主机名不能为空。我正在使用Http-post方法从webservice获取响应

Question

以下是我用于从Web service.getJSONFromUrl方法获取响应的代码，用于从Web服务获取响应。

我收到java.lang.IllegalStateException，Target host不能为null或在参数中设置的错误。 scheme = null，host = null，path = org.apache.http.client.methods.HttpGet

final String TAG = "JsonParser.java";

static InputStream is = null;
static JSONObject jObj = null;
static String json = "";

public JSONObject getJSONFromUrl(String url) 
{

    // make HTTP request
    try 
{

        DefaultHttpClient httpClient = new DefaultHttpClient();
        HttpPost httpPost = new HttpPost(url);

        HttpResponse httpResponse = httpClient.execute(httpPost);
        HttpEntity httpEntity = httpResponse.getEntity();
        is = httpEntity.getContent();          

    } catch (UnsupportedEncodingException e) {
        e.printStackTrace();
    } catch (ClientProtocolException e) {
        e.printStackTrace();
    } catch (IOException e) {
        e.printStackTrace();
    }

    try {

        BufferedReader reader = new BufferedReader(new InputStreamReader(is, 
"iso-8859-1"), 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(TAG, "Error converting result " + e.toString());
    }

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

    // return JSON String
    return jObj;
}