版权声明：本文为博主原创文章，未经博主允许不得转载。 https://blog.csdn.net/u010479969/article/details/79532235
上一篇文章中介绍了cordova插件初始化流程，本文开始介绍，任何调用到java代码
上文已经介绍到调用
navigator.camera.getPicture(onSuccess, onFail, {
quality: 50,
sourceType: Camera.PictureSourceType.CAMERA,
destinationType: Camera.DestinationType.FILE_URI
});Camera.js
cameraExport.getPicture = function (successCallback, errorCallback, options) {
console.log('takePicture getPicture ')
argscheck.checkArgs('fFO', 'Camera.getPicture', arguments);
options = options || {};
var getValue = argscheck.getValue;
var quality = getValue(options.quality, 50);
var destinationType = getValue(options.destinationType, Camera.DestinationType.FILE_URI);
var sourceType = getValue(options.sourceType, Camera.PictureSourceType.CAMERA);
var targetWidth = getValue(options.targetWidth, -1);
var targetHeight = getValue(options.targetHeight, -1);
var encodingType = getValue(options.encodingType, Camera.EncodingType.JPEG);
var mediaType = getValue(options.mediaType, Camera.MediaType.PICTURE);
var allowEdit = !!options.allowEdit;
var correctOrientation = !!options.correctOrientation;
var saveToPhotoAlbum = !!options.saveToPhotoAlbum;
var popoverOptions = getValue(options.popoverOptions, null);
var cameraDirection = getValue(options.cameraDirection, Camera.Direction.BACK);
var args = [quality, destinationType, sourceType, targetWidth, targetHeight, encodingType,
mediaType, allowEdit, correctOrientation, saveToPhotoAlbum, popoverOptions, cameraDirection];
console.log('takePicture click 3')
exec(successCallback, errorCallback, 'Camera', 'takePicture', args);//关键代码
// XXX: commented out
// return new CameraPopoverHandle();
};
上面引入了exec方法
var exec = require('cordova/exec');
定义实在cordova.js中定义的
function androidExec(success, fail, service, action, args) {
if (bridgeSecret < 0) {
// If we ever catch this firing, we'll need to queue up exec()s
// and fire them once we get a secret. For now, I don't think
// it's possible for exec() to be called since plugins are parsed but
// not run until until after onNativeReady.
throw new Error('exec() called without bridgeSecret');
}
// Set default bridge modes if they have not already been set.
// By default, we use the failsafe, since addJavascriptInterface breaks too often
if (jsToNativeBridgeMode === undefined) {
androidExec.setJsToNativeBridgeMode(jsToNativeModes.JS_OBJECT);
}
// If args is not provided, default to an empty array
args = args || [];
// Process any ArrayBuffers in the args into a string.
for (var i = 0; i < args.length; i++) {
if (utils.typeName(args[i]) == 'ArrayBuffer') {
args[i] = base64.fromArrayBuffer(args[i]);
}
}
var callbackId = service + cordova.callbackId++,
argsJson = JSON.stringify(args);
if (success || fail) {
cordova.callbacks[callbackId] = {success:success, fail:fail};//这个后面有用
}
var msgs = nativeApiProvider.get().exec(bridgeSecret, service, action, callbackId, argsJson);//继续深入代码分析
// If argsJson was received by Java as null, try again with the PROMPT bridge mode.
// This happens in rare circumstances, such as when certain Unicode characters are passed over the bridge on a Galaxy S2. See CB-2666.
if (jsToNativeBridgeMode == jsToNativeModes.JS_OBJECT && msgs === "@Null arguments.") {
androidExec.setJsToNativeBridgeMode(jsToNativeModes.PROMPT);
androidExec(success, fail, service, action, args);
androidExec.setJsToNativeBridgeMode(jsToNativeModes.JS_OBJECT);
} else if (msgs) {
messagesFromNative.push(msgs);
// Always process async to avoid exceptions messing up stack.
nextTick(processMessages);
}
}下面我们看看nativeApiProvider是从哪里来的
define("cordova/android/nativeapiprovider", function(require, exports, module) {
/**
* Exports the ExposedJsApi.java object if available, otherwise exports the PromptBasedNativeApi.
*/
var nativeApi = this._cordovaNative || require('cordova/android/promptbasednativeapi');//这里是关键
var currentApi = nativeApi;
module.exports = {
get: function() { return currentApi; },
setPreferPrompt: function(value) {
currentApi = value ? require('cordova/android/promptbasednativeapi') : nativeApi;
},
// Used only by tests.
set: function(value) {
currentApi = value;
}
};
});看到_cordovaNative这个是和native通信的桥
在SystemWebViewEngine.java中（这里在介绍java端代码的时候，会详细介绍，目前只有一个印象即可）
@SuppressLint("AddJavascriptInterface")
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.addJavascriptInterface(exposedJsApi, "_cordovaNative");//与js建立通信
} @JavascriptInterface
public String exec(int bridgeSecret, String service, String action, String callbackId, String arguments) throws JSONException, IllegalAccessException {
return bridge.jsExec(bridgeSecret, service, action, callbackId, arguments);
}接着调用到CordovaBridge.java中
public String jsExec(int bridgeSecret, String service, String action, String callbackId, String arguments) throws JSONException, IllegalAccessException {
if (!verifySecret("exec()", bridgeSecret)) {
return null;
}
// If the arguments weren't received, send a message back to JS. It will switch bridge modes and try again. See CB-2666.
// We send a message meant specifically for this case. It starts with "@" so no other message can be encoded into the same string.
if (arguments == null) {
return "@Null arguments.";
}
jsMessageQueue.setPaused(true);
try {
// Tell the resourceApi what thread the JS is running on.
CordovaResourceApi.jsThread = Thread.currentThread();
pluginManager.exec(service, action, callbackId, arguments);//到插件管理中心去进行分发
String ret = null;
if (!NativeToJsMessageQueue.DISABLE_EXEC_CHAINING) {
ret = jsMessageQueue.popAndEncode(false);
}
return ret;
} catch (Throwable e) {
e.printStackTrace();
return "";
} finally {
jsMessageQueue.setPaused(false);
}
}PluginManager.java中
public void exec(final String service, final String action, final String callbackId, final String rawArgs) {
LOG.d(TAG, "exec() call stack: " + Log.getStackTraceString(new Throwable()));
CordovaPlugin plugin = getPlugin(service);//获取插件
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;
}
CallbackContext callbackContext = new CallbackContext(callbackId, app);
try {
long pluginStartTime = System.currentTimeMillis();
boolean wasValidAction = plugin.execute(action, rawArgs, callbackContext);//执行插件代码
long duration = System.currentTimeMillis() - pluginStartTime;
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().");
}
if (!wasValidAction) {
PluginResult cr = new PluginResult(PluginResult.Status.INVALID_ACTION);
callbackContext.sendPluginResult(cr);
}
} catch (JSONException e) {
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());
}
}下面以相机插件为例:CameraLauncher.java,后面就是吊起照相机的逻辑
public boolean execute(String action, JSONArray args, CallbackContext callbackContext) throws JSONException {
this.callbackContext = callbackContext;
//Adding an API to CoreAndroid to get the BuildConfigValue
//This allows us to not make this a breaking change to embedding
this.applicationId = (String) BuildHelper.getBuildConfigValue(cordova.getActivity(), "APPLICATION_ID");
this.applicationId = preferences.getString("applicationId", this.applicationId);
if (action.equals("takePicture")) {
this.srcType = CAMERA;
this.destType = FILE_URI;
this.saveToPhotoAlbum = false;
this.targetHeight = 0;
this.targetWidth = 0;
this.encodingType = JPEG;
this.mediaType = PICTURE;
this.mQuality = 50;
//Take the values from the arguments if they're not already defined (this is tricky)
this.destType = args.getInt(1);
this.srcType = args.getInt(2);
this.mQuality = args.getInt(0);
this.targetWidth = args.getInt(3);
this.targetHeight = args.getInt(4);
this.encodingType = args.getInt(5);
this.mediaType = args.getInt(6);
this.allowEdit = args.getBoolean(7);
this.correctOrientation = args.getBoolean(8);
this.saveToPhotoAlbum = args.getBoolean(9);
// If the user specifies a 0 or smaller width/height
// make it -1 so later comparisons succeed
if (this.targetWidth < 1) {
this.targetWidth = -1;
}
if (this.targetHeight < 1) {
this.targetHeight = -1;
}
// We don't return full-quality PNG files. The camera outputs a JPEG
// so requesting it as a PNG provides no actual benefit
if (this.targetHeight == -1 && this.targetWidth == -1 && this.mQuality == 100 &&
!this.correctOrientation && this.encodingType == PNG && this.srcType == CAMERA) {
this.encodingType = JPEG;
}
try {
if (this.srcType == CAMERA) {
this.callTakePicture(destType, encodingType);
}
else if ((this.srcType == PHOTOLIBRARY) || (this.srcType == SAVEDPHOTOALBUM)) {
// FIXME: Stop always requesting the permission
if(!PermissionHelper.hasPermission(this, Manifest.permission.READ_EXTERNAL_STORAGE)) {
PermissionHelper.requestPermission(this, SAVE_TO_ALBUM_SEC, Manifest.permission.READ_EXTERNAL_STORAGE);
} else {
this.getImage(this.srcType, destType, encodingType);
}
}
}
catch (IllegalArgumentException e)
{
callbackContext.error("Illegal Argument Exception");
PluginResult r = new PluginResult(PluginResult.Status.ERROR);
callbackContext.sendPluginResult(r);
return true;
}
PluginResult r = new PluginResult(PluginResult.Status.NO_RESULT);
r.setKeepCallback(true);
callbackContext.sendPluginResult(r);
return true;
}
return false;
}