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GridView异步刷新图片(网络中取图片)

2018年07月13日 ⁄ 综合 ⁄ 共 7282字 ⁄ 字号 小 中 大 ⁄ 评论关闭

图片加载过程中



图片加载结束

MainActivity.java

package com.entel.research;

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

import android.app.Activity;
import android.os.Bundle;
import android.widget.GridView;

public class MainActivity extends Activity {
    /** Called when the activity is first created. */
    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.main);
        GridView gridView = (GridView) findViewById(R.id.gridview);
        List<ImageAndText> list = new ArrayList<ImageAndText>();
        list.add(new ImageAndText("http://www.qqtheme.com/touxiang/UploadPic/2009-11/2009119101320367.gif", "灰太狼"));
        list.add(new ImageAndText("http://www.qqtai.com/qqhead/UploadFiles_3178/200809/2008092004121344.jpg", "小米"));
        list.add(new ImageAndText("http://i2.itc.cn/20111107/965_cbc1dac4_dcb2_1638_c3b1_d3d57d816c78_1.jpg", "谷歌"));
        list.add(new ImageAndText("http://www.baidu.com/img/baidu_sylogo1.gif", "百度"));
        list.add(new ImageAndText("http://i1.itc.cn/20111107/70b_3bbc312b_a7d6_24bf_5e85_f8f181f25d0a_1.jpg", "灰太狼"));
        list.add(new ImageAndText("http://i1.itc.cn/20111107/2b7c_ca94ecbd_c09e_1d97_1de1_f14109b686e1_1.jpg", "小米"));
        list.add(new ImageAndText("http://i3.itc.cn/20111107/3ab_8ac7b5d8_442b_d8fe_a4fd_62df63bd0a54_1.jpg", "灰太狼"));
        list.add(new ImageAndText("http://i3.itc.cn/20111107/29e_9251f52f_9701_341e_672c_5caa426c8501_1.jpg", "小米"));
        list.add(new ImageAndText("http://i2.itc.cn/20111107/focus_5a_c1ecc3bf_05db_49ff_b005_37a10bc87e86_0.jpg", "灰太狼"));
        list.add(new ImageAndText("http://i2.itc.cn/20111107/616_fd2be256_04f2_02d5_cf93_31c9028f65b2_1.jpg", "小米"));
        list.add(new ImageAndText("http://www.qqtheme.com/touxiang/UploadPic/2009-11/2009119101320367.gif", "灰太狼"));
        list.add(new ImageAndText("http://i2.itc.cn/20111107/22d_4642f7a7_4676_a98f_7d72_5977d0980cac_1.jpg", "小米"));
        gridView.setAdapter(new ImageAndTextListAdapter(this, list, gridView));
    }
}

ImageAndTextListAdapter.java 

package com.entel.research;

import java.util.List;

import android.app.Activity;
import android.graphics.drawable.Drawable;
import android.util.Log;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.ArrayAdapter;
import android.widget.GridView;
import android.widget.ImageView;
import android.widget.TextView;

import com.entel.research.AsyncImageLoader.ImageCallback;

public class ImageAndTextListAdapter extends ArrayAdapter<ImageAndText>
{
	private GridView gridView;
	private AsyncImageLoader asyncImageLoader;

	public ImageAndTextListAdapter(Activity activity,
			List<ImageAndText> imageAndTexts, GridView gridView)
	{
		super(activity, 0, imageAndTexts);
		this.gridView = gridView;
		asyncImageLoader = new AsyncImageLoader();
	}

	public View getView(int position, View convertView, ViewGroup parent)
	{
		Activity activity = (Activity) getContext();

		// Inflate the views from XML
		View rowView = convertView;
		ViewCache viewCache;
		if (rowView == null)
		{
			LayoutInflater inflater = activity.getLayoutInflater();
			rowView = inflater.inflate(R.layout.imageitem, null);
			viewCache = new ViewCache(rowView);
			rowView.setTag(viewCache);
		}
		else
		{
			viewCache = (ViewCache) rowView.getTag();
		}
		ImageAndText imageAndText = getItem(position);

		// Load the image and set it on the ImageView
		String imageUrl = imageAndText.getImageUrl();
		ImageView imageView = viewCache.getImageView();
		imageView.setTag(imageUrl);
		Drawable cachedImage = asyncImageLoader.loadDrawable(imageUrl,
				new ImageCallback()
				{
					public void imageLoaded(Drawable imageDrawable,
							String imageUrl)
					{
						ImageView imageViewByTag = (ImageView) gridView
								.findViewWithTag(imageUrl);
						if (imageViewByTag != null)
						{
							imageViewByTag.setImageDrawable(imageDrawable);
						}
					}
				});
		if (cachedImage == null)
		{
			imageView.setImageResource(R.drawable.icon);
			Log.e("Adapter", "null");
		}
		else
		{
			imageView.setImageDrawable(cachedImage);
		}
		// Set the text on the TextView
		TextView textView = viewCache.getTextView();
		textView.setText(imageAndText.getText());
		return rowView;
	}
}

ImageAndText.java 

package com.entel.research;

public class ImageAndText
{
	private String imageUrl;
	private String text;

	public ImageAndText(String imageUrl, String text)
	{
		this.imageUrl = imageUrl;
		this.text = text;
	}

	public String getImageUrl()
	{
		return imageUrl;
	}

	public String getText()
	{
		return text;
	}
}

ViewCache.java 

package com.entel.research;

import android.view.View;
import android.widget.ImageView;
import android.widget.TextView;

public class ViewCache
{
	private View baseView;
	private TextView textView;
	private ImageView imageView;

	public ViewCache(View baseView)
	{
		this.baseView = baseView;
	}

	public TextView getTextView()
	{
		if (textView == null)
		{
			textView = (TextView) baseView.findViewById(R.id.ItemText);
		}
		return textView;
	}

	public ImageView getImageView()
	{
		if (imageView == null)
		{
			imageView = (ImageView) baseView.findViewById(R.id.ItemImage);
		}
		return imageView;
	}
}

AsyncImageLoader.java 

package com.entel.research;

import java.io.IOException;
import java.io.InputStream;
import java.lang.ref.SoftReference;
import java.net.MalformedURLException;
import java.net.URL;
import java.util.HashMap;
import java.util.Random;

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

public class AsyncImageLoader
{
	private HashMap<String, SoftReference<Drawable>> imageCache;

	public AsyncImageLoader()
	{
		imageCache = new HashMap<String, SoftReference<Drawable>>();
	}

	public Drawable loadDrawable(final String imageUrl,
			final ImageCallback imageCallback)
	{
		if (imageCache.containsKey(imageUrl))
		{
			SoftReference<Drawable> softReference = imageCache.get(imageUrl);
			Drawable drawable = softReference.get();
			if (drawable != null)
			{
				return drawable;
			}
		}
		final Handler handler = new Handler()
		{
			public void handleMessage(Message message)
			{
				imageCallback.imageLoaded((Drawable) message.obj, imageUrl);
			}
		};
		new Thread()
		{
			@Override
			public void run()
			{
				Drawable drawable = loadImageFromUrl(imageUrl);
				imageCache.put(imageUrl, new SoftReference<Drawable>(drawable));
				Message message = handler.obtainMessage(0, drawable);
				try
				{
					Thread.sleep(new Random().nextInt(3000));
				}
				catch (Exception e)
				{
					e.printStackTrace();
				}
				handler.sendMessage(message);
			}
		}.start();
		return null;
	}

	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 interface ImageCallback
	{
		public void imageLoaded(Drawable imageDrawable, String imageUrl);
	}
}

main.xml 

<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout
	xmlns:android="http://schemas.android.com/apk/res/android"
	android:layout_height="wrap_content"
	android:layout_width="fill_parent">

	<TextView android:id="@+id/text"
		android:layout_height="wrap_content"
		android:layout_width="fill_parent">
	</TextView>
	<GridView android:id="@+id/gridview"
		android:layout_width="fill_parent" android:layout_height="fill_parent"
		android:numColumns="auto_fit" android:verticalSpacing="10dp"
		android:horizontalSpacing="10dp" android:columnWidth="70dp"
		android:stretchMode="columnWidth" android:gravity="center" android:layout_below="@id/text"/>
</RelativeLayout>

imageitem.xml

<?xml version="1.0" encoding="utf-8"?>  
<RelativeLayout    
         xmlns:android="http://schemas.android.com/apk/res/android"    
         android:layout_height="wrap_content"    
         android:paddingBottom="4dip" android:layout_width="fill_parent">  
         <ImageView    
               android:layout_height="wrap_content"    
               android:id="@+id/ItemImage"    
               android:layout_width="wrap_content"    
               android:layout_centerHorizontal="true">    
         </ImageView>  
         <TextView    
               android:layout_width="wrap_content"    
               android:layout_below="@+id/ItemImage"    
               android:layout_height="wrap_content"    
               android:layout_centerHorizontal="true"    
               android:id="@+id/ItemText">  
         </TextView>  
</RelativeLayout>

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