您好我正在开发一个可以从this url
获取JSON的应用我是新手HttpConnection并在Android中解析。
实际上我使用名为JSONParser.java的单独类来获取JSON并将其作为String返回到另一个名为SecondFragment.java的类（尝试使用ViewPager中的回收列表视图列出）
我无法从URL获取Json字符串。 即。问题出在JSONParser中，它不是从URL中提取字符串来返回。
以下是JSONParser.java的代码
public class JSONParser {
// static InputStream is = null;
// static JSONObject jObj = null;
static String json = "";
String TAG="JSON Parser kbt";
// constructor
public JSONParser() {
}
public String getJSONFromUrl(String url) {
// Making HTTP request
try {
Log.d(TAG,"STAET GETJSONFROMURL");
// defaultHttpClient
DefaultHttpClient httpClient = new DefaultHttpClient();
HttpPost httpPost = new HttpPost(url);
Log.d(TAG,"STAET AFTR HTTP POST");
HttpResponse httpResponse = httpClient.execute(httpPost);
Log.d(TAG,"STAET Aftr HTTP RESPONSE");
HttpEntity httpEntity = httpResponse.getEntity();
Log.d(TAG,"STAET AFTR HTTP ENTITY");
is = httpEntity.getContent();
Log.d(TAG,"END GETJSONFROMURL");
} catch (UnsupportedEncodingException e) {Log.d(TAG,"Unsupported Encoding");
e.printStackTrace();
} catch (ClientProtocolException e) {Log.d(TAG,"ClientProtocolEx");
e.printStackTrace();
} catch (IOException e) {Log.d(TAG,"IOEX");
e.printStackTrace();
}
try {
BufferedReader reader = new BufferedReader(new InputStreamReader(
is, "iso-8859-1"), 8);
StringBuilder sb = new StringBuilder();
String line = null;
while ((line = reader.readLine()) != null) {
sb.append(line + "\n");
}
is.close();
json = sb.toString();
} catch (Exception e) {
Log.e("Buffer Error", "Error converting result " + e.toString());
}
// return JSON String
Log.d(TAG,"RETURN JSON AS A STRING");
return json; // String is not returning
}
}
在这一行之后，
HttpResponse httpResponse = httpClient.execute(httpPost);
Log.d未打印。
我也会在我调用JSONParser类的地方发布SecondFragment.java类。
在doInBackground（）中调用JSONParser的方法。
public class SecondFragment extends Fragment {
ArrayList<FeedItem> feedItemList;
private static final String TAG = "SecondFragment kbt";
private SimpleRecyclerAdapter adapter;
RecyclerView recyclerView;String parsedJson;
String urls = "https://api.myjson.com/bins/1vx7x";
public SecondFragment() {
}
// @Nullable
@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {
Log.d(TAG, "Start second fragment");
View view = inflater.inflate(R.layout.secondfragment, container, false);
recyclerView = (RecyclerView) view.findViewById(R.id.jsonrecyclerview);
LinearLayoutManager linearLayoutManager = new LinearLayoutManager(getActivity().getBaseContext());
recyclerView.setLayoutManager(linearLayoutManager);
recyclerView.setHasFixedSize(true);
feedItemList = new ArrayList<>();
new AsyncHttpTask().execute(urls);
Log.d(TAG, "Last second fragment");
return view;
}
public class AsyncHttpTask extends AsyncTask<String, String, Integer> {
BufferedReader reader=null;
@Override
protected void onPreExecute() {
// setProgressBarIndeterminateVisibility(true);
Log.d(TAG, "OnPreExecute");
}
@Override
protected Integer doInBackground(String... params) {
Log.d(TAG,"DO IN BG START");
Integer result = 0;
JSONParser jobj=new JSONParser();
parsedJson=jobj.getJSONFromUrl("http://api.myjson.com/bins/1vx7x");
Log.d(TAG,"parsedJson string i s "+parsedJson);
parseResult(parsedJson);
result=1; Log.d(TAG,"RETURN DO IN BG");
return result;
}
@Override
protected void onPostExecute(Integer result) {
//setProgressBarIndeterminateVisibility(false);
/* Download complete. Lets update UI */
/* Download complete. Lets update UI */
if (result == 1) {
Log.i(TAG,"ON post exe");
adapter = new SimpleRecyclerAdapter(getActivity(), feedItemList);
recyclerView.setAdapter(adapter);
} else {
Log.e(TAG, "Failed to fetch data!");
}
}
private void parseResult(String result) {
try {
JSONObject response = new JSONObject(result);
JSONArray posts = response.optJSONArray("posts");
/*Initialize array if null*/
if (null == feedItemList) {
feedItemList = new ArrayList<FeedItem>();
}
for (int i = 0; i < posts.length(); i++) {
JSONObject post = posts.optJSONObject(i);
FeedItem item = new FeedItem();
item.setTitle(post.optString("title"));
item.setThumbnail(post.optString("thumbnail"));
feedItemList.add(item);
}
} catch (JSONException e) {
e.printStackTrace();
}
}
}
}
感谢您抽出时间阅读我的问题，并提前感谢您的宝贵答案:)
这是我的SimpleRecyclerAdapter类
public class SimpleRecyclerAdapter extends RecyclerView.Adapter<SimpleRecyclerAdapter.MainViewHolder> {
List<String> versionModels;
private ArrayList<FeedItem> feedItemList = new ArrayList<FeedItem>();
private Context mContext;
Boolean isHomeList = false;
Boolean isJson=false;
RecyclerView rv;
private static final int TYPE_SIMPLELIST = 0;
private static final int TYPE_JSONLIST = 1;
public static List<String> homeActivitiesList = new ArrayList<String>();
public static List<String> homeActivitiesSubList = new ArrayList<String>();
Context context;
OnItemClickListener clickListener;
public void setHomeActivitiesList(Context context) {
String[] listArray = context.getResources().getStringArray(R.array.home_activities);
String[] subTitleArray = context.getResources().getStringArray(R.array.home_activities_subtitle);
for (int i = 0; i < listArray.length; ++i) {
homeActivitiesList.add(listArray[i]);
homeActivitiesSubList.add(subTitleArray[i]);
}
}
public SimpleRecyclerAdapter(Context context) {
isHomeList = true; Log.d("kbt","Constructor SIMPLE");
this.context = context;
setHomeActivitiesList(context);
}
// FOR JSON
public SimpleRecyclerAdapter(Context context, ArrayList<FeedItem> feedItemList) {
Log.d("kbt","Constructor JSON");
isJson=true;
this.feedItemList = feedItemList;
this.mContext = context;
}
public SimpleRecyclerAdapter(List<String> versionModels) {
isHomeList = false;
this.versionModels = versionModels;
}
@Override
public int getItemViewType(int position) {
return position == 0 ? TYPE_SIMPLELIST : TYPE_JSONLIST;
}
@Override
public MainViewHolder onCreateViewHolder(ViewGroup viewGroup, int i) {
Log.d("kbt","Adapter Start OnCreate");
switch(i){
case TYPE_SIMPLELIST:Log.d("kbt","ADAP STAR ONCR first switch");
View view = LayoutInflater.from(viewGroup.getContext()).inflate(R.layout.recyclerlist_item, viewGroup, false);
VersionViewHolder viewHolder = new VersionViewHolder(view);
return viewHolder;
case TYPE_JSONLIST:Log.d("kbt","ADAP STAR ONCR second switch");
View view2 = LayoutInflater.from(viewGroup.getContext()).inflate(R.layout.recyclerlist2_item, viewGroup, false);
Log.d("kbt","ADAP STAR ONCR second switch 2nd line");
JSONHolder viewHolder2 = new JSONHolder(view2);
Log.d("kbt","ADAP STAR ONCR second switch 3nd line");
return viewHolder2;
}
return null;
}
@Override
public void onBindViewHolder(MainViewHolder holder, int i) {
switch (holder.getItemViewType()){
case TYPE_SIMPLELIST:Log.d("kbt","ONBIND First switch start");
VersionViewHolder versionViewHolder=(VersionViewHolder)holder;
if (isHomeList) {
versionViewHolder.title.setText(homeActivitiesList.get(i));
versionViewHolder.subTitle.setText(homeActivitiesSubList.get(i));
} else {
versionViewHolder.title.setText(versionModels.get(i));
}Log.d("kbt","ONBIND First switch end");
break;
case TYPE_JSONLIST:Log.d("kbt","ONBIND second switch start");
JSONHolder jsonHolder=(JSONHolder)holder;
Log.d("kbt","ONBIND second switch premiddle");
FeedItem feedItem = feedItemList.get(i);
Log.d("kbt","ONBIND second switch middle");
Picasso.with(mContext).load(feedItem.getThumbnail())
.error(R.drawable.placeholder)
.placeholder(R.drawable.placeholder)
.into(jsonHolder.thumbnail);
Log.d("kbt", "ONBIND second switch 2nd middle");
jsonHolder.title.setText(Html.fromHtml(feedItem.getTitle()));
Log.d("kbt", "ONBIND second switch end");
}
}
@Override
public int getItemCount() {
if(isJson){
return (null != feedItemList ? feedItemList.size() : 0);
}
else{
if (isHomeList)
return homeActivitiesList == null ? 0 : homeActivitiesList.size();
else
return versionModels == null ? 0 : versionModels.size();
}
}
class VersionViewHolder extends MainViewHolder implements View.OnClickListener {
CardView cardItemLayout;
TextView title;
TextView subTitle;
public VersionViewHolder(View itemView) {
super(itemView);
rv=(RecyclerView)itemView.findViewById(R.id.dummyfrag_scrollableview);
cardItemLayout = (CardView) itemView.findViewById(R.id.cardlist_item);
title = (TextView) itemView.findViewById(R.id.listitem_name);
subTitle = (TextView) itemView.findViewById(R.id.listitem_subname);
if (isHomeList) {
itemView.setOnClickListener(this);
Log.d("kbt","Inside first");
} else {
subTitle.setVisibility(View.GONE);
/*View.GONE This view is invisible, and it doesn't take any space for layout purposes.
View.INVISIBLE This view is invisible, but it still takes up space for layout purposes.*/
}
}
@Override
public void onClick(View v) {
Log.d("kbt", "Inside second first");
clickListener.onItemClick(v,getAdapterPosition());
Log.d("kbt", "Inside second");
}
}
public interface OnItemClickListener {
void onItemClick(View view, int position);
}
public void SetOnItemClickListener(final OnItemClickListener itemClickListener) {
this.clickListener = itemClickListener;
}
class JSONHolder extends MainViewHolder {
protected ImageView thumbnail;
protected TextView title;
public JSONHolder(View itemView) {
super(itemView);
Log.d("kbt","JSON Inside HOLDER");
rv=(RecyclerView)itemView.findViewById(R.id.jsonrecyclerview);
thumbnail = (ImageView) itemView.findViewById(R.id.thumbnail);
title = (TextView) itemView.findViewById(R.id.title);
}
}
public class MainViewHolder extends RecyclerView.ViewHolder {
public MainViewHolder(View v) {
super(v);
}
}
}
错误：
11-13 14:36:43.645 21502-21502/? I/Process﹕ Sending signal. PID: 21502 SIG: 9
11-13 14:36:43.645 21502-21502/? D/AndroidRuntime﹕ procName from cmdline: corp.trees.com.mdesign
11-13 14:36:43.645 21502-21502/? E/AndroidRuntime﹕ in writeCrashedAppName, pkgName :corp.trees.com.mdesign
11-13 14:36:43.645 21502-21502/? D/AndroidRuntime﹕ file written successfully with content: corp.trees.com.mdesign StringBuffer : ;corp.trees.com.mdesign
11-13 14:36:43.645 21502-21502/? E/AndroidRuntime﹕ FATAL EXCEPTION: main
Process: corp.trees.com.mdesign, PID: 21502
java.lang.IndexOutOfBoundsException: Invalid index 1, size is 0
at java.util.ArrayList.throwIndexOutOfBoundsException(ArrayList.java:255)
at java.util.ArrayList.get(ArrayList.java:308)
at corp.trees.com.mdesign.SimpleRecyclerAdapter.onBindViewHolder(SimpleRecyclerAdapter.java:108)
at corp.trees.com.mdesign.SimpleRecyclerAdapter.onBindViewHolder(SimpleRecyclerAdapter.java:21)
at android.support.v7.widget.RecyclerView$Adapter.bindViewHolder(RecyclerView.java:5084)
at android.support.v7.widget.RecyclerView$Recycler.getViewForPosition(RecyclerView.java:4385)
at android.support.v7.widget.RecyclerView$Recycler.getViewForPosition(RecyclerView.java:4278)
at android.support.v7.widget.LinearLayoutManager$LayoutState.next(LinearLayoutManager.java:1947)
at android.support.v7.widget.LinearLayoutManager.layoutChunk(LinearLayoutManager.java:1359)
at android.support.v7.widget.LinearLayoutManager.fill(LinearLayoutManager.java:1322)
at android.support.v7.widget.LinearLayoutManager.onLayoutChildren(LinearLayoutManager.java:556)
at android.support.v7.widget.RecyclerView.dispatchLayout(RecyclerView.java:2673)
at android.support.v7.widget.RecyclerView.onLayout(RecyclerView.java:2971)
at android.view.View.layout(View.java:14852)
at android.view.ViewGroup.layout(ViewGroup.java:4631)
at android.widget.FrameLayout.layoutChildren(FrameLayout.java:453)
at android.widget.FrameLayout.onLayout(FrameLayout.java:388)
at android.view.View.layout(View.java:14852)
at android.view.ViewGroup.layout(ViewGroup.java:4631)
at android.support.v4.view.ViewPager.onLayout(ViewPager.java:1626)
at android.view.View.layout(View.java:14852)
at android.view.ViewGroup.layout(ViewGroup.java:4631)
at android.support.design.widget.CoordinatorLayout.layoutChild(CoordinatorLayout.java:1009)
at android.support.design.widget.CoordinatorLayout.onLayoutChild(CoordinatorLayout.java:719)
at android.support.design.widget.ViewOffsetBehavior.onLayoutChild(ViewOffsetBehavior.java:42)
at android.support.design.widget.AppBarLayout$ScrollingViewBehavior.onLayoutChild(AppBarLayout.java:984)
at android.support.design.widget.CoordinatorLayout.onLayout(CoordinatorLayout.java:732)
at android.view.View.layout(View.java:14852)
at android.view.ViewGroup.layout(ViewGroup.java:4631)
at android.support.v4.widget.DrawerLayout.onLayout(DrawerLayout.java:907)
at android.view.View.layout(View.java:14852)
at android.view.ViewGroup.layout(ViewGroup.java:4631)
at android.widget.FrameLayout.layoutChildren(FrameLayout.java:453)
at android.widget.FrameLayout.onLayout(FrameLayout.java:388)
at android.view.View.layout(View.java:14852)
at android.view.ViewGroup.layout(ViewGroup.java:4631)
at android.widget.LinearLayout.setChildFrame(LinearLayout.java:1671)
at android.widget.LinearLayout.layoutVertical(LinearLayout.java:1525)
at android.widget.LinearLayout.onLayout(LinearLayout.java:1434)
at android.view.View.layout(View.java:14852)
at android.view.ViewGroup.layout(ViewGroup.java:4631)
at android.widget.FrameLayout.layoutChildren(FrameLayout.java:453)
at android.widget.FrameLayout.onLayout(FrameLayout.java:388)
at android.view.View.layout(View.java:14852)
at android.view.ViewGroup.layout(ViewGroup.java:4631)
at android.widget.LinearLayout.setChildFrame(LinearLayout.java:1671)
at android.widget.LinearLayout.layoutVertical(LinearLayout.java:1525)
at android.widget.LinearLayout.onLayout(LinearLayout.java:1434)
at android.view.View.layout(View.java:14852)
at android.view.ViewGroup.layout(ViewGroup.java:4631)
at android.widget.FrameLayout.layoutChildren(FrameLayout.java:453)
at android.widget.FrameLayout.onLayout(FrameLayout.java:388)
at android.view.View.layout(View.java:14852)
at android.view.ViewGroup.layout(ViewGroup.java:4631)
at android.view.ViewRootImpl.performLayout(ViewRootImpl.java:1994)
at android.view.ViewRootImpl.performTraversals(ViewRootImpl.java:1751)
at android.view.ViewRootImpl.doTraversal(ViewRootImpl.java:1007)
at android.view.ViewRootImpl$T
答案 0 :(得分：1)
我认为你最好使用GET方法而不是POST，并尝试HttpURLConnection，这里有一个示例：
URL requestUrl = new URL(url);
HttpURLConnection conn = (HttpURLConnection)requestUrl.openConnection();
conn.setDoInput(true);
conn.connect();
InputStream is = conn.getInputStream();
答案 1 :(得分：1)
我在你的适配器中看到许多奇怪的东西，如果我错了，请纠正我
根据documentation getItemCount()必须返回适配器所拥有的项目总数。在您的适配器中，您使用多个列表，并且getItemCount()根据某些变量返回一个大小，但getItemCount()将仅由回收器视图调用一次，因此这仅在您只使用其中一个时才会起作用每个SimpleRecyclerAdapter实例的那些列表。您只是初始化feedItemList，其他列表保持为空或空。所以我会假设这是你要做的事情。
但是在获取当前的elementType时使用：
@Override
public int getItemViewType(int position) {
return position == 0 ? TYPE_SIMPLELIST : TYPE_JSONLIST;
}
这意味着您的第一个元素将是TYPE_SIMPLELIST，其他元素将是TYPE_JSONLIST。这对我来说没有意义，因为只有一个列表被初始化（feedItemList），所以我认为你应该返回类似的东西：
@Override
public int getItemViewType(int position) {
return isJson? TYPE_JSONLIST : TYPE_SIMPLELIST;
}
因此它始终从feedItemList读取数据。