Android ListView 滚动翻页效果
前面说过了ListView的下拉刷新效果，有些时候我们需要让ListView在滑动到最底部时，自动去向服务器请求下一页数据。这时候就需要监听的ListView的滑动状态了。
mListView.setOnScrollListener(OnScrollListener l);
OnScrollListener 内部有3个常量来记录ListView的滚动状态
int SCROLL_STATE_FLING The user had previously been scrolling using touch and had performed a fling.
int SCROLL_STATE_IDLE The view is not scrolling.
int SCROLL_STATE_TOUCH_SCROLL The user is scrolling using touch, and their finger is still on the screen
知道这些常量代表的含义，我们就可以很轻松的实现 滚动翻页的效果了。
footer_more.xml
<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="fill_parent"
android:layout_height="fill_parent"
android:gravity="center_horizontal"
android:orientation="horizontal"
android:padding="15dp" >
<ProgressBar
android:id="@+id/pb_load_progress"
style="@android:style/Widget.ProgressBar.Small.Inverse"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:gravity="center"
android:indeterminate="true">
</ProgressBar>
<TextView
android:id="@+id/tv_load_more"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_marginLeft="10.0dp"
android:gravity="center"
android:text="@string/load_more_data"
android:textColor="@color/black" >
</TextView>
</LinearLayout>
activity_main.xml
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="match_parent"
tools:context=".MainActivity" >
<TextView
android:id="@+id/tv_title"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_centerHorizontal="true"
android:layout_marginTop="5dp"
android:text="@string/load_more"
android:textSize="15sp" />
<ListView
android:id="@+id/mListView"
android:layout_below="@id/tv_title"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:cacheColorHint="@android:color/transparent" />
</RelativeLayout>
list_item.xml
<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="match_parent"
android:layout_height="wrap_content" >
<ImageView
android:id="@+id/iv_icon"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:contentDescription="@string/app_name"
android:src="@drawable/ic_launcher" />
<TextView
android:id="@+id/tv_title"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_toRightOf="@id/iv_icon"
android:textSize="18sp"
android:textColor="@color/black"/>
<TextView
android:id="@+id/tv_content"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_toRightOf="@id/iv_icon"
android:layout_below="@id/tv_title"
android:layout_marginTop="5dp"
android:textSize="15sp"
android:textColor="@color/black"/>
</RelativeLayout>
package com.example.loadmore;
import java.util.ArrayList;
import java.util.List;
import com.example.loadmore.entity.DataNews;
import android.app.Activity;
import android.content.Context;
import android.os.Bundle;
import android.os.Handler;
import android.util.Log;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.AbsListView;
import android.widget.AbsListView.OnScrollListener;
import android.widget.BaseAdapter;
import android.widget.ListView;
import android.widget.ProgressBar;
import android.widget.TextView;
public class MainActivity extends Activity implements OnScrollListener {
private static final int LOAD_DATA_FINISH = 1;
private static final String TAG = MainActivity.class.getName();
private List<DataNews> dataList = new ArrayList<DataNews>();
private Handler handler = new Handler() {
public void handleMessage(android.os.Message msg) {
switch (msg.what) {
case LOAD_DATA_FINISH:
tv_load_more.setText(R.string.load_more_data);
pb_load_progress.setVisibility(View.GONE);
if(mAdapter!=null){
mAdapter.notifyDataSetChanged();
}
break;
default:
break;
}
};
};
private int startIndex = 0;
private int requestSize = 10;
private ListView mListView;
private View moreView;
private DataAdapter mAdapter;
private int lastItem;
private TextView tv_load_more;
private ProgressBar pb_load_progress;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
findView();
setListener();
}
private void findView() {
LayoutInflater inflater = LayoutInflater.from(getApplicationContext());
moreView = inflater.inflate(R.layout.footer_more, null);
tv_load_more = (TextView) moreView.findViewById(R.id.tv_load_more);
pb_load_progress = (ProgressBar) moreView.findViewById(R.id.pb_load_progress);
mListView = (ListView) findViewById(R.id.mListView);
for (int i = 0; i < 10; i++) {
DataNews dn = new DataNews();
dn.setTitle("第 " + i + " 行标题");
dn.setContent("" + i + " 行内容");
dataList.add(dn);
}
mListView.addFooterView(moreView);
mAdapter = new DataAdapter(getApplicationContext());
mListView.setAdapter(mAdapter);
}
private void setListener() {
mListView.setOnScrollListener(this);
}
@Override
public void onScroll(AbsListView view, int firstVisibleItem,
int visibleItemCount, int totalItemCount) {
lastItem = firstVisibleItem + visibleItemCount - 1;
// Log.i(TAG,
// "firstVisibleItem:"+firstVisibleItem+"visibleItemCount:"+visibleItemCount+" lastItem:"+lastItem);
}
@Override
public void onScrollStateChanged(AbsListView view, int scrollState) {
if (lastItem == mAdapter.getCount()
&& scrollState == OnScrollListener.SCROLL_STATE_IDLE) {
Log.e(TAG, "load more");
startIndex += requestSize;
loadMoreData();
}
}
private void loadMoreData() {
tv_load_more.setText(R.string.loading_data);
pb_load_progress.setVisibility(View.VISIBLE);
new Thread(){
public void run() {
if (startIndex + requestSize <50) {
for (int i = startIndex; i < startIndex + requestSize; i++) {
DataNews dn = new DataNews();
dn.setTitle("增加 第 " + i + " 行标题");
dn.setContent("增加 第 " + i + " 行内容");
dataList.add(dn);
}
try {
Thread.sleep(3000);
} catch (InterruptedException e) {
e.printStackTrace();
}
handler.sendEmptyMessage(LOAD_DATA_FINISH);
}else{
handler.postDelayed(new Runnable() {
@Override
public void run() {
tv_load_more.setText(R.string.no_more_data);
pb_load_progress.setVisibility(View.GONE);
}
}, 1000);
}
};
}.start();
}
private class DataAdapter extends BaseAdapter {
private Context ctx;
private LayoutInflater inflater;
public DataAdapter(Context ctx) {
this.ctx = ctx;
inflater = LayoutInflater.from(ctx);
}
@Override
public int getCount() {
return dataList == null ? 0 : dataList.size();
}
@Override
public Object getItem(int position) {
// TODO Auto-generated method stub
return dataList.get(position);
}
@Override
public long getItemId(int position) {
// TODO Auto-generated method stub
return position;
}
@Override
public View getView(int position, View convertView, ViewGroup parent) {
ViewHolder holder;
if (convertView == null) {
convertView = inflater.inflate(R.layout.list_item, null);
holder = new ViewHolder();
holder.tv_title = (TextView) convertView
.findViewById(R.id.tv_title);
holder.tv_content = (TextView) convertView
.findViewById(R.id.tv_content);
convertView.setTag(holder);
} else {
holder = (ViewHolder) convertView.getTag();
}
DataNews dn = dataList.get(position);
holder.tv_title.setText(dn.getTitle());
holder.tv_content.setText(dn.getContent());
return convertView;
}
}
static class ViewHolder {
public TextView tv_title;
public TextView tv_content;
}
}
运行效果截图
正常状态时
滚动到底部时
没有更多数据时
