Android ExecutorService 和 ProgressBar

Question

我正在尝试实现一个 executorService 以在后台删除一个巨大的 Firebase 节点。该节点每十秒获取一条新记录，以提供实时线性图形（259K 记录/月）。用户需要定时清理数据的功能，需要手动触发。

我已经编写了以下方法：

    ExecutorService executorService = Executors.newFixedThreadPool(1);
    executorService.execute(() -> {
        Log.i(TAG, "cleanTable: execute");
        tabelasRef = fbDB.child(tableName).child(dispositivoSel.getIdDispositivo());
        tabelasEventListener = new ValueEventListener() {
            @Override
            public void onDataChange(@NonNull @NotNull DataSnapshot snapshot) {
                try{
                    Log.i(TAG, "onDataChange: childrencount " + snapshot.getChildrenCount());
                    if (snapshot.getChildrenCount() > 0) {
                        // Inicializa a ProgressBar
                        new Handler(Looper.getMainLooper()).post(() -> {
                            progressBarLimpaTabela.setMax((int) snapshot.getChildrenCount());
                            progressBarLimpaTabela.setVisibility(View.VISIBLE);
                            Log.i(TAG, "Tornando a ProgressBar visível e definindo max=" + snapshot.getChildrenCount());
                        });

                        progress = 1;
                        for (DataSnapshot ds : snapshot.getChildren()) {
                            // Apaga registro
                            fbDB.child(tableName).child(dispositivoSel.getIdDispositivo()).child(ds.getKey()).removeValue();

                            // Atualiza a ProgressBar
                            new Handler(Looper.getMainLooper()).post(() -> {
                                progressBarLimpaTabela.setProgress(progress);
                                Log.i(TAG, "Atualizando progress: " + progress);
                            });

                            progress ++;
                        }

                        // Finaliza a ProgressBar
                        new Handler(Looper.getMainLooper()).post(() -> {
                            progressBarLimpaTabela.setVisibility(View.INVISIBLE);
                            Log.i(TAG, "fechando ProgressBar.");
                        });
                    }
                }catch (Exception ex){
                    new Handler(Looper.getMainLooper()).post(() ->
                            logMsg(AdminActivity.this, tableName + "-EventListener.onDataChange(Exception): " + ex.getMessage(), true, true, false, false)
                    );
                }
            }

            @Override
            public void onCancelled(@NonNull @NotNull DatabaseError error) {
                new Handler(Looper.getMainLooper()).post(new Runnable() {
                    public void run() {
                        logMsg(AdminActivity.this, tableName + "-EventListener.onCancelled(DatabaseError): " + error.getMessage(), true, true, false, false);
                    }
                });
             }
        };
        tabelasRef.addListenerForSingleValueEvent(tabelasEventListener);
    });
    executorService.shutdown();

问题是进度条永远不会显示或更新。我可以在 logcat 中看到显示日志需要一段时间，当它显示时是这样的：

2021-06-11 18:29:17.833 14051-14272/projectname I/LOGCAT: cleanTable: execute
2021-06-11 18:29:29.394 14051-14051/projectname I/LOGCAT: onDataChange: childrencount 105606
2021-06-11 18:30:42.405 14051-14051/projectname I/LOGCAT: Tornando a ProgressBar visível de definindo max=105606
2021-06-11 18:30:42.406 14051-14051/projectname I/LOGCAT: Atualizando progress: 105607
2021-06-11 18:30:42.526 14051-14051/projectname I/LOGCAT: Atualizando progress: 105607
2021-06-11 18:30:42.526 14051-14051/projectname I/LOGCAT: Atualizando progress: 105607
2021-06-11 18:30:42.531 14051-14051/projectname I/LOGCAT: Atualizando progress: 105607
2021-06-11 18:30:42.531 14051-14051/projectname I/LOGCAT: Atualizando progress: 105607
2021-06-11 18:30:42.607 14051-14051/projectname I/LOGCAT: Atualizando progress: 105607
2021-06-11 18:30:42.607 14051-14051/projectname I/LOGCAT: Atualizando progress: 105607
2021-06-11 18:30:42.851 14051-14051/projectname I/LOGCAT: Atualizando progress: 105607
2021-06-11 18:30:42.851 14051-14051/projectname I/LOGCAT: Atualizando progress: 105607
...
...
...
2021-06-11 18:30:48.473 14051-14051/projectname I/LOGCAT: Atualizando progress: 105607
2021-06-11 18:30:49.433 14051-14051/projectname I/LOGCAT: Atualizando progress: 105607
2021-06-11 18:30:49.433 14051-14051/projectname I/LOGCAT: fechando ProgressBar.

请帮我找出我的错误在哪里。谢谢！

Answer 1

我想我找到了问题所在。碰巧当我在firebase上执行“removeValue（）”时，它会异步触发它。所以，for 循环很快就完成了，给了我上面的 LogCat。 我在删除命令中添加了一个 OnSuccessListener 并正在增加其中的进度。另外，我添加了一个控制变量，以便知道处理何时完成，从而关闭进度条。结束代码，是这样的：

    ExecutorService executorService = Executors.newSingleThreadExecutor();
    executorService.execute(() -> {
        tabelasRef = fbDB.child(tableName).child(dispositivoSel.getIdDispositivo());
        tabelasEventListener = new ValueEventListener() {
            @Override
            public void onDataChange(@NonNull @NotNull DataSnapshot snapshot) {
                try{
                    Log.i(TAG, "onDataChange: childrencount " + snapshot.getChildrenCount());
                    if (snapshot.getChildrenCount() > 0) {
                        deleteRecCount = (int) snapshot.getChildrenCount();

                        // Inicializa a ProgressBar
                        new Handler(Looper.getMainLooper()).post(() -> {
                            progressBarLimpaTabela.setMax(deleteRecCount);
                            llayProgress.setVisibility(View.VISIBLE);
                        });

                        progress = 1;
                        for (DataSnapshot ds : snapshot.getChildren()) {
                            // Apaga registro
                            fbDB.child(tableName).child(dispositivoSel.getIdDispositivo()).child(ds.getKey()).removeValue()
                                    .addOnSuccessListener(unused -> {
                                        // Atualiza a ProgressBar
                                        new Handler(Looper.getMainLooper()).post(() -> {
                                            progressBarLimpaTabela.setProgress(progress);
                                            // Finaliza a ProgressBar
                                            if (progress == deleteRecCount){
                                                llayProgress.setVisibility(View.INVISIBLE);
                                            }
                                            progress ++;
                                        });
                                    })
                                    .addOnFailureListener(e -> Log.i(TAG, "onFailure:(" + progress + "): " + e.getMessage()))
                                    .addOnCanceledListener(() -> Log.i(TAG, "onCanceled: " + progress));
                        }

                    }
                }catch (Exception ex){
                    new Handler(Looper.getMainLooper()).post(() ->
                        logMsg(AdminActivity.this, tableName + "-EventListener.onDataChange(Exception): " + ex.getMessage(), true, true, false, false)
                    );
                }
            }

            @Override
            public void onCancelled(@NonNull @NotNull DatabaseError error) {
                new Handler(Looper.getMainLooper()).post(new Runnable() {
                    public void run() {
                        logMsg(AdminActivity.this, tableName + "-EventListener.onCancelled(DatabaseError): " + error.getMessage(), true, true, false, false);
                    }
                });
             }
        };
        tabelasRef.addListenerForSingleValueEvent(tabelasEventListener);
    });
    executorService.shutdown();