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我的抽屉导航应用程序中有这些文件
main_list_row.xml
<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:minHeight="100dp"
android:background="@mipmap/itembg"
>
<ImageView
android:id="@+id/thumb"
android:layout_width="100dp"
android:layout_height="wrap_content"
android:layout_alignParentEnd="true"
android:layout_centerVertical="true"
android:layout_marginEnd="13dp"
android:contentDescription="@string/todo"
android:minHeight="80dp"
android:padding="5dp" />
<RelativeLayout
android:layout_width="wrap_content"
android:minWidth="260dp"
android:layout_height="wrap_content"
android:minHeight="80dp"
android:layout_toStartOf="@id/thumb"
android:layout_marginEnd="10dp"
>
<TextView
android:id="@+id/title"
android:layout_width="wrap_content"
android:minWidth="260dp"
android:layout_height="wrap_content"
android:minHeight="30dp"
android:fontFamily="@font/droidkufiregularfontfamily"
android:text="@string/title"
android:textColor="@color/colorRed"
android:textSize="20sp"
android:layout_alignParentEnd="true"
android:layout_marginTop="10dp"
/>
<TextView
android:id="@+id/description"
android:layout_width="wrap_content"
android:minWidth="260dp"
android:layout_height="wrap_content"
android:minHeight="30dp"
android:fontFamily="@font/droidkufiregularfontfamily"
android:text="@string/description"
android:textColor="@color/colorPrimaryDark"
android:textSize="16sp"
android:layout_marginTop="55dp"
android:layout_alignParentEnd="true"
/>
</RelativeLayout>
<TextView
android:id="@+id/thumbID"
android:layout_width="0dp"
android:layout_height="0dp"
android:text="@string/thumbID"
android:textSize="1sp"
/>
</RelativeLayout>
fragment_main.xml
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="match_parent"
tools:context="com.emadzedan.iveandroid.iveandroid.MainFragment">
<RelativeLayout
android:id="@+id/wordBG"
android:layout_width="match_parent"
android:layout_height="60dp"
android:layout_alignParentStart="true"
android:layout_alignParentTop="true"
android:background="@mipmap/wordbg">
<TextView
android:id="@+id/word2"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_alignParentEnd="true"
android:layout_centerVertical="true"
android:layout_marginEnd="22dp"
android:fontFamily="@font/droidkufiregularfontfamily"
android:text="@string/word2"
android:textColor="@color/colorAccent"
android:textSize="12sp" />
<TextView
android:id="@+id/word1"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_alignParentStart="true"
android:layout_centerVertical="true"
android:layout_marginStart="25dp"
android:fontFamily="@font/droidkufiregularfontfamily"
android:text="@string/word1"
android:textColor="@color/colorAccent"
android:textSize="16sp" />
</RelativeLayout>
<ListView
android:id="@+id/listView"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:layout_alignParentStart="true"
android:layout_alignParentTop="true"
android:layout_marginBottom="100dp"
android:layout_marginTop="60dp"
android:layout_toEndOf="@id/wordBG"
android:background="@color/colorRed" />
<RelativeLayout
android:id="@+id/quickMenu"
android:layout_width="match_parent"
android:layout_height="100dp"
android:layout_alignParentBottom="true">
<ImageView
android:layout_width="match_parent"
android:layout_height="match_parent"
android:background="@mipmap/quickmenubg" />
</RelativeLayout>
</RelativeLayout>
Java类如下:
HttpHandler.java
package com.emadzedan.iveandroid.iveandroid;
import android.util.Log;
import java.io.BufferedInputStream;
import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.net.HttpURLConnection;
import java.net.MalformedURLException;
import java.net.ProtocolException;
import java.net.URL;
import java.net.URLEncoder;
public class HttpHandler {
private static final String TAG = HttpHandler.class.getSimpleName();
public HttpHandler() {
}
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);
//URLEncoder.encode(response, "utf-8");
} 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();
}
}
MainClass.java
package com.emadzedan.iveandroid.iveandroid;
public class MainClass {
private String thumb;
private String title;
private String description;
public MainClass(String thumb, String title, String description) {
this.thumb = thumb;
this.title = title;
this.description = description;
}
public String getThumb() {
return thumb;
}
public void setThumb(String thumb) {
this.thumb = thumb;
}
public String getTitle() {
return title;
}
public void setTitle(String title) {
this.title = title;
}
public String getDescription() {
return description;
}
public void setDescription(String description) {
this.description = description;
}
}
MainFragment.java
package com.emadzedan.iveandroid.iveandroid;
import android.annotation.SuppressLint;
import android.content.SharedPreferences;
import android.os.AsyncTask;
import android.os.Bundle;
import android.support.annotation.NonNull;
import android.support.v4.app.Fragment;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.AdapterView;
import android.widget.ListAdapter;
import android.widget.ListView;
import android.widget.SimpleAdapter;
import android.widget.TextView;
import android.widget.Toast;
import org.json.JSONArray;
import org.json.JSONException;
import org.json.JSONObject;
import java.util.ArrayList;
import java.util.HashMap;
import java.util.Objects;
import static android.content.Context.MODE_PRIVATE;
public class MainFragment extends Fragment {
SharedPreferences prefs;
ArrayList<MainClass> mainClasses;
ListView listView;
MainDetailsFragment mainDetailsFragment;
TextView thumbID;
TextView title;
TextView description;
// URL to get contacts JSON
private static String url = "http://www.emadzedan.com/IVEArabicData/en/home.json";
ArrayList<HashMap<String, String>> mainList;
public MainFragment() {
}
public View onCreateView(@NonNull LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {
final View view = inflater.inflate(R.layout.fragment_main, container, false);
prefs = Objects.requireNonNull(getContext()).getSharedPreferences("SelectedItemsCookies", MODE_PRIVATE);
mainClasses = new ArrayList<>();
listView = (ListView) view.findViewById(R.id.listView);
mainList = new ArrayList<>();
listView = (ListView) view.findViewById(R.id.listView);
new GetMainList().execute();
mainDetailsFragment = new MainDetailsFragment();
listView.setOnItemClickListener(new AdapterView.OnItemClickListener() {
@Override
public void onItemClick(AdapterView<?> parent, View view, int position, long id) {
thumbID = (TextView) view.findViewById(R.id.thumbID);
title = (TextView) view.findViewById(R.id.title);
description = (TextView) view.findViewById(R.id.description);
SharedPreferences.Editor editor = getContext().getSharedPreferences("SelectedItemsCookies", MODE_PRIVATE).edit();
editor.putString("thumbID", thumbID.getText().toString());
editor.putString("title", title.getText().toString());
editor.putString("description", title.getText().toString());
editor.apply();
MainActivity.CurrentFragment = "MainDestails";
Objects.requireNonNull(getActivity()).getSupportFragmentManager().beginTransaction().replace(R.id.fragmentContainer, mainDetailsFragment).addToBackStack(MainActivity.CurrentFragment).commit();
}
});
return view;
}
@SuppressLint("StaticFieldLeak")
private class GetMainList extends AsyncTask<Void, Void, Void> {
@Override
protected void onPreExecute() {
super.onPreExecute();
}
@Override
protected Void doInBackground(Void... arg0) {
HttpHandler sh = new HttpHandler();
// Making a request to url and getting response
String jsonStr = sh.makeServiceCall(url);
if (jsonStr != null) {
try {
JSONObject jsonObj = new JSONObject(jsonStr);
// Getting JSON Array node
JSONArray mainlistContent = jsonObj.getJSONArray("home");
// looping through All Contacts
Toast.makeText(getActivity(), mainlistContent.length()+"",Toast.LENGTH_SHORT).show();
for (int i = 0; i < mainlistContent.length(); i++) {
JSONObject c = mainlistContent.getJSONObject(i);
String thumb = c.getString("thumb");
String title = c.getString("title");
String description = c.getString("description");
// tmp hash map for single contact
HashMap<String, String> mainListHashMap = new HashMap<>();
// adding each child node to HashMap key => value
mainListHashMap.put("thumb", thumb);
mainListHashMap.put("title", title);
mainListHashMap.put("description", description);
// adding contact to contact list
mainList.add(mainListHashMap);
}
} catch (final JSONException e) {
getActivity().runOnUiThread(new Runnable() {
@Override
public void run() {
Toast.makeText(getActivity(),"Json parsing error: " + e.getMessage(), Toast.LENGTH_LONG).show();
}
});
}
} else {
getActivity().runOnUiThread(new Runnable() {
@Override
public void run() {
Toast.makeText(getActivity(),"Couldn't get json from server. Check LogCat for possible errors!", Toast.LENGTH_LONG).show();
}
});
}
return null;
}
@Override
protected void onPostExecute(Void result) {
super.onPostExecute(result);
ListAdapter adapter = new SimpleAdapter(getActivity(), mainList, R.layout.main_list_row, new String[]{"thumb", "title", "description"}, new int[]{R.id.thumb, R.id.title, R.id.description});
listView.setAdapter(adapter);
//Toast.makeText(getActivity(), adapter.getCount()+"",Toast.LENGTH_SHORT).show();
}
}
}
我相信错误出现在主 fragment 类中,但我无法解决它抛出的错误“无法从服务器获取 JSON。检查 Log Cat 是否存在可能的错误!”错误有人可以帮忙吗?编辑:错误就在这里
JSONArray mainlistContent = jsonObj.getJSONArray("home");
编辑2:
我可以获得响应,这是模拟器未连接到互联网,但现在我的应用程序崩溃了,我得到致命异常:主要错误有人可以帮忙吗?
最佳答案
// HTTP GET request
public String makeServiceCall(String reqUrl) throws Exception {
URL obj = new URL(reqUrl);
HttpURLConnection con = (HttpURLConnection) obj.openConnection();
// optional default is GET
con.setRequestMethod("GET");
//add request header //OPTINAL
con.setRequestProperty("User-Agent", USER_AGENT);
int responseCode = con.getResponseCode();
if (responseCode == 200) {
BufferedReader in = new BufferedReader(
new InputStreamReader(con.getInputStream()));
String inputLine;
StringBuffer response = new StringBuffer();
while ((inputLine = in.readLine()) != null) {
response.append(inputLine);
}
//print result
Log.d("Response", response.toString());
in.close();
return response;
} else {
//can not connect to server
Log.d("Response code", responseCode +" ");
}
return "";
}
你可以使用上面的代码从服务器获取json字符串,如果responseCode != 200。这意味着你出错了。
完整源代码
public class MainActivity extends AppCompatActivity {
private static String url = "http://www.emadzedan.com/IVEArabicData/en/home.json";
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
new AsyncTask<Void, Void, Void>(){
@Override
protected Void doInBackground(Void... voids) {
try {
makeServiceCall(url);
} catch (Exception e) {
e.printStackTrace();
}
return null;
}
}.execute();
}
// HTTP GET request
public String makeServiceCall(String reqUrl) throws Exception {
URL obj = new URL(reqUrl);
HttpURLConnection con = (HttpURLConnection) obj.openConnection();
// optional default is GET
con.setRequestMethod("GET");
//add request header //OPTINAL
//con.setRequestProperty("User-Agent", USER_AGENT);
int responseCode = con.getResponseCode();
if (responseCode == 200) {
BufferedReader in = new BufferedReader(
new InputStreamReader(con.getInputStream()));
String inputLine;
StringBuffer response = new StringBuffer();
while ((inputLine = in.readLine()) != null) {
response.append(inputLine);
}
//print result
Log.d("Response", response.toString());
in.close();
return response.toString();
} else {
//can not connect to server
Log.d("Response code", responseCode +" ");
}
return "";
}
}
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