玩转 Android MediaPlayer之视频预加载
本文来自http://blog.csdn.net/hellogv/ ，引用必须注明出处！
本文是在《Android MediaPlayer与Http Proxy结合之提高篇》基础上，进一步优化代理服务器，支持了Http的302、301重定向，获取Http Request和Http Response的文本内容。本文以视频播放结合Http Proxy，讲述MediaPlayer播放过程中的握手过程。
吐槽一下：用google搜索“代理服务器”无效，所以本文用Media Proxy，大家懂的......
先来看看本文程序运行的截屏动画：
再来看看程序运行时输出的Log信息.....这里是关键：
07-29 15:51:30.692: E/HttpGetProxy(449): ..........sckPlayer connected.......... MediaPlayer发出请求
07-29 15:51:30.692: E/to Media Server---->(449): GET /vids/family_guy_penis_car.3gp HTTP/1.1
07-29 15:51:30.692: E/to Media Server---->(449): User-Agent: stagefright/1.0 (Linux;Android 2.2)
07-29 15:51:30.692: E/to Media Server---->(449): Host: daily3gp.com
07-29 15:51:30.692: E/to Media Server---->(449):
07-29 15:51:31.119: E/HttpGetProxy(449): ..........remote Server connected..........
07-29 15:51:31.122: E/HttpGetProxy(449): ..........remote start to receive..........
07-29 15:51:31.775: E/from Media Server---->(449): HTTP/1.1 200 OK
07-29 15:51:31.775: E/from Media Server---->(449): Date: Sun, 29 Jul 2012 15:51:33 GMT
07-29 15:51:31.775: E/from Media Server---->(449): Server: Apache
07-29 15:51:31.775: E/from Media Server---->(449): Last-Modified: Thu, 14 Jan 2010 23:29:02 GMT
07-29 15:51:31.775: E/from Media Server---->(449): Accept-Ranges: bytes
07-29 15:51:31.775: E/from Media Server---->(449): Content-Length: 754777
07-29 15:51:31.775: E/from Media Server---->(449): Content-Type: video/3gpp
07-29 15:51:34.512: E/HttpGetProxy(449): ..........sckPlayer connected..........MediaPlayer发出请求
07-29 15:51:34.532: E/to Media Server---->(449): GET /vids/family_guy_penis_car.3gp HTTP/1.1
07-29 15:51:34.532: E/to Media Server---->(449): User-Agent: stagefright/1.0 (Linux;Android 2.2)
07-29 15:51:34.532: E/to Media Server---->(449): Host: daily3gp.com
07-29 15:51:34.532: E/to Media Server---->(449): Range: bytes=720896-
07-29 15:51:34.532: E/to Media Server---->(449):
07-29 15:51:34.873: E/HttpGetProxy(449): ..........remote Server connected..........
07-29 15:51:34.873: E/HttpGetProxy(449): ..........remote start to receive..........
07-29 15:51:35.505: E/from Media Server---->(449): HTTP/1.1 206 Partial Content
07-29 15:51:35.505: E/from Media Server---->(449): Date: Sun, 29 Jul 2012 15:51:36 GMT
07-29 15:51:35.505: E/from Media Server---->(449): Server: Apache
07-29 15:51:35.505: E/from Media Server---->(449): Last-Modified: Thu, 14 Jan 2010 23:29:02 GMT
07-29 15:51:35.505: E/from Media Server---->(449): Accept-Ranges: bytes
07-29 15:51:35.505: E/from Media Server---->(449): Content-Length: 33881
07-29 15:51:35.505: E/from Media Server---->(449): Content-Range: bytes 720896-754776/754777
07-29 15:51:35.505: E/from Media Server---->(449): Content-Type: video/3gpp
07-29 15:51:38.754: E/HttpGetProxy(449): ..........over..........
07-29 15:51:51.461: E/HttpGetProxy(449): ..........sckPlayer connected..........MediaPlayer发出请求
07-29 15:51:51.471: E/to Media Server---->(449): GET /vids/family_guy_penis_car.3gp HTTP/1.1
07-29 15:51:51.471: E/to Media Server---->(449): User-Agent: stagefright/1.0 (Linux;Android 2.2)
07-29 15:51:51.471: E/to Media Server---->(449): Host: daily3gp.com
07-29 15:51:51.471: E/to Media Server---->(449): Range: bytes=196608-
07-29 15:51:51.471: E/to Media Server---->(449):
07-29 15:51:51.722: E/HttpGetProxy(449): ..........remote Server connected..........
07-29 15:51:51.722: E/HttpGetProxy(449): ..........remote start to receive..........
07-29 15:51:52.285: E/from Media Server---->(449): HTTP/1.1 206 Partial Content
07-29 15:51:52.285: E/from Media Server---->(449): Date: Sun, 29 Jul 2012 15:51:53 GMT
07-29 15:51:52.285: E/from Media Server---->(449): Server: Apache
07-29 15:51:52.285: E/from Media Server---->(449): Last-Modified: Thu, 14 Jan 2010 23:29:02 GMT
07-29 15:51:52.285: E/from Media Server---->(449): Accept-Ranges: bytes
07-29 15:51:52.285: E/from Media Server---->(449): Content-Length: 558169
07-29 15:51:52.285: E/from Media Server---->(449): Content-Range: bytes 196608-754776/754777
07-29 15:51:52.285: E/from Media Server---->(449): Content-Type: video/3gpp
07-29 15:51:54.812: E/HttpGetProxy(449): ..........sckPlayer connected..........MediaPlayer发出请求
07-29 15:51:54.822: E/to Media Server---->(449): GET /vids/family_guy_penis_car.3gp HTTP/1.1
07-29 15:51:54.822: E/to Media Server---->(449): User-Agent: stagefright/1.0 (Linux;Android 2.2)
07-29 15:51:54.822: E/to Media Server---->(449): Host: daily3gp.com
07-29 15:51:54.822: E/to Media Server---->(449): Range: bytes=589824-
07-29 15:51:54.822: E/to Media Server---->(449):
07-29 15:51:55.117: E/HttpGetProxy(449): ..........remote Server connected..........
07-29 15:51:55.117: E/HttpGetProxy(449): ..........remote start to receive..........
07-29 15:51:55.693: E/from Media Server---->(449): HTTP/1.1 206 Partial Content
07-29 15:51:55.693: E/from Media Server---->(449): Date: Sun, 29 Jul 2012 15:51:57 GMT
07-29 15:51:55.693: E/from Media Server---->(449): Server: Apache
07-29 15:51:55.693: E/from Media Server---->(449): Last-Modified: Thu, 14 Jan 2010 23:29:02 GMT
07-29 15:51:55.693: E/from Media Server---->(449): Accept-Ranges: bytes
07-29 15:51:55.693: E/from Media Server---->(449): Content-Length: 164953
07-29 15:51:55.693: E/from Media Server---->(449): Content-Range: bytes 589824-754776/754777
07-29 15:51:55.693: E/from Media Server---->(449): Content-Type: video/3gpp
07-29 15:51:59.620: E/HttpGetProxy(449): ..........over..........
从截屏动画和Log信息看出，手动seek一次，但MediaPlayer进行了多次Range请求，这说明了“MediaPlayer会自动seek”，或许与MediaPlayer本地缓存有关。另外，不同硬解厂家实现的MediaPlayer估计会有不同的操作。
本文的代码可以到这里下载:
http://download.csdn.net/detail/hellogv/4463651
HttpGetProxy.JAVA还是本文的关键部分：
- public class HttpGetProxy {
- final static private String TAG = "HttpGetProxy";
- final static private String LOCAL_IP_ADDRESS_1 = "127.0.0.1";
- final static private String LOCAL_IP_ADDRESS_2 = "10.0.2.2";
- final static private int HTTP_PORT = 80;
- final static private String HTTP_END="\r\n\r\n";
- /**代理服务器使用的端口*/
- private int proxy_ip_port;
- /**链接带的端口*/
- private String original_ip_port;
- /**远程服务器地址*/
- private String remoteHost;
- /**本地服务器地址*/
- private String localHost;
- private ServerSocket localServer = null;
- /**收发Media Player请求的Socket*/
- private Socket sckPlayer = null;
- /**收发Media Server请求的Socket*/
- private Socket sckServer = null;
- private SocketAddress address;
- /**
- * 初始化代理服务器
- * @param localport 代理服务器监听的端口
- */
- public HttpGetProxy(int localport) {
- try {
- _HttpGetProxy(LOCAL_IP_ADDRESS_1,localport);
- } catch (Exception e) {
- Log.e(TAG,LOCAL_IP_ADDRESS_1+"???"+e.toString());
- try {
- _HttpGetProxy(LOCAL_IP_ADDRESS_2,localport);
- }catch (Exception e1) {
- Log.e(TAG,LOCAL_IP_ADDRESS_2+"???"+e.toString());
- System.exit(0);
- }
- }
- }
- private void _HttpGetProxy(String ipAddress,int localport) throws UnknownHostException, IOException {
- proxy_ip_port=localport;
- localServer = new ServerSocket(localport,1,InetAddress.getByName(ipAddress));
- localHost=ipAddress;
- }
- /**
- * 把网络URL转为本地URL，127.0.0.1替换网络域名
- * @param url 网络URL
- * @return 本地URL
- */
- public String getLocalURL(String urlString){
- //----排除HTTP特殊----//
- String targetUrl=ProxyUtils.getRedirectUrl(urlString);
- //----获取对应本地代理服务器的链接----//
- String result = null;
- URI originalURI=URI.create(targetUrl);
- remoteHost=originalURI.getHost();
- if(originalURI.getPort()!=-1){//URL带Port
- address = new InetSocketAddress(remoteHost,originalURI.getPort());//使用默认端口
- original_ip_port = originalURI.getPort()+"";//保存端口，中转时替换
- result=targetUrl.replace(remoteHost+":"+originalURI.getPort(),
- localHost+":"+proxy_ip_port);
- }
- else{//URL不带Port
- address = new InetSocketAddress(remoteHost,HTTP_PORT);//使用80端口
- original_ip_port = "";
- result=targetUrl.replace(remoteHost,localHost+":"+proxy_ip_port);
- }
- return result;
- }
- /**
- * 启动代理服务器
- * @throws IOException
- */
- public void asynStartProxy(){
- new Thread() {
- public void run() {
- int bytes_read;
- byte[] local_request = new byte[1024];
- byte[] remote_reply = new byte[1024];
- while (true) {
- try {
- //--------------------------------------
- //监听MediaPlayer的请求，MediaPlayer->代理服务器
- //--------------------------------------
- sckPlayer = localServer.accept();
- Log.e(TAG, "..........sckPlayer connected..........");
- String requestStr = "";
- while ((bytes_read = sckPlayer.getInputStream().read(local_request)) != -1) {
- byte[] tmpBuffer=new byte[bytes_read];
- System.arraycopy(local_request,0,tmpBuffer,0,bytes_read);
- String str = new String(tmpBuffer);
- //Log.e("from MediaPlayer---->", str);
- requestStr = requestStr + str;
- if (requestStr.contains("GET")
- && requestStr.contains(HTTP_END)) {
- break;
- }
- }
- //把request中的本地ip改为远程ip
- requestStr = requestStr.replace(localHost,remoteHost);
- //把代理服务器端口改为原URL端口
- if(TextUtils.isEmpty(original_ip_port))
- requestStr = requestStr.replace(":"+proxy_ip_port, "");
- else
- requestStr = requestStr.replace(":"+proxy_ip_port, ":"+original_ip_port);
- Log.e("to Media Server---->", requestStr);
- //--------------------------------------
- //把MediaPlayer的请求发到网络服务器，代理服务器->网络服务器
- //--------------------------------------
- sckServer = new Socket();
- sckServer.connect(address);
- Log.e(TAG,"..........remote Server connected..........");
- sckServer.getOutputStream().write(requestStr.getBytes());//发送MediaPlayer的请求
- //------------------------------------------------------
- //把网络服务器的反馈发到MediaPlayer，网络服务器->代理服务器->MediaPlayer
- //------------------------------------------------------
- Log.e(TAG,"..........remote start to receive..........");
- String responseStr = "";
- boolean isCaptured=false;
- while ((bytes_read = sckServer.getInputStream().read(remote_reply)) != -1) {
- byte[] tmpBuffer=new byte[bytes_read];
- System.arraycopy(remote_reply,0,tmpBuffer,0,bytes_read);
- //----捕获收到的Response文本内容----//
- if (!isCaptured) {
- String str = new String(tmpBuffer);
- responseStr += str;
- if (responseStr.contains("HTTP/")
- && responseStr.contains(HTTP_END)) {
- int endIndex=responseStr.indexOf(HTTP_END, 0);
- responseStr=responseStr.substring(0, endIndex);
- Log.e("from Media Server---->", responseStr);
- isCaptured=true;
- }
- }
- sckPlayer.getOutputStream().write(tmpBuffer);
- sckPlayer.getOutputStream().flush();
- }
- Log.e(TAG, "..........over..........");
- //关闭对内，对内 2个SOCKET
- sckPlayer.close();
- sckServer.close();
- } catch (IOException e) {
- // TODO Auto-generated catch block
- e.printStackTrace();
- }
- }
- }
- }.start();
- }
- }