【Android】Handler的应用（三）：从服务器端分页加载更新ListView

在前面两节中，我们了解了如何从服务器中加载JSON数据。

现在，我们将把服务器中的JSON数据加载更新到ListView。

并且，结合之前博文的  “动态追加分页ListView数据”的相关知识，实现将服务器中的分页JSON数据，填充到ListView中。

回顾

以BaseAdapter做适配器的ListView：http://blog.csdn.net/jueblog/article/details/12114513

ListView内数据的动态追加：http://blog.csdn.net/jueblog/article/details/12148259

Activity的实现

package com.app.myhandler;

import org.json.JSONArray;
import org.json.JSONException;
import org.json.JSONObject;

import android.app.Activity;
import android.os.Bundle;
import android.os.Handler;
import android.view.ContextMenu;
import android.view.ContextMenu.ContextMenuInfo;
import android.view.LayoutInflater;
import android.view.MenuItem;
import android.view.View;
import android.widget.AdapterView;
import android.widget.AdapterView.AdapterContextMenuInfo;
import android.widget.ListView;
import android.widget.TextView;
import android.widget.Toast;

import com.app.adapter.MyWeixinJSON;
import com.app.util.MyApplication;
import com.app.util.MyThread;

/**
 * 点击 追加数据的ListView
 * @author 402-9
 */
public class ListViewPage extends Activity {
	private ListView lv;
	private MyWeixinJSON mJson;
	private JSONArray mData = new JSONArray();// JSON数据源
	private View view_page_footer;// 底部视图
	private int page = 1;// 加载页码
	private int totalPage;// 总数据
	private String url = new String("http://192.168.8.4/wt_guang.php?frm=3g&cid=100");
	private TextView text_page;

	private Handler handler = new Handler() {
		public void handleMessage(android.os.Message msg) {
			try {
				String result = msg.obj.toString();
				JSONObject object = new JSONObject(result);
				totalPage = (Integer) object.get("totalPage");
				if(mJson==null) {
					mData = (JSONArray) object.get("items");
					mJson = new MyWeixinJSON(mData, ListViewPage.this);
					lv.setAdapter(mJson);//为ListView绑定适配器
				} else {
					mData = MyApplication.joinJSONArray(mData, (JSONArray) object.get("items"));
					mJson.setList(mData);
					mJson.notifyDataSetChanged();
				}
				text_page.setText("下一页");
			} catch (JSONException e) {
				// TODO Auto-generated catch block
				e.printStackTrace();
			}
		};
	};

	@Override
	protected void onCreate(Bundle savedInstanceState) {
		// TODO Auto-generated method stub
		super.onCreate(savedInstanceState);
		setContentView(R.layout.weixin);
		lv = (ListView) findViewById(R.id.lv);

		new MyThread(handler, url.toString(), 1).start();

		view_page_footer = LayoutInflater.from(this).inflate(R.layout.view_page_footer, null);
		lv.addFooterView(view_page_footer);// 添加底部视图
		lv.setOnItemClickListener(new AdapterView.OnItemClickListener() {
			@Override
			public void onItemClick(AdapterView<?> parent, View view,
					int position, long id) {
				// TODO Auto-generated method stub
				try {
					JSONObject jsonObject = (JSONObject) mData.get(position);
					Toast.makeText(ListViewPage.this,
							jsonObject.getString("title"), Toast.LENGTH_SHORT)
							.show();
				} catch (JSONException e) {
					// TODO Auto-generated catch block
					e.printStackTrace();
				}
			}
		});

		text_page = (TextView) view_page_footer.findViewById(R.id.text_page);
		text_page.setOnClickListener(new View.OnClickListener() {
			// 点击按钮 追加数据 并通知适配器
			@Override
			public void onClick(View v) {
				// TODO Auto-generated method stub
				page++;
				if(page<=totalPage) {
					text_page.setText("正在加载中...");
					new MyThread(handler, url+"&p="+page, 1).start();
				} else {
					text_page.setText("已是最末页...");
					text_page.setEnabled(false);
				}
			}
		});
	}
}

mData = MyApplication.joinJSONArray(mData, (JSONArray) object.get("items"));

所调用的方法为 http://blog.csdn.net/jueblog/article/details/12622423中提供的方法。

适配器的修改

package com.app.adapter;

import org.json.JSONArray;
import org.json.JSONObject;

import android.content.Context;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.BaseAdapter;
import android.widget.ImageView;
import android.widget.TextView;

import com.app.myhandler.R;

public class MyWeixinJSON extends BaseAdapter {
	private LayoutInflater mInflater;// 动态布局映射
	private JSONArray list;
	private Context context;
//	private int i = 0;

	public void setList(JSONArray list) {
		this.list = list;
	}

	public MyWeixinJSON(JSONArray list, Context context) {
		this.list = list;
		this.context = context;
		this.mInflater = LayoutInflater.from(context);
	}

	@Override
	public int getCount() {
		// TODO Auto-generated method stub
		return list.length();
	}

	@Override
	public Object getItem(int position) {
		// TODO Auto-generated method stub
		return null;
	}

	@Override
	public long getItemId(int position) {
		// TODO Auto-generated method stub
		return 0;
	}

	@Override
	public View getView(int position, View convertView, ViewGroup parent) {
		// TODO Auto-generated method stub
		// System.out.println("正在渲染第"+position+"行  +++  "+ i++);
		OneView oneView;
		if (convertView == null) {
			convertView = mInflater.inflate(R.layout.item_weixin, null);// 根据布局文件实例化view
			oneView = new OneView();
			oneView.title = (TextView) convertView.findViewById(R.id.title);// 找某个控件
			oneView.time = (TextView) convertView.findViewById(R.id.time);
			oneView.info = (TextView) convertView.findViewById(R.id.info);
			oneView.img = (ImageView) convertView.findViewById(R.id.img);
			convertView.setTag(oneView);// 把View和某个对象关联起来
		} else {
			oneView = (OneView) convertView.getTag();
		}
		JSONObject jObject = null;
		try {
			jObject = list.getJSONObject(position);// 根据position获取集合类中某行数据
			oneView.title.setText(jObject.get("itemID").toString());// 给该控件设置数据(数据从集合类中来)
			oneView.time.setText(jObject.get("price").toString());
			oneView.info.setText(jObject.get("title").toString());
			oneView.img.setBackgroundResource(R.drawable.special_spring_head2);
			// oneView.img.setImageDrawable(Drawable.createFromStream(new
			// URI(jObject.getString("pic_url"))., "src"));
		} catch (Exception e) {
			// TODO: handle exception
		}
		return convertView;
	}

	/** 把每行布局文件的各个控件包装成一个对象 */
	private class OneView {
		TextView title;
		TextView time;
		TextView info;
		ImageView img;
	}
}

JSON数据

最后 瞄一眼服务器上的JSON数据：

{
    "totalCount": 9,
    "totalPage": 2,
    "items": [
        {
            "itemID": "13889239752",
            "title": "PEACE DOVE 正品* 真兔毛 范儿厚毛衣开衫 清库价",
            "pic_url": "http://img01.taobaocdn.com/bao/uploaded/i5/T1ELuGXj0yXXbAjkA._083138.jpg",
            "click_url": "http://item.taobao.com/item.htm?id=13889239752",
            "price": "98.00",
            "promotion_price": "0.00",
            "liked": "0"
        },
        {
            "itemID": "13357878044",
            "title": "现货 呛口小辣椒11月29日香港行snidel 翻领双排扣毛呢大衣外套",
            "pic_url": "http://img03.taobaocdn.com/bao/uploaded/i3/T1KTWDXipfXXXmSFDX_113804.jpg",
            "click_url": "http://item.taobao.com/item.htm?id=13357878044",
            "price": "278.00",
            "promotion_price": "0.00",
            "liked": "0"
        },
        {
            "itemID": "12740033159",
            "title": "2011新款呛口小辣椒子萱王翔貉子毛毛领军绿色工装棉服棉衣大衣",
            "pic_url": "http://img01.taobaocdn.com/bao/uploaded/i1/T1WiCoXi4BXXad.Qs9_073952.jpg",
            "click_url": "http://item.taobao.com/item.htm?id=12740033159",
            "price": "628.00",
            "promotion_price": "0.00",
            "liked": "0"
        },
        {
            "itemID": "8603809978",
            "title": "圣诞款大衣 三色入",
            "pic_url": "http://img01.taobaocdn.com/bao/uploaded/i1/T1GWXTXhhxXXaMGqo3_045745.jpg",
            "click_url": "http://s.click.taobao.com/t_8?e=7HZ6jHSTZTlU5Xur%2B%2F50d2poSR5Ba0A%2Fi8tpiW6m04z%2BWKzb6yELcZsJq6zxF7EMTqmpst%2FNOGepsZQvjjXKR0huW7F8S1whVzYKzICAu1lT&p=mm_10009952_0_0",
            "price": "165.00",
            "promotion_price": "0.00",
            "liked": "0"
        },
        {
            "itemID": "10629952619",
            "title": "裁诺 春装新款2012女装 韩版带帽中长款加厚卫衣 女 秋冬外套大码",
            "pic_url": "http://img01.taobaocdn.com/bao/uploaded/i1/T1PASfXfpoXXc.O0vb_093452.jpg",
            "click_url": "http://item.taobao.com/item.htm?id=10629952619",
            "price": "158.00",
            "promotion_price": "0.00",
            "liked": "0"
        },
        {
            "itemID": "9158721999",
            "title": "清仓包邮 出口欧美大码超酷水洗打磨斜开襟修身加厚抓绒卫衣外套",
            "pic_url": "http://img03.taobaocdn.com/bao/uploaded/i3/T12t5KXXJqXXbjSw.8_100610.jpg",
            "click_url": "http://s.click.taobao.com/t_8?e=7HZ6jHSTZPhaK%2FmBeumaH2YuQWkORNRTfXSCf08v9iowvo%2F0Akhswsb9gfNlScFQL%2Bc%2Bp%2BFUQiV5QW7qQyiq%2BJQ4CS399exvrZIKVVH3ZZNULw%3D%3D&p=mm_10009952_0_0",
            "price": "398.00",
            "promotion_price": "0.00",
            "liked": "0"
        }
    ]
}

效果图

由于服务器JSON数据是比较随意找的，所以内容不是很适合“微信”屏幕。

不要在意这些细节、、、

程序执行的第一页：

点击下一页，将会动态追加第二页的数据

由于服务器中只有两页数据，所以当再次点击“下一页”时，会显示“已是最末页”