使用MediaRecorder和MediaPlayer实现录音和播放功能-以及碰到的问题

碰到的一些问题：

1. permission的问题，由于需要录音，同时需要把录音文件存入sdcard外部存储设备，需要两个权限。

<uses-permission android:name="android.permission.RECORD_AUDIO"/>
<uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE" />

2.  使用模拟器的时候，也许并没有sdcard外部设备，所以需要以下步骤在模拟器上模拟sdcard。

用“mksdcard 125M ./sdcard.img” 命令在当前文件夹下创建一个125m的镜像文件，

用“emulator -avd my_avd -sdcard ./sdcard.img” 命令

启动my_avd模拟器，同时mount sdcard.img镜像。

这样用“adb shell” 进入shell之后再sdcard目录下，可以写东西了。

3. 还有就是在MediaRecorder.setOutputFile(mPath);  如果mPath = "/sdcard/mvideo/a.3pg",不过sdcard文件夹中没有mvideo文件夹，那么就会爆filenotfindexception，所以在这个程序中用的是"/sdcard/a.3pg"路径。

java代码如下:

package test.exampleMediaRecordTest;


import android.app.Activity;
import android.media.MediaPlayer;
import android.media.MediaRecorder;
import android.os.Bundle;
import android.os.Environment;
import android.view.View;
import android.view.View.OnClickListener;
import android.widget.Button;
import android.widget.Toast;

public class MediaRecordTestActivity extends Activity {
    
	MediaRecorder mMediaRecorder;
	Button mStartButton;
	Button mEndButton;
	MediaPlayer mMediaPlayer;
	String mPath;
    
	
	/** Called when the activity is first created. */
    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.main);
        
        mMediaRecorder = new MediaRecorder();
        mMediaPlayer = new MediaPlayer();
        
        mPath = Environment.getExternalStorageDirectory().getAbsolutePath();
        mPath += "/a.3pg";
        
        mStartButton = (Button) findViewById(R.id.startbutton);
        mEndButton = (Button) findViewById(R.id.stopbutton);
        
        
        mStartButton.setOnClickListener(new OnClickListener() {
			
			@Override
			public void onClick(View v) {
				// TODO Auto-generated method stub
				
				try
				{
					mMediaRecorder.setAudioSource(MediaRecorder.AudioSource.MIC);
					
					mMediaRecorder.setOutputFormat(MediaRecorder.OutputFormat.THREE_GPP);
					
					mMediaRecorder.setAudioEncoder(MediaRecorder.AudioEncoder.DEFAULT);
					
					mMediaRecorder.setOutputFile(mPath);
					
					mMediaRecorder.prepare();
					
					mMediaRecorder.start();
					
				}
				catch(Exception e)
				{
					mMakeTextToast(e.toString(), true);
				}
				
				
			}
		});
        
        mEndButton.setOnClickListener(new OnClickListener() {
			
			@Override
			public void onClick(View v) {
				// TODO Auto-generated method stub
				
				try
				{
					
					mMediaRecorder.stop();
				
					mMediaPlayer.setDataSource(mPath);
					mMediaPlayer.prepare();
					mMediaPlayer.start();
					
				
				}
				catch(Exception e)
				{
					mMakeTextToast(e.toString(), true);
					e.printStackTrace();
				}
				
			}
		});
       
        
    }
    
    public void mMakeTextToast(String str, boolean isLong)
    {
        if(isLong==true)
        {
          Toast.makeText(this, str, Toast.LENGTH_LONG).show();
        }
        else
        {
          Toast.makeText(this, str, Toast.LENGTH_SHORT).show();
        }
    }
}

manifest.xml文件如下：

<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
    package="test.exampleMediaRecordTest"
    android:versionCode="1"
    android:versionName="1.0" >

    <uses-sdk android:minSdkVersion="7" />
	<uses-permission android:name="android.permission.RECORD_AUDIO"/>
	<uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE" />
    <application
        android:icon="@drawable/ic_launcher"
        android:label="@string/app_name" >
        <activity
            android:label="@string/app_name"
            android:name=".MediaRecordTestActivity" >
            <intent-filter >
                <action android:name="android.intent.action.MAIN" />

                <category android:name="android.intent.category.LAUNCHER" />
            </intent-filter>
        </activity>
    </application>
    
</manifest>

layout main.xml文件：

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="fill_parent"
    android:layout_height="fill_parent"
    android:orientation="vertical" >

    <TextView
        android:layout_width="fill_parent"
        android:layout_height="wrap_content"
        android:text="@string/hello" />
    
    <Button
        android:id="@+id/startbutton"
        android:text = "Record"
        android:layout_width = "fill_parent"
        android:layout_height="wrap_content"
        />

    <Button
        android:id="@+id/stopbutton"
        android:text = "End"
        android:layout_width = "fill_parent"
        android:layout_height="wrap_content"
        />
</LinearLayout>