MyHandler对'desc'消息的处理

本文主要是介绍MyHandler对'desc'消息的处理，希望对大家解决编程问题提供一定的参考价值，需要的开发者们随着小编来一起学习吧！

            case 'desc':{//从消息msg里的"result"字段得到错误码的值int32_t result;CHECK(msg->findInt32("result", &result));ALOGI("DESCRIBE completed with result %d (%s)",result, strerror(-result));if (result == OK) {//如果result的值为OK，说明成功收到了服务端发送过来的应答消息//从消息msg的"response"字段获取服务端发送过来的应答消息对象responsesp<RefBase> obj;CHECK(msg->findObject("response", &obj));sp<ARTSPResponse> response =static_cast<ARTSPResponse *>(obj.get());if (response->mStatusCode == 301 || response->mStatusCode == 302) {//对从服务端发送过来的应答消息的状态码为301或者302的情况进行处理//本文不分析对301,301状态码的处理流程ssize_t i = response->mHeaders.indexOfKey("location");CHECK_GE(i, 0);mOriginalSessionURL = response->mHeaders.valueAt(i);mSessionURL = mOriginalSessionURL;// Strip any authentication info from the session url, we don't// want to transmit user/pass in cleartext.AString host, path, user, pass;unsigned port;if (ARTSPConnection::ParseURL(mSessionURL.c_str(), &host, &port, &path, &user, &pass)&& user.size() > 0) {mSessionURL.clear();mSessionURL.append("rtsp://");mSessionURL.append(host);mSessionURL.append(":");mSessionURL.append(AStringPrintf("%u", port));mSessionURL.append(path);ALOGI("rewritten session url: '%s'", mSessionURL.c_str());}sp<AMessage> reply = new AMessage('conn', this);mConn->connect(mOriginalSessionURL.c_str(), reply);break;}//代码执行到这里说明该从服务端发送过来的应答消息的//状态码不为301,302if (response->mStatusCode != 200) {//如果状态码不为200，将错误码UNKNOWN_ERROR赋值给resultresult = UNKNOWN_ERROR;} else if (response->mContent == NULL) {//代码执行到这里说明。状态码为200，//但是应答消息的内容为空，//则将错误码ERROR_MALFORMED赋值给resultresult = ERROR_MALFORMED;ALOGE("The response has no content.");} else {//代码执行到这里说明状态码为200//并且应答消息的内容也不为空//创建一个会话描述对象mSessionDesc = new ASessionDescription;//将应答消息的内容的缓冲区赋值给该会话描述对象mSessionDesc mSessionDesc->setTo(response->mContent->data(),response->mContent->size());if (!mSessionDesc->isValid()) {//如果mSessionDesc->isValid()的返回值是false//则说明该会话描述对象是无效的//将错误码ERROR_MALFORMED赋值给resultALOGE("Failed to parse session description.");result = ERROR_MALFORMED;} else {//代码执行到这里说明该会话描述对象是有效的//从应答消息对象response的mHeaders//成员变量获取key为"content-base"的值ssize_t i = response->mHeaders.indexOfKey("content-base");if (i >= 0) {//将获取到key为"content-base"的值赋值给mBaseURLmBaseURL = response->mHeaders.valueAt(i);} else {//代码执行到这里//说明i的值小于０，即不存在key为"content-base"的头部//则需要查询key为"content-location"的头部i = response->mHeaders.indexOfKey("content-location");if (i >= 0) {//将key为"content-location"头部的//内容赋值给mBaseURLmBaseURL = response->mHeaders.valueAt(i);} else {//代码执行到这里//说明在应答消息对象response里//即不存在key为"content-base"//也不存在key为"content-location"的头部//则将mSessionURL的值赋值给mBaseURLmBaseURL = mSessionURL;}}//判断该媒体是否能被seek//如果不为直播媒体流则可以被seekmSeekable = !isLiveStream(mSessionDesc);if (!mBaseURL.startsWith("rtsp://")) {//mBaseURL.startsWith("rtsp://")的值为fasle//说明服务端给出的是相对的url//需要将该相对url与绝对url合并在一起来定位媒体的位置// Some misbehaving servers specify a relative// URL in one of the locations above, combine// it with the absolute session URL to get// something usable...ALOGW("Server specified a non-absolute base URL"", combining it with the session URL to ""get something usable...");AString tmp;//合并相对url和绝对url//相对url是mBaseURL.c_str()//绝对url是mSessionURL.c_str()//具体是怎样的合并规则后续再研究介绍给大家CHECK(MakeURL(mSessionURL.c_str(),mBaseURL.c_str(),&tmp));mBaseURL = tmp;}//对于Control信息的处理//详细的处理过程后续介绍mControlURL = getControlURL();if (mSessionDesc->countTracks() < 2) {//如果会话描述的媒体的Tracks小于２//则将错误码ERROR_UNSUPPORTED赋值给result// There's no actual tracks in this session.// The first "track" is merely session meta// data.ALOGW("Session doesn't contain any playable ""tracks. Aborting.");result = ERROR_UNSUPPORTED;} else {//创建索引为１的tarcksetupTrack(1);}}}}if (result != OK) {//如果在上面过程中result的值不为OK//发送消息消息名为'disc'取消连接sp<AMessage> reply = new AMessage('disc', this);mConn->disconnect(reply);}break;}