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一、功能分析----ListView“加载更多”,功能如下图所示:
这个效果是当你上拉拖动页面时（注意有区别于下拉刷新），页面提示正在加载，2秒后显示留言更多内容；具体功能知道那我就来讲解下如何实现这个功能。
二、创建自定义ListView及其底部布局footer
①首先做一个加载提示布局，布局footer_layout如下图：
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<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:id="@+id/load_layout"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:orientation="horizontal"
android:layout_gravity="center" >
<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:text="正在加载..." />
</LinearLayout>
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②将布局添加至ListView，自定义一个ListView
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package com.mg.message.view;
import android.content.Context;
import android.util.AttributeSet;
import android.view.LayoutInflater;
import android.view.View;
import android.widget.AbsListView;
import android.widget.AbsListView.OnScrollListener;
import android.widget.ListView;
import com.mg.message.R;
public class LX_LoadListView extends ListView implements OnScrollListener{
View footer;//底部布局
int totalItemCount;//总数量
int lastVisibleItem;//最后一个可见的Item
boolean isLoading;//正在加载
ILoadListener iLoadListener;
public LX_LoadListView(Context context) {
super(context);
initView(context);
}
public LX_LoadListView(Context context, AttributeSet attrs) {
super(context, attrs);
initView(context);
}
public LX_LoadListView(Context context, AttributeSet attrs, int defStyle) {
super(context, attrs, defStyle);
initView(context);
}
/**
* 添加底部加载提示布局到listview
* @param context
*/
private void initView(Context context) {
LayoutInflater layoutInflater=LayoutInflater.from(context);
footer=layoutInflater.inflate(R.layout.lx_footer_layout, null);
footer.findViewById(R.id.load_layout).setVisibility(View.GONE);
this.addFooterView(footer);
this.setOnScrollListener(this);
}
@Override
public void onScroll(AbsListView view, int firstVisibleItem, int visibleItemCount, int totalItemCount)
{
this.lastVisibleItem=firstVisibleItem+visibleItemCount;
this.totalItemCount=totalItemCount;
}
@Override
public void onScrollStateChanged(AbsListView view, int scrollState) {
if (totalItemCount==lastVisibleItem&&scrollState==SCROLL_STATE_IDLE) {
if (!isLoading) {
isLoading=true;
footer.findViewById(R.id.load_layout).setVisibility(View.VISIBLE);
iLoadListener.onLoad();//加载更多数据
}
}
}
//加载完毕
public void loadComplete() {
isLoading=false;
footer.findViewById(R.id.load_layout).setVisibility(View.GONE);
}
public void setInterface(ILoadListener iLoadListener) {
this.iLoadListener=iLoadListener;
}
//加载更多数据的回调接口
public interface ILoadListener
{
public void onLoad();
}
}
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三、给ListView设置Adapter并实现接口中的Load方法
①自定义ListView布局，lx_get_content_activity
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<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:orientation="vertical"
android:layout_marginTop="2dp"
android:layout_marginBottom="2dp"
android:layout_marginLeft="2dp"
android:layout_marginRight="2dp"
android:background="@drawable/edit_normal">
<com.mg.message.view.LX_LoadListView
android:id="@+id/list_content"
android:layout_width="match_parent"
android:background="@drawable/edit_normal"
android:layout_height="0dip"
android:focusable="true"
android:layout_weight="1.20" >
</com.mg.message.view.LX_LoadListView>
</LinearLayout>
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②给ListView设置Adapter，并实现接口的Load方法
package com.mg.message.ui;
import java.util.ArrayList;
import java.util.List;
import android.os.Bundle;
import android.view.View;
import android.widget.AdapterView;
import android.widget.AdapterView.OnItemLongClickListener;
import android.widget.AdapterView.OnItemClickListener;
import com.mg.core.base.BaseActivity;
import com.mg.core.net.OperateCode;
import com.mg.core.net.ThreadMessage;
import com.mg.message.R;
import com.mg.message.data.GetMessageData;
import com.mg.message.domain.Message;
import com.mg.message.ui.adapter.ContentAdapter;
import com.mg.message.utils.ViewUtil;
import com.mg.message.view.LX_LoadListView;
import com.mg.message.view.LX_LoadListView.ILoadListener;
/* * 获得留言*/
public class LX_GetContentActivity extends BaseActivity implements ILoadListener
{
private LX_LoadListView listView;
private List<Message> totalMessages=new ArrayList<Message>();
private static ContentAdapter myAdapter;
private int totalSize;
List<Message> messages=new ArrayList<Message>();
@Override
protected void initEvents()
{
listView.setOnItemClickListener(new OnItemClickListener() //进入删除页
{
@Override
public void onItemClick(AdapterView<?> arg0, View arg1, int position,
long arg3)
{
Bundle bundle = new Bundle(); //传递多参数时使用Bundle
bundle.putString("ID", messages.get(position).getID());
bundle.putString("UContent", messages.get(position).getContent().toString());
bundle.putString("UTime", messages.get(position).getCreateTime());
startCOActivity(LX_DeleteActivity.class,bundle);
finish();
}
});
//修改留言
listView.setOnItemLongClickListener(new OnItemLongClickListener()
{
@Override
public boolean onItemLongClick(AdapterView<?> arg0, View arg1,
int position, long arg3) {
Bundle bundle = new Bundle(); //传递多参数时使用Bundle
bundle.putString("ID", messages.get(position).getID());
startCOActivity(LX_AddMessageActivity.class,bundle);
finish();
return false;
}
});
}
@Override
protected void initViews()
{
setContentView(R.layout.lx_get_content_activity);
mTopBar.setVisibility(View.VISIBLE);
mTopBar.SetTvName("查看留言");
listView=(LX_LoadListView)findViewById(R.id.list_content);
listView.setInterface(this);
myAdapter=new ContentAdapter(messages);
listView.setAdapter(myAdapter);
}
@Override
protected void onResume() {
super.onResume();
showToast("onResume", false);
sendToBackgroud(OperateCode.i_getMessageInfo);
}
@Override
protected void receiveRequest(ThreadMessage threadMessage)
{
hideProgressDialog();
OperateCode operateCode = threadMessage.getOperateCode();
List<Message> messageList;
switch (operateCode)
{ //查看留言
case i_getMessageInfo:
messageList=GetMessageData.getMessagesList();
if(ViewUtil.isNotEmpty(messageList))
{
totalMessages.clear();
messages.clear();
totalMessages.addAll(messageList);
totalSize=totalMessages.size();
getData();
myAdapter.notifyDataSetChanged();
}
break;
default:
break;
}
}
//listview初始化条数
private void getData()
{
try {
if (totalSize<9) {
messages.addAll(GetMessageData.getMessagesList());
showToast("留言小于9加载完毕", false);
}
else {
messages.addAll(GetMessageData.getMessagesList().subList(0, 8));
}
}
catch (Exception e) {
}
}
//加载数据
private void getLoadData()
{
int lastsize=totalSize-messages.size();
if(messages.size()<totalSize)
{
if (lastsize<5) {
messages.clear();
messages.addAll(GetMessageData.getMessagesList());
showToast("加载项<5加载完毕", false);
}
else {
messages.addAll(totalMessages.subList(messages.size(), messages.size()+5));
}
}
else
{
messages.clear();
messages.addAll(GetMessageData.getMessagesList());
showToast("全部加载完毕", false);
}
myAdapter.notifyDataSetChanged();
}
@Override
public void onLoad()
{
android.os.Handler handler=new android.os.Handler();
handler.postDelayed(new Runnable()
{
@Override
public void run() {
getLoadData();//获取更多数据
listView.loadComplete();//通知listview加载完毕
}
}, 2000);
}
}
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