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
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<?xml version="1.0" encoding="utf-8"?> |
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<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android" |
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android:orientation="vertical" |
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android:layout_width="fill_parent" |
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android:layout_height="fill_parent" |
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> |
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<ListView |
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android:id="@id/android:list" |
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android:layout_width="match_parent" |
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android:layout_height="match_parent" |
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android:layout_weight="1" |
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android:drawSelectorOnTop="false" |
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/> |
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</LinearLayout> |
footer.xml
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<?xml version="1.0" encoding="utf-8"?> |
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<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android" |
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android:layout_width="fill_parent" |
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android:layout_height="wrap_content" |
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android:gravity="center" |
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android:orientation="horizontal" |
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> |
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<ProgressBar |
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android:id="@+id/progressbar" |
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android:layout_width="wrap_content" |
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android:layout_height="wrap_content" |
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style="\?android:attr/progressBarStyleSmall" |
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/> |
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<TextView |
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android:layout_width="wrap_content" |
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android:layout_height="wrap_content" |
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android:textSize="20.0sp" |
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android:text="正在加载..." |
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/> |
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</LinearLayout> |
MainActicity.xml
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package com.szy.listview; |
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import android.app.ListActivity; |
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import android.os.Bundle; |
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import android.os.Handler; |
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import android.os.Message; |
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import android.view.Gravity; |
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import android.view.View; |
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import android.view.ViewGroup; |
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import android.widget.AbsListView; |
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import android.widget.BaseAdapter; |
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import android.widget.ListView; |
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import android.widget.TextView; |
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/** |
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*@author coolszy |
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*@date 2012-3-27 |
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*@blog http://blog.92coding.com |
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*/ |
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public class MainActivity extends ListActivity |
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{ |
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private ListView mListView; |
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private CustomAdapter mAdapter; |
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private int mScrollState; |
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private View mFooter; |
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@Override |
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public void onCreate(Bundle savedInstanceState) |
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{ |
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super.onCreate(savedInstanceState); |
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setContentView(R.layout.main); |
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//获取ListView |
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mListView = getListView(); |
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//根据footer.xml描述创建View |
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mFooter = getLayoutInflater().inflate(R.layout.footer, null); |
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// 在ListView底部添加正在加载视图 |
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//注意：addFooterView方法需要在调用setListAdapter方法前调用！ |
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mListView.addFooterView(mFooter); |
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mAdapter = new CustomAdapter(); |
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setListAdapter(mAdapter); |
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//给ListView添加滚动监听器 |
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mListView.setOnScrollListener(new AbsListView.OnScrollListener() |
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{ |
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@Override |
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public void onScrollStateChanged(AbsListView view, int scrollState) |
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{ |
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//记录当前状态 |
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mScrollState = scrollState; |
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} |
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@Override |
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public void onScroll(AbsListView view, int firstVisibleItem, int visibleItemCount, int totalItemCount) |
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{ |
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// 可视的最后一个列表项的索引 |
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int lastVisibleItem = firstVisibleItem + visibleItemCount - 1; |
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//当列表正处于滑动状态且滑动到列表底部时，执行 |
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if (mScrollState != AbsListView.OnScrollListener.SCROLL_STATE_IDLE |
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&& lastVisibleItem == totalItemCount - 1) |
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{ |
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// 执行线程，模拟睡眠5秒钟后添加10个列表项 |
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new Thread() |
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{ |
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private Handler handler = new Handler() |
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{ |
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@Override |
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public void handleMessage(Message msg) |
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{ |
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super.handleMessage(msg); |
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//增加Item数量 |
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mAdapter.count += 10; |
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//通知数据集变化 |
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mAdapter.notifyDataSetChanged(); |
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} |
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}; |
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@Override |
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public void run() |
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{ |
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super.run(); |
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try |
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{ |
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sleep(5000); |
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handler.sendEmptyMessage(0); |
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} catch (InterruptedException e) |
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{ |
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e.printStackTrace(); |
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} |
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} |
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}.start(); |
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} |
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} |
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}); |
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} |
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private class CustomAdapter extends BaseAdapter |
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{ |
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// 初始列表项数量 |
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int count = 20; |
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@Override |
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public int getCount() |
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{ |
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return count; |
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} |
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@Override |
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public Object getItem(int position) |
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{ |
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return position; |
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} |
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@Override |
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public long getItemId(int position) |
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{ |
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return position; |
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} |
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@Override |
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public View getView(int position, View convertView, ViewGroup parent) |
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{ |
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TextView result = (TextView) convertView; |
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//动态创建TextView添加早ListView中 |
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if (result == null) |
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{ |
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result = new TextView(MainActivity.this); |
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result.setTextAppearance(MainActivity.this, android.R.style.TextAppearance_Large); |
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AbsListView.LayoutParams layoutParams = new AbsListView.LayoutParams |
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(AbsListView.LayoutParams.FILL_PARENT, |
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AbsListView.LayoutParams.WRAP_CONTENT); |
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result.setLayoutParams(layoutParams); |
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result.setGravity(Gravity.CENTER); |
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} |
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result.setText("第 " + (position + 1)+"行"); |
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return result; |
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} |
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} |
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} |