Question

在我的Android应用程序中，我想将图像上传到twitpic。我的SD卡有一些图像。当我单击按钮时，图像将上传到twitpic。这是我的代码......

    @Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);

    uploadImage = (Button) findViewById(R.id.uploadImage);
    uploadImage.setOnClickListener(new View.OnClickListener() {

        @Override
        public void onClick(View v) 
        {
        new ImageSender().execute();

        }
    });
}

private class ImageSender extends AsyncTask<URL, Integer, Long> {
     private String url;

     protected void onPreExecute() {
mProgressDialog = ProgressDialog.show(MainActivity.this, "", "Sending image...", true);

mProgressDialog.setCancelable(false);
mProgressDialog.show();
}

        protected Long doInBackground(URL... urls) {
            long result = 0;

            TwitterSession twitterSession   = new TwitterSession(MainActivity.this);
            AccessToken accessToken = twitterSession.getAccessToken();

Configuration conf = new ConfigurationBuilder()
            .setOAuthConsumerKey(twitter_consumer_key)
            .setOAuthConsumerSecret(twitter_secret_key)
            .setOAuthAccessToken(accessToken.getToken())
            .setOAuthAccessTokenSecret(accessToken.getTokenSecret())
            .build();

OAuthAuthorization auth = new OAuthAuthorization (conf, conf.getOAuthConsumerKey (), conf.getOAuthConsumerSecret (),
new AccessToken (conf.getOAuthAccessToken (), conf.getOAuthAccessTokenSecret ()));

ImageUpload upload = ImageUpload.getTwitpicUploader (twitpic_api_key, auth);

Log.d(TAG, "Start sending image...");

try {
    String ExternalStorageDirectoryPath = Environment
              .getExternalStorageDirectory()
              .getAbsolutePath();

    String targetPath = ExternalStorageDirectoryPath + "/Friends/"+"image2.jpg";


    File targetDirector = new File(targetPath);
url = upload.upload(new File(targetDirector.getAbsolutePath()));
result = 1;

Log.d(TAG, "Image uploaded, Twitpic url is " + url);    
} catch (Exception e) { 
Log.e(TAG, "Failed to send image");

e.printStackTrace();
}

            return result;
        }

        protected void onProgressUpdate(Integer... progress) {
        }

        protected void onPostExecute(Long result) {
         mProgressDialog.cancel();

         String text = (result == 1) ? "Image sent successfully.\n Twitpic url is: " + url : "Failed to send image";

         Toast.makeText(getApplicationContext(), text, Toast.LENGTH_LONG).show();
        }
    }



@Override
public boolean onCreateOptionsMenu(Menu menu) {
    // Inflate the menu; this adds items to the action bar if it is present.
    getMenuInflater().inflate(R.menu.main, menu);
    return true;
}

}

TwitterSession课程就在这里......

public class TwitterSession {
private SharedPreferences sharedPref;
private Editor editor;

private static final String TWEET_AUTH_KEY = "auth_key";
private static final String TWEET_AUTH_SECRET_KEY = "auth_secret_key";
private static final String TWEET_USER_NAME = "user_name";
private static final String SHARED = "Twitter_Preferences";

public TwitterSession(Context context) {
    sharedPref    = context.getSharedPreferences(SHARED, Context.MODE_PRIVATE);

    editor        = sharedPref.edit();
}

public void storeAccessToken(AccessToken accessToken, String username) {
    editor.putString(TWEET_AUTH_KEY, accessToken.getToken());
    editor.putString(TWEET_AUTH_SECRET_KEY, accessToken.getTokenSecret());
    editor.putString(TWEET_USER_NAME, username);

    editor.commit();
}

public void resetAccessToken() {
    editor.putString(TWEET_AUTH_KEY, null);
    editor.putString(TWEET_AUTH_SECRET_KEY, null);
    editor.putString(TWEET_USER_NAME, null);

    editor.commit();
}

public String getUsername() {
    return sharedPref.getString(TWEET_USER_NAME, "");
}

public AccessToken getAccessToken() {
    String token        = sharedPref.getString(TWEET_AUTH_KEY, null);
    String tokenSecret  = sharedPref.getString(TWEET_AUTH_SECRET_KEY, null);

    if (token != null && tokenSecret != null) 
    {
        AccessToken accessToken =  new AccessToken(token, tokenSecret);
        int userID = accessToken.getUserId();
        User user = null;
        try {
            user = twitter.showUser(userID);
        } catch (TwitterException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        }
        String username = user.getName();

        storeAccessToken(accessToken, username);
        return accessToken;
    }
    else
        return null;
}

} 这是我的日志 -

03-27 11：47：34.427：E / AndroidRuntime（2676）：致命异常：AsyncTask＃1 03-27 11:47:34.427：E / AndroidRuntime（2676）：java.lang.RuntimeException：执行doInBackground（）时发生错误 03-27 11:47:34.427：E / AndroidRuntime（2676）：在android.os.AsyncTask $ 3.done（AsyncTask.java:299） 03-27 11:47:34.427：E / AndroidRuntime（2676）：at java.util.concurrent.FutureTask.finishCompletion（FutureTask.java:352） 03-27 11:47:34.427：E / AndroidRuntime（2676）：at java.util.concurrent.FutureTask.setException（FutureTask.java:219） 03-27 11:47:34.427：E / AndroidRuntime（2676）：at java.util.concurrent.FutureTask.run（FutureTask.java:239） 03-27 11:47:34.427：E / AndroidRuntime（2676）：在android.os.AsyncTask $ SerialExecutor $ 1.run（AsyncTask.java:230） 03-27 11:47:34.427：E / AndroidRuntime（2676）：at java.util.concurrent.ThreadPoolExecutor.runWorker（ThreadPoolExecutor.java:1080） 03-27 11:47:34.427：E / AndroidRuntime（2676）：at java.util.concurrent.ThreadPoolExecutor $ Worker.run（ThreadPoolExecutor.java:573） 03-27 11:47:34.427：E / AndroidRuntime（2676）：at java.lang.Thread.run（Thread.java:856） 03-27 11:47:34.427：E / AndroidRuntime（2676）：引起：java.lang.NullPointerException 03-27 11:47:34.427：E / AndroidRuntime（2676）：at com.my.androidtwitpicapplication.MainActivity $ ImageSender.doInBackground（MainActivity.java:78） 03-27 11:47:34.427：E / AndroidRuntime（2676）：at com.my.androidtwitpicapplication.MainActivity $ ImageSender.doInBackground（MainActivity.java:1） 03-27 11:47:34.427：E / AndroidRuntime（2676）：在android.os.AsyncTask $ 2.call（AsyncTask.java:287） 03-27 11:47:34.427：E / AndroidRuntime（2676）：at java.util.concurrent.FutureTask.run（FutureTask.java:234） 03-27 11:47:34.427：E / AndroidRuntime（2676）：... 4更多

Null Pointer即将到来

.setOAuthAccessToken(accessToken.getToken())

如何删除错误？感谢...

Answer 1

在你的方法getAccessToken（）中，token或tokenSecret或者两者都从共享首选项中出现null。

public AccessToken getAccessToken() {


     // either or both of them below are coming up as null
    String token        = sharedPref.getString(TWEET_AUTH_KEY, null);
    String tokenSecret  = sharedPref.getString(TWEET_AUTH_SECRET_KEY, null);

    if (token != null && tokenSecret != null) 
        //here you are retreiving the accesstoken when it is not there in the shared preference then you need to save it as well because otherwise it will create a new AccessToken every time

        AccessToken accToken =  new AccessToken(token, tokenSecret);

        storeAccessToken(accToken, userName); /// you need to sort out where the userName will come from as it is needed by your StoreAccessToken method so next time getAccessToken is called it will retrieve the AccessToken from SharedPreference

        return 
    else
        return null;
}

现在我可以从代码中看到，storeAccessToken正在存储上面需要的所有信息。我无法看到它是否被调用。那么请看看它是否被调用了？

错误：在android中将图片上传到twitpic

1 个答案: