连接本地主机时出错

Question

我知道这个问题已经被问了好几次了，但现在我很无助。

我在 localhost 上有一个 php 网页，它回应了"你好"。（在本地主机工作完美）。 我有以下代码，在我的应用程序中显示从本地主机网页到 TextView 的响应。

tv = (TextView) findViewById(R.id.txtTest);
InputStream is = null;
String result = "";
    String url = "http://10.0.2.2/android/try.php";
    HttpClient httpclient = new DefaultHttpClient();
    try {               
        HttpPost httppost = new HttpPost(url);
        HttpResponse response = httpclient.execute(httppost);
        Log.d("myapp", "response " + response.getEntity());
        HttpEntity entity = response.getEntity();
        is = entity.getContent();
        String st = EntityUtils.toString(response.getEntity());

    } catch (Exception e) {
        Log.e("log_tag", "Error in http connection " + e.toString());
    }
    // convert response to string
    try {
        BufferedReader reader = new BufferedReader(new InputStreamReader(
                is, "UTF-8"), 8);
        StringBuilder sb = new StringBuilder();
        String line = null;
        while ((line = reader.readLine()) != null) {
            sb.append(line + "n");
        }
        is.close();
        result = sb.toString();
    } catch (Exception e) {
        Log.e("log_tag", "Error converting result " + e.toString());
    }
    tv.setText(result.toString());

我收到以下错误（日志猫）。

09-24 13:34:42.654: E/log_tag(2032): Error in http connection android.os.NetworkOnMainThreadException
09-24 13:34:42.654: E/log_tag(2032): Error converting result java.lang.NullPointerException

附言我在清单中添加了互联网权限。

Answer 1

您应该从与主 （UI） 线程不同的线程执行网络操作（连接等）。这就是您得到的错误android.os.NetworkOnMainThreadException的意思。

您应该查看ASyncTask或Thread来执行此操作。

也阅读这篇文章...

将您当前的代码替换为以下内容：

    AsyncTask<Void,Void,Void> my_task = new AsyncTask<Void,Void,Void>() {
        @Override
        protected void onPostExecute() {
            TextView  tv = (TextView) findViewById(R.id.txtTest);
            tv.setText(result.toString());
        }
        @Override
        protected Void doInBackground(Void... voids) {
            InputStream is = null;
            String result = "";
            String url = "http://10.0.2.2/android/try.php";
            HttpClient httpclient = new DefaultHttpClient();
            try {
                HttpPost httppost = new HttpPost(url);
                HttpResponse response = httpclient.execute(httppost);
                Log.d("myapp", "response " + response.getEntity());
                HttpEntity entity = response.getEntity();
                is = entity.getContent();
                String st = EntityUtils.toString(response.getEntity());

            } catch (Exception e) {
                Log.e("log_tag", "Error in http connection " + e.toString());
            }
            // convert response to string
            try {
                BufferedReader reader = new BufferedReader(new InputStreamReader(
                        is, "UTF-8"), 8);
                StringBuilder sb = new StringBuilder();
                String line = null;
                while ((line = reader.readLine()) != null) {
                    sb.append(line + "n");
                }
                is.close();
                result = sb.toString();
            } catch (Exception e) {
                Log.e("log_tag", "Error converting result " + e.toString());
            }
        }
    }.execute();