从android中的HttpURLConnection获取InputStream时获取UnknownLengthHttpInputStream

Question

HttpURLConnection.getInputStream（）给出UnknownLengthHttpInputStream，由于此Document解析引发SAX解析器异常。

以下是代码

try{
    URL url = new URL(uri);
    HttpURLConnection connection =
    (HttpURLConnection) url.openConnection();
    connection.setRequestMethod("GET");
    connection.setRequestProperty("Accept", "application/xml");

    InputStream xml = connection.getInputStream();
    System.out.println(connection.getResponseCode());
    DocumentBuilderFactory dbf = DocumentBuilderFactory.newInstance();
    DocumentBuilder db = dbf.newDocumentBuilder();
    Document doc = db.parse(connection.getInputStream());
    doc.getDocumentElement().normalize();

}catch(Exception e){
    e.printStackTrace();
}

任何人都知道UnknownLengthHttpInputStream的原因。 我只在android中遇到此错误，此代码在Java Project中完美运行。

以下是LogCat的例外情况：

08-08 11:07:40.490: W/System.err(1493): org.xml.sax.SAXParseException: Unexpected end of document
08-08 11:07:40.504: W/System.err(1493): at org.apache.harmony.xml.parsers.DocumentBuilderImpl.parse(DocumentBuilderImpl.java:129)
08-08 11:07:40.510: W/System.err(1493): at javax.xml.parsers.DocumentBuilder.parse(DocumentBuilder.java:107)
08-08 11:07:40.510: W/System.err(1493): at com.example.testws.MainActivity.onCreate(MainActivity.java:59)
08-08 11:07:40.520: W/System.err(1493): at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1047)
08-08 11:07:40.520: W/System.err(1493): at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:1611)
08-08 11:07:40.520: W/System.err(1493): at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:1663)
08-08 11:07:40.520: W/System.err(1493): at android.app.ActivityThread.access$1500(ActivityThread.java:117)
08-08 11:07:40.530: W/System.err(1493): at android.app.ActivityThread$H.handleMessage(ActivityThread.java:931)

提前致谢。

Answer 1

它可能是一个Http 1.0（旧服务器或配置错误）服务器或没有保持活动配置。 在这种情况下，在从服务器关闭连接时，流的长度是已知的。 尝试在请求标头中指定http1.1和keep-alive（一些谷歌搜索将有助于此）。 仅当在服务器响应中指定了内容长度属性时，才会提前知道流长度。

解决方法：将http流完全read()入ByteBufferStream （直到read()返回-1 ）。 然后将ByteBufferInputStream抛出到您的库中（现在知道长度）

Answer 2

您是否尝试过使用apache库？ 我建议如下：

try {
        HttpClient client = new DefaultHttpClient();  
        String getURL = "http://www.google.com";
        HttpGet get = new HttpGet(getURL);
        HttpResponse responseGet = client.execute(get);  
        HttpEntity resEntityGet = responseGet.getEntity();  
        if (resEntityGet != null) {  
                    //do something with the response
                    Log.i("GET RESPONSE",EntityUtils.toString(resEntityGet));
                }
} catch (Exception e) {
    e.printStackTrace();
}

然后获取HttpEntity本身的流。 Smth喜欢：

InputStream st = entity.getContent();

更多示例： http ： //www.softwarepassion.com/android-series-get-post-and-multipart-post-requests/

Answer 3

要处理响应使用这种方法，它将照顾所有！

public static ResponseHandler<String> getResponseHandlerInstance(final Handler handler) {
      final ResponseHandler<String> responseHandler = new ResponseHandler<String>() {

         public String handleResponse(final HttpResponse response) {
            Message message = handler.obtainMessage();
            Bundle bundle = new Bundle();
            StatusLine status = response.getStatusLine();
            Log.d(CLASSTAG, " " + HTTPRequestHelper.CLASSTAG + " statusCode - " + status.getStatusCode());
            Log.d(CLASSTAG, " " + HTTPRequestHelper.CLASSTAG + " statusReasonPhrase - " + status.getReasonPhrase());
            HttpEntity entity = response.getEntity();
            String result = null;
            if (entity != null) {
               try {
                  result = HTTPRequestHelper.inputStreamToString(entity.getContent());
                  bundle.putString("RESPONSE", result);
                  message.setData(bundle);
                  handler.sendMessage(message);
               } catch (IOException e) {
                  Log.e(CLASSTAG, " " + HTTPRequestHelper.CLASSTAG, e);
                  bundle.putString("RESPONSE", "Error - " + e.getMessage());
                  message.setData(bundle);
                  handler.sendMessage(message);
               }
            } else {
               Log.w(CLASSTAG, " " + HTTPRequestHelper.CLASSTAG + " empty response entity, HTTP error occurred");
               bundle.putString("RESPONSE", "Error - " + response.getStatusLine().getReasonPhrase());
               message.setData(bundle);
               handler.sendMessage(message);
            }
            return result;
         }
      };
      return responseHandler;
   }

   private static String inputStreamToString(final InputStream stream) throws IOException {
      BufferedReader br = new BufferedReader(new InputStreamReader(stream));
      StringBuilder sb = new StringBuilder();
      String line = null;
      while ((line = br.readLine()) != null) {
         sb.append(line + "\n");
      }
      br.close();
      return sb.toString();
   }

Answer 4

当SAX解析器无法获得InputStream数据的长度时，问题出现了。 要解决此问题，请将从xml （ InputStream ）读取的内容保存到String变量中，并从DocumentBuilder parse方法的变量中创建一个InputStream 。 为此，请按如下方式修改代码：

try {
            URL url = new URL(uri);
            HttpURLConnection connection = (HttpURLConnection) url.openConnection();
            connection.setRequestMethod("GET");
            connection.setRequestProperty("Accept", "application/xml");
            InputStream xml = connection.getInputStream();

            DataInputStream dis = new DataInputStream(xml);
            StringBuilder sb = new StringBuilder();
            int asci = dis.read();
            while (asci > 0) {
                sb.append((char) asci);
                asci = dis.read();
            }
            String inputXML = sb.toString();            
            String predefinedXML = "<?xml version=\"1.0\" encoding=\"UTF-8\"?> <EmotionDB></EmotionDB>";
            InputStream inputStream = new ByteArrayInputStream(inputXML.getBytes());//use predefinedXML.getBytes() instead of inputXML.getBytes() for sample test


            System.out.println(connection.getResponseCode());
            DocumentBuilderFactory dbf = DocumentBuilderFactory.newInstance();
            DocumentBuilder db = dbf.newDocumentBuilder();
            Document doc = db.parse(inputStream);
            doc.getDocumentElement().normalize();

        } catch (Exception e) {
            e.printStackTrace();
        }

这里inputStream将具有正确的内容长度，因为它是从具有固定字节数的ByteArrayInputStream构建的。

Answer 5

一旦尝试就像这样

if(connection.getResponseCode() ==HttpURLConnection.HTTP_OK){

  InputStream xml = connection.getInputStream();   
  ..........
}else{

//problem in URI/connection .....
}

Answer 6

您需要在服务中正确关闭输出流以避免此异常。 如果您使用的是第三方库，请确保已设置响应标头

Content-Type
Content-Length

如果您使用的是java服务，则可以从方法获取内容长度

File.length()