Android下拉刷新

下拉刷新
1.怎么下载开源工具
github.com上下载PullToRefresh

  * 2.怎么导入
创建Android Project From Existing Code, 选中library, 并且拷贝到工作空间中
在要使用的项目上右键点击Properties, Android选项中导入Library
3.怎么使用

对activity的xml进行配置：

<com.handmark.pulltorefresh.library.PullToRefreshListView
android:id="@+id/ptrlv"
android:layout_width="match_parent"
android:layout_height="match_parent" />
Java代码中获取PullToRefreshListView
调用setOnRefreshListener()方法添加监听器, 监听刷新操作
当刷新时会执行onRefresh()
定义一个AsyncTask的子类, 该类实现doInBackground()和onPostExecute()

在onRefresh()中创建该类对象, 调用execute()

关键部分代码为：

package com.itheima.sqlite.ui;

import java.util.List;

import android.app.Activity;
import android.database.ContentObserver;
import android.net.Uri;
import android.os.AsyncTask;
import android.os.Bundle;
import android.os.Handler;
import android.view.View;
import android.view.ViewGroup;
import android.widget.BaseAdapter;
import android.widget.ListView;
import android.widget.TextView;
import android.widget.Toast;

import com.handmark.pulltorefresh.library.PullToRefreshBase;
import com.handmark.pulltorefresh.library.PullToRefreshBase.Mode;
import com.handmark.pulltorefresh.library.PullToRefreshBase.OnRefreshListener;
import com.handmark.pulltorefresh.library.PullToRefreshListView;
import com.itheima.sqlite.R;
import com.itheima.sqlite.bean.Account;
import com.itheima.sqlite.dao.ClassicAccountDao;

public class RefreshActivity extends Activity {

private List<Account> list;
private int pageNum = 1;
private PullToRefreshListView ptrlv;
private ClassicAccountDao dao;
private MyAdapter adapter;

@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_refresh);

dao = new ClassicAccountDao(this);
list = dao.queryPage(20, pageNum);
adapter = new MyAdapter();
//获取view对象；
ptrlv = (PullToRefreshListView) findViewById(R.id.ptrlv);
ptrlv.setAdapter(adapter);
ptrlv.setMode(Mode.PULL_FROM_END);//设置下来的模式为从底部刷新；

ptrlv.setOnRefreshListener(new OnRefreshListener<ListView>() { // 添加刷新监听器, 如果需要监听2个方向, 用OnRefreshListener2
public void onRefresh(PullToRefreshBase<ListView> refreshView) { // 当刷新的时候执行
System.out.println("onRefresh");
new GetDataTask().execute();
}
});

// 注册一个ContentObserver(类似一个监听器), 其中需要实现onChange()方法, 在数据修改的时候, 会自动执行onChange()方法
Uri uri = Uri.parse("content://ItheimaProvider");
getContentResolver().registerContentObserver(uri , true, new MyObserver());
}

private class MyObserver extends ContentObserver {
public MyObserver() {
super(new Handler());
}
public void onChange(boolean selfChange) {
list = dao.queryPage(20, pageNum); // 重新查询数据
adapter.notifyDataSetChanged(); // 刷新ListView(把数据和ListView显示的内容同步)
}
}

private class GetDataTask extends AsyncTask<Void, Void, String[]> {
protected String[] doInBackground(Void... params) { // 开启新线程, 执行该方法
System.out.println("doInBackground");
return null;
}
protected void onPostExecute(String[] result) { // 执行doInBackground()之后, 在主线程执行该方法
System.out.println("onPostExecute");
List<Account> newData = dao.queryPage(20, ++pageNum); // 查询下一页的数据
Toast.makeText(getApplicationContext(), newData.size() + "", Toast.LENGTH_SHORT).show();
list.addAll(newData); // 把数据添加到list中
adapter.notifyDataSetChanged(); // 刷新界面
ptrlv.onRefreshComplete();
}
}
//自己定义的适配器；
private class MyAdapter extends BaseAdapter {
public int getCount() {
return list.size();
}
public Object getItem(int position) {
return null;
}
public long getItemId(int position) {
return 0;
}
public View getView(int position, View convertView, ViewGroup parent) {
View v = convertView != null ? convertView : View.inflate(RefreshActivity.this, R.layout.account_item, null);
TextView idTV = (TextView) v.findViewById(R.id.idTV);
TextView nameTV = (TextView) v.findViewById(R.id.nameTV);
TextView balanceTV = (TextView) v.findViewById(R.id.balanceTV);

Account a = list.get(position);
idTV.setText(a.getId() + "");
nameTV.setText(a.getName());
balanceTV.setText(a.getBalance() + "");
return v;
}
}

}