Question

我想要的是什么：

我有ListView。

在fly中将数据加载到ListView（当用户滚动listView时）。数据来自SQLite表。

但是当SQLite表结束时 - 以JSON格式从GitHub API获取新数据。

然后将此数据保存到SQLite表，然后在lisview中显示新项目。

我该怎么做？提前致谢！

Answer 1

您的自定义ListView类。

import android.content.Context;
import android.util.AttributeSet;
import android.util.Log;
import android.widget.AbsListView;

/**
 * Created by ozgur on 11/3/15 at 4:48 PM.
 */
public class ListView extends android.widget.ListView implements AbsListView.OnScrollListener {

    private boolean inEndOfList = false;
    private ListViewListener listViewListener;

    public ListView(Context context) {
        super(context);
        init(context);
    }

    public ListView(Context context, AttributeSet attrs) {
        super(context, attrs);
        init(context);
    }

    public ListView(Context context, AttributeSet attrs, int defStyleAttr) {
        super(context, attrs, defStyleAttr);
        init(context);
    }

    @Override
    public void onScrollStateChanged(AbsListView absListView, int scrollState) {
        //Log("onScrollStateChanged(..), scrollState =" + scrollState);
    }

    @Override
    public void onScroll(AbsListView absListView, int firstVisibleItem, int visibleItemCount, int totalItemCount) {

        int tot = firstVisibleItem + visibleItemCount;
        if(tot >= totalItemCount) {

           if(!inEndOfList) {
               Log("onScroll, end of list");
               inEndOfList = true;

               if(listViewListener != null)
                   listViewListener.onEndOfList();
           }
        } else
            inEndOfList = false;
    }


    private void init(Context context) {
        this.setOnScrollListener(this);
    }

    private void Log(String str) {
        Log.d("ListView", str);
    }

    public void setListViewListener(ListViewListener listViewListener) {
        this.listViewListener = listViewListener;
    }

    public static interface ListViewListener {
        public void onEndOfList() ;
    }

}

在您的活动中，实现ListView.ListViewListener

private ArrayList<Object> listObjects = new ArrayList<>();
int limit = 20;
int offset = 0;
private ListView customListView;


@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_your);

    initYourViews();
    customListView.setListViewListener(this);

}

@Override
public void onEndOfList() {
    this.offset += 10 + limit;
    this.initData();
}

private void initData() {

    new AsyncTask<Void, Void, ArrayList<Object> /* or whatever */>() {
        @Override
        protected ArrayList<Object> doInBackground(Void... voids) {

             ArrayList<Object> temp = YourSqLiteController.getData(limit, offset);
             if(temp.size == 0 /* assume db data consumed, get from REST API*/) {
                 temp = YourApi.getData();                  
             }

        }

        @Override
        protected void onPostExecute(ArrayList<Object> temp){

            if(temp != null && temp.size() > 0)
                listObjects.addAll(temp);                

            update();

        }

    }.execute();

}

private void update(){
    this.listAdapter.notifyDataSetChanged(); /* your adapter */
}

来自SQLite的ListView延迟加载（来自API JSON的表填充）

1 个答案: