從android中的HttpURLConnection獲取InputStream時獲取UnknownLengthHttpInputStream

Question

HttpURLConnection.getInputStream（）給出UnknownLengthHttpInputStream，由於此Document解析引發SAX解析器異常。

以下是代碼

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中遇到此錯誤，此代碼在Java Project中完美運行。

以下是LogCat的例外情況：

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)

提前致謝。

Answer 1

它可能是一個Http 1.0（舊服務器或配置錯誤）服務器或沒有保持活動配置。 在這種情況下，在從服務器關閉連接時，流的長度是已知的。 嘗試在請求標頭中指定http1.1和keep-alive（一些谷歌搜索將有助於此）。 僅當在服務器響應中指定了內容長度屬性時，才會提前知道流長度。

解決方法：將http流完全read()入ByteBufferStream （直到read()返回-1 ）。 然后將ByteBufferInputStream拋出到您的庫中（現在知道長度）

Answer 2

您是否嘗試過使用apache庫？ 我建議如下：

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();
}

然后獲取HttpEntity本身的流。 Smth喜歡：

InputStream st = entity.getContent();

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

Answer 3

要處理響應使用這種方法，它將照顧所有！

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

當SAX解析器無法獲得InputStream數據的長度時，問題出現了。 要解決此問題，請將從xml （ InputStream ）讀取的內容保存到String變量中，並從DocumentBuilder parse方法的變量中創建一個InputStream 。 為此，請按如下方式修改代碼：

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();
        }

這里inputStream將具有正確的內容長度，因為它是從具有固定字節數的ByteArrayInputStream構建的。

Answer 5

一旦嘗試就像這樣

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

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

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

Answer 6

您需要在服務中正確關閉輸出流以避免此異常。 如果您使用的是第三方庫，請確保已設置響應標頭

Content-Type
Content-Length

如果您使用的是java服務，則可以從方法獲取內容長度

File.length()