java - HttpURLConnection 不适用于 Android

Question

我有一个问题，真的不知道出了什么问题:-/

我有一个简单的函数，在单击按钮后调用

public void clickFunc(View view) {

        StringBuilder result = new StringBuilder();
        try {
            URL url = new URL("http://google.com");

            HttpURLConnection conn = (HttpURLConnection) url.openConnection();
            conn.setReadTimeout(15000 /* milliseconds */);
            conn.setConnectTimeout(15000 /* milliseconds */);
            conn.setRequestMethod("POST");
            conn.setDoInput(true);
            conn.setDoOutput(true);
            conn.connect();
            int responseCode=conn.getResponseCode();

            if (responseCode == HttpsURLConnection.HTTP_OK) {

                InputStream in = new BufferedInputStream(conn.getInputStream());
                BufferedReader reader = new BufferedReader(new InputStreamReader(in));

                String line;

                while ((line = reader.readLine()) != null) {

                    result.append(line);
                }
                in.close();
                httpTxt.setText(result.toString());

            }
            else {
                httpTxt.setText("false : "+responseCode);
            }
        }
        catch(Exception e){
            httpTxt.setText("Exception: " + e.getMessage());
        }


    }

但是单击后我的输出是 Exception: null

在 list 中我有<uses-permission android:name="android.permission.INTERNET" />

我认为此代码与此处或互联网上提到的所有代码相同:-/

httptxt 是我的页面输出的 texview

谢谢

Answer 1

好吧，我不知道我必须在后台执行此操作...它现在正在工作，谢谢!

public void clickFunc(View view) {

        new SendPostRequest().execute();
    }
    private class SendPostRequest extends AsyncTask<Void, Void, String> {

    protected String doInBackground (Void... params) {

        StringBuilder result = new StringBuilder();
        HttpURLConnection conn = null;
        BufferedReader reader;

        try {
            URL url = new URL("http://stackoverflow.com"); 

            conn = (HttpURLConnection) url.openConnection();
            conn.setRequestMethod("GET");
            conn.setReadTimeout(15000);
            conn.setConnectTimeout(15000);
            conn.setDoInput(true);
            conn.setDoOutput(true);
            conn.connect();
            int responseCode=conn.getResponseCode();

            if (responseCode == HttpsURLConnection.HTTP_OK) {

                InputStream in = new BufferedInputStream(conn.getInputStream());
                reader = new BufferedReader(new InputStreamReader(in));

                String line;

                while ((line = reader.readLine()) != null) {

                    result.append(line);
                }
                in.close();
                return(result.toString());

            }
            else {
                return("false : "+responseCode);
            }
        }
        catch(Exception e){
            return("Exception: " + e.getMessage());
        }
    }
        protected void onPostExecute(String s) {
            super.onPostExecute(s);
            httpTxt.setText(s);
        }

    }

我不是一个 Android 程序员，所以即使它是基本的我也不知道，对不起大家:)

关于我的应用程序，如果您感兴趣，为什么我想要它 - 我读取条形码，转到 php 脚本，查看数据库是否有此代码并返回 true 或 false