Android base64发送到servlet的字符串不起作用

Question

我的Android代码：

HttpClient client=new DefaultHttpClient();
HttpPost request=null;
for(StudentInfo stdInfo : stdInfoList) {
JSONObject reqObject=dao.createjsonreq(stdInfo);    
StringEntity requestSet = new StringEntity(reqObject.toString());
//appUrl = http://192.168.1.1/StudentInfo/std?
request=new HttpPost(appUrl+"Request="+URLEncoder.encode(reqObject.toString()));
//now URl is = http://192.168.1.1/StudentInfo/std?Request={"RequestData":{"StringImge":"/9A/.."}}
requestSet.setContentType("application/json;charset=UTF-8");
requestSet.setContentEncoding(new BasicHeader
(HTTP.CONTENT_TYPE,"application/json;charset=UTF-8"));
request.setEntity(requestSet);
HttpResponse response=client.execute(request);
.....
}

此处为createjsonrequest创建方法

JSONObject sentRequestJson = new JSONObject(); 
JSONObject sentRequestJson = new JSONObject(); 
Bitmap image=BitmapFactory.decodeFile(stdInfo.getPicFile());
ByteArrayOutputStream baosimg = new ByteArrayOutputStream();
if (image != null) {
image.compress(Bitmap.CompressFormat.PNG,60,baos);
byte[] byteimg=baosimg.toByteArray();
String strImage = Base64.encodeToString(byteimg, Base64.DEFAULT);
requestJsonObj.put("StringImage",strImage );
}
sentRequestJson.put("RequestData":requestJsonObj);
return sentRequestJson;

我的Servlet代码：

log.debug("I got request");
 req.setCharacterEncoding("UTF-8");
 Enumeration<String> parameterNames = req.getParameterNames();
 while (parameterNames.hasMoreElements()) {
 String jsonObject = parameterNames.nextElement();
 log.debug(jsonObject + "names");
 }

当我从Android应用程序发送POST请求到java服务器时，它不执行java服务器中的任何代码（我给出了调试）（当我在android中调试时看到base64图像字符串），

如果我使用android代码requestJsonObj.put("StringImage","");，则请求调用服务器并调试执行。 请帮忙。 base64字符串图像的内容类型的任何更改。