安卓项目3

这几天一直在为一个问题纠结...这是一个连接服务器的类，提供不同的参数返回不同的结果。

public final class ServiceLink {
/*    
    功能：连接服务器
    API：link(String url);
        get(String bundle, String value);
*/
    static InputStream is = null;
    static JSONObject jObj = null;
    static String json = "";           
    private HttpResponse httpResponse  =null;
    private    String url = null;
    HttpPost httpPost = new HttpPost(url);

    ServiceLink(){
        Log.i("linkService", "ServiceLink");
        
    }
    public void setURL(String urll){
        this.url = urll;
        Log.i("setURL",url);
    }
    public JSONObject serviceLogin(String hostname,String username, String password){
        List<NameValuePair> params = new ArrayList<NameValuePair>();
        params.add(new BasicNameValuePair("operate","login"));
        params.add(new BasicNameValuePair("hostname", hostname));
        params.add(new BasicNameValuePair("username",username));
        params.add(new BasicNameValuePair("password", password));
        return putParamsToHttp(params);
        
    }
    public JSONObject serviceClean(){
        List<NameValuePair> params = new ArrayList<NameValuePair>();
        params.add(new BasicNameValuePair("operate", "clean"));
        return putParamsToHttp(params);
    }
    

    public JSONObject putParamsToHttp(List<NameValuePair> params){
        try {
            //设置httpPost请求参数
            httpPost.setEntity(new UrlEncodedFormEntity(params, HTTP.UTF_8));
            //
            httpResponse = new DefaultHttpClient().execute(httpPost);
            if(httpResponse.getStatusLine().getStatusCode() == 200){
                   HttpEntity httpEntity = httpResponse.getEntity();
                    is = httpEntity.getContent();                
     
            }
        } catch (UnsupportedEncodingException e) {
            // TODO Auto-generated catch block
            Log.i("linkService", "Link failed");
        } catch (ClientProtocolException e) {
            // TODO Auto-generated catch block
            Log.i("linkService", "Link failed");
        } catch (IOException e) {
            // TODO Auto-generated catch block
            Log.i("linkService", "Link failed");
        }
        try {
                BufferedReader reader = new BufferedReader(new InputStreamReader(
                        is, "UTF-8"));
                StringBuilder sb = new StringBuilder();
                String line = null;
                while ((line = reader.readLine()) != null) {
                    sb.append(line + "\n");
            }
                is.close();
                json = sb.toString();
        } catch (Exception e) {
                Log.e("Buffer Error", "Error converting result " + e.toString());
                Log.d("json", json.toString());
        }

            // try parse the string to a JSON object
        try {
                jObj = new JSONObject(json);
        } catch (JSONException e) {
                Log.e("JSON Parser", "Error parsing data " + e.toString());
        }

            // return JSON String
        return jObj;

    }
}

我在activity下写一个按键提交，代码如下

            public void onClick(View view) {
                // TODO Auto-generated method stub
                Log.i("login","reading JSON!");
                String hostnamestring = hostname.getText().toString();
                String usernamestring = username.getText().toString();
                String passwordstring = password.getText().toString();
                JSONObject jsonobject= new JSONObject();
                                ServiceLink servicelink =  new ServiceLink();
                servicelink.setURL(hostnamestring);

                jsonobject = servicelink.serviceLogin(hostnamestring, usernamestring, passwordstring);
                Log.i("login",jsonobject.toString());
            } 

但是会出错

好吧...我继续看为什么会这样....郁闷