Android视频/音频缓存框架AndroidVideoCache（Okhttp）详解

package com.danikula.videocache;
import android.text.TextUtils;
import java.io.BufferedInputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.InterruptedIOException;
import java.util.Map;
import java.util.concurrent.TimeUnit;
import com.danikula.videocache.file.MyLog;
import okhttp3.Call;
import okhttp3.OkHttpClient;
import okhttp3.Request;
import okhttp3.Response;
import static com.danikula.videocache.ProxyCacheUtils.DEFAULT_BUFFER_SIZE;
import static com.danikula.videocache.ProxyCacheUtils.LOG_TAG;
import static java.net.HttpURLConnection.HTTP_OK;
import static java.net.HttpURLConnection.HTTP_PARTIAL;
/**
* {@link Source} that uses http resource as source for {@link ProxyCache}.
*
* @author Alexey Danilov (danikula@gmail.com).
* 
* 从URL 获取数据
*/
public class HttpUrlSource implements Source {
private static final int MAX_REDIRECTS = 5;
public final String url;
private static OkHttpClient okHttpClient = new OkHttpClient();
private Call requestCall = null;
private InputStream inputStream;
private volatile int length = Integer.MIN_VALUE;
private volatile String mime;
private Map<String, String  headers;
public HttpUrlSource(String url) {
this(url, ProxyCacheUtils.getSupposablyMime(url));
}
public HttpUrlSource(String url, Map<String, String  headers) {
this(url, ProxyCacheUtils.getSupposablyMime(url));
this.headers = headers;
}
public HttpUrlSource(String url, String mime) {
this.url = Preconditions.checkNotNull(url);
this.mime = mime;
}
public HttpUrlSource(HttpUrlSource source) {
this.url = source.url;
this.mime = source.mime;
this.length = source.length;
}
@Override
public synchronized int length() throws ProxyCacheException {
if (length == Integer.MIN_VALUE) {
fetchContentInfo();
}
return length;
}
@Override
public void open(int offset) throws ProxyCacheException {
try {
Response response = openConnection(offset, -1);
mime = response.header("Content-Type");
inputStream = new BufferedInputStream(response.body().byteStream(), DEFAULT_BUFFER_SIZE);
length = readSourceAvailableBytes(response, offset, response.code());
} catch (IOException e) {
throw new ProxyCacheException("Error opening okHttpClient for " + url + " with offset " + offset, e);
}
}
private int readSourceAvailableBytes(Response response, int offset, int responseCode) throws IOException {
int contentLength = Integer.valueOf(response.header("Content-Length", "-1"));
return responseCode == HTTP_OK ? contentLength
: responseCode == HTTP_PARTIAL ? contentLength + offset : length;
}
@Override
public void close() throws ProxyCacheException {
if (okHttpClient != null && inputStream != null && requestCall != null) {
try {
inputStream.close();
requestCall.cancel();
} catch (IOException e) {
e.printStackTrace();
}
}
}
@Override
public int read(byte[] buffer) throws ProxyCacheException {
if (inputStream == null) {
throw new ProxyCacheException("Error reading data from " + url + ": okHttpClient is absent!");
}
try {
return inputStream.read(buffer, 0, buffer.length);
} catch (InterruptedIOException e) {
throw new InterruptedProxyCacheException("Reading source " + url + " is interrupted", e);
} catch (IOException e) {
throw new ProxyCacheException("Error reading data from " + url, e);
}
}
private void fetchContentInfo() throws ProxyCacheException {
MyLog.d(LOG_TAG, "Read content info from " + url);
Response response = null;
InputStream inputStream = null;
try {
response = openConnection(0, 20000);
length = Integer.valueOf(response.header("Content-Length", "-1"));
mime = response.header("Content-Type");
inputStream = response.body().byteStream();
MyLog.i(LOG_TAG, "Content info for `" + url + "`: mime: " + mime + ", content-length: " + length);
} catch (IOException e) {
MyLog.e(LOG_TAG, "Error fetching info from " + url, e);
} finally {
ProxyCacheUtils.close(inputStream);
if (response != null) {
requestCall.cancel();
}
}
}
private Response openConnection(int offset, int timeout) throws IOException, ProxyCacheException {
boolean redirected;
int redirectCount = 0;
String url = this.url;
Request request = null;
//do {
MyLog.d(LOG_TAG, "Open okHttpClient " + (offset   0 ? " with offset " + offset : "") + " to " + url);
//      okHttpClient = (HttpURLConnection) new URL(url).openConnection();
Request.Builder builder = new Request.Builder();
builder.url(url);
//flac
if(headers != null) {
//设置请求头
for (Map.Entry<String, String  entry : headers.entrySet()) {
MyLog.i(LOG_TAG, "请求头信息 key:" + entry.getKey() +" Value" + entry.getValue());
//          okHttpClient.setRequestProperty(entry.getKey(), entry.getValue());
builder.addHeader(entry.getKey(), entry.getValue());
}
}
if (offset   0) {
builder.addHeader("Range", "bytes=" + offset + "-");
}
request = builder.build();
requestCall = okHttpClient.newCall(request);
/*if (redirected) {
url = okHttpClient.getHeaderField("Location");
redirectCount++;
okHttpClient.disconnect();
}
if (redirectCount   MAX_REDIRECTS) {
throw new ProxyCacheException("Too many redirects: " + redirectCount);
}*/
//} while (redirected);
return requestCall.execute();
}
public synchronized String getMime() throws ProxyCacheException {
if (TextUtils.isEmpty(mime)) {
fetchContentInfo();
}
return mime;
}
public String getUrl() {
return url;
}
@Override
public String toString() {
return "HttpUrlSource{url='" + url + "}";
}
}