HttpResponse使用android问题:执行总是导致异常？

Question

我一直在研究一个Android项目,我想要一些API来获取信息.看起来这应该是非常基本的!

这是我的代码的一般要点:

private InputStream retrieveStream2(String url)
{
    DefaultHttpClient client = new DefaultHttpClient();

    HttpGet getRequest = new HttpGet(url);
    System.out.println("getRequest == " + getRequest);
    try {


        HttpResponse getResponse = client.execute(getRequest);//here is teh problem
        final int statusCode = getResponse.getStatusLine().getStatusCode();


        if (statusCode != HttpStatus.SC_OK)
        {
            Log.w(getClass().getSimpleName(),
                    "Error " + statusCode + " for URL " + url);
            return null;
        }

        HttpEntity getResponseEntity = getResponse.getEntity();
        return getResponseEntity.getContent();

    }
    catch (Exception e)
    {
        getRequest.abort();
        Log.w(getClass().getSimpleName(), "Error for URL, YO " + url, e);
    }
    return null;
}

其中url变量是字符串"http://search.twitter.com/search.json?q=javacodegeeks".

正如您所看到的,该站点有一些不错的JSON信息; 我的问题是,每次调用'client.execute(getRequest);''时,程序都会抛出并捕获异常.没有用!

我听说过两件事:

1)您必须为模拟器/设备设置使用互联网的权限! - 我想我已经覆盖了这个,但也许我做错了!在我添加的androidmanifest.xml中

< uses-permission android:name="android.permission.INTERNET" >< /uses-permission>

就是这样.

2)(我不太确定)你不能在'ui'线程中启动'网络'线程.我不完全确定这意味着什么,但我继续前进并遵循Android Threads,Handlers和AsyncTasks的一些教程.这里:请查看我遵循的AsyncTask教程下的代码:

http://www.vogella.de/articles/AndroidPerformance/article.html

继AsyncTask教程之后,我发现我仍然遇到同样的问题 -

行:HttpGet httpGet = new HttpGet(url)总是抛出异常,就像之前一样.

这是我尝试上面的线程教程的logcat:

02-27 20:43:28.565: I/ActivityManager(92): START {cmp=com.Prometheus.R1/.JsonParsingActivity} from pid 574
02-27 20:43:28.565: W/WindowManager(92): Failure taking screenshot for (180x300) to layer 21010
02-27 20:43:28.896: I/System.out(574): pre execute
02-27 20:43:29.236: I/ActivityManager(92): Displayed com.Prometheus.R1/.JsonParsingActivity: +638ms
02-27 20:43:29.329: I/ARMAssembler(35): generated scanline__00000077:03010104_00008001_00000000 [ 89 ipp] (110 ins) at [0x40fad6a8:0x40fad860] in 7204915 ns
02-27 20:43:30.016: W/System.err(574): java.net.UnknownHostException: Unable to resolve host "search.twitter.com": No address associated with hostname
02-27 20:43:30.016: W/System.err(574):  at java.net.InetAddress.lookupHostByName(InetAddress.java:426)
02-27 20:43:30.026: W/System.err(574):  at java.net.InetAddress.getAllByNameImpl(InetAddress.java:242)
02-27 20:43:30.026: W/System.err(574):  at java.net.InetAddress.getAllByName(InetAddress.java:220)
02-27 20:43:30.026: W/System.err(574):  at org.apache.http.impl.conn.DefaultClientConnectionOperator.openConnection(DefaultClientConnectionOperator.java:137)
02-27 20:43:30.036: W/System.err(574):  at org.apache.http.impl.conn.AbstractPoolEntry.open(AbstractPoolEntry.java:164)
02-27 20:43:30.036: W/System.err(574):  at org.apache.http.impl.conn.AbstractPooledConnAdapter.open(AbstractPooledConnAdapter.java:119)
02-27 20:43:30.046: W/System.err(574):  at org.apache.http.impl.client.DefaultRequestDirector.execute(DefaultRequestDirector.java:360)
02-27 20:43:30.046: W/System.err(574):  at org.apache.http.impl.client.AbstractHttpClient.execute(AbstractHttpClient.java:555)
02-27 20:43:30.046: W/System.err(574):  at org.apache.http.impl.client.AbstractHttpClient.execute(AbstractHttpClient.java:487)
02-27 20:43:30.055: W/System.err(574):  at org.apache.http.impl.client.AbstractHttpClient.execute(AbstractHttpClient.java:465)
02-27 20:43:30.055: W/System.err(574):  at com.Prometheus.R1.JsonParsingActivity$DownloadWebPageTask.doInBackground(JsonParsingActivity.java:88)
02-27 20:43:30.055: W/System.err(574):  at com.Prometheus.R1.JsonParsingActivity$DownloadWebPageTask.doInBackground(JsonParsingActivity.java:1)
02-27 20:43:30.055: W/System.err(574):  at android.os.AsyncTask$2.call(AsyncTask.java:264)<br/>
02-27 20:43:30.066: W/System.err(574):  at java.util.concurrent.FutureTask$Sync.innerRun(FutureTask.java:305)
02-27 20:43:30.066: W/System.err(574):  at java.util.concurrent.FutureTask.run(FutureTask.java:137)<br/>
02-27 20:43:30.066: W/System.err(574):  at android.os.AsyncTask$SerialExecutor$1.run(AsyncTask.java:208)
02-27 20:43:30.076: W/System.err(574):  at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1076)
02-27 20:43:30.076: W/System.err(574):  at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:569)
02-27 20:43:30.087: W/System.err(574):  at java.lang.Thread.run(Thread.java:856)
02-27 20:43:30.108: W/System.err(574): Caused by: libcore.io.GaiException: getaddrinfo failed: EAI_NODATA (No address associated with hostname)
02-27 20:43:30.116: W/System.err(574):  at libcore.io.Posix.getaddrinfo(Native Method)
02-27 20:43:30.116: W/System.err(574):  at libcore.io.ForwardingOs.getaddrinfo(ForwardingOs.java:55)
02-27 20:43:30.126: W/System.err(574):  at java.net.InetAddress.lookupHostByName(InetAddress.java:411)
02-27 20:43:30.126: W/System.err(574):  ... 18 more
02-27 20:43:30.136: I/System.out(574): Except thrown by url http://search.twitter.com/search.json?q=javacodegeeks, .... 
02-27 20:43:30.136: I/System.out(574): response =

例外是UnknownHostException,你可以看到:
"ava.net.UnknownHostException:无法解析主机"search.twitter.com":没有与主机名相关的地址"
但我不认为该网站是不可接受的......

任何人都可以告诉我发生了什么+我需要做些什么来度过难关？

Answer 1

检查清单的权限,确保添加了以下内容:

<uses-permission android:name="android.permission.ACCESS_NETWORK_STATE"/>
<uses-permission android:name="android.permission.ACCESS_WIFI_STATE"/>
<uses-permission android:name="android.permission.INTERNET"/>

Answer 2

弄清楚了.显然我把AVD从"飞机模式"上移开了.

对于任何与我有同样问题的人,你可能正在使用无线.出于某种原因,andriod会查看您的LAN卡,因此请转到您的网络连接并右键单击LAN卡 - 禁用该功能!问题解决了.

Answer 3

我认为问题出在您在 http 请求或互联网连接中给出的 url 中，请检查下面的链接，它将帮助您链接