1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
|
/* -*- Mode: Java; c-basic-offset: 4; tab-width: 20; indent-tabs-mode: nil; -*-
* This Source Code Form is subject to the terms of the Mozilla Public
* License, v. 2.0. If a copy of the MPL was not distributed with this
* file, You can obtain one at http://mozilla.org/MPL/2.0/. */
package org.mozilla.gecko.feeds;
import android.support.annotation.NonNull;
import android.support.annotation.Nullable;
import org.mozilla.gecko.feeds.parser.Feed;
import org.mozilla.gecko.feeds.parser.SimpleFeedParser;
import org.mozilla.gecko.util.IOUtils;
import java.io.BufferedInputStream;
import java.io.IOException;
import java.io.InputStream;
import java.net.HttpURLConnection;
import java.net.URL;
import ch.boye.httpclientandroidlib.util.TextUtils;
/**
* Helper class for fetching and parsing a feed.
*/
public class FeedFetcher {
private static final int CONNECT_TIMEOUT = 15000;
private static final int READ_TIMEOUT = 15000;
public static class FeedResponse {
public final Feed feed;
public final String etag;
public final String lastModified;
public FeedResponse(Feed feed, String etag, String lastModified) {
this.feed = feed;
this.etag = etag;
this.lastModified = lastModified;
}
}
/**
* Fetch and parse a feed from the given URL. Will return null if fetching or parsing failed.
*/
public static FeedResponse fetchAndParseFeed(String url) {
return fetchAndParseFeedIfModified(url, null, null);
}
/**
* Fetch and parse a feed from the given URL using the given ETag and "Last modified" value.
*
* Will return null if fetching or parsing failed. Will also return null if the feed has not
* changed (ETag / Last-Modified-Since).
*
* @param eTag The ETag from the last fetch or null if no ETag is available (will always fetch feed)
* @param lastModified The "Last modified" header from the last time the feed has been fetch or
* null if no value is available (will always fetch feed)
* @return A FeedResponse or null if no feed could be fetched (error or no new version available)
*/
@Nullable
public static FeedResponse fetchAndParseFeedIfModified(@NonNull String url, @Nullable String eTag, @Nullable String lastModified) {
HttpURLConnection connection = null;
InputStream stream = null;
try {
connection = (HttpURLConnection) new URL(url).openConnection();
connection.setInstanceFollowRedirects(true);
connection.setConnectTimeout(CONNECT_TIMEOUT);
connection.setReadTimeout(READ_TIMEOUT);
if (!TextUtils.isEmpty(eTag)) {
connection.setRequestProperty("If-None-Match", eTag);
}
if (!TextUtils.isEmpty(lastModified)) {
connection.setRequestProperty("If-Modified-Since", lastModified);
}
final int statusCode = connection.getResponseCode();
if (statusCode != HttpURLConnection.HTTP_OK) {
return null;
}
String responseEtag = connection.getHeaderField("ETag");
if (!TextUtils.isEmpty(responseEtag) && responseEtag.startsWith("W/")) {
// Weak ETag, get actual ETag value
responseEtag = responseEtag.substring(2);
}
final String updatedLastModified = connection.getHeaderField("Last-Modified");
stream = new BufferedInputStream(connection.getInputStream());
final SimpleFeedParser parser = new SimpleFeedParser();
final Feed feed = parser.parse(stream);
return new FeedResponse(feed, responseEtag, updatedLastModified);
} catch (IOException e) {
return null;
} catch (SimpleFeedParser.ParserException e) {
return null;
} finally {
if (connection != null) {
connection.disconnect();
}
IOUtils.safeStreamClose(stream);
}
}
}
|
