例子中用于解析Json的Gson请自己Google下载
主Activity：
package COM.Example.Main;import java.util.HashMap;import java.util.Iterator;import java.util.LinkedList;import java.util.List;import java.util.Map;import COM.Example.Main.R;import COM.Example.Main.stringGetJson.User;import android.app.Activity;import android.app.ListActivity;import android.os.AsyncTask;import android.os.Bundle;import android.view.Gravity;import android.view.LayoutInflater;import android.view.View;import android.view.ViewGroup;import android.widget.AbsListView;import android.widget.AbsListView.OnScrollListener;import android.widget.ArrayAdapter;import android.widget.ImageView;import android.widget.LinearLayout;import android.widget.ListView;import android.widget.ProgressBar;import android.widget.TextView;public class stringListActivity extends ListActivity { private MyAdapter mMyAdapter; private LinkedList<User> users = null; // 当前Activity中的ListView ListView listView = null; int lastItem = 0; LinearLayout loadingLayout = null; @Override public void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.foodlistactivity); listView = getListView(); setLoadingLayout(); new readTask().execute(null); } private final class MyAdapter extends ArrayAdapter<User> { public MyAdapter(Activity activity, List<User> newsList) { super(activity, 0, newsList); } private Map<Integer, View> viewMap = new HashMap<Integer, View>(); @Override public View getView(int position, View 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 = new ViewHolder(); rowView = inflater .inflate(R.layout.foodlistactivity_item, 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); new downImageTask().execute(holder.mPhoto); holder.mPhoto.setDrawingCacheEnabled(true); } viewMap.put(position, rowView); } else { holder = (ViewHolder) rowView.getTag(); } return rowView; } public class ViewHolder { public TextView mNameText; public ImageView mPhoto; } } public void setLoadingLayout() { LinearLayout layout = new LinearLayout(this); layout.setOrientation(LinearLayout.HORIZONTAL); ProgressBar progressBar = new ProgressBar(this);
progressBar.setPadding(0, 0, 15, 0);
layout.addView(progressBar);
TextView textView = new TextView(this);
textView.setText("加载中...");
textView.setGravity(Gravity.CENTER_VERTICAL);
layout.addView(textView);
layout.setGravity(Gravity.CENTER);
loadingLayout = new LinearLayout(this);
loadingLayout.addView(layout);
loadingLayout.setGravity(Gravity.CENTER);
}
private class scrollListener implements OnScrollListener {
@Override
public void onScroll(AbsListView view, int firstVisibleItem,
int visibleItemCount, int totalItemCount) {
// 当listView中没有数据，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FootView
} @Override
public void onScrollStateChanged(AbsListView view, int scrollState) {
if (lastItem == mMyAdapter.getCount()
&& scrollState == OnScrollListener.SCROLL_STATE_IDLE) {
// 进行翻页操作
new scrollTask().execute(null);
} }
}
public class readTask extends AsyncTask<Object, Void, Void> {
@Override
protected Void doInBackground(Object... arg0) {
users = new stringGetJson().getJson();
return null;
} @Override
protected void onPostExecute(Void result) {
listView.addFooterView(loadingLayout);
mMyAdapter = new MyAdapter(stringListActivity.this, users);
setListAdapter(mMyAdapter);
listView.setOnScrollListener(new scrollListener());
}
} public class scrollTask extends AsyncTask<Object, Void, Void> {
@Override
protected Void doInBackground(Object... arg0) {
for (Iterator iterator = new stringGetJson().getJson()
.iterator(); iterator.hasNext();) {
User user = (User) iterator.next();
users.add(user);
}
return null;
} @Override
protected void onPostExecute(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，实际项目中需要改成从网络读取，例子中已经使用了多线程）：
package COM.Example.Main;import java.lang.reflect.Type;import java.util.Iterator;import java.util.LinkedList;import android.database.MatrixCursor;import android.widget.ListView;import android.widget.TextView;import com.google.gson.Gson;import com.google.gson.reflect.TypeToken;public class stringGetJson { // 设置临时ID，在项目中将被现实的id取代 private int id = 0; public stringGetJson() { super(); } //通过getJson方法从Json字符串获取User的列表 public LinkedList<User> getJson() { String jsonData = "[{\"Name\":\"xinuxForJson1\",\"Pic\":\"http://www.qqjay.com/uploads/110414/1_234626_5.jpg\"},{\"Name\":\"xinuxForJson2\",\"Pic\":\"http://www.qqjay.com/uploads/110414/1_234626_3.jpg\"},{\"Name\":\"xinuxForJson3\",\"Pic\":\"http://www.qqjay.com/uploads/110414/1_234626_4.jpg\"},{\"Name\":\"xinuxForJson4\",\"Pic\":\"http://sucai.qqjay.com/fengmian/201104/tupian1/8.jpg\"},{\"Name\":\"xinuxForJson5\",\"Pic\":\"http://sucai.qqjay.com/fengmian/201104/tupian1/10.jpg\"},{\"Name\":\"xinuxForJson6\",\"Pic\":\"http://sucai.qqjay.com/fengmian/201104/tupian1/7.jpg\"},{\"Name\":\"xinuxForJson7\",\"Pic\":\"http://sucai.qqjay.com/fengmian/201104/tupian1/11.jpg\"},{\"Name\":\"xinuxForJson8\",\"Pic\":\"http://sucai.qqjay.com/fengmian/201104/tupian1/12.jpg\"},{\"Name\":\"xinuxForJson9\",\"Pic\":\"http://sucai.qqjay.com/fengmian/201104/tupian1/9.jpg\"},{\"Name\":\"xinuxForJson10\",\"Pic\":\"http://sucai.qqjay.com/fengmian/201104/tupian/7.jpg\"}]"; Type listType = new TypeToken<LinkedList<User>>() {}.getType(); Gson gson = new Gson(); LinkedList<User> users = gson.fromJson(jsonData, listType); return users; } //为getJson提供了数据实体类 final static class User { public String Name; public String Pic; }}
图片下载AsyncTask
package COM.Example.Main;import COM.Example.FunctionUtility.Download;
import android.graphics.Bitmap;
import android.os.AsyncTask;
import android.widget.ImageView;public class downImageTask extends AsyncTask<ImageView, Void, Bitmap> {
ImageView gView = null;
@Override
protected Bitmap doInBackground(ImageView... arg0) {
gView = (ImageView)arg0[0];
return Download.getBitmapFromUrl(gView.getTag().toString());
} @Override
protected void onPostExecute(Bitmap result) {
if(result != null){
this.gView.setImageBitmap(result);
}
this.gView = null;
}
}
网络图片下载类：
package COM.Example.FunctionUtility;
import java.io.BufferedInputStream;
import java.io.IOException;
import java.io.InputStream;
import java.net.MalformedURLException;
import java.net.URL;
import android.graphics.Bitmap;
import android.graphics.BitmapFactory;
public class Download {
public static Bitmap getBitmapFromUrl(String imgUrl) {
URL url;
Bitmap bitmap = null;
try {
url = new URL(imgUrl);
InputStream is = url.openConnection().getInputStream();
BufferedInputStream bis = new BufferedInputStream(is);
bitmap = BitmapFactory.decodeStream(bis);
bis.close();
} catch (MalformedURLException e) {
e.printStackTrace();
} catch (IOException e) {
e.printStackTrace();
}
return bitmap;
}
}转自：http://www.cnblogs.com/yeagen/archive/2011/04/19/2020985.html
