如何在Android中利用MediaRecorder实现一个录像功能

<uses-permission android:name="android.permission.CAMERA" />
<uses-permission android:name="android.permission.RECORD_AUDIO" />
<uses-permission android:name="android.permission.MOUNT_UNMOUNT_FILESYSTEMS" />
<uses-permission android:name="android.permission.READ_EXTERNAL_STORAGE" />
<uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE"/>
<!-- 硬件支持 -->
<uses-feature android:name="android.hardware.camera"/>
<uses-feature android:name="android.hardware.camera.autofocus"/>
activity_main.xml
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
 xmlns:tools="http://schemas.android.com/tools"
 android:layout_width="match_parent"
 android:layout_height="match_parent" >

 <SurfaceView
 android:id="@+id/camera_preview"
 android:layout_width="match_parent"
 android:layout_height="match_parent" />

 <LinearLayout
 android:layout_width="wrap_content"
 android:layout_height="wrap_content"
 android:layout_alignParentTop="true"
 android:layout_centerHorizontal="true"
 android:orientation="horizontal">

 <TextView
  android:id="@+id/timestamp_minute_prefix"
  android:layout_width="wrap_content"
  android:layout_height="wrap_content"
  android:textColor="#7F00FF"
  android:textSize="30sp"
  android:text="0"/>

 <TextView
  android:id="@+id/timestamp_minute_text"
  android:layout_width="wrap_content"
  android:layout_height="wrap_content"
  android:textColor="#7F00FF"
  android:textSize="30sp"
  android:text="0"/>

 <TextView
  android:layout_width="wrap_content"
  android:layout_height="wrap_content"
  android:textColor="#7F00FF"
  android:textSize="30sp"
  android:text=":"/>

 <TextView
  android:id="@+id/timestamp_second_prefix"
  android:layout_width="wrap_content"
  android:layout_height="wrap_content"
  android:textColor="#7F00FF"
  android:textSize="30sp"
  android:text="0"/>

 <TextView
  android:id="@+id/timestamp_second_text"
  android:layout_width="wrap_content"
  android:layout_height="wrap_content"
  android:textColor="#7F00FF"
  android:textSize="30sp"
  android:text="0"/>
 </LinearLayout>

 <ImageButton
 android:id="@+id/record_shutter"
 android:layout_width="64dp"
 android:layout_height="64dp"
 android:layout_alignParentBottom="true"
 android:layout_centerHorizontal="true"
 android:layout_marginBottom="15dp"
 android:background="@android:color/transparent"
 android:scaleType="centerCrop"
 android:src="@drawable/recording_shutter" />

</RelativeLayout>

package com.jackie.videorecorder;

import java.io.File;

import android.app.Activity;
import android.hardware.Camera;
import android.hardware.Camera.Parameters;
import android.hardware.Camera.Size;
import android.media.MediaRecorder;
import android.os.Bundle;
import android.os.Environment;
import android.os.Handler;
import android.util.Log;
import android.view.SurfaceHolder;
import android.view.SurfaceView;
import android.view.View;
import android.view.View.OnClickListener;
import android.widget.ImageButton;
import android.widget.TextView;

import org.w3c.dom.Text;

public class MainActivity extends Activity implements OnClickListener {
 private SurfaceView mCameraPreview;
 private SurfaceHolder mSurfaceHolder;
 private ImageButton mShutter;
 private TextView mMinutePrefix;
 private TextView mMinuteText;
 private TextView mSecondPrefix;
 private TextView mSecondText;

 private Camera mCamera;
 private MediaRecorder mRecorder;

 private final static int CAMERA_ID = 0;

 private boolean mIsRecording = false;
 private boolean mIsSufaceCreated = false;

 private static final String TAG = "Jackie";

 private Handler mHandler = new Handler();

 @Override
 protected void onCreate(Bundle savedInstanceState) {
 super.onCreate(savedInstanceState);
 setContentView(R.layout.activity_main);

 mCameraPreview = (SurfaceView) findViewById(R.id.camera_preview);
 mMinutePrefix = (TextView) findViewById(R.id.timestamp_minute_prefix);
 mMinuteText = (TextView) findViewById(R.id.timestamp_minute_text);
 mSecondPrefix = (TextView) findViewById(R.id.timestamp_second_prefix);
 mSecondText = (TextView) findViewById(R.id.timestamp_second_text);

 mSurfaceHolder = mCameraPreview.getHolder();
 mSurfaceHolder.addCallback(mSurfaceCallback);
 mSurfaceHolder.setType(SurfaceHolder.SURFACE_TYPE_PUSH_BUFFERS);

 mShutter = (ImageButton) findViewById(R.id.record_shutter);
 mShutter.setOnClickListener(this);
 }

 @Override
 protected void onPause() {
 super.onPause();
 if (mIsRecording) {
  stopRecording();
 }
 stopPreview();
 }

 private SurfaceHolder.Callback mSurfaceCallback = new SurfaceHolder.Callback() {

 @Override
 public void surfaceDestroyed(SurfaceHolder holder) {
  mIsSufaceCreated = false;
 }

 @Override
 public void surfaceCreated(SurfaceHolder holder) {
  mIsSufaceCreated = true;
 }

 @Override
 public void surfaceChanged(SurfaceHolder holder, int format, int width, int height) {
  startPreview();
 }
 };

 //启动预览
 private void startPreview() {
 //保证仅仅有一个Camera对象
 if (mCamera != null || !mIsSufaceCreated) {
  Log.d(TAG, "startPreview will return");
  return;
 }

 mCamera = Camera.open(CAMERA_ID);

 Parameters parameters = mCamera.getParameters();
 Size size = getBestPreviewSize(CameraUtils.PREVIEW_WIDTH, CameraUtils.PREVIEW_HEIGHT, parameters);
 if (size != null) {
  parameters.setPreviewSize(size.width, size.height);
 }

 parameters.setFocusMode(Parameters.FOCUS_MODE_CONTINUOUS_VIDEO);
 parameters.setPreviewFrameRate(20);

 //设置相机预览方向
 mCamera.setDisplayOrientation(90);

 mCamera.setParameters(parameters);

 try {
  mCamera.setPreviewDisplay(mSurfaceHolder);
// mCamera.setPreviewCallback(mPreviewCallback);
 } catch (Exception e) {
  Log.d(TAG, e.getMessage());
 }

 mCamera.startPreview();
 }

 private void stopPreview() {
 //释放Camera对象
 if (mCamera != null) {
  try {
  mCamera.setPreviewDisplay(null);
  } catch (Exception e) {
  Log.e(TAG, e.getMessage());
  }

  mCamera.stopPreview();
  mCamera.release();
  mCamera = null;
 }
 }

 private Camera.Size getBestPreviewSize(int width, int height, Camera.Parameters parameters) {
 Camera.Size result = null;

 for (Camera.Size size : parameters.getSupportedPreviewSizes()) {
  if (size.width <= width && size.height <= height) {
  if (result == null) {
   result = size;
  } else {
   int resultArea = result.width * result.height;
   int newArea = size.width * size.height;

   if (newArea > resultArea) {
   result = size;
   }
  }
  }
 }

 return result;
 }

 @Override
 public void onClick(View v) {
 if (mIsRecording) {
  stopRecording();
 } else {
  initMediaRecorder();
  startRecording();

  //開始录像后，每隔1s去更新录像的时间戳
  mHandler.postDelayed(mTimestampRunnable, 1000);
 }
 }

 private void initMediaRecorder() {
 mRecorder = new MediaRecorder();//实例化
 mCamera.unlock();
 //给Recorder设置Camera对象，保证录像跟预览的方向保持一致
 mRecorder.setCamera(mCamera);
 mRecorder.setOrientationHint(90); //改变保存后的视频文件播放时是否横屏(不加这句。视频文件播放的时候角度是反的)
 mRecorder.setAudioSource(MediaRecorder.AudioSource.MIC); // 设置从麦克风採集声音
 mRecorder.setVideoSource(MediaRecorder.VideoSource.CAMERA); // 设置从摄像头採集图像
 mRecorder.setOutputFormat(MediaRecorder.OutputFormat.MPEG_4); // 设置视频的输出格式 为MP4
 mRecorder.setAudioEncoder(MediaRecorder.AudioEncoder.DEFAULT); // 设置音频的编码格式
 mRecorder.setVideoEncoder(MediaRecorder.VideoEncoder.H264); // 设置视频的编码格式
 mRecorder.setVideoSize(176, 144); // 设置视频大小
 mRecorder.setVideoFrameRate(20); // 设置帧率
// mRecorder.setMaxDuration(10000); //设置最大录像时间为10s
 mRecorder.setPreviewDisplay(mSurfaceHolder.getSurface());

 //设置视频存储路径
 File file = new File(Environment.getExternalStoragePublicDirectory(Environment.DIRECTORY_MOVIES) + File.separator + "VideoRecorder");
 if (!file.exists()) {
  //多级目录的创建
  file.mkdirs();
 }
 mRecorder.setOutputFile(file.getPath() + File.separator + "VID_" + System.currentTimeMillis() + ".mp4");
 }

 private void startRecording() {
 if (mRecorder != null) {
  try {
  mRecorder.prepare();
  mRecorder.start();
  } catch (Exception e) {
  mIsRecording = false;
  Log.e(TAG, e.getMessage());
  }
 }

 mShutter.setImageDrawable(getResources().getDrawable(R.drawable.recording_shutter_hl));
 mIsRecording = true;
 }

 private void stopRecording() {
 if (mCamera != null) {
  mCamera.lock();
 }

 if (mRecorder != null) {
  mRecorder.stop();
  mRecorder.release();
  mRecorder = null;
 }

 mShutter.setImageDrawable(getResources().getDrawable(R.drawable.recording_shutter));
 mIsRecording = false;

 mHandler.removeCallbacks(mTimestampRunnable);

 //将录像时间还原
 mMinutePrefix.setVisibility(View.VISIBLE);
 mMinuteText.setText("0");
 mSecondPrefix.setVisibility(View.VISIBLE);
 mSecondText.setText("0");

 //重新启动预览
 startPreview();
 }

 private Runnable mTimestampRunnable = new Runnable() {
 @Override
 public void run() {
  updateTimestamp();
  mHandler.postDelayed(this, 1000);
 }
 };

 private void updateTimestamp() {
 int second = Integer.parseInt(mSecondText.getText().toString());
 int minute = Integer.parseInt(mMinuteText.getText().toString());
 second++;
 Log.d(TAG, "second: " + second);

 if (second < 10) {
  mSecondText.setText(String.valueOf(second));
 } else if (second >= 10 && second < 60) {
  mSecondPrefix.setVisibility(View.GONE);
  mSecondText.setText(String.valueOf(second));
 } else if (second >= 60) {
  mSecondPrefix.setVisibility(View.VISIBLE);
  mSecondText.setText("0");

  minute++;
  mMinuteText.setText(String.valueOf(minute));
 } else if (minute >= 60) {
  mMinutePrefix.setVisibility(View.GONE);
 }
 }
}