Question

我的onCreate

中包含此代码

    tv = (TextView) findViewById(R.id.tv);

    HttpHelper helper = new HttpHelper("http://www.pinoyfitness.com/");
    helper.execute();

我在onCreate

之外有这个方法

private class HttpHelper extends AsyncTask<Void, Void, String> {
    String urlString;
    public HttpHelper(String urlString) {
        this.urlString = urlString;
    }

    public String downloadText() {
        URL url = null;
        HttpURLConnection urlConnection = null;
        InputStream in = null;

        try {
            url = new URL(urlString);
            urlConnection = (HttpURLConnection) url.openConnection();
            in = new BufferedInputStream(urlConnection.getInputStream());
        } catch (MalformedURLException e) {
            e.printStackTrace();
        } catch (IOException e) {
            e.printStackTrace();
        }

        InputStreamReader isr = new InputStreamReader(in);
        int charRead;
        StringBuffer str = new StringBuffer("");

        char[] inputBuffer = new char[2000];

        try {
            while((charRead=isr.read(inputBuffer))>0){
                str.append(String.copyValueOf(inputBuffer,0,charRead));
                inputBuffer = new char[2000];
            }
            in.close();
        } catch (IOException e) {
            e.printStackTrace();
        }

        urlConnection.disconnect();

        return str.toString();
    }

    @Override
    protected String doInBackground(Void... params) {

        // This commented code will run the conventional way to connect to the
        // return downloadText();

        String s = "";

        try {
            // The next line does what downloadText() does. You'll need JSoup for this.
            Document d = Jsoup.connect(urlString).timeout(0).get();
            Elements links = d.select("h2.entry-title a");


            for(Element e: links){
                s += e.text() +"\n\n"; 
            }

        } catch (IOException e) {
            e.printStackTrace();
        }

        return s;
    }

    @Override
    protected void onPostExecute(String result) {
        // TODO Auto-generated method stub
        // super.onPostExecute(result);
        tv.setText(result);
    }


}

错误在于：Document d = Jsoup.connect(urlString).timeout(0).get();。它说：在com.example.pinoyfitness.Timeline $ HttpHelper.doInBackground（Timeline.java:115）我想知道这行代码有什么问题。我尝试将整个代码复制并粘贴到一个新的android项目中，它可以工作。我已经完成了所有必要的操作，例如添加Internet权限和配置构建路径：Jsoup

Answer 1

首先，考虑使用网络库，它将极大地改善您的代码并摆脱这些错误。例如，使用OkHTTP或Android Async HTTP

Answer 2

我发现了错误。这是一个空指针异常，因为我忘了在Java Build Path中检查导入的Jsoup - ＆gt;订单和出口

访问互联网上的信息

2 个答案: