基于Android官方AsyncListUtil优化经典ListView分页加载机制（二）

标签：long   rar   you   import   else   lstat   设定   定时   over   

package zhangphil.app;

import android.app.ListActivity;
import android.content.Context;
import android.graphics.Color;
import android.os.Bundle;
import android.os.SystemClock;
import android.support.annotation.NonNull;
import android.support.annotation.Nullable;
import android.support.v7.util.AsyncListUtil;
import android.util.Log;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.AbsListView;
import android.widget.ArrayAdapter;
import android.widget.ListView;
import android.widget.TextView;

public class MainActivity extends ListActivity {
    private final String TAG = "调试";
    private final int NULL = -1;
    private AsyncListUtil<DataItem> mAsyncListUtil;
    private MyAdapter mAdapter;
    private int mFirstVisibleItem = NULL, mVisibleItemCount = NULL;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);

        MyDataCallback mDataCallback = new MyDataCallback();
        MyViewCallback mViewCallback = new MyViewCallback();
        mAsyncListUtil = new AsyncListUtil(DataItem.class, 20, mDataCallback, mViewCallback);

        mAdapter = new MyAdapter(this, NULL);
        setListAdapter(mAdapter);

        getListView().setOnScrollListener(new AbsListView.OnScrollListener() {
            @Override
            public void onScrollStateChanged(AbsListView absListView, int scrollState) {
                mAsyncListUtil.onRangeChanged();
            }

            @Override
            public void onScroll(AbsListView absListView, int firstVisibleItem, int visibleItemCount, int totalItemCount) {
                mFirstVisibleItem = firstVisibleItem;
                mVisibleItemCount = visibleItemCount;
            }
        });
    }

    @Override
    protected void onListItemClick(ListView l, View v, int position, long id) {
        mAsyncListUtil.refresh();
    }

    private class MyDataCallback extends AsyncListUtil.DataCallback<DataItem> {

        @Override
        public int refreshData() {
            //更新数据的个数。
            //假设预先设定更新若干条。
            return Integer.MAX_VALUE;
        }

        /**
         * 在这里完成数据加载的耗时任务。
         *
         * @param data
         * @param startPosition
         * @param itemCount
         */
        @Override
        public void fillData(DataItem[] data, int startPosition, int itemCount) {
            Log.d(TAG, "fillData:" + startPosition + "," + itemCount);

            for (int i = 0; i < itemCount; i++) {
                DataItem dataItem = new DataItem();
                dataItem.pos = startPosition + i;
                dataItem.content = String.valueOf(System.currentTimeMillis());

                data[i] = dataItem;

                //模拟耗时任务，故意休眠一定时延。
                SystemClock.sleep(100);
            }
        }
    }

    private class MyViewCallback extends AsyncListUtil.ViewCallback {

        /**
         * @param outRange
         */
        @Override
        public void getItemRangeInto(int[] outRange) {
            outRange[0] = mFirstVisibleItem;
            outRange[1] = mFirstVisibleItem + mVisibleItemCount;

            /**
             * 如果当前ListView为空，主动为用户加载数据.
             * 假设预先加载若干条数据
             *
             */
            if (outRange[0] == NULL && outRange[1] == NULL) {
                Log.d(TAG, "当前ListView为空！");
                outRange[0] = 0;
                outRange[1] = 9;
            }

            Log.d(TAG, "getItemRangeInto,当前可见position: " + outRange[0] + " ~ " + outRange[1]);
        }

        @Override
        public void onDataRefresh() {
            mAdapter.notifyDataSetChanged();
            Log.d(TAG, "onDataRefresh");
        }

        @Override
        public void onItemLoaded(int position) {
            mAdapter.notifyDataSetChanged();
            Log.d(TAG, "onItemLoaded:" + position);
        }
    }

    private class MyAdapter extends ArrayAdapter {
        private ViewHolder holder;

        public MyAdapter(@NonNull Context context, int resource) {
            super(context, resource);
        }

        @NonNull
        @Override
        public View getView(int position, @Nullable View convertView, @NonNull ViewGroup parent) {
            if (convertView == null) {
                convertView = LayoutInflater.from(getApplicationContext()).inflate(android.R.layout.simple_list_item_2, null);
                holder = new ViewHolder(convertView);
                convertView.setTag(holder);
            } else {
                holder = (ViewHolder) convertView.getTag();
            }

            holder.setData(getItem(position));

            return convertView;
        }

        @Override
        public int getCount() {
            return mAsyncListUtil.getItemCount();
        }

        @Nullable
        @Override
        public DataItem getItem(int position) {
            return mAsyncListUtil.getItem(position);
        }
    }

    private class ViewHolder {
        public TextView text1;
        public TextView text2;

        public ViewHolder(View view) {
            text1 = view.findViewById(android.R.id.text1);
            text1.setTextColor(Color.RED);
            text2 = view.findViewById(android.R.id.text2);
            text2.setTextColor(Color.BLUE);
        }

        public void setData(DataItem dataItem) {
            if (dataItem == null) {
                text1.setText("pos加载中...");
                text2.setText("content加载中...");
            } else {
                text1.setText(String.valueOf(dataItem.pos));
                text2.setText(dataItem.content);
            }
        }
    }

    private class DataItem {
        public int pos;
        public String content;
    }
}

基于Android官方AsyncListUtil优化经典ListView分页加载机制（二）

标签：long   rar   you   import   else   lstat   设定   定时   over   

原文地址：http://blog.csdn.net/zhangphil/article/details/78645089