Question

我写了一个程序我想从URL下载一个json文件并在文本视图中显示它。单击按钮后，程序将在几秒钟后停止。我不知道问题是什么。请帮帮我..

java代码：

 public class MainActivity extends Activity {
 TextView tx;
@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);
    Button b=(Button)findViewById(R.id.button2);
    b.setOnClickListener(new OnClickListener() {

        @Override
        public void onClick(View v) {
            // TODO Auto-generated method stub
            new GetJsonTask().execute("http://shahid.ifilmtv.ir/query/englishcurrentshows");

        }
    });


}
public class GetJsonTask extends AsyncTask<String, Void, String>
{

    @Override
    protected String doInBackground(String... urls) {
        // TODO Auto-generated method stub
        return getJson(urls[0]);
    }
    @Override
    protected void onPostExecute(String result) {
        // TODO Auto-generated method stub
        super.onPostExecute(result);
        JSONArray jsonArray;
        try {
            jsonArray = new JSONArray(result);
         JSONObject object = jsonArray.getJSONObject(1);
        tx.setText(object.getString("id"));
    }
    catch (JSONException e) {
        // TODO Auto-generated catch block
        e.printStackTrace();
    }
}

}

   public String getJson(String url) {

        try {
            InputStream inputStream = null;
            DefaultHttpClient defaultHttpClient = new DefaultHttpClient();
            HttpPost httpPost = new HttpPost(url);
            HttpResponse httpResponse = defaultHttpClient.execute(httpPost);
            HttpEntity httpEntity = httpResponse.getEntity();
            inputStream = httpEntity.getContent();
            BufferedReader reader = new BufferedReader(new InputStreamReader(inputStream, "iso-8859-1"), 8);
            StringBuilder sb = new StringBuilder();
            String line = null;
            while ((line = reader.readLine()) != null) {
                sb.append(line + "\n");
            }
            inputStream.close();
            String result = sb.toString();
            return result;
        } catch (Exception ex) {
              Toast.makeText(getApplicationContext(), "ERROR : " + ex, Toast.LENGTH_LONG).show();
            return null;
        }

    }

}

Answer 1

我认为问题出在getJSON方法中。我重写了以下代码。请试试这个。

    public String getJson(String url) {
  try {
        DefaultHttpClient defaultHttpClient = new DefaultHttpClient();
        HttpPost httpPost = new HttpPost(url);
        httpost.setHeader("Accept", "application/json");
        httpost.setHeader("Content-type", "application/json");

        ResponseHandler responseHandler = new BasicResponseHandler();
        Object resp = defaultHttpClient.execute(httpPost, responseHandler);
        String json =  resp.toString();
        // create a object here if you want
        JSONObject obj = new JSONObject(json);
        return json;        
   } catch (Exception ex) {
          Toast.makeText(getApplicationContext(), "ERROR : " + ex, Toast.LENGTH_LONG).show();
        return null;
   }

}

如何从URL读取Json文件？

1 个答案: