Android 的WebView使用CookieManager崩溃的问题

应用里，如果用户退出登陆了，而WebView里还没有退出登陆，这就有点蛋疼了。所以在用户退出时，要清除WebView的Cookie。但是据说调用CookieManager应用可能会崩溃。

先来看下微信是怎么做的，反编绎了下微信的apk，发现是这样的：

private void a(Activity paramActivity, String[] paramArrayOfString)
{
  Bundle localBundle = new Bundle();
  if (paramArrayOfString.length > 0) {
    localBundle.putString("scope", TextUtils.join(",", paramArrayOfString));
  }
  CookieSyncManager.createInstance(paramActivity);
  a(paramActivity, "oauth", localBundle, new f(this));
}
public final String cl(Context paramContext)
{
  CookieSyncManager.createInstance(paramContext);
  CookieManager.getInstance().removeAllCookie();
  AX(null);

http://blog.csdn.net/shichaosong/article/details/7949580 里面的FackBook的代码的注释提到 CookieSyncManager如果没有创建，就有可能会导致app crash。

 public static void clearCookies(Context context) {
        // Edge case: an illegal state exception is thrown if an instance of
        // CookieSyncManager has not be created.  CookieSyncManager is normally
        // created by a WebKit view, but this might happen if you start the
        // app, restore saved state, and click logout before running a UI
        // dialog in a WebView -- in which case the app crashes
        @SuppressWarnings("unused")
        CookieSyncManager cookieSyncMngr =
            CookieSyncManager.createInstance(context);
        CookieManager cookieManager = CookieManager.getInstance();
        cookieManager.removeAllCookie();
    }