android.os.NetworkOnMainThreadException 。需要使用异步任务吗？

Question

我的 android 登录功能出现问题，收到 android.os.NetworkOnMainThreadException

我暂时删除了密码字段以测试是否仅发布了用户名，我知道这是 android 3.2+ 的问题。

这是我的代码：

package com.example.toknapp;

import java.util.ArrayList;

public class login2 extends Activity {
    EditText un;
    TextView error;
    Button ok;
    /** Called when the activity is first created. */
    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.login);
        un=(EditText)findViewById(R.id.et_un);
        ok=(Button)findViewById(R.id.btn_login);
        error=(TextView)findViewById(R.id.tv_error);

        ok.setOnClickListener(new View.OnClickListener() {

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

                ArrayList<NameValuePair> postParameters = new ArrayList<NameValuePair>();
                postParameters.add(new BasicNameValuePair("username", un.getText().toString()));
                //String valid = "1";
                String response = null;
                try {
                    response = CustomHttpClient.executeHttpPost("http://tokn.me/android_merchant_login.php", postParameters);
                    String res=response.toString();
                   // res = res.trim();
                    res= res.replaceAll("\\s+","");                              
                    //error.setText(res);

                   if(res.equals("1"))
                        error.setText("Correct Username or Password");
                    else
                        error.setText("Sorry!! Incorrect Username or Password"); 
                } catch (Exception e) {
                    un.setText(e.toString());
                }

            }
        });
    }
}


package com.example.toknapp;

import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;
import java.net.URI;
import java.util.ArrayList;

import org.apache.http.HttpResponse;
import org.apache.http.NameValuePair;
import org.apache.http.client.HttpClient;
import org.apache.http.client.entity.UrlEncodedFormEntity;
import org.apache.http.client.methods.HttpGet;
import org.apache.http.client.methods.HttpPost;
import org.apache.http.conn.params.ConnManagerParams;
import org.apache.http.impl.client.DefaultHttpClient;
import org.apache.http.params.HttpConnectionParams;
import org.apache.http.params.HttpParams;

public class CustomHttpClient {
    /** The time it takes for our client to timeout */
    public static final int HTTP_TIMEOUT = 30 * 1000; // milliseconds

    /** Single instance of our HttpClient */
    private static HttpClient mHttpClient;

    /**
     * Get our single instance of our HttpClient object.
     *
     * @return an HttpClient object with connection parameters set
     */
    private static HttpClient getHttpClient() {
        if (mHttpClient == null) {
            mHttpClient = new DefaultHttpClient();
            final HttpParams params = mHttpClient.getParams();
            HttpConnectionParams.setConnectionTimeout(params, HTTP_TIMEOUT);
            HttpConnectionParams.setSoTimeout(params, HTTP_TIMEOUT);
            ConnManagerParams.setTimeout(params, HTTP_TIMEOUT);
        }
        return mHttpClient;
    }

    /**
     * Performs an HTTP Post request to the specified url with the
     * specified parameters.
     *
     * @param url The web address to post the request to
     * @param postParameters The parameters to send via the request
     * @return The result of the request
     * @throws Exception
     */
    public static String executeHttpPost(String url, ArrayList<NameValuePair> postParameters) throws Exception {
        BufferedReader in = null;
        try {
            HttpClient client = getHttpClient();
            HttpPost request = new HttpPost(url);
            UrlEncodedFormEntity formEntity = new UrlEncodedFormEntity(postParameters);
            request.setEntity(formEntity);
            HttpResponse response = client.execute(request);
            in = new BufferedReader(new InputStreamReader(response.getEntity().getContent()));

            StringBuffer sb = new StringBuffer("");
            String line = "";
            String NL = System.getProperty("line.separator");
            while ((line = in.readLine()) != null) {
                sb.append(line + NL);
            }
            in.close();

            String result = sb.toString();
            return result;
        } finally {
            if (in != null) {
                try {
                    in.close();
                } catch (IOException e) {
                    e.printStackTrace();
                }
            }
        }
    }

    /**
     * Performs an HTTP GET request to the specified url.
     *
     * @param url The web address to post the request to
     * @return The result of the request
     * @throws Exception
     */
    public static String executeHttpGet(String url) throws Exception {
        BufferedReader in = null;
        try {
            HttpClient client = getHttpClient();
            HttpGet request = new HttpGet();
            request.setURI(new URI(url));
            HttpResponse response = client.execute(request);
            in = new BufferedReader(new InputStreamReader(response.getEntity().getContent()));

            StringBuffer sb = new StringBuffer("");
            String line = "";
            String NL = System.getProperty("line.separator");
            while ((line = in.readLine()) != null) {
                sb.append(line + NL);
            }
            in.close();

            String result = sb.toString();
            return result;
        } finally {
            if (in != null) {
                try {
                    in.close();
                } catch (IOException e) {
                    e.printStackTrace();
                }
            }
        }
    }
}

Answer 1

我猜你正试图在你的主线程上执行一些网络操作

NetworkOnMainThreadException 来自文档

当应用程序尝试执行 在其主线程上进行网络操作。

更新：

最好使用AsyncTask

private class MyAsyncTask extends AsyncTask<Void, Void, Void>
    {

        ProgressDialog mProgressDialog;
        @Override
        protected void onPostExecute(Void result) {
            mProgressDialog.dismiss();
        }

        @Override
        protected void onPreExecute() {
            mProgressDialog = ProgressDialog.show(ActivityName.this, 
                                            "Loading...", "Data is Loading...");
        }

        @Override
        protected Void doInBackground(Void... params) {
           // your network operation
            return null;
        }
    }

Answer 2

只需将清单文件中的目标版本更改为情人而不是 Honeycomb。

<uses-sdk
    android:minSdkVersion="8"
    android:targetSdkVersion="8" />

编辑：但是使用 AsyncTask 是解决这个问题的更方便的方法。