Android圖片異步加載

import java.io.File;
import java.io.FileNotFoundException;
import java.io.FileOutputStream;
import java.io.InputStream;
import java.io.OutputStream;
import java.lang.ref.SoftReference;
import java.net.HttpURLConnection;
import java.net.URL;
import java.util.HashMap;
import java.util.Map;

import com.mosjoy.ad.MosJoyAdApplication;
import com.mosjoy.ad.R;
import com.mosjoy.ad.utils.FileCache;
import com.mosjoy.ad.utils.ImageCache;
import com.mosjoy.ad.utils.Utils;
import android.content.Context;
import android.graphics.Bitmap;
import android.graphics.BitmapFactory;
import android.os.AsyncTask;
import android.os.Environment;
import android.os.StatFs;
import android.util.AttributeSet;
import android.util.Log;
import android.view.View;
import android.widget.ImageView;
/**

圖片異步加載工具類
@author zouyb
/
public class RemoteImageView extends ImageView {
/**

下載失敗最大重復次數
*/
private static int MAX_FAILURES = 3;
/**

下載圖片網址
*/
private String mUrl;
/**

當前下載成功圖片網址
*/
private String mCurrentlyGrabbedUrl;
/**

下載失敗次數
*/
private int mFailure;
/**

默認圖片資源id
*/
private Integer mDefaultImage;
/**

上下文
*/
private Context mContext;
/**

文件操作
*/
private FileCache fileCache;
private final static int MB = 1048576;
//圖片寬度
private int pwidth=-1;
//圖片高度
private int pheight=-1;
//是否顯示默認圖片
private boolean isShowDefault=false;
public RemoteImageView(Context context, AttributeSet attrs, int defStyle) {
super(context, attrs, defStyle);
mContext = context;
init();
}
public RemoteImageView(Context context, AttributeSet attrs) {
super(context, attrs);
mContext = context;
init();
}
public RemoteImageView(Context context) {
super(context);
mContext = context;
init();
}
/**

Sharable code between constructors
*/
private void init() {
 fileCache = new FileCache(mContext);
}
public void setImageUrl(String url) {
 System.out.println("width="+pwidth+",height="+pheight);
 System.out.println("url="+url);
 if(("").equals(url) || url == null||url.contains("null")){

 if(isShowDefault){
     setImageResource(R.drawable.default_image);
 }else{
     setVisibility(View.GONE);
 }
 return;

}
 setVisibility(View.VISIBLE);
 url = url.replace("\", "/");
 mUrl = url;
 MosJoyAdApplication instance = MosJoyAdApplication.getInstance();
 ImageCache imageCache = instance.getImageCache();
 if (imageCache.isCached(mUrl)) {

 // 圖片在緩存中
 this.setImageBitmap(imageCache.get(mUrl).get());
 Log.e(MosJoyAdApplication.TAG, "從內存加載圖片 " + url);

} else {

 File f = new File(mUrl);
 Bitmap b = decodeFile(f);
 if(b != null){
     //從內存卡加載
     this.setImageBitmap(b);
     imageCache.put(mUrl,new SoftReference<Bitmap>(b));
     Log.e(MosJoyAdApplication.TAG, "從本地加載圖片 " + url);
 }else{
     //防止重復下載
     //if(YYQMusicApplication.getInstance().getDownLoadImageList().contains(mUrl)) return;
     //下載圖片
     Log.e(MosJoyAdApplication.TAG, "從網絡下載圖片 " + url);
     Map<String,Object> map = new HashMap<String,Object>();
     map.put("url", mUrl);
     map.put("file", f);
     try{
         new DownloadTask().execute(map);
     }catch(Exception e){}
 }

}
}
public void setDefaultImage(Integer resid) {
 mDefaultImage = resid;
}
private void loadDefaultImage() {
 if (mDefaultImage != null)

 setImageResource(mDefaultImage);

}
class DownloadTask extends AsyncTask<Map<String, Object>,Void, Bitmap>{
private String mTaskUrl;
 private File f;
@Override
 public void onPreExecute() {

 loadDefaultImage();
 super.onPreExecute();

}
@Override
 protected Bitmap doInBackground(Map<String, Object>... params) {

 mTaskUrl = params[0].get("url").toString();
 //YYQMusicApplication.getInstance().getDownLoadImageList().add(mTaskUrl);
 f = (File) params[0].get("file");
 try {
     Bitmap bitmap=null;
     URL imageUrl = new URL(mTaskUrl);
     HttpURLConnection conn = (HttpURLConnection)imageUrl.openConnection();
     conn.setConnectTimeout(30000);
     conn.setReadTimeout(30000);
     InputStream is=conn.getInputStream();
     OutputStream os = new FileOutputStream(f);
     Utils.CopyStream(is, os);
     os.close();
     bitmap = decodeFile(f);
     return bitmap;
 } catch(FileNotFoundException fileNotFoundException){
     fileNotFoundException.printStackTrace();
     return null;
 }
 catch (Exception ex){
    ex.printStackTrace();
 }
 return null;

}
@Override
 public void onPostExecute(Bitmap b) {

 super.onPostExecute(b);
 if(b == null){
     //下載失敗，繼續下載
     //RemoteImageView.this.setImageUrl(mTaskUrl);
 }else{
     //下載成功
     MosJoyAdApplication.getInstance().getImageCache().put(mTaskUrl, new SoftReference<Bitmap>(b));
     RemoteImageView.this.setImageBitmap(b);            
     mCurrentlyGrabbedUrl = mTaskUrl;               
 }

}
};
/**

解碼圖片
@param f
@return
*/
private Bitmap decodeFile(File f) {
 if(!f.exists()){

 return null;

}
 if(pwidth>0&&pheight>0){

 System.out.println("加載縮略圖");
 return decodeFile(f, pwidth, pheight);

}
 try {

 BitmapFactory.Options options = new BitmapFactory.Options();
 options.inSampleSize = 1;
 return BitmapFactory.decodeFile(f.getAbsolutePath(), options);

} catch (Exception e) {
 }
 return null;
}
private int freeSpaceOnSd() {
 StatFs stat = new StatFs(Environment.getExternalStorageDirectory()

     .getPath());

double sdFreeMB = ((double) stat.getAvailableBlocks() * (double) stat

     .getBlockSize()) / MB;


return (int) sdFreeMB;
}
private Bitmap decodeFile(File file,int width,int height){
 BitmapFactory.Options options=new BitmapFactory.Options();
 int scale=1;
 if(width>0||height>0){

 //設置次參數為true，解碼時返回的Bitmap為空，不分配內存
 options.inJustDecodeBounds=true;
 BitmapFactory.decodeFile(file.getAbsolutePath(), options);
 //得到原始圖片的寬度和高度
 int outWidth=options.outWidth;
 int outHeight=options.outHeight;
 while(true){
     if((width>0&&outWidth/2<width)||(height>0&&outHeight/2<height)){
         break;
     }
     outWidth/=2;
     outHeight/=2;
     scale*=2;
 }

}
 //縮放比例為1/scale
 options.inSampleSize=scale;
 options.inJustDecodeBounds=false;
 //處理之后，加載進內存的就是圖片的縮略圖
 return BitmapFactory.decodeFile(file.getAbsolutePath(), options);
}
public void setPwidth(int pwidth) {
 this.pwidth = pwidth;
}
public void setPheight(int pheight) {
 this.pheight = pheight;
}
public void setShowDefault(boolean isShowDefault) {
 this.isShowDefault = isShowDefault;
}




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