Android 主线程不等待 AsyncTask

Question

我正在尝试进行一些加密并在它们处于运行时显示进度对话框，因为根据加密次数的不同，这可能需要几分钟甚至几小时。我正在尝试测量前后的电池电量，以查看给定的回合数会耗尽多少电池电量。我的问题是主线程没有等待 AsyncTask 完成加密。

这是我目前的情况：

    private void performEncryption(String name) throws InterruptedException {
        int times = this.getNumTimes();

        float batteryPercentageBefore = (new Battery(this)).percentage();
        Log.d("BATTERY", String.valueOf(batteryPercentageBefore));

        long timeBefore = System.currentTimeMillis();

        EncryptionHandler algo = new EncryptionHandler(name);

        (new EncryptionWorker()).execute(new EncryptorParams(algo, times));

        float batteryPercentageAfter = (new Battery(this)).percentage();
        Log.d("BATTERY", String.valueOf(batteryPercentageAfter));

        long timeAfter = System.currentTimeMillis();

        float batteryUsed = batteryPercentageBefore - batteryPercentageAfter;
        Log.d("BATTERY", "Change: " + String.valueOf(batteryUsed));
        long totalTime = timeAfter - timeBefore;

        String text = "It took " + Double.toString(totalTime/1000.0) + " seconds to run " + name
                + " algorithm " + Integer.toString(times) + " times, and it used " + Float.toString(batteryUsed) + "% of battery.";
        Toast.makeText(getApplicationContext(), text,
                Toast.LENGTH_LONG).show();
        lblEncryption.setText(text);
    }
    @Override
    public boolean onCreateOptionsMenu(Menu menu) {
        // Inflate the menu; this adds items to the action bar if it is present.
        getMenuInflater().inflate(R.menu.menu_encryption, 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();

        //noinspection SimplifiableIfStatement
        if (id == R.id.action_settings) {
            return true;
        }

        return super.onOptionsItemSelected(item);
    }

    private class EncryptionWorker extends AsyncTask<EncryptorParams, Integer, Integer> {
        private ProgressDialog dialog;

        @Override
        public void onPreExecute() {
            super.onPreExecute();

            this.dialog = new ProgressDialog(EncryptionActivity.this);
            this.dialog.setTitle("Encrypting");
            this.dialog.setMessage("Please wait. This may take a while");

            this.dialog.show();
        }

        @Override
        public Integer doInBackground(EncryptorParams... params) {
            for (int i = 0; i < params[0].rounds; i++) {
                try {
                    params[0].encryptor.encrypt("Performs the encryption algorithm", "the name of the encryption algorithm, can be: AES, 3DES, Blowfish");
                } catch (Exception e) {
                    Log.e("EXCEPTION", e.getMessage());
                    return 1;
                }
            }

            return 0;
        }

        @Override
        protected void onPostExecute(Integer result) {
            super.onPostExecute(result);

            this.dialog.dismiss();
        }
    }
}

Answer 1

My problem is that the main thread isn't waiting for the AsyncTask to finish the encryptions

这就是首先拥有后台线程的意义所在。

当 AsyncTask 完成它的工作时，无论你想做什么，输入 onPostExecute()。

Android 主线程不等待 AsyncTask

Android main thread not waiting for AsyncTask

java

concurrency

multithreading

android

android-asynctask