设计一个每 20 秒刷新一次的测验活动（重做）

Question

我正在制作一个测验应用程序，其中我有一个测验活动，我正在做以下工作。

1. 从服务器获取数据（现在使用 Asynctask 获取所有数据）。
2. 为我的 UI 设置数据（进展顺利）。
3. 获取用户输入并检查标记的答案。
4. 每 20 秒刷新一次活动，包含新问题（我正在使用处理程序）

我拥有所有数据，现在希望我的 UI 刷新我拥有的数据中的新问题。我该怎么做？
任何帮助表示赞赏。

以下是我正在使用的代码。

public class Quiz extends ActionBarActivity {
private SessionManager session;
Intent intent;
String categoryid,userid,uri="http://demopurpose.com/Quiz/API/";
JSONArray jArray;
InputStream is;
JSONObject json_data;
String[] data;
int len,countdown=20,lastquestion=0;
private Handler mHandler,handler;
protected static final long TIME_DELAY = 20000;
TextView txtcountdown,txtquestion,txtanswer;
Button btn1,btn2,btn3,btn4;
String opt1,opt2,opt3,opt4,question,answer ;

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_quiz);
    this.session = new SessionManager(this);
    mHandler = new Handler();
    handler = new Handler();

    AdView mAdView = (AdView) findViewById(R.id.adView);
    AdRequest adRequest = new AdRequest.Builder().build();
    mAdView.loadAd(adRequest);

    txtcountdown =(TextView)findViewById(R.id.txtcountdown);
    txtquestion = (TextView)findViewById(R.id.txtquestion);

    btn1 =(Button)findViewById(R.id.btn1);
    btn2 =(Button)findViewById(R.id.btn2);
    btn3 =(Button)findViewById(R.id.btn3);
    btn4 =(Button)findViewById(R.id.btn4);

    userid= session.getuserid();
    intent =getIntent();
    categoryid = intent.getExtras().getString("categoryid");


    data = new String[3]; 
    data[0] = userid;
    data[1] = categoryid;
    data[2] = Integer.toString(lastquestion);

    btn1.setOnClickListener(new View.OnClickListener() {

        @Override
        public void onClick(View v) {
            // TODO Auto-generated method stub
            opt1 = btn1.getText().toString();
            opt2 = btn2.getText().toString();
            opt3 = btn3.getText().toString();
            opt4 = btn4.getText().toString();

            if (opt1.equals(answer)) {
                btn2.setEnabled(false);
                btn3.setEnabled(false);
                btn4.setEnabled(false);
                btn1.setBackgroundResource(R.color.colortrue);
            }
            else{
                btn1.setBackgroundResource(R.color.colorfalse);
                btn2.setEnabled(false);
                btn3.setEnabled(false);
                btn4.setEnabled(false);
            }
        }
    });

    btn2.setOnClickListener(new View.OnClickListener() {

        @Override
        public void onClick(View v) {
            // TODO Auto-generated method stub
            opt1 = btn1.getText().toString();
            opt2 = btn2.getText().toString();
            opt3 = btn3.getText().toString();
            opt4 = btn4.getText().toString();

            if (opt2.equals(answer)) {
                btn1.setEnabled(false);
                btn3.setEnabled(false);
                btn4.setEnabled(false);
                btn2.setBackgroundResource(R.color.colortrue);
            }
            else{
                btn2.setBackgroundResource(R.color.colorfalse);
                btn1.setEnabled(false);
                btn3.setEnabled(false);
                btn4.setEnabled(false);
            }
        }
    });

    btn3.setOnClickListener(new View.OnClickListener() {

        @Override
        public void onClick(View v) {
            // TODO Auto-generated method stub
            opt1 = btn1.getText().toString();
            opt2 = btn2.getText().toString();
            opt3 = btn3.getText().toString();
            opt4 = btn4.getText().toString();

            if (opt3.equals(answer)) {
                btn2.setEnabled(false);
                btn1.setEnabled(false);
                btn4.setEnabled(false);
                btn3.setBackgroundResource(R.color.colortrue);
            }
            else{
                btn3.setBackgroundResource(R.color.colorfalse);
                btn2.setEnabled(false);
                btn1.setEnabled(false);
                btn4.setEnabled(false);
            }
        }
    });

    btn4.setOnClickListener(new View.OnClickListener() {

        @Override
        public void onClick(View v) {
            // TODO Auto-generated method stub
            opt1 = btn1.getText().toString();
            opt2 = btn2.getText().toString();
            opt3 = btn3.getText().toString();
            opt4 = btn4.getText().toString();

            if (opt4.equals(answer)) {
                btn2.setEnabled(false);
                btn3.setEnabled(false);
                btn1.setEnabled(false);
                btn4.setBackgroundResource(R.color.colortrue);
            }
            else{
                btn4.setBackgroundResource(R.color.colorfalse);
                btn2.setEnabled(false);
                btn3.setEnabled(false);
                btn1.setEnabled(false);
            }
        }
    });
    new GetData().execute(data);
}


Runnable refreshActivity=new Runnable(){  
    public void run() {  
          countdown =20;
          lastquestion++;
          mHandler.postDelayed(this, TIME_DELAY);  
         }  
     };  

Runnable refreshCounter = new Runnable() {

    @Override
    public void run() {
        // TODO Auto-generated method stub
        countdown--;
        txtcountdown.setText("Time Remaining"+countdown);
        handler.postDelayed(this, 1000);
    }
}; 

public JSONArray getquiz(String uid, String cid,String lastindex) {

    String result = "";
    try{
            HttpClient httpclient = new DefaultHttpClient();
            HttpPost httppost = new HttpPost(uri+"question.php");
            List<NameValuePair> nameValuePairs = new ArrayList<NameValuePair>(3);
            nameValuePairs.add(new BasicNameValuePair("userId", uid));
            nameValuePairs.add(new BasicNameValuePair("categoryId", cid));
            nameValuePairs.add(new BasicNameValuePair("lastquestionId", lastindex));

            httppost.setEntity(new UrlEncodedFormEntity(nameValuePairs));
            HttpResponse response = httpclient.execute(httppost);
            HttpEntity entity = response.getEntity();
            is = entity.getContent();
    }
    catch(Exception e){
            Log.e("log_tag", "Error in http connection "+e.toString());
    }
    //convert response to string
    try{
            BufferedReader reader = new BufferedReader(new InputStreamReader(is,"iso-8859-1"),8);
            StringBuilder sb = new StringBuilder();
            String line = null;
            while ((line = reader.readLine()) != null) {
                    sb.append(line + "\n");
            }
            is.close();

            result=sb.toString();
            Log.e("result...",result);
            jArray = new JSONArray(result);
            Log.e("Array...", ""+jArray);

    }catch(Exception e){
            Log.e("log_tag", "Error converting result "+e.toString());
    }
    return jArray;
}


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

@Override
public boolean onOptionsItemSelected(MenuItem item) {
    // Handle action bar item clicks here. The action bar will
    // automatically handle clicks on the Home/Up button, so long
    // as you specify a parent activity in AndroidManifest.xml.
    int id = item.getItemId();
    if (id == R.id.action_settings) {
        Log.e("click...", "");
        return true;
    }
    return super.onOptionsItemSelected(item);
}

private class GetData extends AsyncTask<String, Void, Object[]>
{
    @Override
    protected Object[] doInBackground(String... params) {
        String cid,uid,lastindex;
        uid = params[0];
        cid = params[1];
        lastindex = params[2];
        Log.e("Data"," "+cid+" "+uid+" "+lastindex);
        JSONArray arr = new JSONArray();
        arr = getquiz(uid, cid, lastindex);

        Object[] obj = new Object[2];
        obj[0]=arr;
        obj[1]=lastindex;

        return obj;
    }      

    @Override
    protected void onPostExecute(Object[] obj) {
        JSONArray arr = new JSONArray();
        String lastindex;
        arr = (JSONArray)obj[0];
        lastindex =(String)obj[1];
        int li;
        if(arr!=null) {
            try{
                    li= Integer.parseInt(lastindex);
                    json_data = arr.getJSONObject(li);

                String flag="";
                flag =json_data.getString("success");

                if(flag.equalsIgnoreCase("0"))
                {   
                    runOnUiThread(new Runnable() {
                        public void run() {
                            Toast.makeText(Quiz.this, "Unable to load Quiz...Try again", Toast.LENGTH_SHORT).show();
                        }
                    });

                }
                else
                {   
                    runOnUiThread(new Runnable() {
                        public void run() {
                            Toast.makeText(Quiz.this, "Loading Quiz...", Toast.LENGTH_SHORT).show();
                            try{
                                txtquestion.setText(json_data.getString("title"));
                                btn1.setText(json_data.getString("option1"));
                                btn1.setBackgroundResource(R.color.colorreset);
                                btn1.setEnabled(true);

                                btn2.setText(json_data.getString("option2"));
                                btn2.setBackgroundResource(R.color.colorreset);
                                btn2.setEnabled(true);

                                btn3.setText(json_data.getString("option3"));
                                btn3.setBackgroundResource(R.color.colorreset);
                                btn3.setEnabled(true);

                                btn4.setText(json_data.getString("option4"));
                                btn4.setBackgroundResource(R.color.colorreset);
                                btn4.setEnabled(true);

                                answer = json_data.getString("answer");

                                mHandler.post(refreshActivity);
                                handler.post(refreshCounter);

                            }
                            catch(JSONException je){
                                je.printStackTrace();
                            }
                        }
                    });
                }
            }
            catch(JSONException je){
                je.printStackTrace();
            }
        }
    }
}
}

Answer 1

有两种方法：

1) 使用 AsyncTask：对于一个一个进程，您应该使用 asynctask。

2) 使用线程：在 asynctask 中调用您的 api，并且每次在 asynctask 中以 20 秒的递归时间在线程中调用，刷新所有，即：布局、ID、视图和所有。

Answer 2

这里是sn-p使用ScheduledExecutorService调度任务的代码，希望能给个方法。此类将每 20 秒更新一次文本视图。最初（启动时）它将等待 20 秒，之后它将开始修改文本视图。基本上，如果服务器足够快，可以在 20 秒内给出响应。您可以在 run() 中下载数据并通过 Message 将其传递给处理程序。但我更喜欢下载问题/数据（以使应用程序更具响应性并减少请求数量），然后使用 ScheduledExecutorService 填充它。

import java.util.concurrent.Executors;
import java.util.concurrent.ScheduledExecutorService;
import java.util.concurrent.TimeUnit;
import android.app.Activity;
import android.os.Bundle;
import android.os.Handler;
import android.os.Message;
import android.widget.TextView;
public class MainActivity extends Activity {
private TextView textView;
private int i=0;
private ScheduledExecutorService executor;
private Handler handler=new Handler()
{
    public void handleMessage(Message msg) {
        textView.setText(msg.arg1+"");
    };
};
@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);
    textView=(TextView)findViewById(R.id.textView1);
    executor=Executors.newSingleThreadScheduledExecutor();
    executor.scheduleAtFixedRate(new Runnable() {

        @Override
        public void run() {
        Message message=Message.obtain();
        message.arg1=i;
        i++;
        handler.sendMessage(message);
        }
    },20, 20, TimeUnit.SECONDS);

    }

@Override
protected void onPause() {
    super.onPause();
    executor.shutdown();

}
}