private CommonsHttpOAuthConsumer httpOauthConsumer;   这里的类和下面的类 怎么导入oauth.signpost的这个包呢??
    private OAuthProvider httpOauthprovider;
    public String consumerKey;
    public String consumerSecret;
    
    public OAuth()
    {    
        // 第一组:(App Key和App Secret)
        // 这组参数就是本系列文本第一篇提到的建一个新的应用获取App Key和App Secret。
        this("3315495489","e2731e7grf592c0fd7fea32406f86e1b");
    }
    public OAuth(String consumerKey,String consumerSecret)
    {
        this.consumerKey=consumerKey;
        this.consumerSecret=consumerSecret;
    }
    
    public Boolean RequestAccessToken(Activity activity,String callBackUrl){
        Boolean ret=false;
        try{
            httpOauthConsumer = new CommonsHttpOAuthConsumer(consumerKey,consumerSecret);
            httpOauthprovider = new DefaultOAuthProvider("http://api.t.sina.com.cn/oauth/request_token","http://api.t.sina.com.cn/oauth/access_token","http://api.t.sina.com.cn/oauth/authorize");
            String authUrl = httpOauthprovider.retrieveRequestToken(httpOauthConsumer, callBackUrl);
            activity.startActivity(new Intent(Intent.ACTION_VIEW, Uri.parse(authUrl)));
            ret=true;
        }catch(Exception e){
        }
        return ret;
    }