您好我是Android的菜鸟，我正在尝试使用自定义适配器将一些数据加载到ListView。我使用以下代码加载数据。第一次，它运作良好。但是当我尝试加载更多时，数据加载和图像在滚动时显示随机。在该列表中显示一些随机图像后，最终显示正确的图像。它也在下一个卷轴上重复
这是我的getView代码
@Override
public View getView(int position, View convertView, ViewGroup parent) {
View v = convertView;
final ViewHolder holder;
if (v == null) {
LayoutInflater vi =
(LayoutInflater)activity.getSystemService(Context.LAYOUT_INFLATER_SERVICE);
v = vi.inflate(R.layout.review_list_m, null);
v.setMinimumHeight(height);
holder = new ViewHolder();
holder.item1 = (TextView) v.findViewById(R.id.name);
holder.image = (ImageView) v.findViewById(R.id.posterView);
v.setTag(holder);
}
else
holder=(ViewHolder)v.getTag();
int colorPos = position % colors.length;
v.setBackgroundColor(Color.parseColor(colors[colorPos]));
final Custom custom = entries.get(position);
if (custom != null) {
holder.image.setBackgroundColor(Color.parseColor(colors[colorPos]));
holder.image.setLayoutParams(new LinearLayout.LayoutParams(height-10,width-10));
String imgUrl=custom.getImage();
AsyncHttpClient client = new AsyncHttpClient();
String[] allowedContentTypes = new String[] { "image/png", "image/jpeg" };
client.get(imgUrl, new BinaryHttpResponseHandler(allowedContentTypes) {
@Override
public void onSuccess(byte[] fileData) {
// Do something with the file
ByteArrayInputStream inputStream = new ByteArrayInputStream(fileData);
Bitmap bitmap = BitmapFactory.decodeStream(inputStream);
holder.image.setImageBitmap(bitmap);
}
});
holder.item1.setHeight(height/3);
Log.v("PATH",custom.getcustomBig());
holder.item1.setText(custom.getcustomBig());
}
return v;
}
有什么想法吗？请帮忙
更新
@Override
public View getView(int position, View convertView, ViewGroup parent) {
View v = convertView;
final ViewHolder holder;
if (v == null) {
LayoutInflater vi =
(LayoutInflater)activity.getSystemService(Context.LAYOUT_INFLATER_SERVICE);
v = vi.inflate(R.layout.review_list_m, null);
v.setMinimumHeight(height);
holder = new ViewHolder();
holder.item1 = (TextView) v.findViewById(R.id.name);
holder.image = (ImageView) v.findViewById(R.id.posterView);
v.setTag(holder);
}
else
holder=(ViewHolder)v.getTag();
int colorPos = position % colors.length;
v.setBackgroundColor(Color.parseColor(colors[colorPos]));
final Custom custom = entries.get(position);
if (custom != null) {
holder.image.setBackgroundColor(Color.parseColor(colors[colorPos]));
holder.image.setLayoutParams(new LinearLayout.LayoutParams(height-10,width-10));
final String imgUrl=custom.getImage();
holder.image.setTag(imgUrl);
holder.image.setImageBitmap(null);
Bitmap cachedBitmap = cache.get(imgUrl);
if( cachedBitmap == null) {
Log.v("HERE","DOWNLOADING");
AsyncHttpClient client = new AsyncHttpClient();
String[] allowedContentTypes = new String[] { "image/png", "image/jpeg" };
client.get(imgUrl, new BinaryHttpResponseHandler(allowedContentTypes) {
@Override
public void onSuccess(byte[] fileData) {
// Do something with the file
ByteArrayInputStream inputStream = new ByteArrayInputStream(fileData);
Bitmap bitmap = BitmapFactory.decodeStream(inputStream);
holder.image.setImageBitmap(bitmap);
}
});
}
else
{
holder.image.setImageBitmap(cachedBitmap);
}
holder.item1.setHeight(height/3);
//Log.v("PATH",custom.getcustomBig());
holder.item1.setText(custom.getcustomBig());
}
答案 0 :(得分：1)
如果v！= null，可以将null位图设置为holder.image。否则，Android可以显示来自其他单元格的位图，直到通过异步http请求下载新图像。
示例代码（有关重新下载图片的问题），它不是睾丸，但应该让您知道它应该是什么样的：
HashMap<String, Bitmap> cache = new HashMap<String, Bitmap>();
@Override
public View getView(int position, View convertView, ViewGroup parent) {
//....
final Custom custom = entries.get(position);
if (custom != null) {
holder.image.setBackgroundColor(Color.parseColor(colors[colorPos]));
holder.image.setLayoutParams(new LinearLayout.LayoutParams(height-10,width-10));
String imgUrl=custom.getImage();
Bitmap cachedBitmap = cache.get(imgUrl);
if( cachedBitmap == null) {
AsyncHttpClient client = new AsyncHttpClient();
String[] allowedContentTypes = new String[] { "image/png", "image/jpeg" };
client.get(imgUrl, new BinaryHttpResponseHandler(allowedContentTypes) {
@Override
public void onSuccess(byte[] fileData) {
// Do something with the file
ByteArrayInputStream inputStream = new ByteArrayInputStream(fileData);
Bitmap bitmap = BitmapFactory.decodeStream(inputStream);
holder.image.setImageBitmap(bitmap);
cache.add( imgUrl, bitmap );
}
});
}
else
{
holder.image.setImageBitmap(cachedBitmap);
}
holder.item1.setHeight(height/3);
Log.v("PATH",custom.getcustomBig());
holder.item1.setText(custom.getcustomBig());
}
答案 1 :(得分：0)
编辑回答 在设置位图之前，验证您的imageview标签没有更改。 你可以尝试：
/**
* Caches an image (or a group of them) async.
* @author
*
*/
public static class ImageCacher extends AsyncTask<String, String, Integer>{
Context context;
ImageView iv;
Bitmap b;
public ImageCacher(Context context, ImageView iv){
this.context = context;
this.iv = iv;
}
@Override
protected Integer doInBackground(String... params) {
for(final String param:params){
//check if already CACHED
String filename = String.format("%d", param.hashCode());
File file = new File(context.getFilesDir(), filename);
if(file.exists()){
try {
b = BitmapFactory.decodeFile(file.getAbsolutePath());
} catch (Exception e) {
}
if(b != null){
if(iv != null){
iv.post(new Runnable() {
public void run() {
String tag = (String) iv.getTag();
if(tag != null){
if(tag.matches(param))
iv.setImageBitmap(b);
}
}
});
}
return 0;
}else{
file.delete();
}
}
//download
file = new File(context.getFilesDir(), filename);
b = saveImageFromUrl(context, param);
if(b != null){
if(iv != null){
iv.post(new Runnable() {
public void run() {
String tag = (String) iv.getTag();
if(tag != null){
if(tag.matches(param))
iv.setImageBitmap(b);
}
}
});
}
}
}
return 0;
}
}
/**
* Gets an image given its url
* @param param
*/
public static Bitmap saveImageFromUrl(Context context, String fullUrl) {
Bitmap b = null;
try {
URL url = new URL(fullUrl);
URLConnection conn = url.openConnection();
conn.setDoInput(true);
conn.connect();
//save bitmap to file
InputStream is = conn.getInputStream();
String filename = String.format("%d", fullUrl.hashCode());
File file = new File(context.getFilesDir(), filename);
if(file.exists()){
//delete
file.delete();
file=null;
}
file = new File(context.getFilesDir(), filename);
FileOutputStream out = new FileOutputStream(file);
byte buffer[] = new byte[256];
while(true){
int cnt = is.read(buffer);
if(cnt <=0){
break;
}
out.write(buffer,0, cnt);
}
out.flush();
out.close();
is.close();
b = BitmapFactory.decodeFile(file.getAbsolutePath());
} catch (Exception e) {
e.printStackTrace();
}
return b;
}
/**
* Gets an already cached photo
*
* @param context
* @param fullUrl
* @return
*/
public static Bitmap getCachedPhoto(Context context, String fullUrl){
System.gc();
String filename = String.format("%d", fullUrl.hashCode());
File file = new File(context.getFilesDir(), filename);
if(file.exists()){
try {
Bitmap b = BitmapFactory.decodeFile(file.getAbsolutePath());
return b;
} catch (Exception e) {
}
}
return null;
}
然后，要在适配器中设置图像，您可以这样做：
//set info
vh.iv.setTag("");
String foto = your_url_goes_here;
vh.iv.setImageResource(R.drawable.fotodefault_2x);
if(!TextUtils.isEmpty(foto)){
vh.iv.setTag(foto);
Bitmap b = getCachedPhoto(context, foto);
if(b != null){
vh.iv.setImageBitmap(b);
}else{
new ImageCacher(context, vh.iv).execute(foto);
}
}
不要忘记正确封装类和方法。 希望它有所帮助。
答案 2 :(得分：0)
我的arrayAdapter出现了这个随机图片问题。然后我使用了Picasso，它负责在listview中重用imageView：http://square.github.io/picasso/
代码示例：
Picasso.with(mContext)
.load(url)
.resize(size, size)
.centerCrop()
.placeholder(R.drawable.image_holder)
.into(holder.imgDefaultImage);