this.loadUrl(javascriptCommand);
}
}
將Message對象轉爲Json並做一些處理,最終轉爲js命令:
"javascript:WebViewJavascriptBridge._handleMessageFromNative('%s');",參數爲json;
最終在java主線程中調用loadUrl方法,去執行WebViewJavascriptBridge.js中的方法_handleMessageFromNative;
WebViewJavascriptBridge.js
//提供給native調用,receiveMessageQueue 在會在頁面加載完後賦值爲null,所以
function _handleMessageFromNative(messageJSON) {
console.log(messageJSON);
if (receiveMessageQueue && receiveMessageQueue.length > 0) {
receiveMessageQueue.push(messageJSON);
} else {
_dispatchMessageFromNative(messageJSON);
}
}
在webview加載完js,即onPageFinished方法後,receiveMessageQueue被置爲null,所以這裏直接執行了_dispatchMessageFromNative方法;
//提供給native使用,
function _dispatchMessageFromNative(messageJSON) {
setTimeout(function() {
var message = JSON.parse(messageJSON);
var responseCallback;
//java call finished, now need to call js callback function
if (message.responseId) {
responseCallback = responseCallbacks[message.responseId];
if (!responseCallback) {
return;
}
responseCallback(message.responseData);
delete responseCallbacks[message.responseId];
} else {
//直接發送
if (message.callbackId) {
var callbackResponseId = message.callbackId;
responseCallback = function(responseData) {
_doSend({
responseId: callbackResponseId,
responseData: responseData
});
};
}
var handler = WebViewJavascriptBridge._messageHandler;
if (message.handlerName) {
handler = messageHandlers[message.handlerName];
}
//查找指定handler
try {
handler(message.data, responseCallback);
} catch (exception) {
if (typeof console != 'undefined') {
console.log("WebViewJavascriptBridge: WARNING: javascript handler threw.", message, exception);
}
}
}
});
}
(若responseId不爲空,意味着js調用Native並且js有回調,這裏表明Native將js回調需要的數據傳過來了,從回調函數隊列里根據responseId取出回調函數,如果該函數不爲空,執行該回調函數,並移除回調函數隊列裏的該回調函數;)
該方法中,首先將json參數轉爲Message對象;
Native調用Js時沒有responseId,所以直接跳轉到else分支,判斷callbackId,即Native是否需要js返回數據,如果需要,則初始化一個回調函數,裏面調用_doSend方法,將responseId和responseData封裝到message中,放入消息隊列裏;
從messageHandlers中通過handlerName匹配對應的handler(即在Js註冊的時候設置的);執行該方法,參數爲message中的data,即native中傳遞的data,以及上面初始化的回調函數;
這裏結合H5註冊接口說一下:
WebViewJavascriptBridge.registerHandler("functionInJs", function(data, responseCallback) {
...
responseCallback(responseData); // 爲Native返回數據
});
WebViewJavascriptBridge.js #
function registerHandler(handlerName, handler) {
messageHandlers[handlerName] = handler;
}
可以看到這裏在H5頁面中註冊的供Native調用的方法被添加到messageHandlers隊列中,key值爲方法名;所以上面取出的handler即爲該註冊的方法中定義的回調方法;其中data爲Java端傳來的data,responseCallback爲上面初始化的function:
responseCallback = function(responseData) {
_doSend({
responseId: callbackResponseId,
responseData: responseData
});
};
再看一下_doSend方法:
//sendMessage add message, 觸發native處理 sendMessage
function _doSend(message, responseCallback) {
...
sendMessageQueue.push(message);
messagingIframe.src = CUSTOM_PROTOCOL_SCHEME + '://' + QUEUE_HAS_MESSAGE;
}
將message對象存入sendMessageQueue隊列,改變iframe的src屬性,觸發Java端WebViewClient的shouldOverrideUrlLoading方法執行;
src=”yy://__QUEUE_MESSAGE__/”;
其實這裏是相當於Js跟Webview定義了一個協議,協議爲該src,當webview攔截url時,如果是這個已經定義好的協議,則做相應的處理;
回到BridgeWebViewClient類的shouldOverrideUrlLoading方法中:
@Override
public boolean shouldOverrideUrlLoading(WebView view, String url) {
...
if (url.startsWith(BridgeUtil.YY_RETURN_DATA)) { // 如果是返回數據
webView.handlerReturnData(url);
return true;
} else if (url.startsWith(BridgeUtil.YY_OVERRIDE_SCHEMA)) { //
webView.flushMessageQueue();
return true;
} else {
return super.shouldOverrideUrlLoading(view, url);
}
}
攔截1:url是以"yy://return/"開頭的,調用BridgeWebView的handlerReturnData方法,這時是js爲Native端返回數據;
攔截2:url是以"yy://"開頭的,調用BridgeWebView的flushMessageQueue方法,去刷新消息隊列;
這裏由於url是滿足第二條,所以先看flushMessageQueue方法:
BridgeWebView#flushMessageQueue:
void flushMessageQueue() {
if (Thread.currentThread() == Looper.getMainLooper().getThread()) {
loadUrl(BridgeUtil.JS_FETCH_QUEUE_FROM_JAVA, new CallBackFunction() {
@Override
public void onCallBack(String data) {
...
}
});
}
}
該方法要在主線程執行,調用loadUrl方法:
private void loadUrl(String jsUrl, CallBackFunction returnCallback) {
this.loadUrl(jsUrl);
responseCallbacks.put(BridgeUtil.parseFunctionName(jsUrl), returnCallback);
}
JS_FETCH_QUEUE_FROM_JAVA = "javascript:WebViewJavascriptBridge._fetchQueue();"
即調用Js的_fetchQueue方法,將創建的回調對象,以_fetchQueue爲key值存入responseCallbacks中;
觸發Js的_fetchQueue方法去返回數據,在Native去根據回調解析數據做出相應的處理;
WebViewJavascriptBridge.js # _fetchQueue:
// 提供給native調用,該函數作用:獲取sendMessageQueue返回給native,由於android不能直接獲取返回的內容,所以使用url shouldOverrideUrlLoading 的方式返回內容
function _fetchQueue() {
var messageQueueString = JSON.stringify(sendMessageQueue);
sendMessageQueue = [];
//android can't read directly the return data, so we can reload iframe src to communicate with java
messagingIframe.src = CUSTOM_PROTOCOL_SCHEME + '://return/_fetchQueue/' + encodeURIComponent(messageQueueString);
}
在該方法中,首先將js需要回傳給Native的所有數據sendMessageQueue轉爲json,然後觸發Native攔截url處理消息,url = “yy://return/_fetchQueue/returncontent”;
這裏攔截到該url,執行handlerReturnData方法:
BridgeWebView # handlerReturnData:
void handlerReturnData(String url) {
String functionName = BridgeUtil.getFunctionFromReturnUrl(url);
CallBackFunction f = responseCallbacks.get(functionName);
String data = BridgeUtil.getDataFromReturnUrl(url);
if (f != null) {
f.onCallBack(data);
responseCallbacks.remove(functionName);
return;
}
}
從url中獲取js傳來的方法名以及Js傳來的值,從responseCallbacks隊列中根據方法名取出回調函數接口對象(該回調對象是在上面存入的key值爲_fetchQueue的回調對象),如果回調接口對象不爲空,則調用其onCallBack函數將js傳來的數據返回給Native端,將該回調函數對象從responseCallbacks隊列中移除;
這裏的回調即flushMessageQueue方法中在loadUrl中設置的回調函數:
loadUrl(BridgeUtil.JS_FETCH_QUEUE_FROM_JAVA, new CallBackFunction() {
@Override
public void onCallBack(String data) {
// deserializeMessage
List<Message> list = null;
try {
list = Message.toArrayList(data);
} catch (Exception e) {
...
}
... // 判空
for (int i = 0; i < list.size(); i++) {
Message m = list.get(i);
String responseId = m.getResponseId();
// 是否是response
if (!TextUtils.isEmpty(responseId)) {
CallBackFunction function = responseCallbacks.get(responseId);
String responseData = m.getResponseData();
function.onCallBack(responseData);
responseCallbacks.remove(responseId);
} else {
...
}
}
}
});
由於這裏是在js _fetchQueue方法中將整個消息隊列都返回來了,所以需要遍歷Message集合,找到對應需要的那一條;取出responseId,我們要取的消息是帶有responseId的(Native調用了js並需要回調),這個responseId其實就是一開始java需要回調時生成的callbackId,根據這個callbackId從responseCallbacks取出最開始存入的回調對象 並且執行該回調方法,在Native端拿到數據並做相應的處理;
Js調用Native
Native爲Js註冊調用接口:
mBridgeWebView.registerHandler("submitFromWeb", new BridgeHandler() {
@Override
public void handler(String data, final CallBackFunction function) {
...
}
});
BridgeWebView # registerHandler:
public void registerHandler(String handlerName, BridgeHandler handler) {
if (handler != null) {
messageHandlers.put(handlerName, handler);
}
}
註冊供Js調用的接口方法,並設置回調,如果回調不爲空,將回調方法放入messageHandlers隊列中,key值爲定義的方法名;
Js調用接口:
WebViewJavascriptBridge.callHandler('submitFromWeb', data, function(responseData) {
...
});
WebViewJavascriptBridge.js中:
function callHandler(handlerName, data, responseCallback) {
_doSend({
handlerName: handlerName,
data: data
}, responseCallback);
}
返回到WebViewJavascriptBridge # _doSend方法中,將Js端的responseCallback回調函數放入responseCallbacks隊列中,key值爲生成的唯一標識callbackId,併爲message對象設置callbackId,觸發Native端去重載url並攔截;
之後的動作與Native中調Js一樣,shouldOverrideUrlLoading中攔截,執行flushMessageQueue,loadUrl,Js#_fetchQueue方法,生成回調,保存responseCallbacks中,後面繼續執行handlerReturnData,接着看loadUrl中的回調,這次由於js傳來的消息沒有responseId,直接看else分支,即上文中省略號的地方:
if (!TextUtils.isEmpty(responseId)) {
...
} else {
CallBackFunction responseFunction = null;
// if had callbackId
final String callbackId = m.getCallbackId();
if (!TextUtils.isEmpty(callbackId)) {
responseFunction = new CallBackFunction() {
@Override
public void onCallBack(String data) {
Message responseMsg = new Message();
responseMsg.setResponseId(callbackId);
responseMsg.setResponseData(data);
queueMessage(responseMsg);
}
};
} else {
responseFunction = new CallBackFunction() {
@Override
public void onCallBack(String data) {
// do nothing
}
};
}
BridgeHandler handler;
if (!TextUtils.isEmpty(m.getHandlerName())) {
handler = messageHandlers.get(m.getHandlerName());
} else {
handler = defaultHandler;
}
if (handler != null){
handler.handler(m.getData(), responseFunction);
}
}
獲取callbackId,如果爲空,直接默認不做處理;
不爲空則說明Js調用了Native,需要Native回調,創建一個回調函數,最後從消息中取出方法名去匹配Native之前註冊的方法,如果不爲空,則調用該對象的回調方法;
上面Native回調不爲空時創建的回調:
responseFunction = new CallBackFunction() {
@Override
public void onCallBack(String data) {
Message responseMsg = new Message();
responseMsg.setResponseId(callbackId);
responseMsg.setResponseData(data);
queueMessage(responseMsg);
}
};
將要回傳的數據封裝成message,原先從js傳過來的callbackId變成responseId,然後調用queueMessage,dispatchMessage,Js#_handleMessageFromNative,_dispatchMessageFromNative,上文中已分析該方法;