如何在android.content.Context和android.app.Activity中創建上下文？

Question

我試圖從Twitter獲取信息，我跟着這個鏈接：

http://code.google.com/p/sociallib/wiki/SocialLibGuide

我不明白下面兩行，它顯示錯誤下面幾行。

 twitter.requestAuthorization(this); 
     twitter.authorize(this); 

下面添加完整的代碼。

它說，anroid.content.Context和android.app.Activity是必需的。我真的不知道如何添加它們。任何幫助表示讚賞。

package sociallibjar; 

import android.R; 
import android.content.Context; 
import com.expertiseandroid.lib.sociallib.connectors.SocialNetworkHelper; 
import com.expertiseandroid.lib.sociallib.connectors.TwitterConnector; 
import com.expertiseandroid.lib.sociallib.model.twitter.TwitterUser; 
import org.scribe.oauth.Token; 

public class TwitterApp { 

    String CONS_KEY = ""; 
    String CONS_SEC = ""; 
    String CALLBACK = ""; 

    public void twiter() { 
     try { 
      TwitterConnector twitter = SocialNetworkHelper.createTwitterConnector(CONS_KEY, CONS_SEC, CALLBACK); 
      twitter.requestAuthorization(this); 
      twitter.authorize(this); 
      Token at = twitter.getAccessToken(); 
      String token = at.getToken(); //You can store these two strings 
      String secret = at.getSecret();//in order to build the token back 


      Token myAccessToken = new Token(token, secret); 
      twitter.authentify(myAccessToken); 
      TwitterUser me = twitter.getUser(); //Retrieves the current user 
      String nickname = me.getUsername(); //Some information is available through method calls 
      int nbFollowers = me.nbFollowers; //Some is available through object fields 

      System.out.println("You are logged in as " + nickname + " and you have " + nbFollowers + " followers"); //Now we can print the information we retrieved onscreen 

      twitter.tweet("Tweeting from code"); //A simple tweet 

      twitter.tweet("I have " + twitter.getUser().nbFollowers + " followers!");//A more elaborate tweet 
      //twitter.logout(this); //Providing this code is located in an Activity (or Context) class 


     } catch (Exception e) { 
     } 

    } 


} 

Answer 1

該鏈接的文檔很清楚。對於行：

twitter.requestAuthorization(this); //Providing this code is located in an Activity (or Context) class 
twitter.authorize(this); 

this表示Context（一個例如Activity）。 現在，因爲您的課程TwitterApp未延伸Activity您需要參考Context才能提供給這些方法。對於這一點，你可以，例如，一個構造函數添加到您的TwitterApp類，需要一個Context：

private Context ctx; //-<field in the TwitterApp class 

public TwitterApp (Context ctx) { 
    this.ctx = ctx; 
} 

，然後你使用這些方法這方面：

twitter.requestAuthorization(ctx); 
twitter.authorize(ctx); 

在你的活動你實例在TwitterApp類只是通過this：

TwitterApp obj = new TwitterApp(this);