android - TargetAPI - 构建无法解析为变量

Question

我正在按照教程创建用于在 Android 中发布推文的 Twitter 客户端。但是我在以下行中收到错误“Build cannot be resolved to a variable”:

@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 TargetAPI 有问题吗？任何帮助将不胜感激

Answer 1

请将你的 android 版本设置为 10 或大于 10 并删除 @TargetAPI line form oncreate()

将这段代码用于严格模式

if (android.os.Build.VERSION.SDK_INT > 9) 
        {
            StrictMode.ThreadPolicy policy = new StrictMode.ThreadPolicy.Builder().permitAll().build();
            StrictMode.setThreadPolicy(policy);
            StrictMode.enableDefaults();
        }