如何更新異步進度欄任務

-1

我正在爲android構建一個簡單的備份應用程序，並且此代碼讀取並將手機內存中的所有消息存儲到csv文件，最初我顯示的是不確定的進度欄，但是應用程序的用戶可能會對此感到不耐煩（如果他們的信息太多），所以我想添加一個確定的水平進度條向他們展示實際的進度，我一直在嘗試做一些事情，但現在我不能得到它的權利，我知道我應該在異步任務類中使用onProgressUpdate方法，但我真的不知道如何實現，所以我得到了很多的例外，所以我試圖在一個不同的沒有方法，這是下面的代碼如何更新異步進度欄任務

package daniel.idea.backup; 

import java.io.File; 
import java.io.FileInputStream; 
import java.io.FileOutputStream; 
import java.io.FileWriter; 
import java.io.IOException; 
import java.util.ArrayList; 

import android.app.Activity; 
import android.app.ProgressDialog; 
import android.content.Context; 
import android.content.res.AssetFileDescriptor; 
import android.database.Cursor; 
import android.net.Uri; 
import android.os.AsyncTask; 
import android.os.Bundle; 
import android.os.Environment; 
import android.provider.ContactsContract; 
import android.util.Log; 
import android.view.View; 
import android.view.View.OnClickListener; 
import android.widget.Button; 
import android.widget.TextView; 
import android.widget.Toast; 

public class MainActivity extends Activity implements OnClickListener { 


public ArrayList<String> smsBuffer = new ArrayList<String>(); 
String smsFile = "SMS"+".csv"; 
Integer x = 0; 
static Integer Total = 0; 


//Initialize the various ui elements 
Button contact,msg; 
ProgressDialog pb; 
TextView total; 
static Context mContext; 

//Method to fetch and write the contacts to the .vcf file 

public static String getVCF() { 
    final String vfile = "Contacts.vcf"; 
    Cursor phones = mContext.getContentResolver().query(
    ContactsContract.CommonDataKinds.Phone.CONTENT_URI, null, null, null, null); 
    phones.moveToFirst(); 
    Total = phones.getCount(); 
    for (int i = 0; i < phones.getCount(); i++) { 
     String lookupKey = phones.getString(phones.getColumnIndex(ContactsContract.Contacts.LOOKUP_KEY)); 
     Uri uri = Uri.withAppendedPath(ContactsContract.Contacts.CONTENT_VCARD_URI, lookupKey); 
     AssetFileDescriptor fd; 
     try { 
      fd = mContext.getContentResolver().openAssetFileDescriptor(uri, "r"); 
      FileInputStream fis = fd.createInputStream(); 
      byte[] buf = new byte[(int) fd.getDeclaredLength()]; 
      fis.read(buf); 
      String VCard = new String(buf); 
      String path = Environment.getExternalStorageDirectory().toString() + File.separator + vfile; 
      FileOutputStream mFileOutputStream = new FileOutputStream(path, true); 
      mFileOutputStream.write(VCard.toString().getBytes()); 
      phones.moveToNext(); 
      Log.d("Vcard", VCard); 
      mFileOutputStream.close(); 
     } catch (Exception e1) { 
      // TODO Auto-generated catch block 
      e1.printStackTrace(); 
     } 
    } 
    return phones.getCount()+ " Contacts"; 
} 


//This is the method used to get the sms and save them to a file 

     private String backupSMS(){ 
     smsBuffer.clear(); 
     Uri mSmsinboxQueryUri = Uri.parse("content://sms"); 
     Cursor cursor1 = mContext.getContentResolver().query(
       mSmsinboxQueryUri, 
       new String[] { "_id", "thread_id", "address", "person", "date", 
         "body", "type" }, null, null, null); 
     //startManagingCursor(cursor1); 
     String[] columns = new String[] { "_id", "thread_id", "address", "person", "date", "body", 
       "type" }; 
     if (cursor1.getCount() > 0) { 
      String count = Integer.toString(cursor1.getCount()); 
      Log.d("Count",count); 
      while (cursor1.moveToNext()) { 

       String messageId = cursor1.getString(cursor1 
         .getColumnIndex(columns[0])); 

       String threadId = cursor1.getString(cursor1 
         .getColumnIndex(columns[1])); 

       String address = cursor1.getString(cursor1 
         .getColumnIndex(columns[2])); 
       String name = cursor1.getString(cursor1 
         .getColumnIndex(columns[3])); 
       String date = cursor1.getString(cursor1 
         .getColumnIndex(columns[4])); 
       String msg = cursor1.getString(cursor1 
         .getColumnIndex(columns[5])); 
       String type = cursor1.getString(cursor1 
         .getColumnIndex(columns[6])); 



       smsBuffer.add(messageId + ","+ threadId+ ","+ address + "," + name + "," + date + " ," + msg + " ," 
         + type); 


      }   
      generateCSVFileForSMS(smsBuffer); 

     } 
     return cursor1.getCount() + "Messages";   
    } 


    private void generateCSVFileForSMS(ArrayList<String> list) 
    { 

     try 
     { 
      String storage_path = Environment.getExternalStorageDirectory().toString() + File.separator + smsFile; 
      FileWriter write = new FileWriter(storage_path); 

      write.append("messageId, threadId, Address, Name, Date, msg, type"); 
      write.append('\n'); 

      for (String s : list) 
      { 
       write.append(s); 
       write.append('\n'); 
      } 
      write.flush(); 
      write.close(); 
     } 

     catch (NullPointerException e) 
     { 
      System.out.println("Nullpointer Exception "+e); 
      // e.printStackTrace(); 
     } 
     catch (IOException e) 
     { 
      e.printStackTrace(); 
     } 
     catch (Exception e) 
     { 
      e.printStackTrace(); 
     } 

    } 


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

    mContext = MainActivity.this; 
    Cursor phones_total = mContext.getContentResolver().query(
    ContactsContract.CommonDataKinds.Phone.CONTENT_URI, null, null, null, null); 

    //This gets the count of all the contacts in the phone memory 
    Integer total_contacts = phones_total.getCount(); 

    contact = (Button) findViewById (R.id.bt_contacts); 
    msg = (Button) findViewById (R.id.bt_messages); 
    total = (TextView) findViewById (R.id.tv_total); 


    contact.setOnClickListener(this); 
    msg.setOnClickListener(this); 
    total.setText(total_contacts +" Contacts"); 
} 

@Override 
public void onClick(View v) { 
    // TODO Auto-generated method stub 

    switch(v.getId()){ 

    case R.id.bt_contacts: 

     MyTask task = new MyTask(); 
     task.execute("Param 1","Param2","Param3"); 


     break; 

    case R.id.bt_messages: 

     SmsTask task2 = new SmsTask(); 
     task2.execute(); 
    } 

} 


public class MyTask extends AsyncTask<String, Integer, String>{ 

    @Override 
    protected void onPreExecute() { 

     //make the progressDialog 
     pb = new ProgressDialog(MainActivity.this); 
     pb.setTitle("Please wait ..."); 
     pb.setIndeterminate(false); 
     pb.setMessage("Backing up contacts..."); 
     pb.setProgressStyle(ProgressDialog.STYLE_HORIZONTAL); 
     pb.setProgress(0); 
     pb.setMax(100); 
     pb.show(); 


    } 

    @Override 
    protected String doInBackground(String... arg0) { 
     // TODO Auto-generated method stub 
     mContext = MainActivity.this; 

     String total_c = getVCF(); 

     //Increment the progress dialog 

     for(int i = 0; i < Total; i++){ 

      publishProgress(i); 

     } 

     return total_c; 

    } 

    @Override 
    protected void onPostExecute(String result) { 
     // TODO Auto-generated method stub 
     super.onPostExecute(result); 

     //hide the progress bar and display a toast message 

     pb.dismiss(); 
     Toast.makeText(MainActivity.this, result + " Succesfully backed up", Toast.LENGTH_LONG).show(); 


    } 

    @Override 
    protected void onProgressUpdate(Integer... values) { 
     // TODO Auto-generated method stub 
     super.onProgressUpdate(values); 

     pb.incrementProgressBy(values[0]); 

     values[0]++; 
    } 


} 


public class SmsTask extends AsyncTask <String,Integer,String>{ 


     protected void onPreExecute() { 

      //show the progress bar 
      pb = ProgressDialog.show(MainActivity.this, "Processing", 
        "please wait", true); 

      } 


     @Override 
     protected String doInBackground(String... params) { 
      // TODO Auto-generated method stub 
      mContext = MainActivity.this; 

      String total_sms = backupSMS(); 

      return total_sms; 



     } 


     @Override 
     protected void onPostExecute(String result) { 
      // TODO Auto-generated method stub 
      super.onPostExecute(result); 

      //hide the progress bar and display a toast 

      pb.dismiss(); 
      Toast.makeText(MainActivity.this, result + " Succesfully backed up", Toast.LENGTH_LONG).show(); 



    } 



} 



}

進度條顯示出來，但它沒有更新...除此之外代碼工作完美...請我需要建議我如何實現一個確定的progess欄到此代碼。謝謝

編輯：我已經經歷了發佈的兩個答案，並且我已經重寫了我的代碼，而不是更新它的進度條，只是在完成時跳過從0到100，請有人指出我在此代碼中的錯誤

來源

2014-09-22 danidee