Java 如何为gridview重置适配器？
我正在开发一个android应用程序，它从服务器下载图像，并将其显示在Java 如何为gridview重置适配器？,java,android,gridview,Java,Android,Gridview,我正在开发一个android应用程序，它从服务器下载图像，并将其显示在GridView上。为此，我使用了扩展BaseAdapter的适配器，其中我使用AsyncTask获取图像并在gridview中显示ti。代码如下 public class CloudImageAdapter extends BaseAdapter { private final String TAG = "CloudImageAdapter"; private Context context; private Thumbn
GridViewBaseAdapterAsyncTaskpublic class CloudImageAdapter extends BaseAdapter {
private final String TAG = "CloudImageAdapter";
private Context context;
private ThumbnailCache mCache;
private LayoutInflater inflater;
private ArrayList<String> images = new ArrayList<String>();
ServerInfo server = null;
public CloudImageAdapter(Context context) {
this.context = context;
inflater = (LayoutInflater) this.context
.getSystemService(Context.LAYOUT_INFLATER_SERVICE);
// Pick cache size based on memory class of device
final ActivityManager am = (ActivityManager) this.context
.getSystemService(Context.ACTIVITY_SERVICE);
final int memoryClassBytes = am.getMemoryClass() * 1024 * 1024;
mCache = new ThumbnailCache(memoryClassBytes / 2);
server = ServerInfo.getServerInstance(context);
}
public void putImages(String imageName) {
images.add(imageName);
}
@Override
public int getCount() {
return images.size();
}
@Override
public Object getItem(int posotion) {
Log.i(TAG, "getItem() returns -> " + images.get(posotion));
return images.get(posotion);
}
@Override
public long getItemId(int position) {
return position;
}
@Override
public View getView(int position, View converView, ViewGroup parent) {
ImageView imageView;
if (converView == null) {
converView = inflater.inflate(R.layout.single_image_frame, null);
imageView = (ImageView) converView
.findViewById(R.id.singleImageFrame);
imageView.setImageBitmap(null);
imageView.setBackgroundResource(R.drawable.empty_photo);
} else {
imageView = (ImageView) converView;
}
final AsyncImageDecoder oldTask = (AsyncImageDecoder) imageView
.getTag();
if (oldTask != null) {
oldTask.cancel(false);
}
Bitmap bitmap = mCache.get(images.get(position));
if (bitmap == null) {
AsyncImageDecoder task = new AsyncImageDecoder(imageView);
task.execute(images.get(position));
imageView.setTag(task);
}
imageView.setImageBitmap(bitmap);
return converView;
}
class Holder {
ImageView frame;
}
/**
* Simple extension that uses {@link Bitmap} instances as keys, using their
* memory footprint in bytes for sizing.
*/
public static class ThumbnailCache extends
android.support.v4.util.LruCache<String, Bitmap> {
public ThumbnailCache(int maxSizeBytes) {
super(maxSizeBytes);
}
@Override
protected int sizeOf(String key, Bitmap data) {
return data.getByteCount();
}
}
class AsyncImageDecoder extends AsyncTask<String, Void, Bitmap> {
private String END = "End-Of-File";
private final WeakReference<ImageView> imageViewReference;
float rotation = 0;
public AsyncImageDecoder(ImageView frame) {
imageViewReference = new WeakReference<ImageView>(frame);
}
@Override
protected Bitmap doInBackground(String... imageName) {
Log.i(TAG, "AsyncImageDecoder::doInBackground() image -> "
+ imageName[0]);
Bitmap bitmap;
try {
bitmap = downloadImage(imageName[0]);
mCache.put(String.valueOf(imageName[0]), bitmap);
// rotation = getCameraPhotoOrientation(imagePath);
return bitmap;
} catch (IOException e) {
e.printStackTrace();
}
return null;
}
@Override
protected void onPostExecute(Bitmap image) {
if (imageViewReference != null && image != null) {
final ImageView imageView = (ImageView) imageViewReference
.get();
if (imageView != null) {
/*
* if(image.getHeight() < image.getWidth())
* imageView.setRotation(90);
*/
imageView.setImageBitmap(image);
}
}
}
private Bitmap downloadImage(String path) throws IOException {
Bitmap thumb = null;
Socket socket = new Socket();
socket.connect(server.getServerAddress());
DataOutputStream out = new DataOutputStream(
socket.getOutputStream());
DataInputStream input = new DataInputStream(socket.getInputStream());
JSONObject header = new JSONObject();
JSONObject inner = new JSONObject();
try {
inner.put("command", "thumbnail");
inner.put("user", server.getUser());
inner.put("path", path);
header.put("header", inner);
} catch (JSONException e) {
e.printStackTrace();
}
out.write(header.toString().getBytes());
out.write(END.getBytes());
/*
* Reading thumbnails from the cloud
*/
byte[] temp = new byte[1024]; // Temporary byte array to read from
// the socket
byte[] store = null; // Reference variable to keep the byte array
int len = 0; // Length of the array
int receivedCount = 0;
while (true) {
receivedCount = input.read(temp);
if (receivedCount <= 0) {
thumb = decodeSampledBitmapFromUri(store, 50, 50);
/*
* thumb = BitmapFactory.decodeByteArray(store, 0,
* store.length);
*/
break; // Break when there is no more data to be read
}
byte[] buffer = new byte[len + receivedCount];
if (store != null) {
System.arraycopy(store, 0, buffer, 0, store.length);
System.arraycopy(temp, 0, buffer, len, receivedCount);
} else {
System.arraycopy(temp, 0, buffer, 0, receivedCount);
}
store = buffer;
len = len + receivedCount;
}
input.close();
out.close();
socket.close();
return thumb;
}
private Bitmap decodeSampledBitmapFromUri(byte[] data, int width,
int height) {
Bitmap bm = null;
// First decode with inJustDecodeBounds=true to check dimensions
final BitmapFactory.Options options = new BitmapFactory.Options();
options.inJustDecodeBounds = true;
BitmapFactory.decodeByteArray(data, 0, data.length, options);
// Calculate inSampleSize
options.inSampleSize = calculateInSampleSize(options, 140, 120);
// Decode bitmap with inSampleSize set
options.inJustDecodeBounds = false;
bm = BitmapFactory.decodeByteArray(data, 0, data.length, options);
return bm;
}
private int calculateInSampleSize(BitmapFactory.Options options,
int reqWidth, int reqHeight) {
// Raw height and width of image
final int height = options.outHeight;
final int width = options.outWidth;
int inSampleSize = 1;
if (height > reqHeight || width > reqWidth) {
if (width > height) {
inSampleSize = Math.round((float) height
/ (float) reqHeight);
} else {
inSampleSize = Math.round((float) width / (float) reqWidth);
}
}
return inSampleSize;
}
}}
公共类CloudImageAdapter扩展了BaseAdapter{
私有最终字符串标记=“CloudImageAdapter”；
私人语境；
私有ThumbnailCache-mCache；
私人充气机；
私有ArrayList图像=新建ArrayList（）；
ServerInfo server=null；
公共CloudImageAdapter（上下文）{
this.context=上下文；
充气器=（LayoutInflater）this.context
.getSystemService（上下文布局\充气机\服务）；
//根据设备的内存类别选择缓存大小
最终ActivityManager am=（ActivityManager）this.context
.getSystemService（Context.ACTIVITY\u服务）；
final int memoryClassBytes=am.getMemoryClass（）*1024*1024；
mCache=new ThumbnailCache（memoryClassBytes/2）；
server=ServerInfo.getServerInstance（上下文）；
}
公共图像（字符串imageName）{
images.add（imageName）；
}
@凌驾
public int getCount（）{
返回图像。size（）；
}
@凌驾
公共对象getItem（int posotion）{
i（标记，“getItem（）返回->”+images.get（posotion））；
返回图像.get（posotion）；
}
@凌驾
公共长getItemId（int位置）{
返回位置；
}
@凌驾
公共视图getView（内部位置、视图对流视图、视图组父视图）{
图像视图图像视图；
如果（converView==null）{
converView=充气机。充气（R.layout.single_image_frame，空）；
imageView=（imageView）converView
.findViewById（R.id.singleImageFrame）；
setImageBitmap（空）；
imageView.setBackgroundResource（R.drawable.empty_photo）；
}否则{
imageView=（imageView）converView；
}
最终AsyncImageDecoder oldTask=（AsyncImageDecoder）图像视图
.getTag（）；
if（oldTask！=null）{
oldTask.cancel（false）；
}
位图Bitmap=mCache.get（images.get（position））；
如果（位图==null）{
AsyncImageDecoder任务=新的AsyncImageDecoder（imageView）；
task.execute（images.get（position））；
setTag（任务）；
}
设置图像位图（位图）；
返回对流视图；
}
阶级持有者{
图像视图框；
}
/**
*使用{@link Bitmap}实例作为键的简单扩展，使用它们的
*用于调整大小的内存占用（字节）。
*/
公共静态类ThumbnailCache扩展
android.support.v4.util.LruCache{
公共ThumbnailCache（int-maxSizeBytes）{
超级（最大尺寸字节）；
}
@凌驾
受保护的int-sizeOf（字符串键、位图数据）{
返回数据。getByteCount（）；
}
}
类AsyncImageDecoder扩展了AsyncTask{
私有字符串END=“文件结束”；
私有最终WeakReference imageViewReference；
浮动旋转=0；
公共异步图像解码器（图像视图帧）{
imageViewReference=新的WeakReference（帧）；
}
@凌驾
受保护位图doInBackground（字符串…图像名称）{
Log.i（标记，“AsyncImageDecoder:：doInBackground（）image->”
+imageName[0]）；
位图；
试一试{
位图=下载图像（imageName[0]）；
mCache.put（String.valueOf（imageName[0]），位图）；
//旋转=getCameraPhotoOrientation（图像路径）；
返回位图；
}捕获（IOE异常）{
e、 printStackTrace（）；
}
返回null；
}
@凌驾
受保护的void onPostExecute（位图图像）{
if（imageViewReference！=null&&image！=null）{
最终图像视图图像视图=（图像视图）图像视图参考
.get（）；
如果（imageView！=null）{
/*
*if（image.getHeight（）要求宽度）{
如果（宽度>高度）{
inSampleSize=数学圆（（浮动）高度
/（浮动）高度）；
}否则{
inSampleSize=数学圆（（浮动）宽度/（浮动）宽度）；
}
}
返回样本大小；
}
}}
异步
if (isCancelled())
break;
task.cancel(true);
class AsyncImageDecoder extends AsyncTask<String, Void, Bitmap> {
private String END = "End-Of-File";
private final WeakReference<ImageView> imageViewReference;
float rotation = 0;
boolean resume = true;
boolean pause = false;
private String WATCH_DOG = "griffin";
public AsyncImageDecoder(ImageView frame) {
imageViewReference = new WeakReference<ImageView>(frame);
}
@Override
protected Bitmap doInBackground(String... imageName) {
Log.i(TAG, "AsyncImageDecoder::doInBackground() image -> "
+ imageName[0]);
Bitmap bitmap;
while(resume){
try {
bitmap = downloadImage(imageName[0]);
mCache.put(String.valueOf(imageName[0]), bitmap);
// rotation = getCameraPhotoOrientation(imagePath);
return bitmap;
} catch (IOException e) {
e.printStackTrace();
}
if(pause){ //This checks if the task has been paused and sleeps it till it has been notified to wake up
syncronized(WATCH_DOG){
try{
WATCH_DOG.wait();
} catch (InterruptedException e){e.printStackTrace();}
pause = false;
}
}
}
return null;
}
public void pauseTask(){
pause = true;
}
public void wakeUp(){
synchronized(WATCH_DOG){
WATCH_DOG.notify();
}
}
@Override
protected void onPostExecute(Bitmap image) {
if (imageViewReference != null && image != null) {
final ImageView imageView = (ImageView) imageViewReference
.get();
if (imageView != null) {
/*
* if(image.getHeight() < image.getWidth())
* imageView.setRotation(90);
*/
imageView.setImageBitmap(image);
}
}
}
private Bitmap downloadImage(String path) throws IOException {
Bitmap thumb = null;
Socket socket = new Socket();
socket.connect(server.getServerAddress());
DataOutputStream out = new DataOutputStream(
socket.getOutputStream());
DataInputStream input = new DataInputStream(socket.getInputStream());
JSONObject header = new JSONObject();
JSONObject inner = new JSONObject();
try {
inner.put("command", "thumbnail");
inner.put("user", server.getUser());
inner.put("path", path);
header.put("header", inner);
} catch (JSONException e) {
e.printStackTrace();
}
out.write(header.toString().getBytes());
out.write(END.getBytes());
/*
* Reading thumbnails from the cloud
*/
byte[] temp = new byte[1024]; // Temporary byte array to read from
// the socket
byte[] store = null; // Reference variable to keep the byte array
int len = 0; // Length of the array
int receivedCount = 0;
while (true) {
receivedCount = input.read(temp);
if (receivedCount <= 0) {
thumb = decodeSampledBitmapFromUri(store, 50, 50);
/*
* thumb = BitmapFactory.decodeByteArray(store, 0,
* store.length);
*/
break; // Break when there is no more data to be read
}
byte[] buffer = new byte[len + receivedCount];
if (store != null) {
System.arraycopy(store, 0, buffer, 0, store.length);
System.arraycopy(temp, 0, buffer, len, receivedCount);
} else {
System.arraycopy(temp, 0, buffer, 0, receivedCount);
}
store = buffer;
len = len + receivedCount;
}
input.close();
out.close();
socket.close();
return thumb;
}
private Bitmap decodeSampledBitmapFromUri(byte[] data, int width,
int height) {
Bitmap bm = null;
// First decode with inJustDecodeBounds=true to check dimensions
final BitmapFactory.Options options = new BitmapFactory.Options();
options.inJustDecodeBounds = true;
BitmapFactory.decodeByteArray(data, 0, data.length, options);
// Calculate inSampleSize
options.inSampleSize = calculateInSampleSize(options, 140, 120);
// Decode bitmap with inSampleSize set
options.inJustDecodeBounds = false;
bm = BitmapFactory.decodeByteArray(data, 0, data.length, options);
return bm;
}
private int calculateInSampleSize(BitmapFactory.Options options,
int reqWidth, int reqHeight) {
// Raw height and width of image
final int height = options.outHeight;
final int width = options.outWidth;
int inSampleSize = 1;
if (height > reqHeight || width > reqWidth) {
if (width > height) {
inSampleSize = Math.round((float) height
/ (float) reqHeight);
} else {
inSampleSize = Math.round((float) width / (float) reqWidth);
}
}
return inSampleSize;
}
}}
@Override
public void onPause(){
super.onPause();
task.pauseTask();
}
@Override
public void onResume(){
super.onResume();
task.wakeUp();
}