我正在尝试从存储在我的在线托管服务器（00webhost.com）中的JSON文件中写入的PHP文件中获取数据。当我运行程序时，它说 未知主机 。但是，该地址将提供JSON格式的文件。
我在AndroidManifest.xml文件中拥有所有许可以及互联网许可。
活动类别：
public class Recmain extends AppCompatActivity {
private String TAG = MainActivity.class.getSimpleName();
private ListView lv;
ArrayList<HashMap<String, String>> contactList;
TextView uid;
TextView name1;
TextView email1;
Button Btngetdata;
//URL to get JSON Array
private static String url = "http://tongue-tied-
papers.000webhostapp.com/data_fetch.php";
//JSON Node Names
private static final String TAG_USER = "user";
private static final String TAG_ID = "id";
private static final String TAG_NAME = "name";
private static final String TAG_EMAIL = "email";
JSONArray user = null;
private List<movie> movieList = new ArrayList<>();
private RecyclerView recyclerView;
private moviesadapter mAdapter;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.rmain);
Toolbar toolbar = (Toolbar) findViewById(R.id.toolbar);
setSupportActionBar(toolbar);
Intent intent=getIntent();
String m=intent.getStringExtra("data");
recyclerView = (RecyclerView) findViewById(R.id.recycler_view);
mAdapter = new moviesadapter(movieList);
RecyclerView.LayoutManager mLayoutManager = new
LinearLayoutManager(getApplicationContext());
recyclerView.setLayoutManager(mLayoutManager);
recyclerView.setItemAnimator(new DefaultItemAnimator());
recyclerView.setAdapter(mAdapter);
prepareMovieData();
}
private void prepareMovieData(){
movie movie = new movie("Mad Max: Fury Road", "Action & Adventure",
"2015");
movieList.add(movie);
mAdapter.notifyDataSetChanged();
new GetContacts().execute();
}
private class GetContacts extends AsyncTask<Void, Void, Void> {
@Override
protected void onPreExecute() {
super.onPreExecute();
Toast.makeText(recmain.this,url,Toast.LENGTH_LONG).show();
}
@Override
protected Void doInBackground(Void... arg0) {
JSONParser sh = new JSONParser();
// Making a request to url and getting response
String url = "https://tongue-tied-
papers.000webhostapp.com/data_fetch.php";
String jsonStr = sh.makeServiceCall(url);
if (jsonStr != null) {
try {
JSONObject jsonObj = new JSONObject(jsonStr);
// Getting JSON Array node
JSONArray contacts = jsonObj.getJSONArray("id");
// looping through All Contacts
for (int i = 0; i < contacts.length(); i++) {
JSONObject c = contacts.getJSONObject(i);
String id = c.getString("id");
Toast.makeText(getApplicationContext(), id ,
Toast.LENGTH_LONG).show();
// tmp hash map for single contact
HashMap<String, String> contact = new HashMap<>();
// adding each child node to HashMap key => value
contact.put("id", id);
// adding contact to contact list
contactList.add(contact);
}
} catch (final JSONException e) {
Log.e(TAG, "Json parsing error: " + e.getMessage());
runOnUiThread(new Runnable() {
@Override
public void run() {
Toast.makeText(getApplicationContext(),
"Json parsing error: " + e.getMessage(),
Toast.LENGTH_LONG).show();
}
});
}
} else {
Log.e(TAG, "Couldn't get json from server.");
runOnUiThread(new Runnable() {
@Override
public void run() {
Toast.makeText(getApplicationContext(),
"Couldn't get json from server. Check LogCat
for possible errors!",
Toast.LENGTH_LONG).show();
}
});
}
return null;
}
@Override
protected void onPostExecute(Void result) {
}
}
}
适配器类：
public class JSONParser {
private static final String TAG = JSONParser.class.getSimpleName();
public JSONParser() {
}
public String makeServiceCall(String reqUrl) {
String response = null;
try {
URL url = new URL(reqUrl);
HttpURLConnection conn = (HttpURLConnection)
url.openConnection();
conn.setRequestMethod("GET");
// read the response
InputStream in = new BufferedInputStream(conn.getInputStream());
response = convertStreamToString(in);
} catch (MalformedURLException e) {
Log.e(TAG, "MalformedURLException: " + e.getMessage());
} catch (ProtocolException e) {
Log.e(TAG, "ProtocolException: " + e.getMessage());
} catch (IOException e) {
Log.e(TAG, "IOException: " + e.getMessage());
} catch (Exception e) {
Log.e(TAG, "Exception: " + e.getMessage());
}
return response;
}
private String convertStreamToString(InputStream is) {
BufferedReader reader = new BufferedReader(new
InputStreamReader(is));
StringBuilder sb = new StringBuilder();
String line;
try {
while ((line = reader.readLine()) != null) {
sb.append(line).append('\n');
}
} catch (IOException e) {
e.printStackTrace();
} finally {
try {
is.close();
} catch (IOException e) {
e.printStackTrace();
}
}
return sb.toString();
}
}
它说，未知主机。
答案 0 :(得分：0)
好像URL的格式不正确。我认为网址的两个部分之间有一个空格。
private static String url = "http://tongue-tied-papers.000webhostapp.com/data_fetch.php"
请尝试使用上面的URL，tied-和papers之间不能有任何空格。您有两个单独的URL声明，一个在类的开头，另一个在doInBackground方法中。请尝试同时更改两者。