【发布时间】：2014-12-29 13:18:14
【问题描述】：
我的应用程序从列表中的服务器加载图像时遇到问题。我的应用程序在列表中显示 5 张图片。问题是应用程序何时应该加载第六张图片。这有点奇怪，因为应用程序加载了 5 张图片。这是我的延迟加载图像适配器
public class FlowerAdapter extends ArrayAdapter<Flower> {
private Context context;
private List<Flower> flowerList;
public FlowerAdapter(Context context, int resource, List<Flower> objects) {
super(context, resource, objects);
this.context = context;
this.flowerList = objects;
}
@Override
public View getView(int position, View convertView, ViewGroup parent) {
LayoutInflater inflater =
(LayoutInflater) context.getSystemService(Activity.LAYOUT_INFLATER_SERVICE);
View view = inflater.inflate(R.layout.item_flower, parent, false);
//Display flower name in the TextView widget
Flower flower = flowerList.get(position);
TextView tv = (TextView) view.findViewById(R.id.textView1);
tv.setText(flower.getPhoto());
//Display flower photo in ImageView widget
if (flower.getBitmap() != null) {
ImageView image = (ImageView) view.findViewById(R.id.imageView1);
image.setImageBitmap(flower.getBitmap());
}
else {
FlowerAndView container = new FlowerAndView();
container.flower = flower;
container.view = view;
ImageLoader loader = new ImageLoader();
loader.execute(container);
}
return view;
}
class FlowerAndView {
public Flower flower;
public View view;
public Bitmap bitmap;
}
private class ImageLoader extends AsyncTask<FlowerAndView, Void, FlowerAndView> {
@Override
protected FlowerAndView doInBackground(FlowerAndView... params) {
FlowerAndView container = params[0];
Flower flower = container.flower;
try {
String imageUrl = MainActivity.PHOTOS_BASE_URL + flower.getPhoto();
InputStream in = (InputStream) new URL(imageUrl).getContent();
Bitmap bitmap = BitmapFactory.decodeStream(in);
flower.setBitmap(bitmap);
in.close();
container.bitmap = bitmap;
return container;
} catch (Exception e) {
e.printStackTrace();
}
return null;
}
@Override
protected void onPostExecute(FlowerAndView result) {
ImageView image = (ImageView) result.view.findViewById(R.id.imageView1);
image.setImageBitmap(result.bitmap);
result.flower.setBitmap(result.bitmap);
}
}
}
这是我的活动代码
public class MainActivity extends ListActivity {
public static final String PHOTOS_BASE_URL =
"http://autoskola.1e29g6m.xip.io/images/";
TextView output;
ProgressBar pb;
List<MyTask> tasks;
List<Flower> flowerList;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
pb = (ProgressBar) findViewById(R.id.progressBar1);
pb.setVisibility(View.INVISIBLE);
tasks = new ArrayList<>();
}
@Override
public boolean onCreateOptionsMenu(Menu menu) {
getMenuInflater().inflate(R.menu.main, menu);
return true;
}
@Override
public boolean onOptionsItemSelected(MenuItem item) {
if (item.getItemId() == R.id.action_get_data) {
if (isOnline()) {
requestData("http://autoskola.1e29g6m.xip.io/webservices/files.php");
} else {
Toast.makeText(this, "Network isn't available", Toast.LENGTH_LONG).show();
}
}
return false;
}
private void requestData(String uri) {
MyTask task = new MyTask();
task.execute(uri);
}
protected void updateDisplay() {
//Use FlowerAdapter to display data
FlowerAdapter adapter = new FlowerAdapter(this, R.layout.item_flower, flowerList);
setListAdapter(adapter);
}
protected boolean isOnline() {
ConnectivityManager cm = (ConnectivityManager) getSystemService(Context.CONNECTIVITY_SERVICE);
NetworkInfo netInfo = cm.getActiveNetworkInfo();
if (netInfo != null && netInfo.isConnectedOrConnecting()) {
return true;
} else {
return false;
}
}
private class MyTask extends AsyncTask<String, String, List<Flower>> {
@Override
protected void onPreExecute() {
if (tasks.size() == 0) {
pb.setVisibility(View.VISIBLE);
}
tasks.add(this);
}
@Override
protected List<Flower> doInBackground(String... params) {
String content = HttpManager.getData(params[0]);
flowerList = FlowerJSONParser.parseFeed(content);
return flowerList;
}
@Override
protected void onPostExecute(List<Flower> result) {
tasks.remove(this);
if (tasks.size() == 0) {
pb.setVisibility(View.INVISIBLE);
}
if (result == null) {
Toast.makeText(MainActivity.this, "Web service not available", Toast.LENGTH_LONG).show();
return;
}
flowerList = result;
updateDisplay();
}
}
}
这就是我的应用程序崩溃时我的 logcat 所说的
12-29 13:02:55.057: E/AndroidRuntime(1113): FATAL EXCEPTION: AsyncTask #3
12-29 13:02:55.057: E/AndroidRuntime(1113): java.lang.RuntimeException: An error occured while executing doInBackground()
12-29 13:02:55.057: E/AndroidRuntime(1113): at android.os.AsyncTask$3.done(AsyncTask.java:299)
12-29 13:02:55.057: E/AndroidRuntime(1113): at java.util.concurrent.FutureTask.finishCompletion(FutureTask.java:352)
12-29 13:02:55.057: E/AndroidRuntime(1113): at java.util.concurrent.FutureTask.setException(FutureTask.java:219)
12-29 13:02:55.057: E/AndroidRuntime(1113): at java.util.concurrent.FutureTask.run(FutureTask.java:239)
12-29 13:02:55.057: E/AndroidRuntime(1113): at android.os.AsyncTask$SerialExecutor$1.run(AsyncTask.java:230)
12-29 13:02:55.057: E/AndroidRuntime(1113): at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1080)
12-29 13:02:55.057: E/AndroidRuntime(1113): at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:573)
12-29 13:02:55.057: E/AndroidRuntime(1113): at java.lang.Thread.run(Thread.java:841)
12-29 13:02:55.057: E/AndroidRuntime(1113): Caused by: java.lang.OutOfMemoryError
12-29 13:02:55.057: E/AndroidRuntime(1113): at android.graphics.BitmapFactory.nativeDecodeStream(Native Method)
12-29 13:02:55.057: E/AndroidRuntime(1113): at android.graphics.BitmapFactory.decodeStream(BitmapFactory.java:530)
12-29 13:02:55.057: E/AndroidRuntime(1113): at android.graphics.BitmapFactory.decodeStream(BitmapFactory.java:603)
12-29 13:02:55.057: E/AndroidRuntime(1113): at com.hanselandpetal.catalog.FlowerAdapter$ImageLoader.doInBackground(FlowerAdapter.java:79)
12-29 13:02:55.057: E/AndroidRuntime(1113): at com.hanselandpetal.catalog.FlowerAdapter$ImageLoader.doInBackground(FlowerAdapter.java:1)
12-29 13:02:55.057: E/AndroidRuntime(1113): at android.os.AsyncTask$2.call(AsyncTask.java:287)
12-29 13:02:55.057: E/AndroidRuntime(1113): at java.util.concurrent.FutureTask.run(FutureTask.java:234)
12-29 13:02:55.057: E/AndroidRuntime(1113): ... 4 more
如果有人知道我在哪里做错了，请帮忙。
非常感谢。
【问题讨论】：
-
为了在后台加载图像，您可以使用一些库，如毕加索或通用图像加载器。
-
是的，我知道 Picasso，但我不知道为什么我的应用在 5 张图片后崩溃。应用程序应该加载大约 30 张图像，但在第五张之后，应用程序崩溃了。如果应用加载 5 张图片，为什么应用无法加载全部 30 张图片。我认为这段代码工作正常，但也许有一些我看不到
-
因为您设备上的法律内存。从日志中清除它显示 java.lang.OutOfMemoryError。因此，请检查您设备的内存。
-
图片太大了尝试缩放位图，一些第三方库会减轻你的任务。
-
是的，我知道，我解决了这个问题。还是谢谢你:)
标签： android performance android-activity android-asynctask