Android視頻點(diǎn)播的實(shí)現(xiàn)代碼(邊播邊緩存)
簡述
一些知名的視頻app客戶端(優(yōu)酷,愛奇藝)播放視頻的時候都有一些緩存進(jìn)度(二級進(jìn)度緩存),還有一些短視頻app,都有邊播邊緩的處理。還有就是當(dāng)文件緩存完畢了再次播放的話就不再請求網(wǎng)絡(luò)了直接播放本地文件了。既節(jié)省了流程又提高了加載速度。
今天我們就是來研究討論實(shí)現(xiàn)這個邊播邊緩存的框架,因?yàn)樗缓腿魏蔚臉I(yè)務(wù)邏輯耦合。
開源的項(xiàng)目
目前比較好的開源項(xiàng)目是:https://github.com/danikula/AndroidVideoCache
代碼的架構(gòu)寫的也很不錯,網(wǎng)絡(luò)用的httpurlconnect,文件緩存處理,文件最大限度策略,回調(diào)監(jiān)聽處理,斷點(diǎn)續(xù)傳,代理服務(wù)等。很值得研究閱讀.
個人覺得項(xiàng)目中有幾個需要優(yōu)化的點(diǎn),今天就來處理這幾個并簡要分析下原理
優(yōu)化點(diǎn)比如:
- 文件的緩存超過限制后沒有按照lru算法刪除,
- 處理返回給播放器的http響應(yīng)頭消息,響應(yīng)頭消息的獲取處理改為head請求(需服務(wù)器支持)
- 替換網(wǎng)絡(luò)庫為okhttp(因?yàn)榇蟛糠值捻?xiàng)目都是以okhttp為網(wǎng)絡(luò)請求庫的)
該開源項(xiàng)目的原理分析-本地代理

- 采用了本地代理服務(wù)的方式,通過原始url給播放器返回一個本地代理的一個url ,代理URL類似:http://127.0.0.1:57430/xxxx;然后播放器播放的時候請求到了你本地的代理上了。
- 本地代理采用ServerSocket監(jiān)聽127.0.0.1的有效端口,這個時候手機(jī)就是一個服務(wù)器了,客戶端就是socket,也就是播放器。
- 讀取客戶端就是socket來讀取數(shù)據(jù)(http協(xié)議請求)解析http協(xié)議。
- 根據(jù)url檢查視頻文件是否存在,讀取文件數(shù)據(jù)給播放器,也就是往socket里寫入數(shù)據(jù)。同時如果沒有下載完成會進(jìn)行斷點(diǎn)下載,當(dāng)然弱網(wǎng)的話數(shù)據(jù)需要生產(chǎn)消費(fèi)同步處理。
優(yōu)化點(diǎn)
1. 文件的緩存超過限制后沒有按照lru算法刪除.
Files類。
由于在移動設(shè)備上file.setLastModified() 方法不支持毫秒級的時間處理,導(dǎo)致超出限制大小后本應(yīng)該刪除老的,卻沒有刪除拋出了異常。注釋掉主動拋出的異常即可。因?yàn)槲募男薷臅r間就是對的。
static void setLastModifiedNow(File file) throws IOException {
if (file.exists()) {
long now = System.currentTimeMillis();
boolean modified = file.setLastModified(now/1000*1000); // on some devices (e.g. Nexus 5) doesn't work
if (!modified) {
modify(file);
// if (file.lastModified() < now) {
// VideoCacheLog.debug("LruDiskUsage", "modified not ok ");
// throw new IOException("Error set last modified date to " + file);
// }else{
// VideoCacheLog.debug("LruDiskUsage", "modified ok ");
// }
}
}
}
2. 處理返回給播放器的http響應(yīng)頭消息,響應(yīng)頭消息的獲取處理改為head請求(需要服務(wù)器支持)
HttpUrlSource類。fetchContentInfo方法是獲取視頻文件的Content-Type,Content-Length信息,是為了播放器播放的時候給播放器組裝http響應(yīng)頭信息用的。所以這一塊需要用數(shù)據(jù)庫保存,這樣播放器每次播放的時候不要在此獲取了,減少了請求的次數(shù),節(jié)省了流量。既然是只需要頭信息,不需要響應(yīng)體,所以我們在獲取的時候可以直接采用HEAD方法。所以代碼增加了一個方法openConnectionForHeader如下:
private void fetchContentInfo() throws ProxyCacheException {
VideoCacheLog.debug(TAG,"Read content info from " + sourceInfo.url);
HttpURLConnection urlConnection = null;
InputStream inputStream = null;
try {
urlConnection = openConnectionForHeader(20000);
long length = getContentLength(urlConnection);
String mime = urlConnection.getContentType();
inputStream = urlConnection.getInputStream();
this.sourceInfo = new SourceInfo(sourceInfo.url, length, mime);
this.sourceInfoStorage.put(sourceInfo.url, sourceInfo);
VideoCacheLog.debug(TAG,"Source info fetched: " + sourceInfo);
} catch (IOException e) {
VideoCacheLog.error(TAG,"Error fetching info from " + sourceInfo.url ,e);
} finally {
ProxyCacheUtils.close(inputStream);
if (urlConnection != null) {
urlConnection.disconnect();
}
}
}
// for HEAD
private HttpURLConnection openConnectionForHeader(int timeout) throws IOException, ProxyCacheException {
HttpURLConnection connection;
boolean redirected;
int redirectCount = 0;
String url = this.sourceInfo.url;
do {
VideoCacheLog.debug(TAG, "Open connection for header to " + url);
connection = (HttpURLConnection) new URL(url).openConnection();
if (timeout > 0) {
connection.setConnectTimeout(timeout);
connection.setReadTimeout(timeout);
}
//只返回頭部,不需要BODY,既可以提高響應(yīng)速度也可以減少網(wǎng)絡(luò)流量
connection.setRequestMethod("HEAD");
int code = connection.getResponseCode();
redirected = code == HTTP_MOVED_PERM || code == HTTP_MOVED_TEMP || code == HTTP_SEE_OTHER;
if (redirected) {
url = connection.getHeaderField("Location");
VideoCacheLog.debug(TAG,"Redirect to:" + url);
redirectCount++;
connection.disconnect();
VideoCacheLog.debug(TAG,"Redirect closed:" + url);
}
if (redirectCount > MAX_REDIRECTS) {
throw new ProxyCacheException("Too many redirects: " + redirectCount);
}
} while (redirected);
return connection;
}
3.替換網(wǎng)絡(luò)庫為okhttp(因?yàn)榇蟛糠值捻?xiàng)目都是以okhttp為網(wǎng)絡(luò)請求庫的)
為什么我們要換呢?!一是OKHttp是一款高效的HTTP客戶端,支持連接同一地址的鏈接共享同一個socket,通過連接池來減小響應(yīng)延遲,還有透明的GZIP壓縮,請求緩存等優(yōu)勢,其核心主要有路由、連接協(xié)議、攔截器、代理、安全性認(rèn)證、連接池以及網(wǎng)絡(luò)適配,攔截器主要是指添加,移除或者轉(zhuǎn)換請求或者回應(yīng)的頭部信息。得到了android開發(fā)的認(rèn)可。二是大部分的app都是采用OKHttp,而且google會將其納入android 源碼中。三是該作者代碼中用的httpurlconnet在HttpUrlSource有這么一段:
@Override
public void close() throws ProxyCacheException {
if (connection != null) {
try {
connection.disconnect();
} catch (NullPointerException | IllegalArgumentException e) {
String message = "Wait... but why? WTF!? " +
"Really shouldn't happen any more after fixing https://github.com/danikula/AndroidVideoCache/issues/43. " +
"If you read it on your device log, please, notify me danikula@gmail.com or create issue here " +
"https://github.com/danikula/AndroidVideoCache/issues.";
throw new RuntimeException(message, e);
} catch (ArrayIndexOutOfBoundsException e) {
VideoCacheLog.error(TAG,"Error closing connection correctly. Should happen only on Android L. " +
"If anybody know how to fix it, please visit https://github.com/danikula/AndroidVideoCache/issues/88. " +
"Until good solution is not know, just ignore this issue :(", e);
}
}
}
在沒有像okhttp這些優(yōu)秀的網(wǎng)絡(luò)開源項(xiàng)目之前,android開發(fā)都是采用httpurlconnet或者h(yuǎn)ttpclient,部分手機(jī)可能會遇到這個問題哈。
這里采用的 compile 'com.squareup.okhttp:okhttp:2.7.5' 版本的來實(shí)現(xiàn)該類的功能。在原作者的架構(gòu)思路上我們只需要增加實(shí)現(xiàn)Source接口的類OkHttpUrlSource即可,可見作者的代碼架構(gòu)還是不錯的,當(dāng)然我們同樣需要處理上文中提高的優(yōu)化點(diǎn)2中的問題。將項(xiàng)目中所有用到HttpUrlSource的地方改為OkHttpUrlSource即可。
源碼如下:
/**
* ================================================
* 作 者:顧修忠
* 版 本:
* 創(chuàng)建日期:2017/4/13-上午12:03
* 描 述:在一些Android手機(jī)上HttpURLConnection.disconnect()方法仍然耗時太久,
* 進(jìn)行導(dǎo)致MediaPlayer要等待很久才會開始播放,因此決定使用okhttp替換HttpURLConnection
*/
public class OkHttpUrlSource implements Source {
private static final String TAG = OkHttpUrlSource.class.getSimpleName();
private static final int MAX_REDIRECTS = 5;
private final SourceInfoStorage sourceInfoStorage;
private SourceInfo sourceInfo;
private OkHttpClient okHttpClient = new OkHttpClient();
private Call requestCall = null;
private InputStream inputStream;
public OkHttpUrlSource(String url) {
this(url, SourceInfoStorageFactory.newEmptySourceInfoStorage());
}
public OkHttpUrlSource(String url, SourceInfoStorage sourceInfoStorage) {
this.sourceInfoStorage = checkNotNull(sourceInfoStorage);
SourceInfo sourceInfo = sourceInfoStorage.get(url);
this.sourceInfo = sourceInfo != null ? sourceInfo :
new SourceInfo(url, Integer.MIN_VALUE, ProxyCacheUtils.getSupposablyMime(url));
}
public OkHttpUrlSource(OkHttpUrlSource source) {
this.sourceInfo = source.sourceInfo;
this.sourceInfoStorage = source.sourceInfoStorage;
}
@Override
public synchronized long length() throws ProxyCacheException {
if (sourceInfo.length == Integer.MIN_VALUE) {
fetchContentInfo();
}
return sourceInfo.length;
}
@Override
public void open(long offset) throws ProxyCacheException {
try {
Response response = openConnection(offset, -1);
String mime = response.header("Content-Type");
this.inputStream = new BufferedInputStream(response.body().byteStream(), DEFAULT_BUFFER_SIZE);
long length = readSourceAvailableBytes(response, offset, response.code());
this.sourceInfo = new SourceInfo(sourceInfo.url, length, mime);
this.sourceInfoStorage.put(sourceInfo.url, sourceInfo);
} catch (IOException e) {
throw new ProxyCacheException("Error opening okHttpClient for " + sourceInfo.url + " with offset " + offset, e);
}
}
private long readSourceAvailableBytes(Response response, long offset, int responseCode) throws IOException {
long contentLength = getContentLength(response);
return responseCode == HTTP_OK ? contentLength
: responseCode == HTTP_PARTIAL ? contentLength + offset : sourceInfo.length;
}
private long getContentLength(Response response) {
String contentLengthValue = response.header("Content-Length");
return contentLengthValue == null ? -1 : Long.parseLong(contentLengthValue);
}
@Override
public void close() throws ProxyCacheException {
if (okHttpClient != null && inputStream != null && requestCall != null) {
try {
inputStream.close();
requestCall.cancel();
} catch (IOException e) {
e.printStackTrace();
throw new RuntimeException(e.getMessage(), e);
}
}
}
@Override
public int read(byte[] buffer) throws ProxyCacheException {
if (inputStream == null) {
throw new ProxyCacheException("Error reading data from " + sourceInfo.url + ": okHttpClient is absent!");
}
try {
return inputStream.read(buffer, 0, buffer.length);
} catch (InterruptedIOException e) {
throw new InterruptedProxyCacheException("Reading source " + sourceInfo.url + " is interrupted", e);
} catch (IOException e) {
throw new ProxyCacheException("Error reading data from " + sourceInfo.url, e);
}
}
private void fetchContentInfo() throws ProxyCacheException {
VideoCacheLog.debug(TAG, "Read content info from " + sourceInfo.url);
Response response = null;
InputStream inputStream = null;
try {
response = openConnectionForHeader(20000);
if (response == null || !response.isSuccessful()) {
throw new ProxyCacheException("Fail to fetchContentInfo: " + sourceInfo.url);
}
long length = getContentLength(response);
String mime = response.header("Content-Type", "application/mp4");
inputStream = response.body().byteStream();
this.sourceInfo = new SourceInfo(sourceInfo.url, length, mime);
this.sourceInfoStorage.put(sourceInfo.url, sourceInfo);
VideoCacheLog.info(TAG, "Content info for `" + sourceInfo.url + "`: mime: " + mime + ", content-length: " + length);
} catch (IOException e) {
VideoCacheLog.error(TAG, "Error fetching info from " + sourceInfo.url, e);
} finally {
ProxyCacheUtils.close(inputStream);
if (response != null && requestCall != null) {
requestCall.cancel();
}
}
}
// for HEAD
private Response openConnectionForHeader(int timeout) throws IOException, ProxyCacheException {
if (timeout > 0) {
// okHttpClient.setConnectTimeout(timeout, TimeUnit.MILLISECONDS);
// okHttpClient.setReadTimeout(timeout, TimeUnit.MILLISECONDS);
// okHttpClient.setWriteTimeout(timeout, TimeUnit.MILLISECONDS);
}
Response response;
boolean isRedirect = false;
String newUrl = this.sourceInfo.url;
int redirectCount = 0;
do {
//只返回頭部,不需要BODY,既可以提高響應(yīng)速度也可以減少網(wǎng)絡(luò)流量
Request request = new Request.Builder()
.head()
.url(newUrl)
.build();
requestCall = okHttpClient.newCall(request);
response = requestCall.execute();
if (response.isRedirect()) {
newUrl = response.header("Location");
VideoCacheLog.debug(TAG, "Redirect to:" + newUrl);
isRedirect = response.isRedirect();
redirectCount++;
requestCall.cancel();
VideoCacheLog.debug(TAG, "Redirect closed:" + newUrl);
}
if (redirectCount > MAX_REDIRECTS) {
throw new ProxyCacheException("Too many redirects: " + redirectCount);
}
} while (isRedirect);
return response;
}
private Response openConnection(long offset, int timeout) throws IOException, ProxyCacheException {
if (timeout > 0) {
// okHttpClient.setConnectTimeout(timeout, TimeUnit.MILLISECONDS);
// okHttpClient.setReadTimeout(timeout, TimeUnit.MILLISECONDS);
// okHttpClient.setWriteTimeout(timeout, TimeUnit.MILLISECONDS);
}
Response response;
boolean isRedirect = false;
String newUrl = this.sourceInfo.url;
int redirectCount = 0;
do {
VideoCacheLog.debug(TAG, "Open connection" + (offset > 0 ? " with offset " + offset : "") + " to " + sourceInfo.url);
Request.Builder requestBuilder = new Request.Builder()
.get()
.url(newUrl);
if (offset > 0) {
requestBuilder.addHeader("Range", "bytes=" + offset + "-");
}
requestCall = okHttpClient.newCall(requestBuilder.build());
response = requestCall.execute();
if (response.isRedirect()) {
newUrl = response.header("Location");
isRedirect = response.isRedirect();
redirectCount++;
}
if (redirectCount > MAX_REDIRECTS) {
throw new ProxyCacheException("Too many redirects: " + redirectCount);
}
} while (isRedirect);
return response;
}
public synchronized String getMime() throws ProxyCacheException {
if (TextUtils.isEmpty(sourceInfo.mime)) {
fetchContentInfo();
}
return sourceInfo.mime;
}
public String getUrl() {
return sourceInfo.url;
}
@Override
public String toString() {
return "OkHttpUrlSource{sourceInfo='" + sourceInfo + "}";
}
}
以上就是本文的全部內(nèi)容,希望對大家的學(xué)習(xí)有所幫助,也希望大家多多支持腳本之家。
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