Question

所以我有一个主Activity，我有一个按钮（ImageView）和一个进度条。当我单击该按钮时，我想执行一系列从远程数据库下载一些数据的AsyncTasks。我想在单击按钮时启动不确定的进度条，并在最后一次AsyncTask完成时隐藏它。我能这样做吗？

所以我有

MainActivity.class（包含按钮，进度条和调用asyncTasks的代码）
AsyncTask1.class（包含从DB获取一些数据的代码）
AsyncTask2.class（包含从DB获取一些数据的代码）
...
AsyncTaskn.class（包含从DB获取一些数据的代码）

我不能在活动中包含所有asyncTask类，所以我可以直接引用progressBar，那么如何从onPostExecute中的最后一个AsyncTask类访问进度条以隐藏它？

所以我的mainActivity看起来像：

ImageView upd = (ImageView) findViewById(R.id.iv_update);
    upd.setOnClickListener( new View.OnClickListener() {
        @Override
        public void onClick(View v) {
                ProgressBar progressBar = (ProgressBar) findViewById(R.id.progressBar);
                progressBar.setIndeterminate(true);
                progressBar.setVisibility(View.VISIBLE);
                new AsyncTask1(getApplicationContext()).execute();
                new AsyncTask2(getApplicationContext()).execute();
                new AsyncTask3(getApplicationContext()).execute();
                new AsyncTask4(getApplicationContext()).execute();
                new AsyncTask5(getApplicationContext()).execute();
                new AsyncTask6(getApplicationContext()).execute();
                new AsyncTask7(getApplicationContext()).execute();
        }
    });

AsyncTask的一个例子（它们都相似）

public class AsyncTask1 extends AsyncTask<String, Integer, Double> {

    private Context mContext;
    InputStream is = null ;
    String result = "";

    public AsyncTask1 (Context context){
        mContext = context;
    }

    public void insSQLite(Integer iduzer, String tip_uzer, String nume, String parola, String numecomplet,
                          String email, String telefon, String idgrup, String den_grup, String idcoord, String nume_coord, String nume_coordfull ) {
        SQLiteDatabase db = new myDbHelper(mContext).getWritableDatabase();
        String sql = "";
        sql = "select iduzer from uzeri where trim(tip_uzer)='"+tip_uzer+"' and trim(numecomplet)='"+numecomplet+"'";
        Cursor cursor = db.rawQuery(sql, null);
        if (cursor != null) {
            if (cursor.moveToFirst()) {
                    Log.e("... It exists ...", Integer.toString(cursor.getInt(0)));
                    sql = "update uzeri set iduzer=" + iduzer + ",parola='" + parola + "',email='" + email + "',telefon='" + telefon + "', idgrup=" + idgrup + ", den_grup='" + den_grup + "', idcoord=" + idcoord + ", nume_coord='" + nume_coord + "', nume_coordfull='" + nume_coordfull + "'  where iduzer=" + Integer.toString(cursor.getInt(0));
                    db.execSQL(sql);
            }
        }else{
                sql = "insert into uzeri (iduzer,tip_uzer,nume,parola,numecomplet,email,telefon, idgrup,den_grup,idcoord,nume_coord,nume_coordfull) values (" +
                        String.valueOf(iduzer) + ",'" + tip_uzer + "','" + nume + "','" + parola + "','" + numecomplet + "','" +
                        email + "','" + telefon + "'," + idgrup + ",'" + den_grup +"'," + idcoord + ",'" + nume_coord + "','" + nume_coordfull + "')";
                db.execSQL(sql);
        }
            db.close();
    }

    @Override
    protected Double doInBackground(String... params) {
        postData("0");
        return null;
    }

    protected void onPostExecute(Double v){
        if (!String.valueOf(result).trim().equals("null")) {
            try {
                JSONArray Jarray = new JSONArray(result);
                for (int i = 0; i < Jarray.length(); i++) {
                    JSONObject Jasonobject = null;
                    Jasonobject = Jarray.getJSONObject(i);
                    Integer iduzer = Jasonobject.getInt("iduser");
                    String tip_uzer = Jasonobject.getString("tip_uzer");
                    String nume = Jasonobject.getString("name");
                    String pass = Jasonobject.getString("pass");
                    String numecomplet = Jasonobject.getString("namecomplete");
                    String email = Jasonobject.getString("email");
                    String telefon = Jasonobject.getString("phone");
                    String idgrup = Jasonobject.getString("idgroup");
                    String den_grup = Jasonobject.getString("den_group");
                    String idcoord = Jasonobject.getString("idcoord");
                    String nume_coord = Jasonobject.getString("nume_coord");
                    String nume_coordfull = Jasonobject.getString("name_coordfull");
                    insSQLite(iduzer, tip_uzer, nume, pass, namecomplete, email, telefon, idgrup,den_grup,idcoord,nume_coord,nume_coordfull);
                }
            } catch (Exception e) {
                Log.e("log_tag", "Error parsing data " + e.toString());
            }
        }else{
            Log.e("ASYNC UZ:","There are no users on the server");
        }
    }    

    protected void onProgressUpdate(Integer... progress){
//        pb.setProgress(progress[0]);
    }

    public void postData(String valueIWantToSend) {
        // Create a new HttpClient and Post Header
        HttpClient httpclient = new DefaultHttpClient();
        HttpPost httppost = new HttpPost("http://www.myserver.com/getusers.php");
        final GlobalClass globalVariable = (GlobalClass) mContext;
        String uzid = globalVariable.getUzer();

        try {
            // Add your data
            List<NameValuePair> nameValuePairs = new ArrayList<NameValuePair>();
            nameValuePairs.add(new BasicNameValuePair("myHttpData", valueIWantToSend));
            nameValuePairs.add(new BasicNameValuePair("uzeru", uzid));
            httppost.setEntity(new UrlEncodedFormEntity(nameValuePairs));
            // Execute HTTP Post Request
            HttpResponse response = httpclient.execute(httppost);
            HttpEntity httpEntity = response.getEntity();
            is =  httpEntity.getContent();
            try {
                BufferedReader br = new BufferedReader(new InputStreamReader(is));
                StringBuilder sb = new StringBuilder();
                String line = "";
                while((line=br.readLine())!=null){ sb.append(line+"\n"); }
                is.close();
                result=sb.toString();

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

        } catch (ClientProtocolException e) {
        } catch (IOException e) {
        }
    }
}

谢谢

Answer 1

我会与你分享一个想法。您可以设置如下变量：

int taskCount = 0;

然后，在每个Asynctask的onPostExecute方法中，您可以添加taskCount并测试taskCount是否获得7值：

taskCount++; //WARN: here you maybe need java synchronized.
if(taskCount == 7){
    //all task is done , just do your work. 
    //hide the progressbar.
}

希望这个想法可以给你一些提示。

显示进度条，直到执行多个异步任务

1 个答案: