仿QQ、微信翻页查看聊天记录

 

主界面MainActivity.class

public class MainActivity extends Activity implements OnScrollListener{

    private ProgressBar loadInfo;

    private ListView listView;

    private LinearLayout loadLayout;

    private ArrayList<string> items;

    private DatabaseService service;

    private int currentPage = 1; //默认在第一页

    private static final int lineSize =10;    //每次显示数

    private int allRecorders = 0;  //全部记录数

    private int pageSize = 1;  //默认共一页

    private Aleph0 baseAdapter;

    @Override

    protected void onCreate(Bundle savedInstanceState) {

        super.onCreate(savedInstanceState);

        setContentView(R.layout.activity_main);

        listView = (ListView) findViewById(R.id.listview);

        service = new DatabaseService(this);

        //创建一个角标线性布局用来显示正在加载

        loadLayout = new LinearLayout(this);

        loadLayout.setGravity(Gravity.CENTER);

        //定义一个ProgressBar表示“正在加载”

        loadInfo = new ProgressBar(this,null,android.R.attr.progressBarStyleSmall);

        //增加组件

        loadLayout.addView(loadInfo, new LayoutParams(LinearLayout.LayoutParams.MATCH_PARENT, LinearLayout.LayoutParams.WRAP_CONTENT));

        //增加到listView头部

        listView.addHeaderView(loadLayout);

        listView.setOnScrollListener(this);

         

        showAllData();

         

         

    }

     

    /**

     * 读取全部数据

     */

    public void showAllData(){

         

        allRecorders = service.getCount();

        //计算总页数

        pageSize = (allRecorders + lineSize -1) / lineSize; 

        items = service.getAllItems(currentPage, lineSize);

        Collections.reverse(items);  //倒序

        baseAdapter = new Aleph0();

        listView.setAdapter(baseAdapter);

        listView.setSelection(items.size());//直接定位到最底部

    }

    int firstItem=-1;

 

    @Override

    public void onScroll(AbsListView absView, int firstVisibleItem,

            int visibleItemCount, int totalItemCount) {

        firstItem=firstVisibleItem;

    }

    @Override

    public void onScrollStateChanged(AbsListView view, int scorllState) {

        if (firstItem==0&& currentPage < pageSize&& scorllState == OnScrollListener.SCROLL_STATE_IDLE) {// 不再滚动

            Log.e(log, 滑到第一位);

            currentPage++;

            // 增加数据

            appendDate();

        }

    }

     

    /**

     * 增加数据

     */

    private void appendDate(){

        final ArrayList<string> additems = service.getAllItems(currentPage, lineSize);

        Collections.reverse(additems);

        baseAdapter.setCount(baseAdapter.getCount() + additems.size());

        //判断，如果到了最末尾则去掉“正在加载”

        if(allRecorders == baseAdapter.getCount()){

            listView.removeHeaderView(loadLayout);

        }

        items.addAll(0, additems);

         

        baseAdapter.notifyDataSetChanged();

        listView.setSelection(additems.size());

         

    }

     

    class Aleph0 extends BaseAdapter {

        int count = lineSize;

 

        public int getCount() {

            return count;

        }

         

        public void setCount(int count){

            this.count = count;

        }

 

        public Object getItem(int pos) {

            return pos;

        }

 

        public long getItemId(int pos) {

            return pos;

        }

 

        public View getView(int pos, View v, ViewGroup p) {

            TextView view = new TextView(MainActivity.this);

            view.setTextSize(60);

            if(items != null){

                view.setText(items.get(pos));

            }else{

                view.setText(pos);

            }

            return view;

        }

    }

     

     

 

}

    /**

     * 刷新视图 *

     */

    public void setList(List<ChatMode.RecentLetter> bcData) {

        Collections.reverse(bcData);

        this.listMsg = bcData;

        notifyDataSetInvalidated();

        lv.setSelection(bcData.size());



    }



    /**

     * 加载更多 *

     */

    public void addList(final List<ChatMode.RecentLetter> newMsgData) {

        if (this.listMsg != null) {

            Collections.reverse(newMsgData);

            this.listMsg.addAll(0, newMsgData);

            notifyDataSetChanged();

            lv.setSelection(newMsgData.size() + 1);

        } else {

            setList(newMsgData);

        }

    }

 

2,主界面布局文件activity_main.xml

<linearlayout android:layout_height="fill_parent" android:layout_width="fill_parent" android:orientation="vertical" xmlns:android="http://schemas.android.com/apk/res/android">

 

    <listview android:id="@+id/listview" android:layout_height="fill_parent" android:layout_width="fill_parent">

 

 

</listview></linearlayout>

 

 

4，效果图