Android多媒体框架包含获取和编码多种音频格式的支持,所以你可以轻松地把音频合并到你的应用中.如果设备支持,你可以使用MediaRecorder APIs 进行录音.
本章向你展示如何写一个应用从设备上的microphone获取音频,然后保存并回放.
注:Android模拟器不具有录音的能力,但是真实的设备一般都具有此功能.
执行音频获取
从设备获取音频比回放音频或视频要复杂一点,但是也还算简单:
- 创建一个android.media.MediaRecorder的新实例.
- 使用MediaRecorder.setAudioSource()设置音频源,一般要使用MediaRecorder.AudioSource.MIC.
- 使用MediaRecorder.setOutputFormat()设置输出文件的格式.
- 使用MediaRecorder.setOutputFile()设置输出文件的名字.
- 使用MediaRecorder.setAudioEncoder()设置音频编码.
- 调用MediaRecorder 实例的MediaRecorder.prepare().
- MediaRecorder.start()开始获取音频.
- 调用MediaRecorder.stop().停止.
- 当你用完MediaRecorder实例后,调用MediaRecorder.release(),就会立即释放资源.
示例:录音并回放录音
下面的例子演示了如何设置,开始以及停止音频获取,以及回放录制的文件.
- /*
- * 如果输出文件被写入外部存储,
- * 本应用需要具有写外部存储的权限,
- * 还要具有录音的权限.这些权限必须
- * 在AndroidManifest.xml 文件中声明,像这样:
- *
- * <uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE" />
- * <uses-permission android:name="android.permission.RECORD_AUDIO" />
- *
- */
- package com.android.audiorecordtest;
- 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 AudioRecordTest extends Activity
- {
- private static final String LOG_TAG = "AudioRecordTest";
- private static String mFileName = null;
- //录音按钮
- private RecordButton mRecordButton = null;
- private MediaRecorder mRecorder = null;
- //回放按钮
- private PlayButton mPlayButton = null;
- private MediaPlayer mPlayer = null;
- //当录音按钮被click时调用此方法,开始或停止录音
- private void onRecord(boolean start) {
- if (start) {
- startRecording();
- } else {
- stopRecording();
- }
- }
- //当播放按钮被click时调用此方法,开始或停止播放
- private void onPlay(boolean start) {
- if (start) {
- startPlaying();
- } else {
- stopPlaying();
- }
- }
- private void startPlaying() {
- mPlayer = new MediaPlayer();
- try {
- //设置要播放的文件
- mPlayer.setDataSource(mFileName);
- mPlayer.prepare();
- //播放之
- mPlayer.start();
- } catch (IOException e) {
- Log.e(LOG_TAG, "prepare() failed");
- }
- }
- //停止播放
- private void stopPlaying() {
- mPlayer.release();
- mPlayer = null;
- }
- private void startRecording() {
- mRecorder = new MediaRecorder();
- //设置音源为Micphone
- mRecorder.setAudioSource(MediaRecorder.AudioSource.MIC);
- //设置封装格式
- mRecorder.setOutputFormat(MediaRecorder.OutputFormat.THREE_GPP);
- mRecorder.setOutputFile(mFileName);
- //设置编码格式
- 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;
- }
- //定义录音按钮
- 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);
- }
- }
- //定义播放按钮
- 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);
- }
- }
- //构造方法
- public AudioRecordTest() {
- mFileName = Environment.getExternalStorageDirectory().getAbsolutePath();
- mFileName += "/audiorecordtest.3gp";
- }
- @Override
- public void onCreate(Bundle icicle) {
- super.onCreate(icicle);
- //构造界面
- 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();
- //Activity暂停时释放录音和播放对象
- if (mRecorder != null) {
- mRecorder.release();
- mRecorder = null;
- }
- if (mPlayer != null) {
- mPlayer.release();
- mPlayer = null;
- }
- }
- }