记一次NegativeArraySizeException

Posted 2022-01-08 bobkingblog

问题描述：服务器接收后台返回的报文时，提示java.lang.NegativeArraySizeException

分析：这种异常返回的原因，一般情况下没有报文提示为返回空报文，初步分析是响应报文流长度出了问题

百度一下类似的情况：https://stackoverflow.com/questions/11207897/negative-array-size-exception

节选部分内容：

try
     connection = (HttpConnection)Connector.open("http://someurl.xml",Connector.READ_WRITE);
     URLEncodedPostData postData = new URLEncodedPostData(URLEncodedPostData.DEFAULT_CHARSET, false);
     postData.append("username", "loginapi");
     postData.append("password", "myapilogin");
     postData.append("term", word);

     connection.setRequestMethod(HttpConnection.POST);
     connection.setRequestProperty("Content-Type","application/x-www-form-urlencoded");
     connection.setRequestProperty("User-Agent","Profile/MIDP-2.0 Configuration/CLDC-1.0");
     requestOut = connection.openOutputStream();
     requestOut.write(postData.getBytes());
     String contentType = connection.getHeaderField("Content-type"); 
     detailIn = connection.openInputStream();         
     int length = (int) connection.getLength();
     ByteArrayOutputStream baos = new ByteArrayOutputStream(); 
     if(length > 0)//这里长度没有判定的情况下，byte array长度若为-1会产生错误
         byte info[] = new byte[length];
         int bytesRead = detailIn.read(info);
         while(bytesRead > 0)  
             baos.write(info, 0, bytesRead); 
             bytesRead = detailIn.read(info); 
             
         baos.close();
         connection.close();
         requestSuceeded(baos.toByteArray(), contentType);

         detailIn.read(info);
     
     else
     
          System.out.println("Negative array size");
     
           requestOut.close();
           detailIn.close();
           connection.close();
    

　　结论：HTTP服务器在返回响应报文的时候，没有进行content.length长度判断，按照常规流程响应了错误长度的报文，导致了接收方报文长度异常