Android实战简易教程-第二十五枪（基于Baas的数据表查询下拉刷新和上拉加载实现！）

上一节我们实现了数据表的加载，但是，当数据表数据很多时，我们就要考虑数据的分页，这里我们选用了PullToRefreshListView控件，先看一下该控件的说明：

效果图： 

                               正在刷新                                                                       刷新后

一、导入Library

下载源码后（​​https://github.com/chrisbanes/Android-PullToRefresh​​），里面有个Library工程，添加工程到Eclipse中；

另外extras文件夹还有两个工程：PullToRefreshListFragment和PullToRefreshViewPager，由于我们的这个用不到他们的库文件，所以不必导入了；

二、实战

1、新建工程，添加Libray库到工程中

新建工程（try_PullToRefresh）后，右键-》Properties-》Android-》Add  选择上面的Library，然后就是这个样子的

2、重写activity_main.xml

XML内容为：

[html]    ​​view plain​​   ​​copy​​   ​​​   ​​​   
 
1. <?xml version="1.0" encoding="utf-8"?>  
2. <LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"  
3. android:layout_width="fill_parent"  
4. android:layout_height="fill_parent"  
5. android:orientation="vertical" >  
6.       
7. <!--     The PullToRefreshListView replaces a standard ListView widget. -->  
8. <com.handmark.pulltorefresh.library.PullToRefreshListView  
9. android:id="@+id/pull_refresh_list"  
10. android:layout_width="fill_parent"  
11. android:layout_height="fill_parent"  
12. android:cacheColorHint="#00000000"  
13. android:divider="#19000000"  
14. android:dividerHeight="4dp"  
15. android:fadingEdge="none"  
16. android:fastScrollEnabled="false"  
17. android:footerDividersEnabled="false"  
18. android:headerDividersEnabled="false"  
19. android:smoothScrollbar="true" />  
20.   
21. </LinearLayout>

其中中间那一大段<com.handmark.pull………………/>就是相当于ListView控件，用这段来代替原是ListView控件的代码

下面我们看一下具体怎么实现的。

先在数据表中插入数据：

然后看代码，MainActivity.java:

package com.bmob.pagingdemo;

import java.util.ArrayList;
import java.util.List;

import android.app.Activity;
import android.content.Context;
import android.os.Bundle;
import android.util.Log;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.AbsListView;
import android.widget.AbsListView.OnScrollListener;
import android.widget.BaseAdapter;
import android.widget.ListView;
import android.widget.TextView;
import android.widget.Toast;
import cn.bmob.v3.Bmob;
import cn.bmob.v3.BmobQuery;
import cn.bmob.v3.listener.FindListener;

import com.handmark.pulltorefresh.library.ILoadingLayout;
import com.handmark.pulltorefresh.library.PullToRefreshBase;
import com.handmark.pulltorefresh.library.PullToRefreshBase.OnRefreshListener2;
import com.handmark.pulltorefresh.library.PullToRefreshListView;

public class MainActivity extends Activity {

  PullToRefreshListView mPullToRefreshView;
  private ILoadingLayout loadingLayout;
  ListView mMsgListView;
  List<TestData> bankCards = new ArrayList<TestData>();// 数据list

  private static final int STATE_REFRESH = 0;// 下拉刷新
  private static final int STATE_MORE = 1;// 加载更多

  private int limit = 10; // 每页的数据是10条
  private int curPage = 0; // 当前页的编号，从0开始

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

    Bmob.initialize(this, "8f3ffb2658d8a3366a70a0b0ca0b71b2");// 初始化
    queryData(0, STATE_REFRESH);

    initListView();// 初始化ListView
  }

  
  private void initListView() {
    mPullToRefreshView = (PullToRefreshListView) findViewById(R.id.list);
    loadingLayout = mPullToRefreshView.getLoadingLayoutProxy();
    loadingLayout.setLastUpdatedLabel("");
    loadingLayout
        .setPullLabel(getString(R.string.pull_to_refresh_bottom_pull));// 下拉标签
    loadingLayout
        .setRefreshingLabel(getString(R.string.pull_to_refresh_bottom_refreshing));// 刷新标签
    loadingLayout
        .setReleaseLabel(getString(R.string.pull_to_refresh_bottom_release));// 释放标签
    // //滑动监听
    mPullToRefreshView.setOnScrollListener(new OnScrollListener() {

      @Override
      public void onScrollStateChanged(AbsListView view, int scrollState) {

      }

      @Override
      public void onScroll(AbsListView view, int firstVisibleItem,
          int visibleItemCount, int totalItemCount) {

        if (firstVisibleItem == 0) {
          loadingLayout.setLastUpdatedLabel("");
          loadingLayout
              .setPullLabel(getString(R.string.pull_to_refresh_top_pull));
          loadingLayout
              .setRefreshingLabel(getString(R.string.pull_to_refresh_top_refreshing));
          loadingLayout
              .setReleaseLabel(getString(R.string.pull_to_refresh_top_release));
        } else if (firstVisibleItem + visibleItemCount + 1 == totalItemCount) {// 加载完毕
          loadingLayout.setLastUpdatedLabel("");
          loadingLayout
              .setPullLabel(getString(R.string.pull_to_refresh_bottom_pull));
          loadingLayout
              .setRefreshingLabel(getString(R.string.pull_to_refresh_bottom_refreshing));
          loadingLayout
              .setReleaseLabel(getString(R.string.pull_to_refresh_bottom_release));
        }
      }
    });

    // 下拉刷新监听
    mPullToRefreshView
        .setOnRefreshListener(new OnRefreshListener2<ListView>() {

          @Override
          public void onPullDownToRefresh(
              PullToRefreshBase<ListView> refreshView) {
            // 下拉刷新(从第一页开始装载数据)
            queryData(0, STATE_REFRESH);
          }

          @Override
          public void onPullUpToRefresh(
              PullToRefreshBase<ListView> refreshView) {
            // 上拉加载更多(加载下一页数据)
            queryData(curPage, STATE_MORE);
          }
        });

    mMsgListView = mPullToRefreshView.getRefreshableView();
    // 再设置adapter
    mMsgListView.setAdapter(new DeviceListAdapter(this));
  }

  /**
   * 分页获取数据
   * 
   * @param page
   *            页码
   * @param actionType
   *            ListView的操作类型（下拉刷新、上拉加载更多）
   */
  private void queryData(final int page, final int actionType) {
    Log.i("bmob", "pageN:" + page + " limit:" + limit + " actionType:"
        + actionType);

    BmobQuery<TestData> query = new BmobQuery<TestData>();
    query.setLimit(limit); // 设置每页多少条数据
    query.setSkip(page * limit); // 从第几条数据开始，
    query.findObjects(this, new FindListener<TestData>() {

      @Override
      public void onSuccess(List<TestData> arg0) {
        // TODO Auto-generated method stub

        if (arg0.size() > 0) {//能加载到数据
          if (actionType == STATE_REFRESH) {
            // 当是下拉刷新操作时，将当前页的编号重置为0，并把bankCards清空，重新添加
            curPage = 0;
            bankCards.clear();
          }

          // 将本次查询的数据添加到bankCards中
          for (TestData td : arg0) {
            bankCards.add(td);
          }

          // 这里在每次加载完数据后，将当前页码+1，这样在上拉刷新的onPullUpToRefresh方法中就不需要操作curPage了
          curPage++;
          showToast("第" + (page + 1) + "页数据加载完成");
        } else if (actionType == STATE_MORE) {//数据加载完毕
          showToast("没有更多数据了");
        } else if (actionType == STATE_REFRESH) {//无数据
          showToast("没有数据");
        }
        mPullToRefreshView.onRefreshComplete();
      }

      @Override
      public void one rror(int arg0, String arg1) {
        // TODO Auto-generated method stub
        showToast("查询失败:" + arg1);
        mPullToRefreshView.onRefreshComplete();
      }
    });
  }

  /**
   * Adapter
   * 
   * @author Administrator
   * 
   */
  private class DeviceListAdapter extends BaseAdapter {

    Context context;

    public DeviceListAdapter(Context context) {
      this.context = context;
    }

    @Override
    public View getView(final int position, View convertView,
        ViewGroup parent) {
      ViewHolder holder = null;
      if (convertView == null) {

        convertView = LayoutInflater.from(context).inflate(
            R.layout.list_item_bankcard, null);
        holder = new ViewHolder();
        holder.tv_cardNumber = (TextView) convertView
            .findViewById(R.id.tv_cardNumber);
        convertView.setTag(holder);
      } else {
        holder = (ViewHolder) convertView.getTag();
      }

      TestData td = (TestData) getItem(position);

      holder.tv_cardNumber.setText(td.getName());
      return convertView;
    }

    class ViewHolder {
      TextView tv_cardNumber;
    }

    @Override
    public int getCount() {
      return bankCards.size();
    }

    @Override
    public Object getItem(int position) {
      return bankCards.get(position);
    }

    @Override
    public long getItemId(int position) {
      return position;
    }

  }

  private void showToast(String msg) {
    Toast.makeText(this, msg, Toast.LENGTH_SHORT).show();
  }

}

TestData.java:

package com.bmob.pagingdemo;

import cn.bmob.v3.BmobObject;

public class TestData extends BmobObject {
  private String name;

  public String getName() {
    return name;
  }

  public void setName(String name) {
    this.name = name;
  }
  
}

main.xml:

<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:orientation="vertical" >

    <com.handmark.pulltorefresh.library.PullToRefreshListView
        xmlns:ptr="http://schemas.android.com/apk/res/com.bmob.pagingdemo"
        android:id="@+id/list"
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        android:fadingEdge="none"
        android:fastScrollEnabled="false"
        android:smoothScrollbar="true"
        ptr:ptrMode="both" />

</LinearLayout>

AndroidManifest.xml:

<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
    package="com.bmob.pagingdemo"
    android:versionCode="1"
    android:versionName="1.0" >

    <uses-sdk
        android:minSdkVersion="14"
        android:targetSdkVersion="14" />

    <uses-permission android:name="android.permission.INTERNET" /> <!-- 允许应用打开网络套接口 -->
    <uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE" />

    <application
        android:allowBackup="true"
        android:icon="@drawable/ic_launcher"
        android:label="@string/app_name"
        android:theme="@style/AppTheme" >
        <activity
            android:name=".MainActivity"
            android:label="@string/app_name" >
            <intent-filter>
                <action android:name="android.intent.action.MAIN" />

                <category android:name="android.intent.category.LAUNCHER" />
            </intent-filter>
        </activity>
    </application>

</manifest>

运行实例，下拉刷新：

上拉加载，每次加载10条数据：