GridView 异步加载SD卡图片

用GridView实现异步加载SD卡图片，图片无错位。

初学安卓，遇到了很多问题，在网上得到了很多帮助，谢谢各位好心人。把代码发下来与大家分享，有啥问题欢迎讨论~

import java.util.ArrayList;import java.util.List;import android.app.Activity;import android.app.ProgressDialog;import android.content.Intent;import android.os.Bundle;import android.os.Environment;import android.util.DisplayMetrics;import android.util.Log;import android.view.Menu;import android.widget.GridView;public class MainActivity extends Activity {private String mRootPath = Environment.getExternalStorageDirectory().getPath()+"/"+"dcim"+"/"; private Intent mIntent;private ProgressDialog m_ProgressDialog = null;    final int MENU_ONE = Menu.FIRST;    final int MENU_TWO = Menu.FIRST + 1;    public static List<String> lstFilePath = null;    /** 清除LST */public static void unloadLstFilePath() {   if (lstFilePath != null) {     lstFilePath.clear();     lstFilePath = null;   } } private void getValues() {   if (lstFilePath == null) {     Log.v("***InLstFilePath***", "OK");     lstFilePath = new ArrayList<String>();     lstFilePath.clear();     new FileTool().ListFiles(mRootPath, lstFilePath);     String addPath = this.getFilesDir().getPath();     new FileTool().ListFiles(addPath, lstFilePath);   } else {     try {       Thread.sleep(500);     } catch (InterruptedException e) {       e.printStackTrace();     }     ;   }   runOnUiThread(returnRes); }    /** Called when the activity is first created. */    @Override    public void onCreate(Bundle savedInstanceState) {        super.onCreate(savedInstanceState);        setContentView(R.layout.activity_main);                mIntent = this.getIntent();                Runnable viewOrders = new Runnable() {            public void run() { getValues();  }        };                  Thread thread = new Thread(null, viewOrders, "MagentoBackground");        thread.start();        m_ProgressDialog = ProgressDialog.show( MainActivity.this, "请稍后", "数据读取中...", true);                             }                        private Runnable returnRes = new Runnable() {        public void run() {          DisplayMetrics metric = new DisplayMetrics();             getWindowManager().getDefaultDisplay().getMetrics(metric);             int columnWidth = metric.widthPixels/4;     // 屏幕宽度（像素）          GridView gridview = (GridView) findViewById(R.id.gv_photolist);          GridViewAdapter iadapter = new GridViewAdapter(MainActivity.this, lstFilePath);             gridview.setAdapter(iadapter);          gridview.setColumnWidth(columnWidth);                              m_ProgressDialog.dismiss();        }      };}

import java.util.List;import com.yjx.yibu.AsyncImageLoader3.ImageCallback;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;public class GridViewAdapter extends BaseAdapter {private LayoutInflater layoutInflater;private List<String> imgUrls;private AsyncImageLoader3 imageLoader = new AsyncImageLoader3();public GridViewAdapter(Context context, List<String> imgUrls) {layoutInflater = LayoutInflater.from(context);this.imgUrls = imgUrls;}@Overridepublic int getCount() {return imgUrls.size();}@Overridepublic Object getItem(int position) {return position;}@Overridepublic long getItemId(int position) {return position;}@Overridepublic View getView(int position, View convertView, ViewGroup parent) {final ViewHolder viewHolder;String path = imgUrls.get(position);if(convertView==null) {viewHolder = new ViewHolder();convertView = layoutInflater.inflate(R.layout.photolist_item, null);viewHolder.ivImage = (ImageView)convertView.findViewById(R.id.iv_photoicon_photolist_item);viewHolder.ivImage.setScaleType(ImageView.ScaleType.CENTER);convertView.setTag(viewHolder);       }else {viewHolder = (ViewHolder)convertView.getTag();}         Bitmap cachedImage = imageLoader.loadBitmap(path,viewHolder.ivImage, new ImageCallback() {     public void imageLoaded(Bitmap imageBitmap,ImageView image,String imageUrl) { viewHolder.ivImage.setImageBitmap(imageBitmap);}});                 if(cachedImage!= null) {        viewHolder.ivImage.setImageBitmap(cachedImage);           }else if(cachedImage == null) {viewHolder.ivImage.setImageResource(R.drawable.icon);        }return convertView;}class ViewHolder {/*** 图片*/public ImageView ivImage;/*** 图片信息*///public TextView tvInfo;}}

import java.lang.ref.SoftReference;import java.util.HashMap;import java.util.Map;import java.util.concurrent.ExecutorService;import java.util.concurrent.Executors;import android.graphics.Bitmap;import android.os.Handler;import android.widget.ImageView;public class AsyncImageLoader3 {// 为了加快速度，在内存中开启缓存（主要应用于重复图片较多时，或者同一个图片要多次被访问，比如在ListView时来回滚动）public Map<String, SoftReference<Bitmap>> imageCache = new HashMap<String, SoftReference<Bitmap>>();private ExecutorService executorService = Executors.newFixedThreadPool(5); // 固定五个线程来执行任务private final Handler handler = new Handler();/*** * @param imageUrl*            图像url地址* @param callback*            回调接口* @return 返回内存中缓存的图像，第一次加载返回null*/public Bitmap loadBitmap(final String imageUrl, final ImageView image,final ImageCallback callback) {// 如果缓存过就从缓存中取出数据if (imageCache.containsKey(imageUrl)) {SoftReference<Bitmap> softReference = imageCache.get(imageUrl);if (softReference.get() != null) {return softReference.get();}}// 缓存中没有图像，则从SDcard取出数据，并将取出的数据缓存到内存中executorService.submit(new Runnable() {public void run() {try {final Bitmap bitmap = loadImageFromSD(imageUrl); imageCache.put(imageUrl, new SoftReference<Bitmap>(bitmap));handler.post(new Runnable() {public void run() {callback.imageLoaded(bitmap, image,imageUrl);}});} catch (Exception e) {throw new RuntimeException(e);}}});return null;}// 从SDcard取数据方法protected Bitmap loadImageFromSD(String path) {try {// 测试时，模拟网络延时，实际时这行代码不能有//SystemClock.sleep(2000);Bitmap bm = new BitmapTool().charge(path);return bm;} catch (Exception e) {throw new RuntimeException(e);}}// 对外界开放的回调接口public interface ImageCallback {// 注意 此方法是用来设置目标对象的图像资源public void imageLoaded(Bitmap imageDrawable, ImageView image, String imageUrl);}}

import android.graphics.Bitmap;import android.graphics.BitmapFactory;import android.graphics.Matrix;public class BitmapTool {public BitmapTool() {}/** 图片适配大小 */  public Bitmap change(String path) {    Bitmap bm = null;           BitmapFactory.Options optsa = new BitmapFactory.Options();    optsa.inSampleSize = 10;    bm = BitmapFactory.decodeFile(path, optsa);        if(bm != null) {    } else {      return null;    }    /**不同尺寸图片的缩放比例*/   if((bm.getHeight() ) <=150 || (bm.getWidth()) <=100 ) {    optsa.inSampleSize = 1;      bm = BitmapFactory.decodeFile(path, optsa);    }   else  if( (bm.getHeight() )<=300  || (bm.getWidth()) <= 200){    optsa.inSampleSize =10;    bm = BitmapFactory.decodeFile(path, optsa);}      else if(  ( (bm.getHeight() )<=450 ) ||(  (bm.getWidth()) <= 300)){    optsa.inSampleSize =20;    bm = BitmapFactory.decodeFile(path, optsa); }    else if(  ((bm.getHeight() )<=600 ) ||(  (bm.getWidth()) <= 400)){    optsa.inSampleSize =30;    bm = BitmapFactory.decodeFile(path, optsa);  }    else if(  ( (bm.getHeight() )<=750 ) ||(   (bm.getWidth()) <= 500)) {    optsa.inSampleSize = 40;    bm = BitmapFactory.decodeFile(path, optsa);  }    else  if(  ((bm.getHeight() )<=900 ) ||(   (bm.getWidth()) <= 600)) {    optsa.inSampleSize = 50;    bm = BitmapFactory.decodeFile(path, optsa);  }    else  {      optsa.inSampleSize = 60;      bm = BitmapFactory.decodeFile(path, optsa);   }        return bm;  }    /** 图片适配大小 ,同时缩放比例*/  public Bitmap charge(String path) {    Bitmap bm = this.change(path);    int sWidth = bm.getWidth();    int sHeigth = bm.getHeight();        if(bm != null) {      bm = this.zoomImage(bm,  sWidth,sHeigth);      }         return bm;  }  /***     * 图片的缩放方法     *     * @param bgimage     *            ：源图片资源     * @param newWidth     *            ：缩放后宽度     * @param newHeight     *            ：缩放后高度     * @return     */    public Bitmap zoomImage(Bitmap bgimage, int newWidth, int newHeight) {            // 获取这个图片的宽和高            int width = bgimage.getWidth();            int height = bgimage.getHeight();            // 创建操作图片用的matrix对象            Matrix matrix = new Matrix();            // 计算缩放率，新尺寸除原始尺寸            float scaleWidth = ((float) newWidth) / width;            float scaleHeight = ((float) newHeight) / height;            // 缩放图片动作            matrix.postScale(scaleWidth, scaleHeight);                        Bitmap bitmap = Bitmap.createBitmap(bgimage, 0, 0, width, height,                            matrix, true);            return bitmap;    }}

import java.io.File;import java.io.FileInputStream;import java.io.FileNotFoundException;import java.io.IOException;import java.util.List;import android.os.Environment;import android.util.Log;public class FileTool { /** 图片内存最小值 5K */ private final static int PIC_FILE_SIZE_MIN = 5; /** 图片内存最大值 300K */ private final static int PIC_FILE_SIZE_MAX = 6000;   /**    * 遍历目录,得到所有图片文件路径集群    * @param path    * @return    */   public void ListFiles(String path, List<String> lstPaths){         File file = new File(path);               if(file == null)       return;          if(file.isDirectory() ) {              String curpath = Environment.getExternalStorageDirectory().getPath()+"/"+"dcim"+"/"+".thumbnails";       if(path.equals(curpath))         return;     }          File[] fs = file.listFiles();     if(fs==null)      return;     for(File f : fs){        if(f==null)             continue;               String fName = f.getName();             String htx = fName.substring(fName.lastIndexOf(".") + 1,        fName.length()).toLowerCase();  //得到扩展名            if(htx.equals("png") || htx.equals("jpg") ||         htx.equals("gif") || htx.equals("bmp")) {              if(fileSizeValidity(f.getPath())) {         lstPaths.add(f.getPath());         Log.v("***PIC_FILE***", fName);       }     } else {     }     path = f.getAbsolutePath();     if(f.isDirectory() == true) {       ListFiles(path, lstPaths);      //当f为文件夹的时候，进入文件夹中           }   }   }      /**     * 判断文件大小有效性    * 如果文件内存在5K-300K之间则有效，否则返回FALSE    * @param path    * @return    */   private boolean fileSizeValidity(String path) {     File f = new File(path);     if(f.exists()) {       int cur = 0;       FileInputStream fis = null;     try {       fis = new FileInputStream(f);              cur = fis.available()/1000;            } catch (FileNotFoundException e) {       e.printStackTrace();     } catch (IOException e) {       e.printStackTrace();     } finally {       try {         fis.close();                   } catch (IOException e) {         e.printStackTrace();       }     }          //图片内存在5K-300K之间，表示有效     if(cur>=PIC_FILE_SIZE_MIN && cur<=PIC_FILE_SIZE_MAX)       return true;          }          return false;   }}

<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"    android:id="@+id/fillable_area"    android:layout_width="fill_parent"    android:layout_height="fill_parent"    android:gravity="center_horizontal"    android:orientation="vertical" ><GridView xmlns:android="http://schemas.android.com/apk/res/android"       android:id="@+id/gv_photolist"          android:layout_width="fill_parent"     android:layout_height="fill_parent"      android:padding="10dp"      android:verticalSpacing="10dp"      android:horizontalSpacing="10dp"      android:numColumns="auto_fit"      android:columnWidth="100dp"      android:stretchMode="columnWidth"      android:gravity="center"  ></GridView></LinearLayout>

<?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="100px"   android:layout_width="150px"   android:layout_centerHorizontal="true"android:id="@+id/iv_photoicon_photolist_item"/>              </RelativeLayout>