Android的SDK在線API上對錄制視頻的方法、步驟都寫得非常清楚，但是如果沒有一點思路，寫起來也比較式費事。錄制視頻的全過程要打開閃光燈（可能是因為項目需要，或者特殊原因），則必須按照一定的順序進行開關，畢竟容易出錯。要實現錄制的同時開啟閃光燈也不難，官方API給出了一個大體的步驟.因為要采集點視頻數據，臨時寫了個簡單的Demo學習下，必要時再深度開發。
首先在工程中的AndroidManifest.xml中添加權限聲明，因為要使用到攝像頭，故需要添加Camera的相關權限，另外還需要寫SD卡的權限，如果同時需要錄制音頻，則還需要添加RECORD_AUDIO權限。
<uses-permission android:name="android.permission.CAMERA" />
<uses-feature android:name="android.hardware.camera" />
<uses-feature android:name="android.hardware.camera.autofocus" />
<uses-permission android:name="android.permission.RECORD_AUDIO"/>
<uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE" />
再來分析下要使用到的類，錄制視頻使用的MediaRecorder類，官方給出了調用MediaRecorder錄制視頻的一個簡單狀態機，展示了各個狀態之間的轉化。然後也給出了一個簡單的調用方法，代碼如下:
MediaRecorder recorder = new MediaRecorder();
recorder.setAudioSource(MediaRecorder.AudioSource.MIC);
recorder.setOutputFormat(MediaRecorder.OutputFormat.THREE_GPP);
recorder.setAudioEncoder(MediaRecorder.AudioEncoder.AMR_NB);
recorder.setOutputFile(PATH_NAME);
recorder.prepare();
recorder.start(); // Recording is now started
...
recorder.stop();
recorder.reset(); // You can reuse the object by going back to setAudioSource() step
recorder.release(); // Now the object cannot be reused
錄制視頻是調用MediaRecorder類，但API中真正介紹如何錄制視頻的一般步驟卻被放在了Camera類中，在線API上有句話提示“For more information about how to use MediaRecorder for recording video, read the Camera developer guide.”。轉到Camera類去看看。
Camera類是用來控制照相機的，沒錯，就是這個類。照相機可以用來拍照，也可以用來錄制視頻（也叫捕捉視頻），但是錄制視頻需要按照一定的步驟來編寫程序，不然發生運行時錯誤是非常正常的。錄制視頻需要調用Camera和MediaRecorder類，下面說說一般步驟。
1) 打開照相機。直接調用Camera.open()來獲取一個Camera的實例。
2) 設置預覽控件。一般是設置在SurfaceView上面，通過調用Camera.setPreviewDisplay()來完成，但是這一步也可以放到MediaRecorder類DataSourceConfigured步驟中完成。
3) 開啟預覽。調用Camera.startPreview()。
4) 開始錄制視頻。為了確保你錄制成功，請務必按要求完成下面的步驟。
A. 解鎖照相機。通過調用Camera.unlock()解鎖照相機，以便照相機被MediaRecorder使用。
B. 設置MediaRecorder。
這裡有一系列的設置，根據需要設置吧。比如說，你只需要錄制視頻，就不必設置音頻的輸入源，也就不用設置音頻的編碼方式。對應於MediaRecorder state diagram中的Initialized和DataSourceConfigured。具體方法調用可以查看Android在線API的MediaRecorder類，上文已經將主要的代碼貼出，下文還會貼出實例代碼，這裡就不詳細介紹了。
C. 准備MediaRecorder。在調用MediaRecorder.prepare()之前一定要先設置好MediaRecorder對象的各項屬性，後面設置會引發運行時錯誤。
D. 開始MediaRecorder。調用MediaRecorder.start()之後，就開始錄制視頻了。
5) 停止錄制。
A. 停止MediaRecorder。調用MediaRecorder.stop()停止錄制。
B. 恢復MediaRecorder的默認設置。調用MediaRecorder.reset()來取消你對MediaRecorder所做的設置，但調用玩之後，MediaRecorder對象還是可以再次使用的。
C. 釋放MediaRecorder對象。調用MediaRecorder.release()釋放資源，之後該MediaRecorder對象銷毀了，再調用會出錯。
D. 給Camera上鎖。為了後面的MediaRecorder對象可以再次使用,需要調用Camera.lock()，Android 4.0以後，這個操作並不是必須的，除非MediaRecorder.prepare()調用失敗。
6) 停止預覽，調用Camera.stopPreview()。
7) 釋放照相機資源，調用Camera.release()。
以上就是打開照相機錄制視頻的一般步驟，當然你可以可以在錄制之前實現預覽，決定什麼時間開始錄制，這個其實可以先開啟照相機進行預覽即可然後，需要錄制時調用Camera.unlock()，然後按流程接入MediaRecorder進行錄制。現在考慮第一種情況，直接開始錄制。
權限要求已經貼出來了，再貼個布局文件,recordvideo.xml。
<?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:background="#ffffff"
android:orientation="vertical" >
<SurfaceView
android:id="@+id/surfaceView"
android:layout_width="fill_parent"
android:layout_height="220dip" />
<LinearLayout
android:layout_width="fill_parent"
android:layout_height="wrap_content"
android:layout_marginLeft="5dp"
android:layout_marginRight="5dp"
android:layout_marginTop="20dp"
android:gravity="right"
android:orientation="horizontal" >
<EditText
android:id="@+id/rv_testusername"
android:layout_width="156dp"
android:layout_height="wrap_content"
android:layout_weight="0.27"
android:ems="10"
android:hint="輸入姓名或標識" />
<Button
android:id="@+id/rv_record"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:minHeight="40dp"
android:minWidth="70dp"
android:text="錄制" />
<Button
android:id="@+id/rv_stop"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_marginLeft="10dip"
android:minHeight="40dp"
android:minWidth="70dp"
android:text="停止" />
</LinearLayout>
<LinearLayout
android:layout_width="fill_parent"
android:layout_height="fill_parent"
android:gravity="center_horizontal"
android:orientation="vertical" >
<ProgressBar
android:id="@+id/rv_schedule"
android:layout_width="fill_parent"
android:layout_height="wrap_content" />
<TextView
android:id="@+id/rv_record_time"
android:layout_width="fill_parent"
android:layout_height="wrap_content"
android:gravity="center"
android:text="00:00:000"
android:textColor="#FF750000"
android:textSize="24sp"
android:text />
</LinearLayout>
</LinearLayout>
Activity代碼，因為非常簡單，就沒有封裝多線程什麼的。
import java.io.File;
import java.text.SimpleDateFormat;
import android.content.Context;
import android.content.pm.FeatureInfo;
import android.content.pm.PackageManager;
import android.hardware.Camera;
import android.media.MediaRecorder;
import android.os.Bundle;
import android.os.Environment;
import android.os.Handler;
import android.os.Message;
import android.support.v7.app.ActionBarActivity;
import android.util.Log;
import android.view.SurfaceHolder;
import android.view.SurfaceView;
import android.view.View;
import android.widget.Button;
import android.widget.EditText;
import android.widget.ProgressBar;
import android.widget.TextView;
import android.widget.Toast;
import com.ict.util.IOUtil;
public class RecordVideoActivity extends ActionBarActivity {
private static final String TAG = "RecordVideo";
private SurfaceView surfaceView;
private MediaRecorder mediaRecorder;
private boolean record;
private TextView testusername;
private Camera camera;
// 計時器相關
private MyChronograph myChronograph;
private TextView chronograph = null;
private ProgressBar schedule;
private boolean recordOver = false;
@Override
protected void onCreate(Bundle savedInstanceState) {
// TODO Auto-generated method stub
super.onCreate(savedInstanceState);
setContentView(R.layout.recordvideo);
setTitle("錄制視頻");
mediaRecorder = new MediaRecorder();
surfaceView = (SurfaceView) this.findViewById(R.id.surfaceView);
this.surfaceView.getHolder().setType(SurfaceHolder.SURFACE_TYPE_PUSH_BUFFERS);
this.surfaceView.getHolder().setFixedSize(320, 240);//設置分辨率
testusername = (EditText)findViewById(R.id.rv_testusername);
chronograph = (TextView)findViewById(R.id.rv_record_time);
schedule = (ProgressBar)findViewById(R.id.rv_schedule);
schedule.setMax(60);
ButtonClickListener listener = new ButtonClickListener();
Button stopButton = (Button) this.findViewById(R.id.rv_stop);
Button recordButton = (Button) this.findViewById(R.id.rv_record);
stopButton.setOnClickListener(listener);
recordButton.setOnClickListener(listener);
}
@Override
protected void onDestroy() {
// TODO Auto-generated method stub
if(mediaRecorder!=null)
mediaRecorder.release();
super.onDestroy();
}
@Override
protected void onPause() {
// TODO Auto-generated method stub
super.onPause();
}
@Override
protected void onResume() {
// TODO Auto-generated method stub
super.onResume();
}
private final class ButtonClickListener implements View.OnClickListener{
@Override
public void onClick(View v) {
if(!Environment.getExternalStorageState().equals(Environment.MEDIA_MOUNTED)){
Toast.makeText(RecordVideoActivity.this, "木有檢測到SD擴展卡", 1).show();
return ;
}
try {
switch (v.getId()) {
case R.id.rv_record:
// 要求輸入用戶名
String testuser;
if(testusername.getText()==null || testusername.getText().toString().equals("")){
Toast.makeText(RecordVideoActivity.this, "請輸入測試者姓名", Toast.LENGTH_LONG).show();
return;
}
Log.i(TAG,"檢測通過");
recordOver = false;
testuser = testusername.getText().toString();
testuser = android.os.Build.MODEL + "-" + testuser;
mediaRecorder.reset();
if(isSurportFlashlight(RecordVideoActivity.this)){
if (camera == null)
camera = Camera.open();
Camera.Parameters myParameters = camera.getParameters();
myParameters.setFlashMode(Camera.Parameters.FLASH_MODE_TORCH);
camera.setParameters(myParameters);
camera.startPreview();
camera.unlock();
mediaRecorder.setCamera(camera);
}
mediaRecorder.setVideoSource(MediaRecorder.VideoSource.CAMERA);
//mediaRecorder.setAudioSource(MediaRecorder.AudioSource.MIC);
mediaRecorder.setOutputFormat(MediaRecorder.OutputFormat.THREE_GPP);
mediaRecorder.setVideoSize(320, 240);
mediaRecorder.setVideoFrameRate(30); //每秒30幀
mediaRecorder.setVideoEncoder(MediaRecorder.VideoEncoder.H263);
//mediaRecorder.setAudioEncoder(MediaRecorder.AudioEncoder.AMR_NB);
SimpleDateFormat ff = new SimpleDateFormat("yyyy-MM-dd HH-mm-ss");
String recordTimeString = String.valueOf(ff.format(System.currentTimeMillis()));
File videoFile = IOUtil.CreateNewFile(Environment.getExternalStorageDirectory().getPath()+"/phonedoctor/video",
testuser + "-" + recordTimeString+".3gp",null);
mediaRecorder.setOutputFile(videoFile.getAbsolutePath());
mediaRecorder.setPreviewDisplay(surfaceView.getHolder().getSurface());
mediaRecorder.prepare();
mediaRecorder.start(); // 開始錄制
// 開啟計時線程
myChronograph = new MyChronograph(mHandler,60000);
myChronograph.start();
Toast.makeText(RecordVideoActivity.this, "開始錄制視頻!", Toast.LENGTH_SHORT).show();
record = true;
((Button)findViewById(R.id.rv_record)).setEnabled(false);
break;
case R.id.rv_stop:
if(record){
record = false;
mediaRecorder.stop();
mediaRecorder.reset();
Log.i(TAG,"TAG-1");
if(camera!=null){
camera.lock();
camera.stopPreview();
Camera.Parameters myParameters = camera.getParameters();
myParameters.setFlashMode(Camera.Parameters.FLASH_MODE_OFF);
camera.setParameters(myParameters);
camera.release();
camera = null;
}
// 秒表線程控制
if(myChronograph!=null){
myChronograph.exit();
myChronograph = null;
}
((Button)findViewById(R.id.rv_record)).setEnabled(true);
}
break;
}
} catch (Exception e) {
Toast.makeText(RecordVideoActivity.this, "發生異常", 1).show();
e.printStackTrace();
}
}
}
private Handler mHandler = new Handler(){
@Override
public void handleMessage(Message msg) {
String[] strMsg;
switch (msg.what) {
case MsgNumber.UPTIME_UI:
strMsg = (String[]) msg.obj;
chronograph.setText(strMsg[0]);
if(!recordOver){
int percent = Integer.parseInt(strMsg[1]);
if(percent==-1){
recordOver = true;
schedule.setProgress(60);
Toast.makeText(RecordVideoActivity.this, "已錄制一分鐘!", Toast.LENGTH_SHORT).show();
return;
}
percent = percent>60?60:percent;
schedule.setProgress(percent);
}
break;
default:
break;
}
}
};
// 閃光燈判斷
public boolean isSurportFlashlight(Context context) {
boolean flag = false;
PackageManager pm = context.getPackageManager();
FeatureInfo[] features = pm.getSystemAvailableFeatures();
for (FeatureInfo f : features) {
if (PackageManager.FEATURE_CAMERA_FLASH.equals(f.name)) {
flag = true;
break;
}
}
return flag;
}
}
Activity代碼，因為非常簡單，就沒有封裝多線程什麼的。
import java.io.File;
import java.text.SimpleDateFormat;
import android.content.Context;
import android.content.pm.FeatureInfo;
import android.content.pm.PackageManager;
import android.hardware.Camera;
import android.media.MediaRecorder;
import android.os.Bundle;
import android.os.Environment;
import android.os.Handler;
import android.os.Message;
import android.support.v7.app.ActionBarActivity;
import android.util.Log;
import android.view.SurfaceHolder;
import android.view.SurfaceView;
import android.view.View;
import android.widget.Button;
import android.widget.EditText;
import android.widget.ProgressBar;
import android.widget.TextView;
import android.widget.Toast;
import com.ict.util.IOUtil;
public class RecordVideoActivity extends ActionBarActivity {
private static final String TAG = "RecordVideo";
private SurfaceView surfaceView;
private MediaRecorder mediaRecorder;
private boolean record;
private TextView testusername;
private Camera camera;
// 計時器相關
private MyChronograph myChronograph;
private TextView chronograph = null;
private ProgressBar schedule;
private boolean recordOver = false;
@Override
protected void onCreate(Bundle savedInstanceState) {
// TODO Auto-generated method stub
super.onCreate(savedInstanceState);
setContentView(R.layout.recordvideo);
setTitle("錄制視頻");
mediaRecorder = new MediaRecorder();
surfaceView = (SurfaceView) this.findViewById(R.id.surfaceView);
this.surfaceView.getHolder().setType(SurfaceHolder.SURFACE_TYPE_PUSH_BUFFERS);
this.surfaceView.getHolder().setFixedSize(320, 240);//設置分辨率
testusername = (EditText)findViewById(R.id.rv_testusername);
chronograph = (TextView)findViewById(R.id.rv_record_time);
schedule = (ProgressBar)findViewById(R.id.rv_schedule);
schedule.setMax(60);
ButtonClickListener listener = new ButtonClickListener();
Button stopButton = (Button) this.findViewById(R.id.rv_stop);
Button recordButton = (Button) this.findViewById(R.id.rv_record);
stopButton.setOnClickListener(listener);
recordButton.setOnClickListener(listener);
}
@Override
protected void onDestroy() {
// TODO Auto-generated method stub
if(mediaRecorder!=null)
mediaRecorder.release();
super.onDestroy();
}
@Override
protected void onPause() {
// TODO Auto-generated method stub
super.onPause();
}
@Override
protected void onResume() {
// TODO Auto-generated method stub
super.onResume();
}
private final class ButtonClickListener implements View.OnClickListener{
@Override
public void onClick(View v) {
if(!Environment.getExternalStorageState().equals(Environment.MEDIA_MOUNTED)){
Toast.makeText(RecordVideoActivity.this, "木有檢測到SD擴展卡", 1).show();
return ;
}
try {
switch (v.getId()) {
case R.id.rv_record:
// 要求輸入用戶名
String testuser;
if(testusername.getText()==null || testusername.getText().toString().equals("")){
Toast.makeText(RecordVideoActivity.this, "請輸入測試者姓名", Toast.LENGTH_LONG).show();
return;
}
Log.i(TAG,"檢測通過");
recordOver = false;
testuser = testusername.getText().toString();
testuser = android.os.Build.MODEL + "-" + testuser;
mediaRecorder.reset();
if(isSurportFlashlight(RecordVideoActivity.this)){
if (camera == null)
camera = Camera.open();
Camera.Parameters myParameters = camera.getParameters();
myParameters.setFlashMode(Camera.Parameters.FLASH_MODE_TORCH);
camera.setParameters(myParameters);
camera.startPreview();
camera.unlock();
mediaRecorder.setCamera(camera);
}
mediaRecorder.setVideoSource(MediaRecorder.VideoSource.CAMERA);
//mediaRecorder.setAudioSource(MediaRecorder.AudioSource.MIC);
mediaRecorder.setOutputFormat(MediaRecorder.OutputFormat.THREE_GPP);
mediaRecorder.setVideoSize(320, 240);
mediaRecorder.setVideoFrameRate(30); //每秒30幀
mediaRecorder.setVideoEncoder(MediaRecorder.VideoEncoder.H263);
//mediaRecorder.setAudioEncoder(MediaRecorder.AudioEncoder.AMR_NB);
SimpleDateFormat ff = new SimpleDateFormat("yyyy-MM-dd HH-mm-ss");
String recordTimeString = String.valueOf(ff.format(System.currentTimeMillis()));
File videoFile = IOUtil.CreateNewFile(Environment.getExternalStorageDirectory().getPath()+"/phonedoctor/video",
testuser + "-" + recordTimeString+".3gp",null);
mediaRecorder.setOutputFile(videoFile.getAbsolutePath());
mediaRecorder.setPreviewDisplay(surfaceView.getHolder().getSurface());
mediaRecorder.prepare();
mediaRecorder.start(); // 開始錄制
// 開啟計時線程
myChronograph = new MyChronograph(mHandler,60000);
myChronograph.start();
Toast.makeText(RecordVideoActivity.this, "開始錄制視頻!", Toast.LENGTH_SHORT).show();
record = true;
((Button)findViewById(R.id.rv_record)).setEnabled(false);
break;
case R.id.rv_stop:
if(record){
record = false;
mediaRecorder.stop();
mediaRecorder.reset();
Log.i(TAG,"TAG-1");
if(camera!=null){
camera.lock();
camera.stopPreview();
Camera.Parameters myParameters = camera.getParameters();
myParameters.setFlashMode(Camera.Parameters.FLASH_MODE_OFF);
camera.setParameters(myParameters);
camera.release();
camera = null;
}
// 秒表線程控制
if(myChronograph!=null){
myChronograph.exit();
myChronograph = null;
}
((Button)findViewById(R.id.rv_record)).setEnabled(true);
}
break;
}
} catch (Exception e) {
Toast.makeText(RecordVideoActivity.this, "發生異常", 1).show();
e.printStackTrace();
}
}
}
private Handler mHandler = new Handler(){
@Override
public void handleMessage(Message msg) {
String[] strMsg;
switch (msg.what) {
case MsgNumber.UPTIME_UI:
strMsg = (String[]) msg.obj;
chronograph.setText(strMsg[0]);
if(!recordOver){
int percent = Integer.parseInt(strMsg[1]);
if(percent==-1){
recordOver = true;
schedule.setProgress(60);
Toast.makeText(RecordVideoActivity.this, "已錄制一分鐘!", Toast.LENGTH_SHORT).show();
return;
}
percent = percent>60?60:percent;
schedule.setProgress(percent);
}
break;
default:
break;
}
}
};
// 閃光燈判斷
public boolean isSurportFlashlight(Context context) {
boolean flag = false;
PackageManager pm = context.getPackageManager();
FeatureInfo[] features = pm.getSystemAvailableFeatures();
for (FeatureInfo f : features) {
if (PackageManager.FEATURE_CAMERA_FLASH.equals(f.name)) {
flag = true;
break;
}
}
return flag;
}
}
運行效果圖
至此，主要代碼已經貼出，沒什麼技術含量，算是Android學習過程中的一個小結，Android在線API的一個閱讀筆記。
更多Android相關信息見Android 專題頁面 http://www.linuxidc.com/topicnews.aspx?tid=11
