没有办法,米公设计的一个UI是stickyheaderlist(头部停留)和分页加载数据功能的整合,笔者原以为是米工自己拍着脑袋想出来的,还想进一步讨论一下,后来才发现支付宝也是这么做的,那好吧,做呗。
先上Demo完成效果图(有点简陋,但是这样代码却也更清晰了)
下面分别介绍一下StickyHeaderListView(这么长!后面都简写成StickyLV好了)和分页加载:
一、StickyLV(头部停留listview)
其实这个没什么好说的,因为是开源组件,github上都有介绍和demo,这里就简单的讲一下几个关键的地方吧
a.StickyLV的对应的Adapter要继承StickyListHeadersAdapter接口,并实现其中的getHeaderView和getHeaderId方法,前者和普通的Adapter的getView方法一样,需要注意的是后者,只有在返回的int值和上一个返回值不同时,才会显示HeaderView,同时,要将返回值的计算式关联到position上。
b.同样在StickyLV对应的Adapter中,尽管为StickyLV添加了HeaderView,但是getCount()返回的仍然是内容列表项的数量,而不包括HeaderView的数量。
二、分页加载更多数据
a.首先分页加载通常出现在服务器数据请求中,因为一次性加载过多的数据可能会带来不好的用户体验,及不要的性能开销。所以通过分页加载来平滑加载过程。
b.分页数据加载事件由listview触发,主要通过重写onScrollStateChanged方法来实现。
c.最后定义一个OnLoadingMoreListener接口,在其中定义一个加载数据的方法OnLoadingMore。并将接口作为参数由外部调用进行初始化动作,这就是所谓的代理或者说监听者模式。
d.最后还有footerView的定义、添加及隐藏。
主要实现代码
StickyListAdapter:
package com.wly.sticky_pagelist; import java.util.ArrayList; import android.content.Context; import android.graphics.Color; import android.view.View; import android.view.ViewGroup; import android.widget.BaseAdapter; import android.widget.TextView; import com.emilsjolander.components.stickylistheaders.StickyListHeadersAdapter; public class StickyListAdapter extends BaseAdapter implements StickyListHeadersAdapter { private ArrayList<String> list; private Context mContext; public void init(Context context,ArrayList<String> list) { this.list = list; this.mContext = context; mContext = context; } @Override public int getCount() { return list.size(); } @Override public Object getItem(int position) { return list.get(position); } @Override public long getItemId(int position) { return 0; } @Override public View getView(int position, View convertView, ViewGroup parent) { TextView itemView = new TextView(mContext); itemView.setText("Item:" + position); itemView.setTextSize(20); return itemView; } @Override public View getHeaderView(int position, View convertView, ViewGroup parent) { TextView headView = new TextView(mContext); headView.setText("Head:" + (position/10)); headView.setTextSize(24); headView.setTextColor(new Color().RED); return headView; } /** * 决定header出现的时机,如果当前的headerid和前一个headerid不同时,就会显示 */ @Override public long getHeaderId(int position) { return position/10 + 0x1234; } }
在导入的StickyListHeadersListView中定义接口OnLoadingMoreListener
/** * 加载更多数据回调接口 * */ public interface OnLoadingMoreLinstener { /** * 加载更多数据回调方法,由组件自身触发 */ void OnLoadingMore(); }
并修改StickyListHeadersListView的mOnScrollListener接口对象的onScrollStateChanged方法,如下:
public OnScrollListener mOnScrollListener = new OnScrollListener() { @Override public void onScrollStateChanged(AbsListView view, int scrollState) { Log.e("parent","onScrollStateChanged"); if (mOnScrollListenerDelegate != null) { mOnScrollListenerDelegate.onScrollStateChanged(view, scrollState); } // 滑到底部后自动加载,判断listview已经停止滚动并且最后可视的条目等于adapter的条目 if (scrollState == OnScrollListener.SCROLL_STATE_FLING) { } else if (scrollState == OnScrollListener.SCROLL_STATE_TOUCH_SCROLL || scrollState == OnScrollListener.SCROLL_STATE_IDLE) { if (getLastVisiblePosition() == (getCount() - 1)) { Log.e("Sticky","--拖动到最后--"); if(loadMoreListener != null) { loadMoreListener.OnLoadingMore(); } } } }
最后,界面MainActivity
package com.wly.sticky_pagelist; import java.util.ArrayList; public class MainActivity extends Activity implements OnHeaderClickListener,AdapterView.OnItemClickListener ,OnLoadingMoreLinstener { private LayoutInflater inflater; ArrayList<String> list; StickyListAdapter adapter; StickyListHeadersListView stickyLV; private RelativeLayout moredata; private View progressBarView; private TextView progressBarTextView; private AnimationDrawable loadingAnimation; //加载更多,动画 private boolean isLoading = false; @Override protected void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.activity_main); list = new ArrayList<String>(); for(int i=1;i<=15;i++) { list.add(i + ""); } adapter = new StickyListAdapter(); adapter.init(this, list); inflater = LayoutInflater.from(this); moredata = (RelativeLayout)inflater.inflate(R.layout.moredata, null); stickyLV = (StickyListHeadersListView)this.findViewById(R.id.stickyList); progressBarView = (View) moredata.findViewById(R.id.loadmore_foot_progressbar); progressBarTextView = (TextView) moredata.findViewById(R.id.loadmore_foot_text); loadingAnimation = (AnimationDrawable) progressBarView.getBackground(); stickyLV.addFooterView(moredata); stickyLV.setAdapter(adapter); stickyLV.setOnItemClickListener(this); stickyLV.setOnHeaderClickListener(this); stickyLV.setLoadingMoreListener(this); } public void loadingFinished() { if (null != loadingAnimation && loadingAnimation.isRunning()) { loadingAnimation.stop(); } progressBarView.setVisibility(View.INVISIBLE); progressBarTextView.setVisibility(View.INVISIBLE); isLoading = false; adapter.notifyDataSetChanged(); } @Override public void OnLoadingMore() { progressBarView.setVisibility(View.VISIBLE); progressBarTextView.setVisibility(View.VISIBLE); loadingAnimation.start(); if(!isLoading) { isLoading = true; new Handler().postDelayed(new Runnable() { @Override public void run() { for(int i=0;i<5;i++) { list.add((Math.random() * 40) + ""); } loadingFinished(); } },1200); } } @Override public void onHeaderClick(StickyListHeadersListView l, View header, int itemPosition, long headerId, boolean currentlySticky) { Toast.makeText(this, "header:" + headerId, Toast.LENGTH_SHORT).show(); } @Override public void onItemClick(AdapterView<?> parent, View view, int position, long id) { Toast.makeText(this, "item:" + position, Toast.LENGTH_SHORT).show(); } }
参考文档:https://github.com/emilsjolander/StickyListHeaders
完整工程下载:http://download.csdn.net/detail/u011638883/7062457
O啦~~~
装载请保留出处:http://blog.csdn.net/u011638883/article/details/21316779
谢谢!!