新浪微博SDK的一些问题，望懂的人帮下忙解答下。感激不尽！


                         Weibo weibo = Weibo.getInstance();
                         weibo.setupConsumerConfig(CONSUMER_KEY, CONSUMER_SECRET);                         // Oauth2.0
                         // 隐式授权认证方式
                         weibo.setRedirectUrl("https://api.weibo.com/oauth2/default.html");
                         // 此处回调页内容应该替换为与appkey对应的应用回调页
                         // 对应的应用回调页可在开发者登陆新浪微博开发平台之后，
                         // 进入我的应用--应用详情--应用信息--高级信息--授权设置--应用回调页进行设置和查看，
                         // 应用回调页不可为空                         weibo.authorize(AuthorizeActivity.this,new AuthDialogListener());                         // try {
                         //  Oauth2.0 认证方式
                         // Weibo.setSERVER("https://api.weibo.com/2/");
                         // Oauth2AccessToken at =weibo.getOauth2AccessToken(AuthorizeActivity.this,Weibo.getAppKey(), Weibo.getAppSecret(), username,password);
                         
                         // // xauth认证方式
                         // * Weibo.setSERVER("http://api.t.sina.com.cn/");
                         // * AccessToken at =
                         // * weibo.getXauthAccessToken(TextActivity.this,
                         // * Weibo.APP_KEY, Weibo.APP_SECRET, "", "");
                         // * mToken.setText(at.getToken());
                         // */
                         // RequestToken requestToken =
                         // weibo.getRequestToken(AuthorizeActivity.this,
                         // Weibo.getAppKey(), Weibo.getAppSecret(),
                         // AuthorizeActivity.URL_ACTIVITY_CALLBACK);
                         // mToken.setText(requestToken.getToken());
                         // Uri uri =
                         // Uri.parse(AuthorizeActivity.URL_ACTIVITY_CALLBACK);
                         // startActivity(new Intent(Intent.ACTION_VIEW, uri));
                         //
                         // } catch (WeiboException e) {
                         // e.printStackTrace();
                         // } // mToken.setText(at.getToken());
                         //
上面的代码是SDK里面的示例项目中写的。
我的问题是
1：隐式授权认证方式，Oauth2.0认证方式，xauth认证方式，有什么不同？
2：上面的这么多代码乱七八糟的，没有写明白。谁能分开的写一下，哪个是哪个？