Android pulltorefresh使用

pulltorefresh插件可以輕鬆實現上拉下拉刷新，github.com上直接搜索進行下載。

佈局文件:

<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:ptrAnimationStyle="flip"
    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，其中主要的是非同步任務處理、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佈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佈局很簡單，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() {
    }
    
}