我正在开发一个 android 应用程序，它使用在 .ashx 请求处理程序中开发的 Web 服务。
- 应用程序等待很多并在第一次启动 aap 时显示黑屏。
- 有时它会给出错误 outofMemory VM 预算。
这是一些代码。
public class Home extends Activity implements AdapterView.OnItemClickListener {
/** Called when the activity is first created. */
Context context = Home.this;
HashMap<String, String> map = new HashMap<String, String>();
ArrayList<String> BookTitle = new ArrayList<String>();
ArrayList<String> BookCoverPhotos = new ArrayList<String>();
URL bookImageURL = null;
Bitmap bitMapImage = null;
View homeTabLayout;
View reviewLayout;
ArrayList<String> ImageUrl = new ArrayList<String>();
ImageButton btnBack;
// XML Parsing
ArrayList<HashMap<String, String>> menuItems = new ArrayList<HashMap<String, String>>();
// All static variables
static final String URL = "http://www.my_url_goes_here.com/rxxxxxxxandler.ashx";
// XML node keys
static final String KEY_ITEM = "Book"; // parent node
static final String KEY_ID = "BookID";
static final String KEY_BOOKTITLE = "BookTitle";
static final String KEY_BOOKCODE = "BookCode";
static final String KEY_BOOKIMAGE = "BookImage";
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.home_activity);
// Get XML Data in a Array List
XMLParser parser = new XMLParser();
String xml = parser.getXmlFromUrl(URL, "Imam Ali"); // getting XML
Document doc = parser.getDomElement(xml); // getting DOM element
NodeList nl = doc.getElementsByTagName(KEY_ITEM);
// looping through all item nodes <item>
for (int i = 0; i < nl.getLength(); i++) {
// creating new HashMap
Node node = nl.item(i);
Element e = (Element) nl.item(i);
// adding each child node to HashMap key => value
map.put(KEY_ID, parser.getValue(e, KEY_ID));
BookTitle.add(parser.getValue(e, KEY_BOOKTITLE));
BookCoverPhotos.add("http://shiaislamicbooks.com/books_Snaps/"+parser.getValue(e, KEY_BOOKCODE)+"/1.jpg");
Log.i("URLs", BookCoverPhotos.toString());
// String
// imgUrl="http://shiaislamicbooks.com/books_Snaps/"+parser.getValue(e,
// KEY_BOOKCODE);
map.put(KEY_BOOKTITLE, parser.getValue(e, KEY_BOOKTITLE));
map.put(KEY_BOOKCODE, parser.getValue(e, KEY_BOOKCODE));
map.put(KEY_BOOKIMAGE, parser.getValue(e, KEY_BOOKIMAGE));
// adding HashList to ArrayList
menuItems.add(map);
Log.i("Array List", menuItems.toString());
}
homeTabLayout = findViewById(R.id.rel_HomeLayout);
reviewLayout = findViewById(R.id.scroll_ReviewLayout);
reviewLayout.setVisibility(View.GONE);
btnBack = (ImageButton) findViewById(R.id.btnBack);
btnBack.setOnClickListener(new OnClickListener() {
@Override
public void onClick(View v) {
reviewLayout.setVisibility(View.GONE);
homeTabLayout.setVisibility(View.VISIBLE);
}
});
final GridView gridView = (GridView) findViewById(R.id.gridview);
gridView.setAdapter(new ImageAdapter(this));
gridView.setOnItemClickListener(new OnItemClickListener() {
@Override
public void onItemClick(AdapterView<?> arg0, View arg1, int pos,
long arg3) {
}
});
}
public class ImageAdapter extends BaseAdapter {
private Context context;
public ImageAdapter(Context c) {
context = c;
}
// ---returns the number of images---
public int getCount() {
return BookCoverPhotos.size();
}
// ---returns the ID of an item---
public Object getItem(int position) {
return position;
}
public long getItemId(int position) {
return position;
}
// ---returns an ImageView view---
public View getView(int position, View convertView, ViewGroup parent) {
// ImageView bmImage;
ImageView img_BookCoverPhoto;
img_BookCoverPhoto = new ImageView(context);
LayoutInflater inflater = (LayoutInflater) context
.getSystemService(Context.LAYOUT_INFLATER_SERVICE);
View row = inflater.inflate(R.layout.grid_style, parent, false);
TextView txt_BooksTitle = (TextView) row
.findViewById(R.id.txt_BookTitle);
txt_BooksTitle.setText(BookTitle.get(position) + "");
img_BookCoverPhoto = (ImageView) row
.findViewById(R.id.imgBookCover);
try {
bookImageURL = new URL(
BookCoverPhotos.get(position));
} catch (MalformedURLException e) {
e.printStackTrace();
Toast.makeText(context, "Network Error", Toast.LENGTH_LONG).show();
Log.i("URL", "ERROR");
}
try {
bitMapImage = BitmapFactory.decodeStream(bookImageURL
.openConnection().getInputStream());
} catch (IOException e) {
// TODO Auto-generated catch block
e.printStackTrace();
Toast.makeText(context, "Bitmap Error", Toast.LENGTH_LONG).show();
Log.i("BITMAP", "ERROR");
}
img_BookCoverPhoto.setImageBitmap(bitMapImage);
return row;
}
}
}
还有一件事要告诉大家，我正在使用本教程中的 XML 解析。
- 我的应用程序中是否有任何多余的不需要的代码。
- 有什么方法可以加载第一个基本 UI，然后应用程序应该开始从 Web 服务器下载数据（即位图中的图像和文本数据）。
- 并建议我应该使用 AsyncTask，请提供一些有关 AsyncTask 的基本教程的链接。
请提供带有一些描述的代码。