android开发--ListView+Json+异步网络图片加载+滚动翻页的例子

1、android开发-ListView+Json+异步网络图片加载+滚动翻页的例子例子中用于解析Json的Gson请自己Google下载主Activity：?123456789101112131415161718192021222324252627282930313233343536373839404142434445464748495051525354555657585960616263646566676869707172737475767778798081828384858687888990919293949596979899100101102103104105106107108109110

2、111112113114115116117118119120121122123124125126127128129130131132133134135136137138139140141142143144145146147148149150151152153154155156157158159160161162163164165166167168169170packageCOM.Example.Main;importjava.util.HashMap;importjava.util.Iterator;importjava.util.LinkedList;importjava.util.List

3、;importjava.util.Map;importCOM.Example.Main.R;importCOM.Example.Main.stringGetJson.User;importandroid.app.Activity;importandroid.app.ListActivity;importandroid.os.AsyncTask;importandroid.os.Bundle;importandroid.view.Gravity;importandroid.view.LayoutInflater;importandroid.view.View;importandroid.view

4、.ViewGroup;importandroid.widget.AbsListView;importandroid.widget.AbsListView.OnScrollListener;importandroid.widget.ArrayAdapter;importandroid.widget.ImageView;importandroid.widget.LinearLayout;importandroid.widget.ListView;importandroid.widget.ProgressBar;importandroid.widget.TextView;publicclassstr

5、ingListActivity extendsListActivity privateMyAdapter mMyAdapter;privateLinkedList users = null;/ 当前Activity中的ListViewListView listView = null;intlastItem = 0;LinearLayout loadingLayout = null;OverridepublicvoidonCreate(Bundle savedInstanceState) super.onCreate(savedInstanceState);setContentView(R.la

6、yout.foodlistactivity);listView = getListView();setLoadingLayout();newreadTask().execute(null);privatefinalclassMyAdapter extendsArrayAdapter publicMyAdapter(Activity activity, List newsList) super(activity, 0, newsList);privateMap viewMap = newHashMap();OverridepublicView getView(intposition, View

7、convertView, ViewGroup parent) ViewHolder holder;View rowView = this.viewMap.get(position);if(rowView = null) User user = users.get(position);LayoutInflater inflater = (Activity) this.getContext().getLayoutInflater();holder = newViewHolder();rowView = inflater.inflate(R.layout.foodlistactivity_item,

8、 null);holder.mNameText = (TextView) rowView.findViewById(R.id.foodItemUsername);holder.mPhoto = (ImageView) rowView.findViewById(R.id.foodItemPic);rowView.setTag(holder);holder.mNameText.setText(user.Name);if(!holder.mPhoto.isDrawingCacheEnabled() holder.mPhoto.setTag(user.Pic);newdownImageTask().e

9、xecute(holder.mPhoto);holder.mPhoto.setDrawingCacheEnabled(true);viewMap.put(position, rowView); elseholder = (ViewHolder) rowView.getTag();returnrowView;publicclassViewHolder publicTextView mNameText;publicImageView mPhoto;publicvoidsetLoadingLayout() LinearLayout layout = newLinearLayout(this);lay

10、out.setOrientation(LinearLayout.HORIZONTAL);ProgressBar progressBar = newProgressBar(this);progressBar.setPadding(0, 0, 15, 0);layout.addView(progressBar);TextView textView = newTextView(this);textView.setText(加载中.);textView.setGravity(Gravity.CENTER_VERTICAL);layout.addView(textView);layout.setGrav

11、ity(Gravity.CENTER);loadingLayout = newLinearLayout(this);loadingLayout.addView(layout);loadingLayout.setGravity(Gravity.CENTER);privateclassscrollListener implementsOnScrollListener OverridepublicvoidonScroll(AbsListView view, intfirstVisibleItem,intvisibleItemCount, inttotalItemCount) / 当listView中

12、没有数据，或者数据超过100条，或者不是10的整数倍（即数据不足）时隐藏“更多”并取消onScroll事件的绑定if(mMyAdapter.getCount() = 100| mMyAdapter.getCount() % 10 0| mMyAdapter.getCount() = 0) listView.removeFooterView(loadingLayout);listView.setOnScrollListener(null);lastItem = firstVisibleItem + visibleItemCount - 1;/ 这里减一是因为有FootViewOverridepu

13、blicvoidonScrollStateChanged(AbsListView view, intscrollState) if(lastItem = mMyAdapter.getCount()& scrollState = OnScrollListener.SCROLL_STATE_IDLE) / 进行翻页操作newscrollTask().execute(null);publicclassreadTask extendsAsyncTask OverrideprotectedVoid doInBackground(Object. arg0) users = newstringGetJson

14、().getJson();returnnull;OverrideprotectedvoidonPostExecute(Void result) listView.addFooterView(loadingLayout);mMyAdapter = newMyAdapter(stringListActivity.this, users);setListAdapter(mMyAdapter);listView.setOnScrollListener(newscrollListener();publicclassscrollTask extendsAsyncTask Overrideprotected

15、Void doInBackground(Object. arg0) for(Iterator iterator = newstringGetJson().getJson().iterator(); iterator.hasNext();) User user = (User) iterator.next();users.add(user);returnnull;OverrideprotectedvoidonPostExecute(Void result) mMyAdapter.notifyDataSetChanged();Json数据来源（这里的例子中把json字符串直接写在代码中了，实际项目

16、中需要改成从网络读取，例子中已经使用了多线程）：?123456789101112131415161718192021222324252627282930313233343536packageCOM.Example.Main;importjava.lang.reflect.Type;importjava.util.Iterator;importjava.util.LinkedList;importandroid.database.MatrixCursor;importandroid.widget.ListView;importandroid.widget.TextView;importcom.g

17、oogle.gson.Gson;importcom.google.gson.reflect.TypeToken;publicclassstringGetJson / 设置临时ID，在项目中将被现实的id取代privateintid = 0;publicstringGetJson() super();/通过getJson方法从Json字符串获取User的列表publicLinkedList getJson() String jsonData = Name:xinuxForJson1,Pic:Type listType = newTypeTokenLinkedList() .getType();G

18、son gson = newGson();LinkedList users = gson.fromJson(jsonData, listType);returnusers;/为getJson提供了数据实体类finalstaticclassUser publicString Name;publicString Pic;图片下载AsyncTask?123456789101112131415161718192021222324packageCOM.Example.Main;importCOM.Example.FunctionUtility.Download;importandroid.graphic

19、s.Bitmap;importandroid.os.AsyncTask;importandroid.widget.ImageView;publicclassdownImageTask extendsAsyncTask ImageView gView = null;OverrideprotectedBitmap doInBackground(ImageView. arg0) gView = (ImageView)arg00;returnDownload.getBitmapFromUrl(gView.getTag().toString();OverrideprotectedvoidonPostExecute(Bitmap result) if(result != null)this.gView.setImageBitmap(result);this.gView = null;网络图片下载类：?12345678910111213141516