易采站长站为您分析Android程序开发ListView+Json+异步网络图片加载+滚动翻页的例子（图片能缓存，图片不错乱） 的相关资料,需要的朋友可以参考下
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(); } } }
