AsyncTask没有更新返回进度

Question

我有一个AsyncTask类。我在AsyncTask类中进行处理。但是我返回这个类，Progress没有更新。而我只使用类，progres是更新。

这是我的AsyncTask类：

AsyncTaskTables.java

public class AsyncTaskTables extends AsyncTask<String, String, ArrayList<String>>{ 

private Context Context; 

private LoginInfo AccountInfo; 

private TextView ProgressStatus; 
private ProgressBar ProgressValue; 

public AsyncTaskTables (Context Context){ 
    this.Context = Context; 

    AccountInfo = new LoginInfo(); 

    ProgressStatus = (TextView) ((Activity)Context).findViewById(R.id.tvStatus); 
    ProgressValue = (ProgressBar) ((Activity)Context).findViewById(R.id.pbProgress); 
} 

@Override 
protected void onPreExecute() { 
    ProgressValue.setIndeterminate(true); 
} 

@Override 
protected ArrayList<String> doInBackground(String... SQLCommand) { 
    publishProgress("Checking Net Connection..."); 
    if(NetConnection()){ 
     try{ 
      publishProgress("Preparing..."); 

      ArrayList<String> TablesList = new ArrayList<String>(); 

      publishProgress("Connecting..."); 

      @SuppressWarnings("static-access") 
      String Url = "jdbc:jtds:sqlserver://" + AccountInfo.Server + ";databaseName=" + AccountInfo.Database + ""; 
      String Driver = "net.sourceforge.jtds.jdbc.Driver"; 

      String SelectTables = "SELECT * FROM INFORMATION_SCHEMA.TABLES"; 

      Class.forName(Driver).newInstance(); 
      @SuppressWarnings("static-access") 
      Connection DatabaseConnection = DriverManager.getConnection(Url, AccountInfo.UserName, AccountInfo.Password); 
      Statement Command = DatabaseConnection.createStatement(); 

      publishProgress("Selecting tables..."); 
      ResultSet Results = Command.executeQuery(SelectTables); 

      TablesList.clear(); 

      while(Results.next()){ 
       TablesList.add(Results.getString(3).toString()); 
      } 

      publishProgress("Done !"); 

      return TablesList; 
     }catch(Exception Error){ 
      publishProgress("Error : " + Error.toString()); 
      return null; 
     } 
    } else { 
     publishProgress("Need Network Connection !"); 
     return null; 
    } 
} 

@Override 
protected void onProgressUpdate(String... Status) { 
    ProgressStatus.setText(Status[0]); 
} 

@Override 
protected void onPostExecute(ArrayList<String> Result) { 
    ProgressValue.setIndeterminate(false); 
} 

@SuppressWarnings("static-access") 
private boolean NetConnection() { 
    ConnectivityManager NetManager = (ConnectivityManager) ((Activity)Context).getSystemService(Context.CONNECTIVITY_SERVICE); 

    if (NetManager.getActiveNetworkInfo() != null && NetManager.getActiveNetworkInfo().isAvailable() && NetManager.getActiveNetworkInfo().isConnected()) 
     return true; 
    else 
     return false; 
} 

} 

这是我MainClass：

ManagementActivity.java

public class ManagementActivity extends Activity { 

private TextView Status; 

private AsyncTaskTables SelectTables; 

private TablesAdapter TablesAdapter = null; 
private ArrayList<String> TablesList = null; 

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

    Status = (TextView) findViewById(R.id.textView1); 

    try { 

//Problem is here... 
//I am calling only "SelectTables.execute("");", progressbar is showing. 
//But I am calling "SelectTables.execute("").get();", progressbar isn't showing... 

     SelectTables = new AsyncTaskTables(this); 
     TablesList = SelectTables.execute("").get(); 
     TablesAdapter = new TablesAdapter (this, R.layout.tables_row, TablesList); 

     ListView Tables = (ListView) findViewById(R.id.lvTables); 
     Tables.setAdapter(TablesAdapter); 
     registerForContextMenu(Tables); 
    } catch (Exception Error) { 
     Status.setText("Error (Select Tables) : " + Error.toString()); 
    } 

    Button btnTablesRefresh = (Button) findViewById(R.id.btnRefresh); 
    btnTablesRefresh.setOnClickListener(new OnClickListener(){ 
     @Override 
     public void onClick(View v) { 
      try { 
       SelectTables = new AsyncTaskTables(ManagementActivity.this); 
       TablesList = SelectTables.execute("").get(); 
       TablesAdapter = new TablesAdapter (ManagementActivity.this, R.layout.tables_row, TablesList); 

       ListView Tables = (ListView) findViewById(R.id.lvTables); 
       Tables.setAdapter(TablesAdapter); 
       registerForContextMenu(Tables); 
      } catch (Exception Error) { 
       Status.setText("Error (Select Tables) : " + Error.toString()); 
      } 
     } 
    }); 
} 
} 

我只打电话“SelectTables.execute（”“）;”，进度条显示。 但我打电话“SelectTables.execute（”“）。get（）;”，进度条不显示...

我该怎么办？

Answer 1

Get函数在必要时等待计算完成，然后检索其结果。这意味着你的UI线程被阻塞直到你的任务完成。由于您正在阻止您的UI线程，进度条，永远不会显示。

Answer 2

尝试在UI线程中包装publishProgress（）方法。

this.runOnUiThread(new Runnable() { 

     public void run() { 
      publishProgress("Your progress"); 

     } 
    });