Cordova插件加载分析

通过cordova plugin add **添加插件，会将插件信息写入config.xml中。

=转换=>
config.xml真实地址 platforms\android\app\src\main\res\config.xml

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CordovaActivity

protected void loadConfig() {
        ConfigXmlParser parser = new ConfigXmlParser();
        parser.parse(this);//解析config.xml中的属性与插件信息（PluginEntery）
        preferences = parser.getPreferences();
        preferences.setPreferencesBundle(getIntent().getExtras());
        launchUrl = parser.getLaunchUrl();
        pluginEntries = parser.getPluginEntries();//获得解析的插件信息（此时还未实例化插件）
        Config.parser = parser;
    }

public void loadUrl(String url) {
        if (appView == null) {
            init();//相关实例化（插件）
        }
        // If keepRunning
        this.keepRunning = preferences.getBoolean("KeepRunning", true);
        appView.loadUrlIntoView(url, true);
    }

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);
        }
    }

ConfigXmlParser

public void parse(Context action) {
        // First checking the class namespace for config.xml
        int id = action.getResources().getIdentifier("config", "xml", action.getClass().getPackage().getName());
        if (id == 0) {
            // If we couldn't find config.xml there, we'll look in the namespace from AndroidManifest.xml
            id = action.getResources().getIdentifier("config", "xml", action.getPackageName());
            if (id == 0) {
                LOG.e(TAG, "res/xml/config.xml is missing!");
                return;
            }
        }
        parse(action.getResources().getXml(id));//加载config.xml并解析
    }

public void parse(XmlPullParser xml) {//解析config.xml中的属性（content ,index ,plugin）
        int eventType = -1;

        while (eventType != XmlPullParser.END_DOCUMENT) {
            if (eventType == XmlPullParser.START_TAG) {
                handleStartTag(xml);//config.xml解析（插件，content）
            }
            else if (eventType == XmlPullParser.END_TAG)
            {
                handleEndTag(xml);
            }
            try {
                eventType = xml.next();
            } catch (XmlPullParserException e) {
                e.printStackTrace();
            } catch (IOException e) {
                e.printStackTrace();
            }
        }
    }

 public void handleStartTag(XmlPullParser xml) {
        String strNode = xml.getName();
        if (strNode.equals("feature")) {//读取到插件标签
            //Check for supported feature sets  aka. plugins (Accelerometer, Geolocation, etc)
            //Set the bit for reading params
            insideFeature = true;
            service = xml.getAttributeValue(null, "name");//获得插件定义的文件名
        }
        else if (insideFeature && strNode.equals("param")) {
            paramType = xml.getAttributeValue(null, "name");
            if (paramType.equals("service")) // check if it is using the older service param
                service = xml.getAttributeValue(null, "value");
            else if (paramType.equals("package") || paramType.equals("android-package"))
                pluginClass = xml.getAttributeValue(null,"value");//获取插件类路径
            else if (paramType.equals("onload"))
                onload = "true".equals(xml.getAttributeValue(null, "value"));//获取插件是否默认加载
        }
    }

public void handleEndTag(XmlPullParser xml) {
        String strNode = xml.getName();
        if (strNode.equals("feature")) {
            //PluginEntry 将插件信息保存在pluginentry中，之后会用到PluginManager进行实例化
            pluginEntries.add(new PluginEntry(service, pluginClass, onload));

            service = "";
            pluginClass = "";
            insideFeature = false;
            onload = false;
        }
    }
//获得解析的插件
public ArrayList getPluginEntries() {
        return pluginEntries;
    }

CordovaWebViewImpl

public void init(CordovaInterface cordova, List pluginEntries, CordovaPreferences preferences) {
        //...
        pluginManager = new PluginManager(this, this.cordova, pluginEntries);
        resourceApi = new CordovaResourceApi(engine.getView().getContext(), pluginManager);
        nativeToJsMessageQueue = new NativeToJsMessageQueue();
        nativeToJsMessageQueue.addBridgeMode(new NativeToJsMessageQueue.NoOpBridgeMode());
        nativeToJsMessageQueue.addBridgeMode(new NativeToJsMessageQueue.LoadUrlBridgeMode(engine, cordova));

        if (preferences.getBoolean("DisallowOverscroll", false)) {
            engine.getView().setOverScrollMode(View.OVER_SCROLL_NEVER);
        }
        engine.init(this, cordova, engineClient, resourceApi, pluginManager, nativeToJsMessageQueue);
        // This isn't enforced by the compiler, so assert here.
        assert engine.getView() instanceof CordovaWebViewEngine.EngineView;

        pluginManager.addService(CoreAndroid.PLUGIN_NAME, "org.apache.cordova.CoreAndroid");
        pluginManager.init();

    }

PluginManager

public void init() {//插件初始化
        LOG.d(TAG, "init()");
        isInitialized = true;
        this.onPause(false);
        this.onDestroy();
        pluginMap.clear();//插件清空
        this.startupPlugins();//插件实例化
    }

private void startupPlugins() {
        for (PluginEntry entry : entryMap.values()) {
            // Add a null entry to for each non-startup plugin to avoid ConcurrentModificationException
            // When iterating plugins.
            if (entry.onload) {
                getPlugin(entry.service);
            } else {
                pluginMap.put(entry.service, null);
            }
        }
    }

public CordovaPlugin getPlugin(String service) {
        CordovaPlugin ret = pluginMap.get(service);
        if (ret == null) {//如果插件未实例化，则进行实例化
            PluginEntry pe = entryMap.get(service);
            if (pe == null) {
                return null;
            }
            if (pe.plugin != null) {
                ret = pe.plugin;
            } else {
                ret = instantiatePlugin(pe.pluginClass);//插件实例化
            }
            ret.privateInitialize(service, ctx, app, app.getPreferences());
            pluginMap.put(service, ret);
        }
        return ret;
    }

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