MediaRecorder第二次非法出现

Question

这是自我解释的。 mediarecorder类的start方法在调用它的第二个时抛出非法状态异常。我第一次按下按钮一切正常。第二次没有。我解决了很多问题，并且发现了什么是错的。我尝试了有关媒体录像机的其他问题的解决方案，但他们没有帮助。权限位于清单中。所以这不是问题，因为它第一次起作用。

MAIN

package com.boomer.omer.notetoself;

import android.app.Activity;
import android.support.v7.app.ActionBarActivity;
import android.os.Bundle;
import android.view.Menu;
import android.view.MenuItem;
import android.view.MotionEvent;
import android.view.View;
import android.widget.Button;
import android.widget.ProgressBar;


public class Activity_Main extends Activity implements View.OnTouchListener {

ProgressBar progressBar_record;
Button button_record;
Recorder recorder;

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);
    progressBar_record = (ProgressBar)findViewById(R.id.progressBar_recorder);
    button_record = (Button)findViewById(R.id.button_record);
    button_record.setOnTouchListener(this);
    recorder = null;
}


@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_activity_main, 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);
}

@Override
public boolean onTouch(View v, MotionEvent event) {

    switch(v.getId()){
        case R.id.button_record:
            if(event.getAction() == MotionEvent.ACTION_DOWN){
                button_record.setText("RECORDING");
                startRecorder();

            }else if (event.getAction() == MotionEvent.ACTION_UP){
                button_record.setText("RECORD");
                stopRecorder();
            }
            break;


    }



    return false;
}

public void startRecorder(){
    recorder = new Recorder(this,progressBar_record);
    recorder.execute();
}
public void stopRecorder(){
    progressBar_record.setProgress(0);
    recorder.cancel(true);
    recorder = null;

}



}

RECORDER CLASS

public class Recorder extends AsyncTask<Void,Integer,Void> {

public static final String LOG_TAG = "NTS:";
static final int MAX_LENGTH = 30;

MediaRecorder mRecorder;
String mFileName = null;

ProgressBar recordBar;
Activity parentActivity;

int mLength = 0;



public Recorder(Activity activity,ProgressBar progressBar) {
    super();
    mFileName = activity.getFilesDir().getAbsolutePath();
    mFileName += "/recentRecord.3gp";

    mRecorder = new MediaRecorder();
    mRecorder.setAudioSource(MediaRecorder.AudioSource.MIC);
    mRecorder.setOutputFormat(MediaRecorder.OutputFormat.THREE_GPP);
    mRecorder.setOutputFile(mFileName);
    mRecorder.setAudioEncoder(MediaRecorder.AudioEncoder.AMR_NB);

    recordBar = progressBar;
    parentActivity =activity;

}

public void startRecording(){

    try {
        mRecorder.prepare();
    } catch (IOException e) {
        Log.e(LOG_TAG, "prepare() failed");
    }

    mRecorder.start();

}

public void stopRecording(){

    mRecorder.stop();
    mRecorder.reset();
    mRecorder.release();
    mRecorder = null;
}

@Override
protected void onPreExecute() {
    super.onPreExecute();
    startRecording();

}

@Override
protected Void doInBackground(Void... params) {
    long secondMillis = System.currentTimeMillis();
   while(mLength < MAX_LENGTH){
       if((System.currentTimeMillis() - secondMillis) >= 1000){
           secondMillis = System.currentTimeMillis();
           mLength++;
           publishProgress(mLength);



       }
   }

    stopRecording();
    return null;
}

@Override
protected void onPostExecute(Void aVoid) {
    super.onPostExecute(aVoid);
    stopRecording();
}

@Override
protected void onProgressUpdate(Integer... values) {
    super.onProgressUpdate(values);
    recordBar.setProgress(values[0]);



}

@Override
protected void onCancelled(Void aVoid) {
    super.onCancelled(aVoid);
    stopRecording();

}

@Override
protected void onCancelled() {
    super.onCancelled();
    stopRecording();
}


 }