您好我试图存储并从SharedPreferences获取值。
我的问题是，当我尝试获取我的值时，我会变为空。
这是我的代码：
public class TwitterSession {
private SharedPreferences sharedPref;
private Editor editor;
private static final String TWEET_AUTH_KEY = "tweet_auth_key";
private static final String TWEET_AUTH_SECRET_KEY = "tweet_auth_secret_key";
private static final String TWEET_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) {
String token = accessToken.getToken();
String tokenSecret = accessToken.getTokenSecret();
Log.i("accessToken.getToken()", token);
Log.i("accessToken.getTokenSecret()", tokenSecret);
editor.putString(TWEET_AUTH_KEY, token);
editor.putString(TWEET_AUTH_SECRET_KEY, tokenSecret);
editor.putString(TWEET_USER_NAME, username);
if(editor.commit())
Log.i("check","ok");
else
Log.i("token","not ok");
}
public AccessToken getAccessToken() {
String token = sharedPref.getString(TWEET_AUTH_KEY, null);
String tokenSecret = sharedPref.getString(TWEET_AUTH_SECRET_KEY, null);
String userName = sharedPref.getString(TWEET_USER_NAME, null);
if(token != null)
Log.i("token",token);
else
Log.i("token","null");
if(tokenSecret != null)
Log.i("tokenSecret", tokenSecret);
else
Log.i("tokenSecret", "null");
if(userName != null)
Log.i("userName", userName);
else
Log.i("userName", "null");
if (token != null && tokenSecret != null)
return new AccessToken(token, tokenSecret);
else
return null;
}
}
首先我使用storeAccessToken（）方法。 我的日志得到了很好的结果。
Log.i("accessToken.getToken()", token);
Log.i("accessToken.getTokenSecret()", tokenSecret);
返回好的值，if(editor.commit())我的日志得到“ok”。
当我尝试调用getAccessToken（）时，我得到空字符串
Log.i("token","null");
Log.i("userName", "null");
Log.i("tokenSecret", "null");
被触发
在我的活动中，我使用它：
TwitterSession twitter = new TwitterSession(this);
twitter.getAccessToken();
感谢帮助
UPDATE1：
public AccessToken getAccessToken() {
sharedPref = contextTwitter.getSharedPreferences(SHARED, Context.MODE_PRIVATE);
String token = sharedPref.getString(TWEET_AUTH_KEY, null);
String tokenSecret = sharedPref.getString(TWEET_AUTH_SECRET_KEY, null);
String userName = sharedPref.getString(TWEET_USER_NAME, null);
if(token != null)
Log.i("token",token);
else
Log.i("token","null");
if(tokenSecret != null)
Log.i("tokenSecret", tokenSecret);
else
Log.i("tokenSecret", "null");
if(userName != null)
Log.i("userName", userName);
else
Log.i("userName", "null");
if (token != null && tokenSecret != null)
return new AccessToken(token, tokenSecret);
else
return null;
}
试过这个，不行。
我尝试通过我的活动访问我的SharedPreferences但也失败了
答案 0 :(得分：1)
我也注意到了这种行为。从我执行的调查来看，只有当退出活动时，我的结果才会持续到专用于SharedPreferences的存储区域。从I / O角度来看，这与API命名法一致;
更一般地......
...重要的是，简单的“提交”定义从未说过“这绝对会立即被保存到真实的地方”......
特别是在Android上......
SharedPreferences...commit =＆gt; "...writes its preferences out to persistent storage synchronously" SharedPreferences...apply =＆gt; "...commits its changes to the in-memory SharedPreferences immediately but starts an asynchronous commit to disk and you won't be notified of any failures"
结论
我得出的结论是，我无法控制何时将项目持久保存到SharedPreferences存储。相反，如果我正在访问变量，我将保存在相同的类/活动（无论如何）中，我应该修改该变量的范围，以便可以通过使用它的类访问它。在您的实例中，将TwitterSession下的令牌信息分配到类级私有变量中。希望有所帮助。
†不确定SharedPreference存储下的机制是否具有此概念，但this社区答案提供了有趣的读取。
答案 1 :(得分：0)
试试如下：
public AccessToken getAccessToken() {
SharedPreferences pref = getSharedPreferences(SHARED, MODE_PRIVATE);
String token = pref .getString(TWEET_AUTH_KEY, null);
String tokenSecret = pref .getString(TWEET_AUTH_SECRET_KEY, null);
String userName = pref .getString(TWEET_USER_NAME, null);
}
答案 2 :(得分：-1)
请查看此代码，希望它能为您提供帮助
import twitter4j.Twitter;
import twitter4j.TwitterException;
import twitter4j.TwitterFactory;
import twitter4j.User;
import twitter4j.auth.AccessToken;
import twitter4j.auth.RequestToken;
import twitter4j.conf.Configuration;
import twitter4j.conf.ConfigurationBuilder;
import android.app.Activity;
import android.app.ProgressDialog;
import android.content.Intent;
import android.content.SharedPreferences;
import android.content.SharedPreferences.Editor;
import android.content.pm.ActivityInfo;
import android.net.Uri;
import android.os.AsyncTask;
import android.os.Bundle;
import android.text.Html;
import android.util.Log;
import android.view.View;
import android.widget.Button;
import android.widget.EditText;
import android.widget.TextView;
import android.widget.Toast;
public class MainActivity extends Activity {
// Constants
/**
* Register your here app https://dev.twitter.com/apps/new and get your
* consumer key and secret
* */
static String TWITTER_CONSUMER_KEY = "LsCQaPOwd8k7WkyRFRZF4Q";
static String TWITTER_CONSUMER_SECRET = "KJbJu5IQrlwxW7Cwnax3mMzAc4j3n6Wd2dG125srgk";
// Preference Constants
static String PREFERENCE_NAME = "twitter_oauth";
static final String PREF_KEY_OAUTH_TOKEN = "oauth_token";
static final String PREF_KEY_OAUTH_SECRET = "oauth_token_secret";
static final String PREF_KEY_TWITTER_LOGIN = "isTwitterLogedIn";
static final String TWITTER_CALLBACK_URL = "oauth://t4jsample";
// Twitter oauth urls
static final String URL_TWITTER_AUTH = "auth_url";
static final String URL_TWITTER_OAUTH_VERIFIER = "oauth_verifier";
static final String URL_TWITTER_OAUTH_TOKEN = "oauth_token";
// Login button
Button btnLoginTwitter;
// Update status button
Button btnUpdateStatus;
// Logout button
Button btnLogoutTwitter;
// EditText for update
EditText txtUpdate;
// lbl update
TextView lblUpdate;
TextView lblUserName;
// Progress dialog
ProgressDialog pDialog;
// Twitter
private static Twitter twitter;
private static RequestToken requestToken;
// Shared Preferences
private static SharedPreferences mSharedPreferences;
// Internet Connection detector
private ConnectionDetector cd;
// Alert Dialog Manager
AlertDialogManager alert = new AlertDialogManager();
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
setRequestedOrientation(ActivityInfo.SCREEN_ORIENTATION_PORTRAIT);
cd = new ConnectionDetector(getApplicationContext());
// Check if Internet present
if (!cd.isConnectingToInternet()) {
// Internet Connection is not present
alert.showAlertDialog(MainActivity.this, "Internet Connection Error",
"Please connect to working Internet connection", false);
// stop executing code by return
return;
}
// Check if twitter keys are set
if(TWITTER_CONSUMER_KEY.trim().length() == 0 || TWITTER_CONSUMER_SECRET.trim().length() == 0){
// Internet Connection is not present
alert.showAlertDialog(MainActivity.this, "Twitter oAuth tokens", "Please set your twitter oauth tokens first!", false);
// stop executing code by return
return;
}
// All UI elements
btnLoginTwitter = (Button) findViewById(R.id.btnLoginTwitter);
btnUpdateStatus = (Button) findViewById(R.id.btnUpdateStatus);
btnLogoutTwitter = (Button) findViewById(R.id.btnLogoutTwitter);
txtUpdate = (EditText) findViewById(R.id.txtUpdateStatus);
lblUpdate = (TextView) findViewById(R.id.lblUpdate);
lblUserName = (TextView) findViewById(R.id.lblUserName);
// Shared Preferences
mSharedPreferences = getApplicationContext().getSharedPreferences(
"MyPref", 0);
/**
* Twitter login button click event will call loginToTwitter() function
* */
btnLoginTwitter.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View arg0) {
// Call login twitter function
loginToTwitter();
}
});
/**
* Button click event to Update Status, will call updateTwitterStatus()
* function
* */
btnUpdateStatus.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
// Call update status function
// Get the status from EditText
String status = txtUpdate.getText().toString();
// Check for blank text
if (status.trim().length() > 0) {
// update status
new updateTwitterStatus().execute(status);
} else {
// EditText is empty
Toast.makeText(getApplicationContext(),
"Please enter status message", Toast.LENGTH_SHORT)
.show();
}
}
});
/**
* Button click event for logout from twitter
* */
btnLogoutTwitter.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View arg0) {
// Call logout twitter function
logoutFromTwitter();
}
});
/** This if conditions is tested once is
* redirected from twitter page. Parse the uri to get oAuth
* Verifier
* */
if (!isTwitterLoggedInAlready()) {
Uri uri = getIntent().getData();
if (uri != null && uri.toString().startsWith(TWITTER_CALLBACK_URL)) {
// oAuth verifier
String verifier = uri
.getQueryParameter(URL_TWITTER_OAUTH_VERIFIER);
try {
// Get the access token
AccessToken accessToken = twitter.getOAuthAccessToken(
requestToken, verifier);
// Shared Preferences
Editor e = mSharedPreferences.edit();
// After getting access token, access token secret
// store them in application preferences
e.putString(PREF_KEY_OAUTH_TOKEN, accessToken.getToken());
e.putString(PREF_KEY_OAUTH_SECRET,
accessToken.getTokenSecret());
// Store login status - true
e.putBoolean(PREF_KEY_TWITTER_LOGIN, true);
e.commit(); // save changes
Log.e("Twitter OAuth Token", "> " + accessToken.getToken());
// Hide login button
btnLoginTwitter.setVisibility(View.GONE);
// Show Update Twitter
lblUpdate.setVisibility(View.VISIBLE);
txtUpdate.setVisibility(View.VISIBLE);
btnUpdateStatus.setVisibility(View.VISIBLE);
btnLogoutTwitter.setVisibility(View.VISIBLE);
// Getting user details from twitter
// For now i am getting his name only
long userID = accessToken.getUserId();
User user = twitter.showUser(userID);
String username = user.getName();
// Displaying in xml ui
lblUserName.setText(Html.fromHtml("<b>Welcome " + username + "</b>"));
} catch (Exception e) {
// Check log for login errors
Log.e("Twitter Login Error", "> " + e.getMessage());
}
}
}
}
/**
* Function to login twitter
* */
private void loginToTwitter() {
// Check if already logged in
if (!isTwitterLoggedInAlready()) {
ConfigurationBuilder builder = new ConfigurationBuilder();
builder.setOAuthConsumerKey(TWITTER_CONSUMER_KEY);
builder.setOAuthConsumerSecret(TWITTER_CONSUMER_SECRET);
Configuration configuration = builder.build();
TwitterFactory factory = new TwitterFactory(configuration);
twitter = factory.getInstance();
try {
requestToken = twitter
.getOAuthRequestToken(TWITTER_CALLBACK_URL);
this.startActivity(new Intent(Intent.ACTION_VIEW, Uri
.parse(requestToken.getAuthenticationURL())));
} catch (TwitterException e) {
e.printStackTrace();
}
} else {
// user already logged into twitter
Toast.makeText(getApplicationContext(),
"Already Logged into twitter", Toast.LENGTH_LONG).show();
}
}
/**
* Function to update status
* */
class updateTwitterStatus extends AsyncTask<String, String, String> {
/**
* Before starting background thread Show Progress Dialog
* */
@Override
protected void onPreExecute() {
super.onPreExecute();
pDialog = new ProgressDialog(MainActivity.this);
pDialog.setMessage("Updating to twitter...");
pDialog.setIndeterminate(false);
pDialog.setCancelable(false);
pDialog.show();
}
/**
* getting Places JSON
* */
protected String doInBackground(String... args) {
Log.d("Tweet Text", "> " + args[0]);
String status = args[0];
try {
ConfigurationBuilder builder = new ConfigurationBuilder();
builder.setOAuthConsumerKey(TWITTER_CONSUMER_KEY);
builder.setOAuthConsumerSecret(TWITTER_CONSUMER_SECRET);
// Access Token
String access_token = mSharedPreferences.getString(PREF_KEY_OAUTH_TOKEN, "");
// Access Token Secret
String access_token_secret = mSharedPreferences.getString(PREF_KEY_OAUTH_SECRET, "");
AccessToken accessToken = new AccessToken(access_token, access_token_secret);
Twitter twitter = new TwitterFactory(builder.build()).getInstance(accessToken);
// Update status
twitter4j.Status response = twitter.updateStatus(status);
Log.d("Status", "> " + response.getText());
} catch (TwitterException e) {
// Error in updating status
Log.d("Twitter Update Error", e.getMessage());
}
return null;
}
/**
* After completing background task Dismiss the progress dialog and show
* the data in UI Always use runOnUiThread(new Runnable()) to update UI
* from background thread, otherwise you will get error
* **/
protected void onPostExecute(String file_url) {
// dismiss the dialog after getting all products
pDialog.dismiss();
// updating UI from Background Thread
runOnUiThread(new Runnable() {
@Override
public void run() {
Toast.makeText(getApplicationContext(),
"Status tweeted successfully", Toast.LENGTH_SHORT)
.show();
// Clearing EditText field
txtUpdate.setText("");
}
});
}
}
/**
* Function to logout from twitter
* It will just clear the application shared preferences
* */
private void logoutFromTwitter() {
// Clear the shared preferences
Editor e = mSharedPreferences.edit();
e.remove(PREF_KEY_OAUTH_TOKEN);
e.remove(PREF_KEY_OAUTH_SECRET);
e.remove(PREF_KEY_TWITTER_LOGIN);
e.commit();
// After this take the appropriate action
// I am showing the hiding/showing buttons again
// You might not needed this code
btnLogoutTwitter.setVisibility(View.GONE);
btnUpdateStatus.setVisibility(View.GONE);
txtUpdate.setVisibility(View.GONE);
lblUpdate.setVisibility(View.GONE);
lblUserName.setText("");
lblUserName.setVisibility(View.GONE);
btnLoginTwitter.setVisibility(View.VISIBLE);
}
/**
* Check user already logged in your application using twitter Login flag is
* fetched from Shared Preferences
* */
private boolean isTwitterLoggedInAlready() {
// return twitter login status from Shared Preferences
return mSharedPreferences.getBoolean(PREF_KEY_TWITTER_LOGIN, false);
}
protected void onResume() {
super.onResume();
}
}`enter code here`