Android中动态更新ListView

在使用ListView时，会遇到当ListView列表滑动到最底端时，添加新的列表项的问题，本文通过代码演示如何动态的添加新的列表项到ListView中。

实现步骤：调用ListView的setOnScrollListener()方法设置滑动监听器，实现OnScrollListener接口的方法，判断当列表滑动到最低端时，加载新的列表项。

其中OnScrollListener接口需要实现如下两个方法：

onScroll(AbsListView view, int firstVisibleItem, int visibleItemCount, int totalItemCount)

view 报告滑动状态的视图

firstVisibleItem 可视的第一个列表项的索引

visibleItemCount 可视的列表项个数

totalItemCount 总共的列表项个数

onScrollStateChanged(AbsListView view, int scrollState)

view 报告滑动状态的视图

scrollState 滑动状态

滑动状态包括

SCROLL_STATE_IDLE : 0 视图没有滑动

SCROLL_STATE_TOUCH_SCROLL : 1 用户正在触摸滑动，手指仍在屏幕上

SCROLL_STATE_FLING : 2 用户之前触摸滑动，现在正在滑行，直到停止

下面通过代码给大家演示效果

main.xml

<?xml version="1.0" encoding="utf-8"?>

<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:orientation="vertical"
android:layout_width="fill_parent"
android:layout_height="fill_parent"
>
<ListView
android:id="@id/android:list"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:layout_weight="1"
android:drawSelectorOnTop="false"
/>
</LinearLayout>

footer.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="wrap_content"
android:gravity="center"
android:orientation="horizontal"
>
<ProgressBar
android:id="@+id/progressbar"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
style="\?android:attr/progressBarStyleSmall"
/>
<TextView
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:textSize="20.0sp"
android:text="正在加载..."
/>
</LinearLayout>

MainActicity.xml

package com.szy.listview;
import android.app.ListActivity;
import android.os.Bundle;
import android.os.Handler;
import android.os.Message;
import android.view.Gravity;
import android.view.View;
import android.view.ViewGroup;
import android.widget.AbsListView;
import android.widget.BaseAdapter;
import android.widget.ListView;
import android.widget.TextView;

public class MainActivity extends ListActivity
{
private ListView mListView;
private CustomAdapter mAdapter;
private int mScrollState;
private View mFooter;
@Override
public void onCreate(Bundle savedInstanceState)
{
super.onCreate(savedInstanceState);
setContentView(R.layout.main);
//获取ListView
mListView = getListView();
//根据footer.xml描述创建View
mFooter = getLayoutInflater().inflate(R.layout.footer, null);
// 在ListView底部添加正在加载视图
//注意：addFooterView方法需要在调用setListAdapter方法前调用！
mListView.addFooterView(mFooter);
mAdapter = new CustomAdapter();
setListAdapter(mAdapter);
//给ListView添加滚动监听器
mListView.setOnScrollListener(new AbsListView.OnScrollListener()
{
@Override
public void onScrollStateChanged(AbsListView view, int scrollState)
{
//记录当前状态
mScrollState = scrollState;
}
@Override
public void onScroll(AbsListView view, int firstVisibleItem, int visibleItemCount, int totalItemCount)
{
// 可视的最后一个列表项的索引
int lastVisibleItem = firstVisibleItem + visibleItemCount - 1;
//当列表正处于滑动状态且滑动到列表底部时，执行
if (mScrollState != AbsListView.OnScrollListener.SCROLL_STATE_IDLE&& lastVisibleItem == totalItemCount - 1)
{
// 执行线程，模拟睡眠5秒钟后添加10个列表项
new Thread()
{
private Handler handler = new Handler()
{
@Override
public void handleMessage(Message msg)
{
super.handleMessage(msg);
//增加Item数量
mAdapter.count += 10;
//通知数据集变化
mAdapter.notifyDataSetChanged();
}
};
@Override
public void run()
{
super.run();
try
{
sleep(5000);
handler.sendEmptyMessage(0);
} catch (InterruptedException e)
{
e.printStackTrace();
}
}
}.start();
}
}
});
}
private class CustomAdapter extends BaseAdapter
{
// 初始列表项数量
int count = 20;
public int getCount()
{
return count;
}
public Object getItem(int position)
{
return position;
}
public long getItemId(int position)
{
return position;
}

public View getView(int position, View convertView, ViewGroup parent)
{
TextView result = (TextView) convertView;
//动态创建TextView添加早ListView中
if (result == null)
{
result = new TextView(MainActivity.this);
result.setTextAppearance(MainActivity.this, android.R.style.TextAppearance_Large);
AbsListView.LayoutParams layoutParams = new AbsListView.LayoutParams(AbsListView.LayoutParams.FILL_PARENT,AbsListView.LayoutParams.WRAP_CONTENT);
result.setLayoutParams(layoutParams);
result.setGravity(Gravity.CENTER);
}
result.setText("第 " + (position + 1)+"行");
return result;
}
}
}