我从网站txt doc加载图片。文本文档包含图像的URL。
我不希望这会阻止主UI，因为它确实从文本doxument加载图像。
我想要做的是在背景中的AsyncTask中加载URL或其他东西。 然后图像URL存储在变量中并发送到我将创建的Lazy Downloader。
有人可以给我一个例子，说明如何实际将部件放在我想从网站文档doc（http://www.example.com/sites/images.txt）加载图片网址的地方我知道如何从文件加载文本，只是不知道如何在AsyncTask中执行此操作。
非常感谢一个例子！
public void getImages() throws IOException{
DefaultHttpClient httpclient = new DefaultHttpClient();
HttpGet httppost = new HttpGet("https://sites.google.com/site/theitrangers/images/webImages.txt");
HttpResponse response;
response = httpclient.execute(httppost);
HttpEntity ht = response.getEntity();
BufferedHttpEntity buf = new BufferedHttpEntity(ht);
InputStream is = buf.getContent();
BufferedReader r = new BufferedReader(new InputStreamReader(is));
StringBuilder total = new StringBuilder();
String line;
while ((line = r.readLine()) != null) {
total.append(line + "\n");
imageUrl = total.toString();
}
}
public void getImage2() throws IOException{
DefaultHttpClient httpclient = new DefaultHttpClient();
HttpGet httppost = new HttpGet("https://sites.google.com/site/theitrangers/images/webImage2.txt");
HttpResponse response;
response = httpclient.execute(httppost);
HttpEntity ht = response.getEntity();
BufferedHttpEntity buf = new BufferedHttpEntity(ht);
InputStream is = buf.getContent();
BufferedReader r = new BufferedReader(new InputStreamReader(is));
StringBuilder total = new StringBuilder();
String line;
while ((line = r.readLine()) != null) {
total.append(line + "\n");
imageUrl2 = total.toString();
}
}
public class ImageAdapter extends BaseAdapter {
/** The parent context */
private Context myContext;public ImageAdapter() {
// TODO Auto-generated constructor stub
}
/** URL-Strings to some remote images. */
private String[] myRemoteImages = {imageUrl,imageUrl2};
/** Simple Constructor saving the 'parent' context. */
public ImageAdapter(Context c) { this.myContext = c; }
/** Returns the amount of images we have defined. */
public int getCount() { return this.myRemoteImages.length; }
/* Use the array-Positions as unique IDs */
public Object getItem(int position) { return position; }
public long getItemId(int position) { return position; }
/** Returns a new ImageView to
* be displayed, depending on
* the position passed. */
public View getView(int position, View convertView, ViewGroup parent) {
ImageView i = new ImageView(this.myContext);
try {
/* Open a new URL and get the InputStream to load data from it. */
URL aURL = new URL(myRemoteImages[position]);
URLConnection conn = aURL.openConnection();
conn.connect();
InputStream is = conn.getInputStream();
/* Buffered is always good for a performance plus. */
BufferedInputStream bis = new BufferedInputStream(is);
/* Decode url-data to a bitmap. */
Bitmap bm = BitmapFactory.decodeStream(bis);
bis.close();
is.close();
/* Apply the Bitmap to the ImageView that will be returned. */
i.setImageBitmap(bm);
} catch (IOException e) {
Log.e("DEBUGTAG", "Remtoe Image Exception", e);
}
/* Image should be scaled as width/height are set. */
i.setScaleType(ImageView.ScaleType.FIT_CENTER);
/* Set the Width/Height of the ImageView. */
i.setLayoutParams(new Gallery.LayoutParams(150, 150));
return i;
}
/** Returns the size (0.0f to 1.0f) of the views
* depending on the 'offset' to the center. */
public float getScale(boolean focused, int offset) {
/* Formula: 1 / (2 ^ offset) */
return Math.max(0, 1.0f / (float)Math.pow(2, Math.abs(offset)));
}
}
public class ImageAdapter2 extends BaseAdapter {
/** The parent context */
private Context myContext;public ImageAdapter2() {
// TODO Auto-generated constructor stub
}
/** URL-Strings to some remote images. */
private String[] myRemoteImages = {imageUrl2};
/** Simple Constructor saving the 'parent' context. */
public ImageAdapter2(Context c) { this.myContext = c; }
/** Returns the amount of images we have defined. */
public int getCount() { return this.myRemoteImages.length; }
/* Use the array-Positions as unique IDs */
public Object getItem(int position) { return position; }
public long getItemId(int position) { return position; }
/** Returns a new ImageView to
* be displayed, depending on
* the position passed. */
public View getView(int position, View convertView, ViewGroup parent) {
ImageView i = new ImageView(this.myContext);
try {
/* Open a new URL and get the InputStream to load data from it. */
URL aURL = new URL(myRemoteImages[position]);
URLConnection conn = aURL.openConnection();
conn.connect();
InputStream is = conn.getInputStream();
/* Buffered is always good for a performance plus. */
BufferedInputStream bis = new BufferedInputStream(is);
/* Decode url-data to a bitmap. */
Bitmap bm = BitmapFactory.decodeStream(bis);
bis.close();
is.close();
/* Apply the Bitmap to the ImageView that will be returned. */
i.setImageBitmap(bm);
} catch (IOException e) {
Log.e("DEBUGTAG", "Remtoe Image Exception", e);
}
/* Image should be scaled as width/height are set. */
i.setScaleType(ImageView.ScaleType.FIT_CENTER);
/* Set the Width/Height of the ImageView. */
i.setLayoutParams(new Gallery.LayoutParams(150, 150));
return i;
}
/** Returns the size (0.0f to 1.0f) of the views
* depending on the 'offset' to the center. */
public float getScale(boolean focused, int offset) {
/* Formula: 1 / (2 ^ offset) */
return Math.max(0, 1.0f / (float)Math.pow(2, Math.abs(offset)));
}
}
}
答案 0 :(得分：1)
在AsyncTask中的onPreExecute()方法中获取txt文件。但在执行此操作之前，请创建进度对话框并将其设置为.setCancelable(false)。在doInBackground()中，获取图像......并在onPostExecute()中执行一些UI操作，例如显示图像。
编辑：
protected class Somename extends AsyncTask<String, String, String>
{
public Somename()
{
}
@Override
protected String doInBackground(String... arg0) {
// here you put the pure processings that DO NOT affect user-interface
getImages();
getImage2();
return null;
}
@Override
protected void onPostExecute(String result) {
ImageAdapter imgAdp = ImageAdapter(); //your constructor of the class that triggers updates on the UI
super.onPostExecute(result);
}
}
请注意发送正确的上下文，在您调用INSIDE AsyncTask类的方法中需要。并为您的ImageAdapter类创建构造函数，以继承您从站点获取的数据。