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這篇文章給大家介紹Android應用中怎么實現一個視頻點播功能，內容非常詳細，感興趣的小伙伴們可以參考借鑒，希望對大家能有所幫助。
采用了本地代理服務的方式，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。
優化點
1. 文件的緩存超過限制后沒有按照lru算法刪除.
Files類。
由于在移動設備上file.setLastModified（） 方法不支持毫秒級的時間處理，導致超出限制大小后本應該刪除老的，卻沒有刪除拋出了異常。注釋掉主動拋出的異常即可。因為文件的修改時間就是對的。
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響應頭消息，響應頭消息的獲取處理改為head請求(需要服務器支持)
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響應頭信息用的。所以這一塊需要用數據庫保存，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，節省了流量。既然是只需要頭信息，不需要響應體，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，既可以提高響應速度也可以減少網絡流量
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.替換網絡庫為okhttp（因為大部分的項目都是以okhttp為網絡請求庫的）
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延遲，還有透明的GZIP壓縮，請求緩存等優勢，其核心主要有路由、連接協議、攔截器、代理、安全性認證、連接池以及網絡適配，攔截器主要是指添加，移除或者轉換請求或者回應的頭部信息。得到了android開發的認可。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這些優秀的網絡開源項目之前，android開發都是采用httpurlconnet或者httpclient，部分手機可能會遇到這個問題哈。
這里采用的 compile 'com.squareup.okhttp:okhttp:2.7.5' 版本的來實現該類的功能。在原作者的架構思路上我們只需要增加實現Source接口的類OkHttpUrlSource即可，可見作者的代碼架構還是不錯的，當然我們同樣需要處理上文中提高的優化點2中的問題。將項目中所有用到HttpUrlSource的地方改為OkHttpUrlSource即可。
源碼如下：
/**
* ================================================
* 作 者：顧修忠
* 版 本：
* 創建日期：2017/4/13-上午12:03
* 描 述：在一些Android手機上HttpURLConnection.disconnect()方法仍然耗時太久，
* 進行導致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，既可以提高響應速度也可以減少網絡流量
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 + "}";
}
}關于Android應用中怎么實現一個視頻點播功能就分享到這里了，希望以上內容可以對大家有一定的幫助，可以學到更多知識。如果覺得文章不錯，可以把它分享出去讓更多的人看到。
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