ListView的分页加载与图文混排以及ExpandableListView的使用

一、ListView的滚动监听

setOnScrollListener 监听

          ListVIew滚动监听

lv.setOnScrollListener(new OnScrollListener() {

/**
* 当滚动状态发生改变时 调用此方法
* 参数1:当前的ListView
* 参数2:ListView 滚动状态
* scrollState:
* SCROLL_STATE_IDLE:停止滚动的状态     常量值  0
* SCROLL_STATE_TOUCH_SCROLL:正在滚动  手指还在屏幕上  常量值 1
*  SCROLL_STATE_FLING :代表滚动  形成惯性的动作   常量值 2
* 
*/
@Override
public void onScrollStateChanged(AbsListView view, int scrollState) {
// TODO Auto-generated method stub

Log.e("AAA", "=====onScrollStateChanged==="+scrollState);
//判断到了底部并且 滚动停止   加载更多
if(isLast&&scrollState ==SCROLL_STATE_IDLE){
Toast.makeText(MainActivity.this, "加载更多", Toast.LENGTH_SHORT).show();
}

}
/**
* 当前控件滚动时  调用此方法
* 参数1:当前的ListView
* 参数2:当前屏幕展示第一条能看到的item的下标
* 参数3:屏幕展示能看到item的条数
* 参数4:listVIew 总的item数
*/
@Override
public void onScroll(AbsListView view, int firstVisibleItem,
int visibleItemCount, int totalItemCount) {
// TODO Auto-generated method stub

Log.e("AAA", "===onScroll==firstVisibleItem"+firstVisibleItem+
"==visibleItemCount=="+visibleItemCount
+"==totalItemCount="+totalItemCount);
isLast = ((firstVisibleItem+visibleItemCount)==totalItemCount);
}
});

二、ListView的分页加载

1,接口是分页加载的 
2,利用滚动监听 进行分页加载

三、ListView的图文混排

概念:,先去下载字符串数据,将文本内容先展示出来,之后再下载图片

注意:图片异位

1,设置给控件一个图片
2,给该控件设置标记(以图片的请求地址为标记)

3,判断反悔的 图片地址和控件里的设置的标记是否是同一个             

//图片异位问题
		String imagePath= cookBook.getPic();
		//1,给控件设置一个图片
		viewHolder.iv.setImageResource(R.drawable.ic_launcher);
		//2,给控件绑定下载图片的地址
		viewHolder.iv.setTag(imagePath);
		
		//判断缓存中是否有图片 如果没有 下载
		if(!map.containsKey(imagePath)){
			//new Callback()使用回调接口获取数据
			new DownLoadImageAsyncTask(new Callback() {
				
				@Override
				public void sendResult(String imagPath, Bitmap bitmap) {
					// 3,判断请求的地址和绑定的地址是否是同一个地址  
					if(imagPath.equals(viewHolder.iv.getTag())){
						
						//缓存存图片
						map.put(imagPath, bitmap);
						
						viewHolder.iv.setImageBitmap(bitmap);
					}
					
				}
			}).execute(cookBook.getPic());
		}else{//如果有  直接从缓存中取
			viewHolder.iv.setImageBitmap(map.get(imagePath));
		}

四、ExpandableListView的使用

使用BaseExpandableListAdapter填充数据

有10个方法 分组4个  子元素4个   底层设计一个   子元素能否点击一个

4个监听

  分组的点击事件
          setOnGroupClickListener
  子元素的点击事件
          setOnChildClickListener
  分组展开的监听
          setOnGroupExpandListener
  分组折叠的监听
          setOnGroupCollapseListener

        ExpandableListView的10个方法 

 getGroupCount():获取分组个数
 getChildrenCount(int groupPosition):获取子元素的个数 
 getGroup(int groupPosition):获取当前下标分组的数据
 getChild(int groupPosition, int childPosition):获取分组下标groupPosition里的子元素下标为childPosition元素的
 getGroupId(int groupPosition):获取下标为groupPosition分组的id
 getChildId(int groupPosition, int childPosition):获取下标为groupPosition里的子元素下标为childPosition的id
 hasStableIds() :底层设计
 getGroupView(int groupPosition, boolean isExpanded,View convertView, ViewGroup parent):分组的视图对象
 getChildView(int groupPosition, int childPosition,boolean isLastChild, View convertView, ViewGroup parent):子元素的视图对象

 isChildSelectable(int groupPosition, int childPosition):子元素是否能被点击   false不能被点击   true可以被点击

有关ListView的分页加载与图文混排

MainActivity：

package com.qf.day09_listview_demo02;

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

import android.app.Activity;
import android.os.Bundle;
import android.view.View;
import android.widget.AbsListView;
import android.widget.Button;
import android.widget.AbsListView.OnScrollListener;
import android.widget.ListView;

import com.qf.day09_listview_demo02.adapter.MyAdapter;
import com.qf.day09_listview_demo02.asynctask.MyTask;
import com.qf.day09_listview_demo02.bean.CookBook;

public class MainActivity extends Activity {
	
	//请求地址
	private static  String path ="http://www.qubaobei.com/ios/cf/dish_list.php?stage_id=1&limit=20&page=";
	
	private ListView lv;
	private Button btnAddMore;
	
	private MyAdapter adapter;
	private MyTask myTask;
	private List totalList;//存总数据
	private int num = 1;//当前请求数据是第几页
	
	//是否到底部
	private boolean isLast =false;

	@Override
	protected void onCreate(Bundle savedInstanceState) {
		super.onCreate(savedInstanceState);
		setContentView(R.layout.activity_main);
		
		lv = (ListView) findViewById(R.id.lv);
		btnAddMore = (Button) findViewById(R.id.btn_addMore);
		
		adapter = new MyAdapter();
		totalList = new ArrayList();
		myTask = new MyTask(MainActivity.this, totalList, adapter, num, lv);
		myTask.execute(path+num);
		
		lv.setOnScrollListener(new OnScrollListener() {
			
			@Override
			public void onScrollStateChanged(AbsListView view, int scrollState) {
				// TODO Auto-generated method stub
				if(isLast&&scrollState ==SCROLL_STATE_IDLE){
					//到底部且滚动状态静止  
					btnAddMore.setVisibility(View.VISIBLE);
				}else{
					btnAddMore.setVisibility(View.GONE);
				}
				
			}
			
			@Override
			public void onScroll(AbsListView view, int firstVisibleItem,
					int visibleItemCount, int totalItemCount) {
				// 判断是否到底部
				isLast = ((firstVisibleItem+visibleItemCount)==totalItemCount);
			}
		});
		
	}

	//加载更多
	public void MyOnclickMore(View v){
		
		//当前页++
		num++;
		new MyTask(MainActivity.this, totalList, adapter, num, lv)
		.execute(path+num);
		btnAddMore.setVisibility(View.GONE);
		
	}
	
	public void MyOnclic(View v){
		//设置lv的位置
		lv.setSelection(0);
	}
}

HttpUtils:

package com.qf.day09_listview_demo02.utils;

import java.io.ByteArrayOutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.net.HttpURLConnection;
import java.net.URL;

public class HttpUtils1 {

	public static byte[] getHttpResult(String path) {
		
		ByteArrayOutputStream outputStream = null;
		
		HttpURLConnection connection = null;
		
		try {
			URL url = new URL(path);
			
			connection = (HttpURLConnection) url.openConnection();
			
			
			connection.setRequestMethod("GET");
			
			connection.setConnectTimeout(5000);
			
			connection.connect();
			
			 outputStream = new ByteArrayOutputStream();
			if (connection.getResponseCode()  == 200) {
				
				
				
				InputStream iStream = connection.getInputStream();
				
				byte[] buffer = new byte[1024];
				
				int len = 0;
				
				while ((len = iStream.read(buffer))!=-1) {
					
					outputStream.write(buffer,0,len);
					outputStream.flush();
				}
				
				return outputStream.toByteArray();
			}
		} catch (Exception e) {
			// TODO Auto-generated catch block
			e.printStackTrace();
		}
		finally {
			if (outputStream!=null) {
				
				try {
					outputStream.close();
				} catch (IOException e) {
					// TODO Auto-generated catch block
					e.printStackTrace();
				}
			}
			if (connection!=null) {
				
				connection.disconnect();
			}
		}
		
		
		
		
		return null;
	}

}

ParseJson:

package com.qf.day09_listview_demo02.utils;

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

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

import com.qf.day09_listview_demo02.bean.CookBook;

public class ParseJson {
	
	public static List parsonJson(String jsonStr){
		
		List data = new ArrayList();
		try {
			JSONObject jsonObject = new JSONObject(jsonStr);
			int ret = jsonObject.getInt("ret");
			if(ret==1){
				JSONArray jsonArray = jsonObject.getJSONArray("data");
				for(int i=0;i

Callback:

package com.qf.day09_listview_demo02.callback;

import android.graphics.Bitmap;
/**
 * 
 * 回调接口  A类从B类里获取数据(数据需要等待)
 *
 */
public interface Callback {
	//参数是我的A类想获取的数据
	public void sendResult(String imagPath,Bitmap bitmap);

}

CookBook:

package com.qf.day09_listview_demo02.bean;

public class CookBook {
//    "title": "油焖大虾",
//    "pic": "http://www.qubaobei.com/ios/cf/uploadfile/132/9/8289.jpg",
	
	private String title;
	private String pic;

	public CookBook(String title, String pic) {
		super();
		this.title = title;
		this.pic = pic;
	}
	public CookBook() {
		super();
		// TODO Auto-generated constructor stub
	}
	public String getTitle() {
		return title;
	}
	public void setTitle(String title) {
		this.title = title;
	}
	public String getPic() {
		return pic;
	}
	public void setPic(String pic) {
		this.pic = pic;
	}
	
	

}

DownLoaderImageAsyncTask:

package com.qf.day09_listview_demo02.asynctask;

import com.qf.day09_listview_demo02.callback.Callback;
import com.qf.day09_listview_demo02.utils.HttpUtils1;

import android.graphics.Bitmap;
import android.graphics.BitmapFactory;
import android.os.AsyncTask;
import android.widget.ImageView;

public class DownLoadImageAsyncTask extends AsyncTask{

//	private ImageView iv;
//	public DownLoadImageAsyncTask(ImageView iv){
//		this.iv = iv;
//	}
	
	private Callback callback;
	public DownLoadImageAsyncTask(Callback callback){
		this.callback = callback;
	}
	
	private String imagePath ="";
	@Override
	protected Bitmap doInBackground(String... params) {
		// TODO Auto-generated method stub
		imagePath = params[0];
		byte[] buffer = HttpUtils1.getHttpResult(imagePath);
		if(buffer!=null&&buffer.length>0){
			Bitmap bitmap = BitmapFactory.decodeByteArray(buffer, 0, buffer.length);
			
			return bitmap;
		}
		
		
		return null;
	}
	
	@Override
	protected void onPostExecute(Bitmap result) {
		// TODO Auto-generated method stub
		super.onPostExecute(result);
		//更新UI
		//数据被回调接口回调回来(鱼咬钩了)
		callback.sendResult(imagePath, result);
		
//		if(result!=null){
//			iv.setImageBitmap(result);
//		}
	}

}

MyTask :

package com.qf.day09_listview_demo02.asynctask;

import java.util.List;

import android.R;
import android.app.ProgressDialog;
import android.content.Context;
import android.os.AsyncTask;
import android.widget.ListView;
import android.widget.Toast;

import com.qf.day09_listview_demo02.adapter.MyAdapter;
import com.qf.day09_listview_demo02.bean.CookBook;
import com.qf.day09_listview_demo02.utils.HttpUtils1;
import com.qf.day09_listview_demo02.utils.ParseJson;

public class MyTask extends AsyncTask>{
	
	private Context context;
	private List totalList;
	private MyAdapter adapter;
	private int num;
	private ListView lv;
	
	private ProgressDialog progressDialog;
	
	public MyTask(Context context,List totalList,MyAdapter adapter,int num,ListView lv){
		this.context = context;
		this.totalList = totalList;
		this.adapter = adapter;
		this.num = num;
		this.lv = lv;
	}

	
	@Override
	protected void onPreExecute() {
		// TODO Auto-generated method stub
		super.onPreExecute();
		
		progressDialog = new ProgressDialog(context);
		progressDialog.setTitle("好吃的");
		progressDialog.setIcon(R.drawable.alert_dark_frame);
		progressDialog.setMessage("正在吃....");
		progressDialog.setCancelable(false);
		progressDialog.show();
	}
	@Override
	protected List doInBackground(String... params) {
		// TODO Auto-generated method stub
		//下载数据
		String path = params[0];
		byte[] buffer  = HttpUtils1.getHttpResult(path);
		String jsonStr = new String(buffer, 0, buffer.length);
		
		//解析数据
		return ParseJson.parsonJson(jsonStr);
	}
	
	@Override
	protected void onPostExecute(List result) {
		// TODO Auto-generated method stub
		super.onPostExecute(result);
		
		progressDialog.dismiss();
		//更新UI
		if(result!=null&&result.size()>0){
			//存总的数据 1,2,3...
			totalList.addAll(result);
			
			//判断是否是第一页  是第一页 使用setAdapter()将adapter设置给lv,
			//如果不是第一页刷新界面将所有数据展示到lvnotifyDataSetChanged();
			if(num ==1){
				adapter.setList(context, totalList);
				lv.setAdapter(adapter);
			}else{
				adapter.setList(context, totalList);
				adapter.notifyDataSetChanged();
				
			}

		}else{
			Toast.makeText(context, "网络异常, 请稍等..",Toast.LENGTH_SHORT).show();
		}
	}

}

MyAdapter :

package com.qf.day09_listview_demo02.adapter;

import java.util.HashMap;
import java.util.List;
import java.util.Map;

import com.qf.day09_listview_demo02.R;
import com.qf.day09_listview_demo02.asynctask.DownLoadImageAsyncTask;
import com.qf.day09_listview_demo02.bean.CookBook;
import com.qf.day09_listview_demo02.callback.Callback;

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

public class MyAdapter extends BaseAdapter {
	
	private Context context;
	private List data;
	
	//假设是 一个缓存器
	private Map map = new HashMap();
	//自定义一个方法传数据
	public void setList(Context context,List data){
		this.context = context;
		this.data = data;
	}

	@Override
	public int getCount() {
		// TODO Auto-generated method stub
		return data==null?0:data.size();
	}

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

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

	@Override
	public View getView(int position, View convertView, ViewGroup parent) {
		// TODO Auto-generated method stub
		final ViewHolder viewHolder ;
		if(convertView ==null){
			convertView = LayoutInflater.from(context)
					.inflate(R.layout.item, parent, false);
			viewHolder = new ViewHolder();
			viewHolder.iv = (ImageView) convertView.findViewById(R.id.iv_item);
			viewHolder.tv = (TextView) convertView.findViewById(R.id.tv_item);
		
			convertView.setTag(viewHolder);
		}else{
			viewHolder = (ViewHolder) convertView.getTag();
		}
		CookBook cookBook = data.get(position);
		viewHolder.tv.setText(cookBook.getTitle());
		//图片
//		DownLoadImageAsyncTask downLoadImageAsyncTask = 
//				new DownLoadImageAsyncTask(viewHolder.iv);
//		downLoadImageAsyncTask.execute(cookBook.getPic());
		
		
		//图片异位问题
		String imagePath= cookBook.getPic();
		//1,给控件设置一个图片
		viewHolder.iv.setImageResource(R.drawable.ic_launcher);
		//2,给控件绑定下载图片的地址
		viewHolder.iv.setTag(imagePath);
		
		//判断缓存中是否有图片 如果没有 下载
		if(!map.containsKey(imagePath)){
			//new Callback()使用回调接口获取数据
			new DownLoadImageAsyncTask(new Callback() {
				
				@Override
				public void sendResult(String imagPath, Bitmap bitmap) {
					// 3,判断请求的地址和绑定的地址是否是同一个地址  
					if(imagPath.equals(viewHolder.iv.getTag())){
						
						//缓存存图片
						map.put(imagPath, bitmap);
						
						viewHolder.iv.setImageBitmap(bitmap);
					}
					
				}
			}).execute(cookBook.getPic());
		}else{//如果有  直接从缓存中取
			viewHolder.iv.setImageBitmap(map.get(imagePath));
		}
		
		
		return convertView;
	}
	
	class  ViewHolder{
		ImageView iv;
		TextView tv;
	}

}