解决NetworkOnMainThreadException

今天在Android 访问 WebService 的时候遇到，错误Caused by: android.os.NetworkOnMainThreadException，查了下原因上在4.0之后在主线程里面执行Http请求都会报这个错，大概是怕Http请求时间太长造成程序假死的情况吧，于是就用另外一个线程处理请求，用的是handler机制，源码如下：

package com.example.webservicetest;

import java.io.IOException;
import java.io.UnsupportedEncodingException;

import org.ksoap2.SoapEnvelope;
import org.ksoap2.serialization.SoapObject;
import org.ksoap2.serialization.SoapSerializationEnvelope;
import org.ksoap2.transport.HttpResponseException;
import org.ksoap2.transport.HttpTransportSE;
import org.xmlpull.v1.XmlPullParserException;

import android.os.Build;
import android.os.Bundle;
import android.os.Handler;
import android.os.Message;
import android.os.StrictMode;
import android.annotation.SuppressLint;
import android.annotation.TargetApi;
import android.app.Activity;
import android.util.Log;
import android.view.Menu;
import android.view.View;
import android.view.View.OnClickListener;
import android.widget.Button;
import android.widget.EditText;
import android.widget.Toast;

@SuppressLint("NewApi")
@TargetApi(Build.VERSION_CODES.GINGERBREAD)
public class MainActivity extends Activity {

    EditText editPara;

    EditText editRes;

    Button btnCal;

    Handler handler = null;

    /*
     * @TargetApi(Build.VERSION_CODES.GINGERBREAD)
     *
     * @SuppressLint("NewApi")
     *
     * @Override
     */
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);

        /*
         * if (android.os.Build.VERSION.SDK_INT > 9) { StrictMode.ThreadPolicy
         * policy = new StrictMode.ThreadPolicy.Builder().permitAll().build();
         * StrictMode.setThreadPolicy(policy); }
         */

        handler = new Handler() {
            @Override
            public void handleMessage(Message msg) {
                super.handleMessage(msg);
                Bundle data = msg.getData();
                String val = data.getString("value");

                Toast.makeText(getApplicationContext(), "获取成功",
                        Toast.LENGTH_LONG);
                editRes.setText(val);
                Log.i("mylog", "请求结果-->" + val);

            }
        };
        InitView();
        InitEvents();
    }

    @Override
    public boolean onCreateOptionsMenu(Menu menu) {
        // Inflate the menu; this adds items to the action bar if it is present.
        getMenuInflater().inflate(R.menu.activity_main, menu);
        return true;
    }

    private void InitView() {
        editPara = (EditText) findViewById(R.id.editCity);
        editRes = (EditText) findViewById(R.id.editRes);

        btnCal = (Button) findViewById(R.id.btnCal);

    }

    private void InitEvents() {
        btnCal.setOnClickListener(new OnClickListener() {

            @Override
            public void onClick(View view) {
                // TODO Auto-generated method stub

                Runnable runnable = new Runnable() {
                    @Override
                    public void run() {
                        //
                        // TODO: http request.

                        String sCity = editPara.getText().toString();

                        SoapObject sResult = TestWs(sCity);

                        try {
                            if (sResult == null) {

                                Message msg = new Message();
                                Bundle data = new Bundle();
                                data.putString("value", "计算错误");
                                msg.setData(data);
                                handler.sendMessage(msg);
                            }
                            else
                            {
                                String sText = parseWeather(sResult);

                                Message msg = new Message();
                                Bundle data = new Bundle();
                                data.putString("value", sText);
                                msg.setData(data);
                                handler.sendMessage(msg);
                            }
                        } catch (UnsupportedEncodingException e) {
                            // TODO Auto-generated catch block
                            e.printStackTrace();
                        }

                        //

                    }
                };

                new Thread(runnable).start();

                /*
                 * String sCity = editPara.getText().toString();
                 *
                 * SoapObject sResult = TestWs(sCity);
                 *
                 * String sText; try { sText = parseWeather(sResult); if
                 * (sResult != null) { Toast.makeText(getApplicationContext(),
                 * "获取成功", Toast.LENGTH_LONG); editRes.setText(sText); } } catch
                 * (UnsupportedEncodingException e) { // TODO Auto-generated
                 * catch block e.printStackTrace(); }
                 */

            }
        });

    }

    private SoapObject TestWs(String sCity) {

        String NAMESPACE = "http://WebXml.com.cn/";

        String URL = "http://www.webxml.com.cn/webservices/weatherwebservice.asmx";

        String METHODNAME = "getWeatherbyCityName";

        String SOAP_ACTION = "http://WebXml.com.cn/getWeatherbyCityName";

        SoapObject so = new SoapObject(NAMESPACE, METHODNAME);

        HttpTransportSE httpSE = new HttpTransportSE(URL);
        httpSE.debug = true;
        SoapSerializationEnvelope soapEnvelope = new SoapSerializationEnvelope(
                SoapEnvelope.VER11);

        soapEnvelope.dotNet = true;
        soapEnvelope.bodyOut = so;
        so.addProperty("theCityName", sCity);
        soapEnvelope.setOutputSoapObject(so);

        try {
            httpSE.call(null, soapEnvelope);

            SoapObject seOut = (SoapObject) soapEnvelope.getResponse();

            return seOut;

            /*
             * if(seOut!=null) { String sResult= (String)
             * seOut.getProperty("getWeatherbyCityNameResult");
             *
             * return sResult;
             *
             * }
             */

        } catch (HttpResponseException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        } catch (IOException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        } catch (XmlPullParserException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        }
        return null;

    }

    private String parseWeather(SoapObject detail)
            throws UnsupportedEncodingException {
        String date = detail.getProperty(6).toString();
        String weatherToday = "今天：" + date.split("")[0];
        weatherToday = weatherToday + "\n天气：" + date.split("")[1];
        weatherToday = weatherToday + "\n气温："
                + detail.getProperty(5).toString();
        weatherToday = weatherToday + "\n风力："
                + detail.getProperty(7).toString() + "\n";
        System.out.println("weatherToday is " + weatherToday);

        return weatherToday;
    }

}