ListView点击底部按钮加载

移动开发 2018-05-14 23:06:22 阅读次数: 2
先上效果图：
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嘎、换个图片吧 这张好看些 哈哈
[img]

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工程结构图：
[img]

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AsyncImageLoader： 
package cn.anycall.testlist;

import java.lang.ref.SoftReference;
import java.util.HashMap;

import android.graphics.drawable.Drawable;
import android.os.Handler;
import android.os.Message;
import android.widget.ImageView;


public class AsyncImageLoader {

	 //SoftReference是软引用，是为了更好的为了系统回收变量
    private static HashMap<String, SoftReference<Drawable>> imageCache;
    
    static {
    	imageCache = new HashMap<String, SoftReference<Drawable>>();
    }
    
    
    public AsyncImageLoader() {
        
    }
    public Drawable loadDrawable(final String imageUrl,final ImageView imageView, final ImageCallback imageCallback){
        if (imageCache.containsKey(imageUrl)) {
            //从缓存中获取
            SoftReference<Drawable> softReference = imageCache.get(imageUrl);
            Drawable drawable = softReference.get();
            System.out.println("111111111111111111111111111111");
            if (drawable != null) {
            	 System.out.println("11111111111122222222211111111111111111");
                return drawable;
            }
        }
        final Handler handler = new Handler() {
            public void handleMessage(Message message) {
                imageCallback.imageLoaded((Drawable) message.obj, imageView,imageUrl);
            }
        };
        //建立新一个新的线程下载图片
        new Thread() {
            @Override
            public void run() {
            	System.out.println("11111111111133333333333211111111111111111");
                Drawable drawable = null;
				try {
					drawable = ImageUtil.geRoundDrawableFromUrl(imageUrl, 20);
				} catch (Exception e) {
					e.printStackTrace();
				}
                imageCache.put(imageUrl, new SoftReference<Drawable>(drawable));
                Message message = handler.obtainMessage(0, drawable);
                handler.sendMessage(message);
            }
        }.start();
        return null;
    }
    //回调接口
    public interface ImageCallback {
        public void imageLoaded(Drawable imageDrawable,ImageView imageView, String imageUrl);
    }
}


ImageUtil 
package cn.anycall.testlist;



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

import android.graphics.Bitmap;
import android.graphics.Bitmap.Config;
import android.graphics.BitmapFactory;
import android.graphics.Canvas;
import android.graphics.ColorMatrix;
import android.graphics.ColorMatrixColorFilter;
import android.graphics.Paint;
import android.graphics.PixelFormat;
import android.graphics.PorterDuff.Mode;
import android.graphics.PorterDuffXfermode;
import android.graphics.Rect;
import android.graphics.RectF;
import android.graphics.drawable.BitmapDrawable;
import android.graphics.drawable.Drawable;

public class ImageUtil {

	public static InputStream getRequest(String path) throws Exception {
		URL url = new URL(path);
		HttpURLConnection conn = (HttpURLConnection) url.openConnection();
		conn.setRequestMethod("GET");
		conn.setConnectTimeout(5000);
		if (conn.getResponseCode() == 200){
			return conn.getInputStream();
		}
		return null;
	}

	public static byte[] readInputStream(InputStream inStream) throws Exception {
		ByteArrayOutputStream outSteam = new ByteArrayOutputStream();
		byte[] buffer = new byte[4096];
		int len = 0;
		while ((len = inStream.read(buffer)) != -1) {
			outSteam.write(buffer, 0, len);
		}
		outSteam.close();
		inStream.close();
		return outSteam.toByteArray();
	}
	
	public static Drawable loadImageFromUrl(String url){
        URL m;
        InputStream i = null;
        try {
            m = new URL(url);
            i = (InputStream) m.getContent();
        } catch (MalformedURLException e1) {
            e1.printStackTrace();
        } catch (IOException e) {
            e.printStackTrace();
        }
        Drawable d = Drawable.createFromStream(i, "src");
        return d;
    }
	
	public static Drawable getDrawableFromUrl(String url) throws Exception{
		 return Drawable.createFromStream(getRequest(url),null);
	}
	
	public static Bitmap getBitmapFromUrl(String url) throws Exception{
		byte[] bytes = getBytesFromUrl(url);
		return byteToBitmap(bytes);
	}
	
	public static Bitmap getRoundBitmapFromUrl(String url,int pixels) throws Exception{
		byte[] bytes = getBytesFromUrl(url);
		Bitmap bitmap = byteToBitmap(bytes);
		return toRoundCorner(bitmap, pixels);
	} 
	
	public static Drawable geRoundDrawableFromUrl(String url,int pixels) throws Exception{
		byte[] bytes = getBytesFromUrl(url);
		BitmapDrawable bitmapDrawable = (BitmapDrawable)byteToDrawable(bytes);
		return toRoundCorner(bitmapDrawable, pixels);
	} 
	
	public static byte[] getBytesFromUrl(String url) throws Exception{
		 return readInputStream(getRequest(url));
	}
	
	public static Bitmap byteToBitmap(byte[] byteArray){
		if(byteArray.length!=0){ 
            return BitmapFactory.decodeByteArray(byteArray, 0, byteArray.length); 
        } 
        else { 
            return null; 
        }  
	}
	
	public static Drawable byteToDrawable(byte[] byteArray){
		ByteArrayInputStream ins = new ByteArrayInputStream(byteArray);
		return Drawable.createFromStream(ins, null);
	}
	
	public static byte[] Bitmap2Bytes(Bitmap bm){ 
		ByteArrayOutputStream baos = new ByteArrayOutputStream();
		bm.compress(Bitmap.CompressFormat.PNG, 100, baos);
		return baos.toByteArray();
	}
	
	public static Bitmap drawableToBitmap(Drawable drawable) {

		Bitmap bitmap = Bitmap
				.createBitmap(
						drawable.getIntrinsicWidth(),
						drawable.getIntrinsicHeight(),
						drawable.getOpacity() != PixelFormat.OPAQUE ? Bitmap.Config.ARGB_8888
								: Bitmap.Config.RGB_565);
		Canvas canvas = new Canvas(bitmap);
		drawable.setBounds(0, 0, drawable.getIntrinsicWidth(),
				drawable.getIntrinsicHeight());
		drawable.draw(canvas);
		return bitmap;
	}
	
	 	/**
	      * 图片去色,返回灰度图片
	      * @param bmpOriginal 传入的图片
	     * @return 去色后的图片
	     */
	    public static Bitmap toGrayscale(Bitmap bmpOriginal) {
	        int width, height;
	        height = bmpOriginal.getHeight();
	        width = bmpOriginal.getWidth();    
	
	        Bitmap bmpGrayscale = Bitmap.createBitmap(width, height, Bitmap.Config.RGB_565);
	        Canvas c = new Canvas(bmpGrayscale);
	        Paint paint = new Paint();
	        ColorMatrix cm = new ColorMatrix();
	        cm.setSaturation(0);
	        ColorMatrixColorFilter f = new ColorMatrixColorFilter(cm);
	        paint.setColorFilter(f);
	        c.drawBitmap(bmpOriginal, 0, 0, paint);
	        return bmpGrayscale;
	    }
	    
	    
	    /**
	     * 去色同时加圆角
	     * @param bmpOriginal 原图
	     * @param pixels 圆角弧度
	     * @return 修改后的图片
	     */
	    public static Bitmap toGrayscale(Bitmap bmpOriginal, int pixels) {
	        return toRoundCorner(toGrayscale(bmpOriginal), pixels);
	    }
	    
	    /**
	     * 把图片变成圆角
	     * @param bitmap 需要修改的图片
	     * @param pixels 圆角的弧度
	     * @return 圆角图片
	     */
	    public static Bitmap toRoundCorner(Bitmap bitmap, int pixels) {
	
	        Bitmap output = Bitmap.createBitmap(bitmap.getWidth(), bitmap.getHeight(), Config.ARGB_8888);
	        Canvas canvas = new Canvas(output);
	
	        final int color = 0xff424242;
	        final Paint paint = new Paint();
	        final Rect rect = new Rect(0, 0, bitmap.getWidth(), bitmap.getHeight());
	        final RectF rectF = new RectF(rect);
	        final float roundPx = pixels;
	
	        paint.setAntiAlias(true);
	        canvas.drawARGB(0, 0, 0, 0);
	        paint.setColor(color);
	        canvas.drawRoundRect(rectF, roundPx, roundPx, paint);
	
	        paint.setXfermode(new PorterDuffXfermode(Mode.SRC_IN));
	        canvas.drawBitmap(bitmap, rect, rect, paint);
	
	        return output;
	    }
	
	    
	   /**
	     * 使圆角功能支持BitampDrawable
	     * @param bitmapDrawable 
	     * @param pixels 
	     * @return
	     */
	    public static BitmapDrawable toRoundCorner(BitmapDrawable bitmapDrawable, int pixels) {
	        Bitmap bitmap = bitmapDrawable.getBitmap();
	        bitmapDrawable = new BitmapDrawable(toRoundCorner(bitmap, pixels));
	        return bitmapDrawable;
	    }
}


TestListViewActivity 
package cn.anycall.testlist;


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

import android.app.ListActivity;
import android.content.Context;
import android.graphics.drawable.Drawable;
import android.os.Bundle;
import android.os.Handler;
import android.os.Looper;
import android.os.Message;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.BaseAdapter;
import android.widget.Button;
import android.widget.ImageView;
import android.widget.LinearLayout;
import android.widget.ListView;
import android.widget.TextView;
import cn.anycall.testlist.AsyncImageLoader.ImageCallback;

public class TestListViewActivity extends ListActivity {

	private List<Map<String, Object>> mData = new ArrayList<Map<String, Object>>(); 
	public final class ViewHolder {
		public ImageView img;
		public TextView title;
		public TextView info;
	}
     
	public List<HashMap<String, String>> data = new ArrayList<HashMap<String, String>>();
	public int a = 0;
	public Button button;
	public LinearLayout layloading;
	public MyHandler myHandler;
	public  MyAdapter adapter ; 
	private AsyncImageLoader asyncImageLoader = new AsyncImageLoader();
	
	
	
	public void onCreate(Bundle savedInstanceState) {
		super.onCreate(savedInstanceState);
		setContentView(R.layout.main);
		
		myHandler = new MyHandler();
		
		
		ListView listView = getListView();// 得到ListView
		LinearLayout listFooter = (LinearLayout) LayoutInflater.from(this)
				.inflate(R.layout.main_foot, null);
		listView.addFooterView(listFooter);// 添加FooterView
		button = (Button) findViewById(R.id.more);
		layloading = (LinearLayout) findViewById(R.id.loading);
		button.setVisibility(View.VISIBLE);
		layloading.setVisibility(View.GONE);
		adapter =  new MyAdapter(this); 
		setListAdapter(adapter);
		button.setOnClickListener(new Button.OnClickListener() {
			public void onClick(View v) {
				//起一个线程更新后台数据
				MyThread m = new MyThread();
				new Thread(m).start();
				
			}
		});
		for(int i=0;i<20;i++){
			a++;
			Map<String, Object> map = new HashMap<String, Object>(); 
			map.put("img", R.drawable.icon); 
			 map.put("title", "G"+a);  
			 map.put("info", "google"+a);  
			 mData.add(map); 
		}
	}
	public class MyAdapter extends BaseAdapter {
		private LayoutInflater mInflater;
		
		public MyAdapter(Context context) {
			this.mInflater = LayoutInflater.from(context);
		}
		public int getCount() {
			return mData.size();
		}
		public Object getItem(int arg0) {
			return null;
		}
		public long getItemId(int arg0) {
			return 0;
		}
		public View getView(int position, View convertView, ViewGroup parent) {
			
			ViewHolder holder = null;
			if (convertView == null) {
				holder = new ViewHolder();
				convertView = mInflater.inflate(R.layout.main_list, null);
				
				holder.img = (ImageView)convertView.findViewById(R.id.img); 
				holder.title = (TextView) convertView
						.findViewById(R.id.listtitle);
				holder.info = (TextView) convertView
						.findViewById(R.id.listtext);
				convertView.setTag(holder);
			} else {
				holder = (ViewHolder) convertView.getTag();
			}
			
			
			
			//holder.img.setBackgroundResource((Integer)mData.get(position).get("img")); 
			holder.title.setText((String) mData.get(position).get("title"));
			holder.info.setText((String) mData.get(position).get("info"));
			

			//异步加载图片
			Drawable cachedImage = asyncImageLoader.loadDrawable("http://t02.pic.sogou.com/eb95234678ecb28d.jpg",holder.img, new ImageCallback(){
                
                public void imageLoaded(Drawable imageDrawable,ImageView imageView, String imageUrl) {
                    imageView.setImageDrawable(imageDrawable);
                }
            });
			System.out.println(cachedImage);
			if (cachedImage == null) {
				holder.img.setImageResource(R.drawable.icon);
			} else {
				holder.img.setImageDrawable(cachedImage);
			}
			
			
			
			
			
			return convertView;

		}

	}
	
	
	
	//更新后台数据
	class MyThread implements Runnable {
		public void run() {

			
			String msglist = "1";
			Message msg = new Message();
			Bundle b = new Bundle();// 存放数据
			b.putString("rmsg", msglist);
			msg.setData(b);
			TestListViewActivity.this.myHandler.sendMessage(msg); // 向Handler发送消息,更新UI
			
			try {
				Thread.sleep(5000);
			} catch (InterruptedException e) {
				// TODO Auto-generated catch block
				e.printStackTrace();
			}
			
			
			 msglist = "2";
			 msg = new Message();
			 b = new Bundle();// 存放数据
			b.putString("rmsg", msglist);
			msg.setData(b);
			TestListViewActivity.this.myHandler.sendMessage(msg); // 向Handler发送消息,更新UI
			

		}
	}
	
	
	
	class MyHandler extends Handler {
		public MyHandler() {
		}

		public MyHandler(Looper L) {
			super(L);
		}

		// 子类必须重写此方法,接受数据
		@Override
		public void handleMessage(Message msg) {
			// TODO Auto-generated method stub
			super.handleMessage(msg);
			// 此处可以更新UI
			Bundle b = msg.getData();
			String rmsg = b.getString("rmsg");
			if ("1".equals(rmsg)) {
				// do nothing
				button.setVisibility(View.GONE);
				layloading.setVisibility(View.VISIBLE);
			
			}else if ("2".equals(rmsg)) { 
				
				try {
					Thread.sleep(3000);
				} catch (InterruptedException e) {
					// TODO Auto-generated catch block
					e.printStackTrace();
				}
				for(int i=0;i<20;i++){
					a++;
					Map<String, Object> map = new HashMap<String, Object>(); 
					map.put("img", R.drawable.icon); 
					 map.put("title", "G"+a);  
					 map.put("info", "google"+a);  
					 mData.add(map); 
				}
				button.setVisibility(View.VISIBLE);
				layloading.setVisibility(View.GONE);
				adapter.notifyDataSetChanged();
			}

		}
	}

}



main_foot.xml 
<?xml version="1.0" encoding="UTF-8"?>
<LinearLayout android:layout_width="fill_parent"
	android:layout_height="wrap_content" android:minHeight="?android:listPreferredItemHeight"
	xmlns:android="http://schemas.android.com/apk/res/android"
	android:background="#FFFFFF"
	>

	<Button android:textSize="16.0sp" android:textColor="#ff545454"
	android:gravity="center" android:id="@+id/more" android:layout_width="fill_parent"
	android:layout_height="fill_parent" android:text="加载下20条" />

	<LinearLayout android:gravity="center"
		android:layout_gravity="center" android:orientation="horizontal"
		android:id="@+id/loading" android:layout_width="fill_parent"
		android:layout_height="fill_parent">

		<ProgressBar android:layout_gravity="center_vertical"
			android:id="@+id/footprogress" android:layout_width="wrap_content"
			android:layout_height="wrap_content" android:indeterminateBehavior="repeat"
			style="?android:progressBarStyleSmallInverse" />

		<TextView android:textColor="#ff000000" android:gravity="left|center"
			android:padding="3.0px" android:layout_width="wrap_content"
			android:layout_height="wrap_content" android:text="加载中" />
   
	</LinearLayout>

</LinearLayout>



main_list.xml 
<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout 
	android:id="@+id/RelativeLayout01" 
	android:layout_width="fill_parent" 
	xmlns:android="http://schemas.android.com/apk/res/android" 
	android:layout_height="wrap_content" 
	android:paddingBottom="4dip" 
	android:paddingLeft="12dip"
	android:paddingRight="12dip"
	android:background="#FFFFFF"
	>
<ImageView 
	android:paddingTop="12dip"
	android:layout_alignParentLeft="true"
	 android:layout_alignParentTop="true"
	android:layout_width="100dp" 
	android:layout_height="100dp" 
	android:id="@+id/img"
	/> 
<TextView 
    android:text="TextView01" 
    android:layout_height="wrap_content" 
    android:textSize="20dip" 
    android:layout_width="fill_parent" 
    android:id="@+id/listtitle"
    android:layout_toRightOf="@id/img"
    />
<TextView 
	android:text="TextView02" 
	android:layout_height="wrap_content" 
	android:layout_width="fill_parent" 
	android:id="@+id/listtext"
	android:layout_toRightOf="@id/img"
    android:layout_below="@id/listtitle"
	/>
</RelativeLayout>


main.xml 
<?xml version="1.0" encoding="utf-8"?>  
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"  
        android:orientation="vertical"  
        android:layout_width="fill_parent"  
        android:layout_height="wrap_content"  
        
        
        >  
 
    <ListView android:id="@id/android:list"  
              android:layout_width="fill_parent"  
              android:layout_height="wrap_content"  
              android:drawSelectorOnTop="false"
              android:footerDividersEnabled="false"
              android:scrollbars="vertical"
              />  
    
</LinearLayout>



AndroidManifest.xml 
<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
      package="cn.anycall.testlist"
      android:versionCode="1"
      android:versionName="1.0">
    <uses-sdk android:minSdkVersion="4" />

    <application android:icon="@drawable/icon" android:label="@string/app_name">
        <activity android:name=".TestListViewActivity"
                  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>
    <!-- 允许应用打开网络套接口 -->
	<uses-permission android:name="android.permission.INTERNET"></uses-permission>
</manifest>

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