Android应用中怎么实现一个视频点播功能
这篇文章给大家介绍Android应用中怎么实现一个视频点播功能，内容非常详细，感兴趣的小伙伴们可以参考借鉴，希望对大家能有所帮助。
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采用了本地代理服务的方式，通过原始url给播放器返回一个本地代理的一个url ，代理URL类似：http://127.0.0.1:57430/xxxx；然后播放器播放的时候请求到了你本地的代理上了。
- 本地代理采用ServerSocket监听127.0.0.1的有效端口，这个时候手机就是一个服务器了，客户端就是socket，也就是播放器。
- 读取客户端就是socket来读取数据（http协议请求）解析http协议。
- 根据url检查视频文件是否存在，读取文件数据给播放器，也就是往socket里写入数据。同时如果没有下载完成会进行断点下载,当然弱网的话数据需要生产消费同步处理。
优化点
1. 文件的缓存超过限制后没有按照lru算法删除.
Files类。
由于在移动设备上file.setLastModified（） 方法不支持毫秒级的时间处理，导致超出限制大小后本应该删除老的，却没有删除抛出了异常。注释掉主动抛出的异常即可。因为文件的修改时间就是对的。
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. 处理返回给播放器的http响应头消息，响应头消息的获取处理改为head请求(需要服务器支持)
HttpUrlSource类。fetchContentInfo方法是获取视频文件的Content-Type，Content-Length信息，是为了播放器播放的时候给播放器组装http响应头信息用的。所以这一块需要用数据库保存，这样播放器每次播放的时候不要在此获取了，减少了请求的次数，节省了流量。既然是只需要头信息，不需要响应体，所以我们在获取的时候可以直接采用HEAD方法。所以代码增加了一个方法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);
}
//只返回头部，不需要BODY，既可以提高响应速度也可以减少网络流量
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.替换网络库为okhttp（因为大部分的项目都是以okhttp为网络请求库的）
为什么我们要换呢？！一是OKHttp是一款高效的HTTP客户端，支持连接同一地址的链接共享同一个socket，通过连接池来减小响应延迟，还有透明的GZIP压缩，请求缓存等优势，其核心主要有路由、连接协议、拦截器、代理、安全性认证、连接池以及网络适配，拦截器主要是指添加，移除或者转换请求或者回应的头部信息。得到了android开发的认可。二是大部分的app都是采用OKHttp，而且google会将其纳入android 源码中。三是该作者代码中用的httpurlconnet在HttpUrlSource有这么一段：
@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);
}
}
}在没有像okhttp这些优秀的网络开源项目之前，android开发都是采用httpurlconnet或者httpclient，部分手机可能会遇到这个问题哈。
这里采用的 compile 'com.squareup.okhttp:okhttp:2.7.5' 版本的来实现该类的功能。在原作者的架构思路上我们只需要增加实现Source接口的类OkHttpUrlSource即可，可见作者的代码架构还是不错的，当然我们同样需要处理上文中提高的优化点2中的问题。将项目中所有用到HttpUrlSource的地方改为OkHttpUrlSource即可。
源码如下：
/**
* ================================================
* 作 者：顾修忠
* 版 本：
* 创建日期：2017/4/13-上午12:03
* 描 述：在一些Android手机上HttpURLConnection.disconnect()方法仍然耗时太久，
* 进行导致MediaPlayer要等待很久才会开始播放，因此决定使用okhttp替换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 {
//只返回头部，不需要BODY，既可以提高响应速度也可以减少网络流量
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 + "}";
}
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