我正在按照教程创建一个Twitter客户端，用于在Android中发布推文。 但是，我在以下行中收到错误“构建无法解析为变量”：
@TargetApi(Build.VERSION_CODES.GINGERBREAD)
这是完整的MainActivity.java代码：
package com.androidhive.twitterconnect;
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.annotation.TargetApi;
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.StrictMode;
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 = "CV78QI1eZAgGe9mMS7A"; // place your cosumer key here
static String TWITTER_CONSUMER_SECRET = "zCYkLsHlAVf7DoWJlDbfqeFsghXQCu2dUaFC2O94HQ"; // place your consumer secret here
// 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();
@TargetApi(Build.VERSION_CODES.GINGERBREAD)
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
StrictMode.ThreadPolicy policy = new StrictMode.ThreadPolicy.Builder().permitAll().build();
StrictMode.setThreadPolicy(policy);
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();
}
}
我想知道我是否必须定义某些东西或者是否对TargetAPI有问题？ 任何帮助都会得到真正的帮助
答案 0 :(得分：2)
请将Android版本设置为10或大于10并删除@TargetAPI行格式oncreate（）
使用这段代码代替Strictmode
if (android.os.Build.VERSION.SDK_INT > 9)
{
StrictMode.ThreadPolicy policy = new StrictMode.ThreadPolicy.Builder().permitAll().build();
StrictMode.setThreadPolicy(policy);
StrictMode.enableDefaults();
}
答案 1 :(得分：0)
更改代码后，我也遇到类似的问题
if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.LOLLIPOP) {
tts.speak(messages.get(0), TextToSpeech.QUEUE_FLUSH, null, null);
} else {
tts.speak(messages.get(0), TextToSpeech.QUEUE_FLUSH, null);
}
收件人：
@SuppressWarnings("deprecation")
private void ttsUnder20(String msgText, final int queueMode) {
tts.speak(msgText, queueMode, null);
}
@TargetApi(Build.VERSION_CODES.LOLLIPOP)
private void ttsGreater21(String msgText, final int queueMode) {
tts.speak(msgText, queueMode, null, null);
}
if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.LOLLIPOP) {
ttsUnder20(messages.get(0), TextToSpeech.QUEUE_FLUSH);
} else {
ttsGreater21(messages.get(0), TextToSpeech.QUEUE_FLUSH);
}
Android Studio显示语法错误：
Cannot resolve symbol 'TargetApi'
为
@TargetApi(Build.VERSION_CODES.LOLLIPOP)
最终解决方案：
添加
import android.annotation.TargetApi;