阅读RSS提要，在数据结束前读取结束

时间：2010-10-21 01:25:01

标签： java android http

我在Java中为Android设备编写代码。我只想阅读RSS提要中的所有数据，然后我有一个解析器准备好对数据采取行动。我遇到的麻烦是我的代码只读取了一小部分数据。然后它说已经到达阅读器的末尾并继续将部分数据返回给解析器。

我的代码是：

try
{
    URL contentUrl = new URL(url); 
    URLConnection conn = contentUrl.openConnection();

    HttpURLConnection httpConn = (HttpURLConnection) conn;
    httpConn.setAllowUserInteraction(false);
    httpConn.setInstanceFollowRedirects(true);
    httpConn.setRequestMethod("GET");

    httpConn.connect();

    if(httpConn.getResponseCode() == HttpURLConnection.HTTP_OK)
    {
        InputStreamReader inStr = new InputStreamReader(httpConn.getInputStream());                                 

        int charsRead;
        char[] buff = new char[BUFFER_SIZE];
        String data = "";
        while((charsRead = inStr.read(buff,0,BUFFER_SIZE))!= -1)
        {
            data += String.copyValueOf(buff, 0, charsRead);
            buff = new char[BUFFER_SIZE];
        }
        Log.d("Http","Data: "+data.);
        return data;
    }
    else
    {
        return null;
    }
}
catch(IOException e)
{
    return null;
}

调试日志输出如下所示：

> D/dalvikvm(19134): GC_FOR_MALLOC freed 24 objects / 757272 bytes in 27ms
D/dalvikvm(19134): GC_FOR_MALLOC freed 2 objects / 48 bytes in 26ms
D/dalvikvm(19134): GC_FOR_MALLOC freed 3 objects / 301112 bytes in 29ms
I/dalvikvm-heap(19134): Grow heap (frag case) to 3.677MB for 305028-byte allocation
D/dalvikvm(19134): GC_FOR_MALLOC freed 0 objects / 0 bytes in 37ms
D/dalvikvm(19134): GC_FOR_MALLOC freed 10 objects / 760856 bytes in 27ms
D/dalvikvm(19134): GC_FOR_MALLOC freed 3 objects / 305112 bytes in 26ms
D/dalvikvm(19134): GC_FOR_MALLOC freed 10 objects / 770856 bytes in 26ms
D/dalvikvm(19134): GC_FOR_MALLOC freed 2 objects / 48 bytes in 26ms
D/dalvikvm(19134): GC_FOR_MALLOC freed 3 objects / 309112 bytes in 27ms
D/dalvikvm(19134): GC_FOR_MALLOC freed 22 objects / 777648 bytes in 27ms
D/dalvikvm(19134): GC_FOR_MALLOC freed 2 objects / 48 bytes in 30ms
D/dalvikvm(19134): GC_FOR_MALLOC freed 3 objects / 309288 bytes in 26ms
D/dalvikvm(19134): GC_FOR_MALLOC freed 27 objects / 778696 bytes in 27ms
D/Http    (19134): Data: <?xml version="1.0" encoding="UTF-8"?>
D/Http    (19134): <?xml-stylesheet type="text/xsl" media="screen" href="/~d/sty
les/atom10full.xsl"?><?xml-stylesheet type="text/css" media="screen" href="http:
//feeds.feedburner.com/~d/styles/itemcontent.css"?><feed xmlns="http://www.w3.or
g/2005/Atom" xmlns:openSearch="http://a9.com/-/spec/opensearch/1.1/" xmlns:geors
s="http://www.georss.org/georss" xmlns:thr="http://purl.org/syndication/thread/1
.0" xmlns:gd="http://schemas.google.com/g/2005" xmlns:feedburner="http://rssname
space.org/feedburner/ext/1.0" gd:etag="W/&quot;CUcFSHc7fip7ImA9Wx5UFk8.&quot;"><
id>tag:blogger.com,1999:blog-11300808</id><updated>2010-10-20T18:03:39.906-07:00
</updated><title type="text">Google Code Blog</title><subtitle type="html">Updat
es from Google's open source projects.</subtitle><link rel="http://schemas.googl
e.com/g/2005#feed" type="application/atom+xml" href="http://googlecode.blogspot.
com/feeds/posts/default" /><link rel="alternate" type="text/html" href="http://g
ooglecode.blogspot.com/" /><link rel="next" type="application/atom+xml" href="ht
tp://www.blogger.com/feeds/11300808/posts/default?start-index=26&amp;max-results
=25&amp;redirect=false&amp;v=2" /><author><name>Chris DiBona</name><email>norepl
y@blogger.com</email></author><generator version="7.00" uri="http://www.blogger.
com">Blogger</generator><openSearch:totalResults>753</openSearch:totalResults><o
penSearch:startIndex>1</openSearch:startIndex><openSearch:itemsPerPage>25</openS
earch:itemsPerPage><atom10:link xmlns:atom10="http://www.w3.org/2005/Atom" rel="
self" type="application/atom+xml" href="http://feeds.feedburner.com/blogspot/Dcn
i" /><feedburner:info uri="blogspot/dcni" /><atom10:link xmlns:atom10="http://ww
w.w3.org/2005/Atom" rel="hub" href="http://pubsubhubbub.appspot.com/" /><entry g
d:etag="W/&quot;CUcFSHc6fCp7ImA9Wx5UFk8.&quot;"><id>tag:blogger.com,1999:blog-11
300808.post-3825033765857847156</id><published>2010-10-20T18:03:00.000-07:00</pu
blished><updated>2010-10-20T18:03:39.914-07:00</updated><app:edited xmlns:app="h
ttp://www.w3.org/2007/app">2010-10-20T18:03:39.914-07:00</app:edited><category s
cheme="http://www.blogger.com/atom/ns#" term="speed tracer" /><category scheme="
http://www.blogger.com/atom/ns#" term="gwt" /><category scheme="http://www.blogg
er.com/atom/ns#" term="eclipse" /><category scheme="http://www.blogger.com/atom/
ns#" term="cloud portability" /><title>Advancing cloud computing with integrated
 developer tools by Google and VMware</title><content type="html">&lt;p&gt;&lt;i
&gt;Cross-posted from the &lt;a href="http://googlewebtoolkit.blogspot.com/"&gt;
Google Web Toolkit Blog&lt;/a&gt;&lt;/i&gt;&lt;/p&gt;
D/Http    (19134):
D/Http    (19134): &lt;p&gt;
D/Http    (19134): Earlier this year at Google I/O, we &lt;a href="http://google
code.blogspot.com/2010/05/enabling-cloud-portability-with-google.html"&gt;announ
ced&lt;/a&gt; a collaboration between &lt;a href="http://www.google.com"&gt;Goog
le&lt;/a&gt; and &lt;a href="http://www.vmware.com"&gt;VMware&lt;/a&gt; focused
on making it easy to build business-oriented, &lt;a href="http://code.google.com
/cloudportability/"&gt;cloud portable&lt;/a&gt; web apps. We showed how business
es could use our integrated developer tools to build modern web apps that are ÔÇ
£cloud readyÔÇØ from the start, and can be deployed to any standard environment,
 including &lt;a href="http://code.google.com/appengine/"&gt;Google App Engine&l
t;/a&gt; and on &lt;a href="http://www.springsource.com/products/cloud-applicati
on-platform"&gt;VMware vFabric&lt;/a&gt; on-premise solutions. Today we are happ
y to announce that these tools will be generally available within the next few w
eeks.
D/Http    (19134): &lt;/p&gt;
D/Http    (19134):
D/Http    (19134): &lt;p&gt;
D/Http    (19134): Of course, if youÔÇÖre itching to get a head start, you can j
ump right in by downloading the release candidate version of &lt;a href="http://
www.springsource.com/landing/best-development-tool-enterprise-java"&gt;SpringSou
rce Tool Suite&lt;/a&gt;.
D/Http    (19134): &lt;/p&gt;
D/Http    (19134):
D/Http    (19134): &lt;p&gt;
D/Http    (19134): If youÔÇÖd prefer to wait for the general release, you can &l
t;a href="http://code.google.com/cloudportability/"&gt;sign up&lt;/a&gt; to be n
otified as soon as they are

如果您查看了Feed（http://feeds2.feedburner.com/blogspot/Dcni），那么您会发现这只是内容的一小部分。我想，因为我收到堆消息，说电话可能已经耗尽了堆空间，因此退出了，但我找到了一个RSS TTS项目，它有自己的http代码：talkingrssreader当我把它们拉出来时尝试使用我的代码它仍然有同样的问题。尝试使用该Feed讨论RSS阅读器应用程序没有这个问题。

我现在不知道还有什么可尝试的。我可以毫无问题地获取和解析较短的RSS源，但似乎在一定长度之后它只是拒绝收集所有数据。我已经浏览了Android市场上的很多RSS阅读器，没有看到任何其他人缩短了Feed，所以这让我相信这是我的代码中的一个问题，而不是设备耗尽的内存。我的代码很容易读取一个119kb的xml文件，但是在Google RSS提要上只有32kb，这个事实进一步证明了这一点。

有人能就这个问题给我一些想法吗？

编辑： 添加100rabh和Isaac建议的更改后，代码现在看起来像这样：

InputStreamReader inStr = new InputStreamReader(httpConn.getInputStream());                                 

int charsRead;
char[] buff = new char[BUFFER_SIZE];
StringBuffer data = new StringBuffer();
while((charsRead = inStr.read(buff,0,BUFFER_SIZE))!= -1)
{
    data.append(buff, 0, charsRead);
}
Log.d("Http","Data: "+data.toString());
return data.toString();

问题仍然存在。它将数据缩短到与之前代码完全相同的位置。

2 个答案:

答案 0 :(得分：1)

我认为如果你每次都避免创建buff，你的问题就会消失

buf = new char [BUFFER_SIZE];

答案 1 :(得分：0)

好的，这是我最近发现的。 Log.d不会打印长消息http://code.google.com/p/android/issues/detail?id=5745&q=logcat%20long%20string&colspec=ID%20Type%20Status%20Owner%20Summary%20Stars

所以会发生什么，虽然你有数据，但logcat不打印它。您可以尝试打破字符串，然后通过logcat打印。您的实际应用程序不会有任何问题。

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