16

HttpURLConnection.getInputStream() 给出 UnknownLengthHttpInputStream 并且由于此 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 中收到此错误，并且此代码在 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。

4

6 回答 6

3

它可能是 Http 1.0（旧服务器或配置错误）服务器或未配置保持活动状态。在这种情况下，流的长度在从服务器关闭连接时是已知的。尝试在您的请求标头中指定 http1.1 和 keep-alive（一些谷歌搜索会有所帮助）。只有在服务器响应中指定了内容长度属性时，您才会提前知道流长度。

解决方法：将 http 流读入ByteBufferStream完全（直到read()返回-1）。然后将 ByteBufferInputStream 扔到您的库中（现在已知长度）

于 2012-12-02T19:36:02.053 回答
0

要处理响应，请使用此方法，它将处理所有问题！

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();
   }
于 2012-10-25T12:25:02.613 回答
0

您是否尝试过为此使用 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自身的流。喜欢：

InputStream st = entity.getContent();

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

于 2012-10-12T09:32:22.023 回答
0

当SAX 解析器无法获取InputStream数据长度时，问题就出现了。xml要解决此问题，将从( InputStream) 中读取的内容保存到String变量中，并InputStream从变量中为 的parse方法创建一个DocumentBuilder。为此，请按如下方式修改您的代码：

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();
        }

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

于 2012-11-27T17:40:03.640 回答
0

一旦像这样尝试

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

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

//problem in URI/connection .....
}
于 2012-12-01T15:37:32.087 回答
-2

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，请确保您已设置响应标头

Content-Type
Content-Length

如果您使用的是 java 服务，您可以从方法获取内容长度

File.length()
于 2012-08-18T03:57:32.810 回答