Java HttpResponse使用android问题:执行总是导致异常?
我一直在做一个安卓项目,现在我想问一些API的信息。似乎这应该是非常基本的 以下是我的代码的一般要点:Java HttpResponse使用android问题:执行总是导致异常?,java,android,android-asynctask,httpresponse,Java,Android,Android Asynctask,Httpresponse,我一直在做一个安卓项目,现在我想问一些API的信息。似乎这应该是非常基本的 以下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 == " + getReq
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“
正如你所看到的,在这个站点上有一些很好的JSON信息;我的问题是每次“client.execute(getRequest)”调用时,程序抛出并捕获异常。没用
我听到两件事:
1) 您必须为模拟器/设备设置使用internet的权限!
--我想我报道了这件事,但也许我做错了!
在androidmanifest.xml中,我添加了
< uses-permission android:name="android.permission.INTERNET" >< /uses-permission>
就是这样
2) (我对此不太确定)您不能在“ui”线程中启动“网络”线程。我不完全确定这意味着什么,但我继续学习了一些关于Android线程、处理程序和异步任务的教程。这里:请查看AsyncTask教程下的代码,我遵循了该教程:
在跟随AsyncTask教程之后,我发现我仍然有同样的问题--
该行:
HttpGet HttpGet=新的HttpGet(url)
总是像以前一样抛出异常
下面是我在上面的线程教程中尝试的日志:
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 =
02-27 20:43:28.565:I/ActivityManager(92):从pid 574启动{cmp=com.Prometheus.R1/.JsonParsingActivity}
02-27 20:43:28.565:W/WindowManager(92):拍摄(180x300)至21010层的故障截图
02-27 20:43:28.896:I/System.out(574):预执行
02-27 20:43:29.236:I/ActivityManager(92):显示com.Prometheus.R1/.JsonParsingActivity:+638ms
02-27 20:43:29.329:I/ARMAssembler(35):在7204915纳秒[0x40fad6a8:0x40fad860]处生成扫描线uuuuu00000077:03010104 0000801 u00000000[89 ipp](110英寸)
02-27 20:43:30.016:W/System.err(574):java.net.UnknownHostException:无法解析主机“search.twitter.com”:没有与主机名关联的地址
02-27 20:43:30.016:W/System.err(574):位于java.net.InetAddress.lookupHostByName(InetAddress.java:426)
02-27 20:43:30.026:W/System.err(574):位于java.net.InetAddress.getAllByNameImpl(InetAddress.java:242)
02-27 20:43:30.026:W/System.err(574):位于java.net.InetAddress.getAllByName(InetAddress.java:220)
02-27 20:43:30.026:W/System.err(574):位于org.apache.http.impl.conn.DefaultClientConnectionOperator.openConnection(DefaultClientConnectionOperator.java:137)
02-27 20:43:30.036:W/System.err(574):位于org.apache.http.impl.conn.AbstractPoolEntry.open(AbstractPoolEntry.java:164)
02-27 20:43:30.036:W/System.err(574):位于org.apache.http.impl.conn.AbstractPooledConnAdapter.open(AbstractPooledConnAdapter.java:119)
02-27 20:43:30.046:W/System.err(574):位于org.apache.http.impl.client.DefaultRequestDirector.execute(DefaultRequestDirector.java:360)
02-27 20:43:30.046:W/System.err(574):位于org.apache.http.impl.client.AbstractHttpClient.execute(AbstractHttpClient.java:555)
02-27 20:43:30.046:W/System.err(574):位于org.apache.http.impl.client.AbstractHttpClient.execute(AbstractHttpClient.java:487)
02-27 20:43:30.055:W/System.err(574):位于org.apache.http.impl.client.AbstractHttpClient.execute(AbstractHttpClient.java:465)
02-27 20:43:30.055:W/System.err(574):在com.Prometheus.R1.JsonParsingActivity$下载webgetask.doInBackground(JsonParsingActivity.java:88)
02-27 20:43:30.055:W/System.err(574):在com.Prometheus.R1.JsonParsingActivity$downloadWebGetTask.doInBackground(JsonParsingActivity.java:1)
02-27 20:43:30.055:W/System.err(574):在android.os.AsyncTask$2.call(AsyncTask.java:264)
02-27 20:43:30.066:W/System.err(574):位于java.util.concurrent.FutureTask$Sync.innerRun(FutureTask.java:305)
02-27 20:43:30.066:W/System.err(574):位于java.util.concurrent.FutureTask.run(FutureTask.java:137)
02-27 20:43:30.066:W/System.err(574):在android.os.AsyncTask$SerialExecutor$1.run(AsyncTask.java:208)
02-27 20:43:30.076:W/System.err(574):位于java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1076)
02-27 20:43:30.076:W/System.err(574):位于java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:569)
02-27 20:43:30.087:W/System.err(574):位于java.lang.Thread.run(Thread.java:856)
02-27 20:43:30.108:W/System.err(574):由以下原因引起:libcore.io.GaiException:getaddrinfo失败:EAI_NODATA(没有与主机名关联的地址)
02-27 20:43:30.116:W/System.err(574):位于libcore.io.Posix.getaddrinfo(本机方法)
02-27 20:43:30.116:W/System.err(574):在libcore.io.ForwardingOs.getaddrinfo(ForwardingOs.java:55)
02-27 20:43:30.126:W/System.err(574):位于java.net.InetAddress.lookupHostByName(InetAddress.java:411)
02-27 20:43:30.126:W/系统错误(574):。。。还有18个
02-27 20:43:30.136:I/System.out(574):由url抛出的除外http://search.twitter.com/search.json?q=javacodegeeks, ....
02-27 20:43:30.136:I/System.out(574):响应=
该异常是一个未知的后异常,如您所见:
“ava.net.UnknownHostException:无法解析主机“search.twitter.com”:没有与主机名关联的地址”
但我不认为这个网站是不可接受的
有人能告诉我发生了什么事+我需要做什么才能通过它吗?我认为问题在于您在http请求中提供的url或internet连接。请检查下面的链接,它将帮助您解决问题。显然我把AVD关掉了“飞行模式”
对于任何和我有同样问题的人来说,你可能正在使用无线。由于某些原因,android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!问题已解决。检查清单的权限,确保已添加以下内容:
<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"/>
您可以在主屏幕中允许网络访问
StrictMode.ThreadPolicy policy = new StrictMode.
ThreadPolicy.Builder().permitAll().build();
StrictMode.setThreadPolicy(policy);
HttpURLConnection connection = null;
BufferedReader reader = null;
String JSON_data = null;
try {
final int half_hour = 30 * 60;
URL fetch = new URL(requestUrl);
connection = (HttpURLConnection) fetch.openConnection();
// FIXED: request to follow redirects - this seems to solve networking issues on older devices < API 21
connection.setInstanceFollowRedirects(true);
connection.setUseCaches(true);
connection.setDefaultUseCaches(true);
connection.setRequestMethod("GET");
connection.addRequestProperty("Cache-Control", "max-age="+half_hour);
connection.addRequestProperty("X-Auth-Token", getString(R.string.api_key));
boolean redirect = false;
int status = connection.getResponseCode();
if (status != HttpURLConnection.HTTP_OK) {
if (status == HttpURLConnection.HTTP_MOVED_TEMP
|| status == HttpURLConnection.HTTP_MOVED_PERM
|| status == HttpURLConnection.HTTP_SEE_OTHER)
redirect = true;
}
Log.d(TAG, "===> HTTP STATUS CODE: " + status + ", redirect=" + redirect);
connection.connect();
// Read the input stream into a String
InputStream inputStream = connection.getInputStream();
if (inputStream == null) {
return;
}
reader = new BufferedReader(new InputStreamReader(inputStream));
StringBuilder buffer = new StringBuilder();
String line;
while ((line = reader.readLine()) != null) {
buffer.append(line);
buffer.append("\n");
}
if (buffer.length() == 0) {
return;
}
JSON_data = buffer.toString();
Log.d(TAG, "JSON_data=" + JSON_data);
} catch (Exception e) {
// possible UnknownHostException on older Android device?
Log.e(TAG, "HttpURLConnection Exception - e=" + e.getMessage());
e.printStackTrace();
} finally {
if (connection != null) {
connection.disconnect();
}
if (reader != null) {
try {
reader.close();
} catch (IOException e) {
Log.e(TAG, "Error closing stream - e=" + e.getMessage());
}
}
}