Android获取浏览器User Agent

获取浏览器User Agent的代码：

       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);

我们来看看getUserAgentString源代码：

 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);
 }

如我获取到自己手机的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

显然它是这样组成的：

首先，web_user_agent的代码为：

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

其中%s为构造的buffer。

对应如下：

4.0.3    Build.VERSION.RELEASE  
U8817 如果Build.VERSION.CODENAME.equal("REL")，哪么值为Build.MODEL
MocorDroid4.0.3  值为Build.ID