我正在尝试根据自定义ArrayAdapter中的字符串设置imageView源，但我无法让它工作。我知道对象rec_gift正确通过，而icon_string变量得到正确的名称，但是setImageResource调用不起作用。
public class MySimpleArrayAdapter extends ArrayAdapter<Gift> {
private final Context context;
private List<Gift> giftz2;
public MySimpleArrayAdapter(Context context, List<Gift> giftx) {
super(context, R.layout.listview_rowlayout, giftx);
this.context = context;
this.giftz2 = giftx;
}
@Override
public View getView(int position, View convertView, ViewGroup parent) {
LayoutInflater inflater = (LayoutInflater) context.getSystemService(Context.LAYOUT_INFLATER_SERVICE);
View rowView = inflater.inflate(R.layout.listview_rowlayout, parent, false);
ImageView iconz = (ImageView) rowView.findViewById(R.id.icon);
Gift rec_gift = (Gift) getItem(position);
String icon_string = "R.drawable." + rec_gift.photo_key;
iconz.setImageResource(getImageId(icon_string));
return rowView;
}
public int getImageId(String imageName) {
return context.getResources().getIdentifier("drawable/" + imageName, null, context.getPackageName());
}
}
在上面的代码中，我想基于icon_string变量设置imageView，因此listView中的每一行都将获得正确的图像，但它根本没有进行任何更改。
答案 0 :(得分：3)
实现自定义适配器的getItem方法：
@Override
public Gift getItem(int position) {
if(this.giftz2 != null) {
this.giftz2.get(position);
} else {
return null;
}
}
并改变这一点：
public int getImageId(String imageName) {
return context.getResources().getIdentifier("drawable/" + imageName, null, context.getPackageName());
}
对此：
public int getImageId(String imageName) {
return context.getResources().getIdentifier(imageName, "drawable", context.getPackageName());
}
并致电方法：
String icon_string = String.valueOf(rec_gift.photo_key);
iconz.setImageResource(getImageId(icon_string));
BTW：尝试在适配器getView方法中重用您的视图。如果继续使用实现，则会出现内存错误。
答案 1 :(得分：1)
如果您尝试从Web服务下载图像并在imageview中设置该图像，则可以使用图像加载器
将此行放在您要显示图像的适配器中并传递参数
ImageLoader_class(image_url, image_view , progressbar);
// new创建一个名为ImageLoader_class的类，并将此代码粘贴到该
中 import java.io.IOException;
import java.io.InputStream;
import java.net.HttpURLConnection;
import java.net.MalformedURLException;
import java.net.URL;
import java.util.Stack;
import android.app.Activity;
import android.content.Context;
import android.graphics.Bitmap;
import android.graphics.BitmapFactory;
import android.graphics.Canvas;
import android.graphics.Path;
import android.graphics.Rect;
import android.graphics.drawable.BitmapDrawable;
import android.view.View;
import android.widget.ImageView;
import android.widget.ProgressBar;
public class ImageLoader_class{
private static MemoryCache memoryCache = new MemoryCache();
// private static FileCache fileCache;
private static boolean isImageLoaderClass = true;
private static ImageLoader_circle_img imageLoader = null;
final static int stub_id = R.drawable.ic_launcher;
private static Bitmap defaultBitmap = null;
private static Context mContext;
/**
* This is constructor of ImageLoader Class make the background thread low
* priority. This way it will not affect the UI performance *
*
* @param mContext
* application context
*/
private ImageLoader_circle_img(Context context) {
mContext = context;
photoLoaderThread.setPriority(Thread.NORM_PRIORITY - 1);
// fileCache = new FileCache(mContext);
}
/**
* This Method is used to implement singleton concept in this class
*
* @param context
* application context
* @return Class object of this class
*/
public static ImageLoader_circle_img getInstanceImageLoader(Context context) {
if (isImageLoaderClass) {
isImageLoaderClass = false;
imageLoader = new ImageLoader_circle_img(context);
return imageLoader;
}
return imageLoader;
}
/**
* This method is used to set image in image view
*
* @param url
* from this URL, image will be down-load
* @param imageView
* in this view set the image bitmap
* @param progressBar
* which is show when image is displaying
*/
@SuppressWarnings("deprecation")
public static void DisplayImage(String url, ImageView imageView,
ProgressBar progressBar) {
if (url == null || url.equals("")) {
imageView.setVisibility(View.VISIBLE);
// imageView.setImageBitmap(getDefaultBitmap());
imageView.setBackgroundDrawable(new BitmapDrawable(
getDefaultBitmap()));
progressBar.setVisibility(View.INVISIBLE);
} else if (memoryCache.get(url) != null) {
imageView.setVisibility(View.VISIBLE);
// imageView.setImageBitmap(memoryCache.get(url));
imageView.setBackgroundDrawable(new BitmapDrawable(memoryCache
.get(url)));
progressBar.setVisibility(View.INVISIBLE);
} else {
queuePhoto(url, imageView, progressBar);
System.out.println("url"+url);
}
}
public static Bitmap getRoundedShape(Bitmap scaleBitmapImage) {
// TODO Auto-generated method stub
int targetWidth = 100;
int targetHeight = 100;
Bitmap targetBitmap = Bitmap.createBitmap(targetWidth, targetHeight,
Bitmap.Config.ARGB_8888);
Canvas canvas = new Canvas(targetBitmap);
Path path = new Path();
path.addCircle(((float) targetWidth - 1) / 2,
((float) targetHeight - 1) / 2,
(Math.min(((float) targetWidth), ((float) targetHeight)) / 2),
Path.Direction.CCW);
canvas.clipPath(path);
Bitmap sourceBitmap = scaleBitmapImage;
canvas.drawBitmap(sourceBitmap, new Rect(0, 0, sourceBitmap.getWidth(),
sourceBitmap.getHeight()), new Rect(0, 0, targetWidth,
targetHeight), null);
return targetBitmap;
}
/**
* this method is used to get default bitmap if image url is null
*
* @return bitmap
*/
private static Bitmap getDefaultBitmap() {
try {
defaultBitmap = BitmapFactory.decodeResource(mContext
.getResources(), stub_id);
int width = defaultBitmap.getWidth();
int height = defaultBitmap.getHeight();
return Bitmap.createScaledBitmap(defaultBitmap, width / 4,
height / 4, true);
} catch (Exception e) {
e.printStackTrace();
}
return null;
}
/**
* If bitmap is not downloaded then add in queue
*
* @param url
* from this URL, image will be down-load
* @param imageView
* in this view set the image bitmap
* @param progressBar
* which is show when image is displaying
*/
private static void queuePhoto(String url, ImageView imageView,
ProgressBar progressBar) {
photosQueue.Clean(imageView);
PhotoToLoad p = new PhotoToLoad(url, imageView, progressBar);
synchronized (photosQueue.photosToLoad) {
photosQueue.photosToLoad.push(p);
photosQueue.photosToLoad.notifyAll();
}
// start thread if it's not started yet
if (photoLoaderThread.getState() == Thread.State.NEW)
photoLoaderThread.start();
}
/**
* this method is used to download bitmap
*
* @param url
* from this URL, image will be down-load
* @return bitmap
*/
private static Bitmap getBitmap(String url) {
URL myFileUrl = null;
Bitmap bmImg = null;
try {
myFileUrl = new URL(url);
} catch (MalformedURLException e) {
e.printStackTrace();
}
try {
HttpURLConnection conn = (HttpURLConnection) myFileUrl
.openConnection();
conn.setDoInput(true);
conn.connect();
InputStream is = conn.getInputStream();
bmImg = BitmapFactory.decodeStream(is);
} catch (IOException e) {
e.printStackTrace();
}
if (bmImg != null)
System.out.println(" bmImg.getWidth()"+ bmImg.getWidth());
if(bmImg.getWidth()>300)
{
bmImg = Bitmap.createScaledBitmap(bmImg, bmImg.getWidth(),
bmImg.getHeight() , true);
// bmImg = Bitmap.createScaledBitmap(bmImg, bmImg.getWidth() / 4,
// bmImg.getHeight() / 4, true);
System.out.println("IF STAT");
}
else
{
bmImg = Bitmap.createScaledBitmap(bmImg, 55,
55, true);
}
//Bitmap bt = ((BitmapDrawable) imageView.getDrawable()).getBitmap();
//imageView.setImageBitmap(getRoundedShape(bmImg));
//if the image needed in round shape
//return getRoundedShape(bmImg);
return bmImg;
}
/**
* This class is used to manage url, imageview and progressBar
*/
private static class PhotoToLoad {
public String url;
public ImageView imageView;
public ProgressBar view;
public PhotoToLoad(String u, ImageView i, ProgressBar v) {
url = u;
imageView = i;
view = v;
}
}
private static PhotosQueue photosQueue = new PhotosQueue();
private static void stopThread() {
photoLoaderThread.interrupt();
}
/**
* this class is used to store list of photoes
*/
private static class PhotosQueue {
private Stack<PhotoToLoad> photosToLoad = new Stack<PhotoToLoad>();
// removes all instances of this ImageView
public void Clean(ImageView image) {
for (int j = 0; j < photosToLoad.size();) {
if (photosToLoad.get(j).imageView == image)
photosToLoad.remove(j);
else
++j;
}
}
}
/**
* This thread is used to set photoes in imageView
*/
private static class PhotosLoader extends Thread {
@Override
public void run() {
try {
while (true) {
// thread waits until there are any images to load in the
// queue
if (photosQueue.photosToLoad.size() == 0) {
synchronized (photosQueue.photosToLoad) {
photosQueue.photosToLoad.wait();
}
}
if (photosQueue.photosToLoad.size() != 0) {
PhotoToLoad photoToLoad;
synchronized (photosQueue.photosToLoad) {
photoToLoad = photosQueue.photosToLoad.pop();
}
Bitmap bmp;
try {
bmp = getBitmap(photoToLoad.url);
memoryCache.put(photoToLoad.url, bmp);
if (((String) photoToLoad.imageView.getTag()).equals(photoToLoad.url)) {
BitmapDisplayer bd = new BitmapDisplayer(bmp,
photoToLoad.imageView, photoToLoad.view);
Activity a = (Activity) photoToLoad.imageView
.getContext();
a.runOnUiThread(bd);
}
} catch (Exception e) {
e.printStackTrace();
}
}
if (Thread.interrupted())
break;
}
} catch (InterruptedException e) {
// allow thread to exit
}
}
}
private static PhotosLoader photoLoaderThread = new PhotosLoader();
/**
* Used to display bitmap in the UI thread
*/
private static class BitmapDisplayer implements Runnable {
Bitmap bitmap;
ImageView imageView;
ProgressBar view;
public BitmapDisplayer(Bitmap b, ImageView i, ProgressBar v) {
bitmap = b;
imageView = i;
view = v;
}
@SuppressWarnings("deprecation")
public void run() {
if (bitmap != null) {
imageView.setVisibility(View.VISIBLE);
// imageView.setImageBitmap(bitmap);
imageView.setBackgroundDrawable(new BitmapDrawable(bitmap));
view.setVisibility(View.INVISIBLE);
}
}
}
/**
* this function is used to clear all stored data
*/
public static void clearCache() {
stopThread();
// clear memory cache
memoryCache.clear();
// clear SD cache
/*
* if (fileCache != null) { fileCache.clear(); }
*/
}
}