Erreur avec IOException e

package calaos.android;

import java.io.IOException;
import java.io.InputStream;
import java.io.UnsupportedEncodingException;
import java.util.Scanner;
import org.apache.http.HttpEntity;
import org.apache.http.client.HttpClient;
import org.apache.http.client.methods.HttpPost;
import org.apache.http.entity.ByteArrayEntity;
import org.apache.http.impl.client.DefaultHttpClient;
import org.apache.http.params.BasicHttpParams;
import org.json.JSONException;
import org.json.JSONObject;

public class CJson {

    private String m_url;

    CJson(String url)
    {
        this.m_url = url;
    }

    public JSONObject queryJsonPost(String params)
    {
        JSONObject jsonreponse = null;
        try {
            HttpClient client = new DefaultHttpClient(new BasicHttpParams());
            HttpPost request = new HttpPost(this.m_url);

            request.setEntity(new ByteArrayEntity(params.getBytes("UTF8")));

            HttpEntity entity = client.execute(request).getEntity();

            if (entity != null) {
                InputStream instream = entity.getContent();
                String result = new Scanner(instream).next();

                jsonreponse = new JSONObject(result);
            }


        } catch (UnsupportedEncodingException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();

        } catch (IOException e) {
            // TODO Auto-generated catch block
            e.printStackTrace(); // erreur! javax.net.ssl.SSLPeerUnverifiedException: No peer certificate
        } catch (JSONException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        }

        return jsonreponse;
    }
}