編輯:關於android開發
pulltorefresh插件可以輕松實現上拉下拉刷新,github.com上直接搜索進行下載。
布局文件:
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android" xmlns:ptr="http://schemas.android.com/apk/res-auto" xmlns:tools="http://schemas.android.com/tools" android:layout_width="match_parent" android:layout_height="match_parent" android:paddingBottom="@dimen/activity_vertical_margin" android:paddingLeft="@dimen/activity_horizontal_margin" android:paddingRight="@dimen/activity_horizontal_margin" android:paddingTop="@dimen/activity_vertical_margin" tools:context=".MainActivity" > <com.handmark.pulltorefresh.library.PullToRefreshListView android:id="@+id/pull_to_refresh_listview" android:layout_height="fill_parent" android:layout_width="fill_parent" ptr:ptrDrawable="@drawable/default_ptr_flip" ptr:ptrAnimation ptr:ptrHeaderBackground="@android:color/transparent" ptr:ptrHeaderTextColor="#919191" /> </RelativeLayout>
核心代碼如下,這裡用到了Android當中不少的知識點,其中主要的是異步任務處理、自定義適配器。
package com.example.pulltorefresh; import java.util.ArrayList; import com.handmark.pulltorefresh.library.ILoadingLayout; import com.handmark.pulltorefresh.library.PullToRefreshBase; import com.handmark.pulltorefresh.library.PullToRefreshListView; import android.os.AsyncTask; import android.os.Bundle; import android.app.Activity; import android.content.Context; import android.view.LayoutInflater; import android.view.Menu; import android.view.View; import android.view.ViewGroup; import android.widget.BaseAdapter; import android.widget.TextView; public class MainActivity extends Activity { private PullToRefreshListView pullToRefreshView; private ArrayList<Music> musics=new ArrayList<Music>(); private DataAdapter dataAdapter; protected void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.activity_main); pullToRefreshView = (PullToRefreshListView) findViewById(R.id.pull_to_refresh_listview); pullToRefreshView.setOnRefreshListener(new PullToRefreshBase.OnRefreshListener2() { @Override public void onPullDownToRefresh(PullToRefreshBase refreshView) { // TODO 自動生成的方法存根 new DataAsyncTask(MainActivity.this).execute(); } @Override public void onPullUpToRefresh(PullToRefreshBase refreshView) { // TODO 自動生成的方法存根 new DataAsyncTask(MainActivity.this).execute(); } }); pullToRefreshView.setMode(PullToRefreshBase.Mode.BOTH); ILoadingLayout startLabels = pullToRefreshView .getLoadingLayoutProxy(true, false); startLabels.setPullLabel("下拉刷新...");// 剛下拉時,顯示的提示 startLabels.setRefreshingLabel("正在載入...");// 刷新時 startLabels.setReleaseLabel("放開刷新...");// 下來達到一定距離時,顯示的提示 ILoadingLayout endLabels = pullToRefreshView.getLoadingLayoutProxy( false, true); endLabels.setPullLabel("上拉刷新...");// 剛下拉時,顯示的提示 endLabels.setRefreshingLabel("正在載入...");// 刷新時 endLabels.setReleaseLabel("放開刷新...");// 下來達到一定距離時,顯示的提示 loadData(); dataAdapter=new DataAdapter(this, musics); pullToRefreshView.setAdapter(dataAdapter); } @Override public boolean onCreateOptionsMenu(Menu menu) { // Inflate the menu; this adds items to the action bar if it is present. getMenuInflater().inflate(R.menu.main, menu); return true; } private int count; private void loadData(){ for(int i=0;i<10;i++){ musics.add(new Music("歌曲-"+count,"歌手-"+count)); count++; } } static class DataAsyncTask extends AsyncTask<Void, Void, String>{ private MainActivity mainActivity; public DataAsyncTask(MainActivity mainActivity){ this.mainActivity=mainActivity; } @Override protected String doInBackground(Void... arg0) { try { Thread.sleep(2000); } catch (InterruptedException e) { // TODO 自動生成的 catch 塊 e.printStackTrace(); } mainActivity.loadData(); return "success"; } @Override protected void onPostExecute(String result) { // TODO 自動生成的方法存根 super.onPostExecute(result); if("success".equals(result)){ mainActivity.dataAdapter.notifyDataSetChanged(); mainActivity.pullToRefreshView.onRefreshComplete(); } } } static class DataAdapter extends BaseAdapter{ private Context ctx; private ArrayList<Music> musics; public DataAdapter(Context ctx,ArrayList<Music> musics){ this.ctx=ctx; this.musics=musics; } @Override public int getCount() { // TODO 自動生成的方法存根 return musics.size(); } @Override public Object getItem(int arg0) { // TODO 自動生成的方法存根 return musics.get(arg0); } @Override public long getItemId(int arg0) { // TODO 自動生成的方法存根 return arg0; } //ViewHolder就是一個持有者的類,他裡面一般沒有方法,只有屬性,作用就是一個臨時的儲存器, //把你getView方法中每次返回的View存起來,可以下次再用。這樣做的好處就是不必每次都到布局文件中去拿到你的View,提高了效率 @Override public View getView(int arg0, View arg1, ViewGroup arg2) { ViewHolder vh; if(arg1==null){ arg1=LayoutInflater.from(ctx).inflate(R.layout.listitem,null); vh=new ViewHolder(); vh.tv_title=(TextView) arg1.findViewById(R.id.gequ); vh.tv_singer=(TextView) arg1.findViewById(R.id.geshou); arg1.setTag(vh); } vh=(ViewHolder) arg1.getTag(); Music m=musics.get(arg0); vh.tv_title.setText(m.getTitle()); vh.tv_singer.setText(m.getSinger()); return arg1; } static class ViewHolder{ TextView tv_title; TextView tv_singer; } } }
附帶核心代碼中用到的Music類,自定義適配器用到的自定義布局很簡單,就兩個TextView,這裡略。
package com.example.pulltorefresh; public class Music { private String title; private String singer; public String getTitle() { return title; } public void setTitle(String title) { this.title = title; } public String getSinger() { return singer; } public void setSinger(String singer) { this.singer = singer; } public Music(String title, String singer) { this.title = title; this.singer = singer; } public Music() { } }
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