Creare programma di Registrazione per Android

Avete necessità di integrare nella vostra applicazione android un registratore di suoni?
Seguendo questa breve guida ci riuscirete in pochi minuti.
Vi occorrerrà solo:

1. Creare una classe MainActivity.java
2. Creare un layout MainActivity.xml
3. Modificare il Manifest.

La classe MainActivity.java

import android.app.Activity;
import android.widget.LinearLayout;
import android.os.Bundle;
import android.os.Environment;
import android.view.ViewGroup;
import android.widget.Button;
import android.view.View;
import android.view.View.OnClickListener;
import android.content.Context;
import android.util.Log;
import android.media.MediaRecorder;
import android.media.MediaPlayer;
import java.io.IOException;
public class MainActivity extends Activity
{
private static final String LOG_TAG = “AudioRecordTest”;
private static String mFileName = null;
private RecordButton mRecordButton = null;
private MediaRecorder mRecorder = null;
private PlayButton   mPlayButton = null;
private MediaPlayer   mPlayer = null;
private void onRecord(boolean start) {
if (start) {
startRecording();
} else {
stopRecording();
}
}
private void onPlay(boolean start) {
if (start) {
startPlaying();
} else {
stopPlaying();
}
}
private void startPlaying() {
mPlayer = new MediaPlayer();
try {
mPlayer.setDataSource(mFileName);
mPlayer.prepare();
mPlayer.start();
} catch (IOException e) {
Log.e(LOG_TAG, “prepare() failed”);
}
}
private void stopPlaying() {
mPlayer.release();
mPlayer = null;
}
private void startRecording() {
mRecorder = new MediaRecorder();
mRecorder.setAudioSource(MediaRecorder.AudioSource.MIC);
mRecorder.setOutputFormat(MediaRecorder.OutputFormat.THREE_GPP);
mRecorder.setOutputFile(mFileName);
mRecorder.setAudioEncoder(MediaRecorder.AudioEncoder.AMR_NB);
try {
mRecorder.prepare();
} catch (IOException e) {
Log.e(LOG_TAG, “prepare() failed”);
}
mRecorder.start();
}
private void stopRecording() {
mRecorder.stop();
mRecorder.release();
mRecorder = null;
}
class RecordButton extends Button {
boolean mStartRecording = true;
OnClickListener clicker = new OnClickListener() {
public void onClick(View v) {
onRecord(mStartRecording);
if (mStartRecording) {
setText(“Stop recording”);
} else {
setText(“Start recording”);
}
mStartRecording = !mStartRecording;
}
};
public RecordButton(Context ctx) {
super(ctx);
setText(“Start recording”);
setOnClickListener(clicker);
}
}
class PlayButton extends Button {
boolean mStartPlaying = true;
OnClickListener clicker = new OnClickListener() {
public void onClick(View v) {
onPlay(mStartPlaying);
if (mStartPlaying) {
setText(“Stop playing”);
} else {
setText(“Start playing”);
}
mStartPlaying = !mStartPlaying;
}
};
public PlayButton(Context ctx) {
super(ctx);
setText(“Start playing”);
setOnClickListener(clicker);
}
}
public MainActivity() {
mFileName = Environment.getExternalStorageDirectory().getAbsolutePath();
mFileName += “/audiorecordtest.3gp”;
}
@Override
public void onCreate(Bundle icicle) {
super.onCreate(icicle);
LinearLayout ll = new LinearLayout(this);
mRecordButton = new RecordButton(this);
ll.addView(mRecordButton,
new LinearLayout.LayoutParams(
ViewGroup.LayoutParams.WRAP_CONTENT,
ViewGroup.LayoutParams.WRAP_CONTENT,
0));
mPlayButton = new PlayButton(this);
ll.addView(mPlayButton,
new LinearLayout.LayoutParams(
ViewGroup.LayoutParams.WRAP_CONTENT,
ViewGroup.LayoutParams.WRAP_CONTENT,
0));
setContentView(ll);
}
@Override
public void onPause() {
super.onPause();
if (mRecorder != null) {
mRecorder.release();
mRecorder = null;
}
if (mPlayer != null) {
mPlayer.release();
mPlayer = null;
}
}
}

Il layout MainActivity .xml

<RelativeLayout xmlns:android=”http://schemas.android.com/apk/res/android&#8221;
xmlns:tools=”http://schemas.android.com/tools&#8221;
android:layout_width=”match_parent”
android:layout_height=”match_parent”
tools:context=”.MainActivity” >
</RelativeLayout>

Il Manifest.xml

<?xml version=”1.0″ encoding=”utf-8″?>
<manifest xmlns:android=”http://schemas.android.com/apk/res/android&#8221;
package=”com.example.registratore”
android:versionCode=”1″
android:versionName=”1.0″ >
<uses-sdk
android:minSdkVersion=”8″
android:targetSdkVersion=”17″ />
<uses-permission android:name=”android.permission.RECORD_AUDIO”/>
<uses-permission android:name=”android.permission.WRITE_EXTERNAL_STORAGE”/>
<application
android:allowBackup=”true”
android:icon=”@drawable/ic_launcher”
android:label=”@string/app_name”
android:theme=”@style/AppTheme” >
<activity
android:name=”com.example.registratore.MainActivity”
android:label=”@string/app_name” >
<intent-filter>
<action android:name=”android.intent.action.MAIN” />
<category android:name=”android.intent.category.LAUNCHER” />
</intent-filter>
</activity>
</application>
</manifest>

Avviate l’app e vi compariranno due pulsanti per far partire e stoppare la registrazione audio.
Come avrete notato i permessi richiesti riguardano la scrittura su memoria esterna e la registrazione audio, infatti il file registrato si troverà nella root della vostra memoria esterna!