Android獲取瀏覽器User Agent

獲取瀏覽器User Agent的代碼：

        WebView webview;
		webview = new WebView(this);
		webview.layout(0, 0, 0, 0);
		WebSettings settings = webview.getSettings();
		String ua = settings.getUserAgentString();
		Log.e("HJJ", "User Agent:" + ua);

我們來看看getUserAgentString源代碼：

    public synchronized String getUserAgentString() {
        if (DESKTOP_USERAGENT.equals(mUserAgent) ||
                IPHONE_USERAGENT.equals(mUserAgent) ||
                !mUseDefaultUserAgent) {
            return mUserAgent;
        }

        boolean doPostSync = false;
        synchronized(sLockForLocaleSettings) {
            Locale currentLocale = Locale.getDefault();
            if (!sLocale.equals(currentLocale)) {
                sLocale = currentLocale;
                mUserAgent = getCurrentUserAgent();
                mAcceptLanguage = getCurrentAcceptLanguage();
                doPostSync = true;
            }
        }
        if (doPostSync) {
            postSync();
        }
        return mUserAgent;
    }

    private synchronized String getCurrentUserAgent() {
        Locale locale;
        synchronized(sLockForLocaleSettings) {
            locale = sLocale;
        }
        StringBuffer buffer = new StringBuffer();
        // Add version
        final String version = Build.VERSION.RELEASE;
        if (version.length() > 0) {
            buffer.append(version);
        } else {
            // default to "1.0"
            buffer.append("1.0");
        }  
        buffer.append("; ");
        final String language = locale.getLanguage();
        if (language != null) {
            buffer.append(language.toLowerCase());
            final String country = locale.getCountry();
            if (country != null) {
                buffer.append("-");
                buffer.append(country.toLowerCase());
            }
        } else {
            // default to "en"
            buffer.append("en");
        }
        // add the model for the release build
        if ("REL".equals(Build.VERSION.CODENAME)) {
            final String model = Build.MODEL;
            if (model.length() > 0) {
                buffer.append("; ");
                buffer.append(model);
            }
        }
        final String id = Build.ID;
        if (id.length() > 0) {
            buffer.append(" Build/");
            buffer.append(id);
        }
        final String base = mContext.getResources().getText(
                com.android.internal.R.string.web_user_agent).toString();
        return String.format(base, buffer);
    }

如我獲取到自己手機的UA如下：

Mozilla/5.0 (Linux; U; Android 4.0.3; zh-cn; U8817 Build/MocorDroid4.0.3) AppleWebKit/533.1 (KHTML, like Gecko) Version/4.0 Mobile Safari/533.1

顯然它是這樣組成的：

首先，web_user_agent的代碼爲：

Mozilla/5.0 (Linux; U; Android %s) AppleWebKit/533.1 (KHTML, like Gecko) Version/4.0 Mobile Safari/533.1

其中%s爲構造的buffer。

對應如下：

4.0.3    Build.VERSION.RELEASE  
U8817 如果Build.VERSION.CODENAME.equal("REL")，哪麼值爲Build.MODEL
MocorDroid4.0.3  值爲Build.ID