我正在开发一个Android项目，我在其中加载来自我们服务器的图像，同时加载有关餐馆的其他信息。问题是，它需要花费大量时间来加载，每当我尝试再次加载信息或将移动设备从横向移动到potrait或反之亦然时，我就会出现内存错误。
当我在网上查看时，用户说的问题是因为位图。在服务器端，我将PNG's转换为字符串并传输它们，然后将字符串转换为位图然后显示。为什么整个加载时间大约4-5秒并且崩溃。谁能帮我。
Android代码：
餐馆列表活动：
public class getListOfRestaurantsForUser extends AsyncTask<Double,Void,ResponseEntity<RestRestaurant[]>>{
RestaurantList restaurantList = null;
getListOfRestaurantsForUser(RestaurantList restaurantList){
this.restaurantList = restaurantList;
}
@Override
protected ResponseEntity<RestRestaurant[]> doInBackground(Double... doubles) {
double longitude = doubles[0];
double latitude = doubles[1];
Log.d("Longitude",String.valueOf(longitude));
final RestTemplate restTemplate = StaticRestTemplate.getRest();
HttpHeaders requestHeaders = new HttpHeaders();
requestHeaders.add("Cookie", "JSESSIONID=" + StaticRestTemplate.jsessionid);
requestHeaders.setAccept(Collections.singletonList(new MediaType("application", "json")));
HttpEntity<?> requestEntity = new HttpEntity<Object>(requestHeaders);
restTemplate.getMessageConverters().add(new MappingJackson2HttpMessageConverter());
return restTemplate.exchange(restaurantListURL+longitude+"/"+latitude, HttpMethod.GET, requestEntity, RestRestaurant[].class);
}
@Override
protected void onPostExecute(ResponseEntity<RestRestaurant[]> responseEntity){
RestRestaurant[] restRestaurantList = responseEntity.getBody();
Collections.addAll(restosAsList, restRestaurantList);
ArrayList<HashMap<String, String>> restaurantsArrayHashList = new ArrayList<>();
for(RestRestaurant restRestaurant : restosAsList){
HashMap<String, String> restDisplay = new HashMap<>();
restDisplay.put(restaurantid, String.valueOf(restRestaurant.getRestaurantId()));
restDisplay.put(restaurantName, restRestaurant.getRestaurantName());
restDisplay.put(restaurantDistance, String.valueOf(restRestaurant.getDistanceFromUser()));
restDisplay.put(restaurantDetails,restRestaurant.getRestaurantDetails());
restDisplay.put(restoProfilePicture,restRestaurant.getProfilePicture());
restaurantsArrayHashList.add(restDisplay);
}
listView = (ListView) findViewById(R.id.restosList);
restaurantListAdapter = new RestaurantListAdapter(restaurantList, restaurantsArrayHashList);
listView.setAdapter(restaurantListAdapter);
listView.setOnItemClickListener(new AdapterView.OnItemClickListener() {
@Override
public void onItemClick(AdapterView<?> parent, View view,
int position, long id) {
int restaurantId = restosAsList.get(position).getRestaurantId();
Intent intent = new Intent(RestaurantList.this, MenuCardList.class);
intent.putExtra("restaurantid", restaurantId);
startActivity(intent);
finish();
}
});
}
}
RestaurantList适配器：
@Override
public View getView(int position, View convertView, ViewGroup parent) {
View view = convertView;
if (convertView == null) {
view = inflater.inflate(R.layout.individual_restaurant_detail, null);
TextView restaurantName = (TextView) view.findViewById(R.id.resturantName);
TextView distanceFromUser = (TextView) view.findViewById(R.id.distanceFromUser);
TextView restaurantDetails = (TextView) view.findViewById(R.id.restaurantDetails);
ImageView restoImage = (ImageView) view.findViewById(R.id.resturantImage);
HashMap<String, String> restaurantList;
restaurantList = data.get(position);
restaurantName.setText(restaurantList.get(RestaurantList.restaurantName));
restaurantName.setTypeface(Typeface.DEFAULT_BOLD);
restaurantName.setTextSize(TypedValue.COMPLEX_UNIT_SP, 15);
double distance = Double.valueOf(restaurantList.get(RestaurantList.restaurantDistance));
if(distance < 1000) {
distanceFromUser.setText("Entfernung " + restaurantList.get(RestaurantList.restaurantDistance)+"m");
}else {
distanceFromUser.setText("Entfernung " + String.valueOf(distance/1000) +"km");
}
restaurantDetails.setText(restaurantList.get(RestaurantList.restaurantDetails));
restoImage.setImageBitmap(convertByteArrayToBitmap(restaurantList.get(RestaurantList.restoProfilePicture)));
}
return view;
} @Override
public View getView(int position, View convertView, ViewGroup parent) {
View view = convertView;
if (convertView == null) {
view = inflater.inflate(R.layout.individual_restaurant_detail, null);
TextView restaurantName = (TextView) view.findViewById(R.id.resturantName);
TextView distanceFromUser = (TextView) view.findViewById(R.id.distanceFromUser);
TextView restaurantDetails = (TextView) view.findViewById(R.id.restaurantDetails);
ImageView restoImage = (ImageView) view.findViewById(R.id.resturantImage);
HashMap<String, String> restaurantList;
restaurantList = data.get(position);
restaurantName.setText(restaurantList.get(RestaurantList.restaurantName));
restaurantName.setTypeface(Typeface.DEFAULT_BOLD);
restaurantName.setTextSize(TypedValue.COMPLEX_UNIT_SP, 15);
double distance = Double.valueOf(restaurantList.get(RestaurantList.restaurantDistance));
if(distance < 1000) {
distanceFromUser.setText("Entfernung " + restaurantList.get(RestaurantList.restaurantDistance)+"m");
}else {
distanceFromUser.setText("Entfernung " + String.valueOf(distance/1000) +"km");
}
restaurantDetails.setText(restaurantList.get(RestaurantList.restaurantDetails));
restoImage.setImageBitmap(convertByteArrayToBitmap(restaurantList.get(RestaurantList.restoProfilePicture)));
}
return view;
}
private Bitmap convertByteArrayToBitmap(String string){
try {
byte [] encodeByte= Base64.decode(string, Base64.DEFAULT);
return BitmapFactory.decodeByteArray(encodeByte, 0, encodeByte.length);
} catch (Exception ignored){}
return null;
}
服务器端代码：
@Override
public List<Restaurant> getNearbyRestaurants(double longitude, double latitude) {
BASE64Encoder base64Encoder = new BASE64Encoder();
final int R = 6371; // Radius of the earth
List<Restaurant> restaurantList = this.listRestaurants();
List<Restaurant> nearbyRestaurantList = new ArrayList<>();
for(Restaurant restaurant : restaurantList){
Double latDistance = toRad(latitude-restaurant.getLatitude());
Double lonDistance = toRad(longitude-restaurant.getLongitude());
Double a = Math.sin(latDistance / 2) * Math.sin(latDistance / 2) +
Math.cos(toRad(latitude)) * Math.cos(toRad(restaurant.getLatitude())) *
Math.sin(lonDistance / 2) * Math.sin(lonDistance / 2);
Double c = 2 * Math.atan2(Math.sqrt(a), Math.sqrt(1-a));
Double distance = R * c;
restaurant.setDistanceFromUser(distance);
if(distance < 10){
restaurant.setDistanceFromUser((restaurant.getDistanceFromUser()*1000));
nearbyRestaurantList.add(restaurant);
}
String restaurantIdentifierImageString = this.restaurantImageService.getProfileIdentifierForRestaurant(restaurant.getRestaurantId());
if(!(restaurantIdentifierImageString == null)){
try {
try {
File imagePath = new File(restaurantImagePath + restaurantIdentifierImageString +".png");
BufferedImage bufferedImage = ImageIO.read(imagePath);
ByteArrayOutputStream byteArrayOutputStream = new ByteArrayOutputStream();
ImageIO.write(bufferedImage, "png", byteArrayOutputStream);
restaurant.setProfilePicture( base64Encoder.encode(byteArrayOutputStream.toByteArray()));
} catch (Exception e) {
File imagePath = new File(defaultProfilePath);
BufferedImage bufferedImage = ImageIO.read(imagePath);
ByteArrayOutputStream byteArrayOutputStream = new ByteArrayOutputStream();
ImageIO.write(bufferedImage, "png", byteArrayOutputStream);
restaurant.setProfilePicture(base64Encoder.encode(byteArrayOutputStream.toByteArray()));
}
}catch (Exception e){
e.printStackTrace();
}
}
}
Collections.sort(nearbyRestaurantList, new Comparator<Restaurant>() {
@Override
public int compare(Restaurant o1, Restaurant o2) {
if(o1.getDistanceFromUser() > o2.getDistanceFromUser()){
return 1;
}
if(o1.getDistanceFromUser() < o2.getDistanceFromUser()){
return -1;
}
return 0;
}
});
return nearbyRestaurantList;
}
错误日志：
Caused by: java.lang.OutOfMemoryError: Failed to allocate a 13176356 byte allocation with 370616 free bytes and 361KB until OOM
at java.lang.AbstractStringBuilder.<init>(AbstractStringBuilder.java:83)
at java.lang.StringBuilder.<init>(StringBuilder.java:67)
at com.fasterxml.jackson.core.util.TextBuffer.contentsAsString(TextBuffer.java:346)
at com.fasterxml.jackson.core.json.UTF8StreamJsonParser._finishAndReturnString(UTF8StreamJsonParser.java:2412)
at com.fasterxml.jackson.core.json.UTF8StreamJsonParser.getText(UTF8StreamJsonParser.java:285)
at com.fasterxml.jackson.databind.deser.std.StringDeserializer.deserialize(StringDeserializer.java:32)
如果需要更多信息，请告知我们。谢谢。
更新
Image retrieval method :
@RequestMapping(value = "/restaurantimage/{identifier}")
public HttpEntity<byte[]> getPhoto(@PathVariable String identifier) {
boolean flag = false;
try {
byte[] image;
try {
image = org.apache.commons.io.FileUtils.readFileToByteArray(new File(restaurantImagePath + identifier +".png"));
} catch (FileNotFoundException e) {
flag = true;
image = org.apache.commons.io.FileUtils.readFileToByteArray(new File(defaultProfilePath));
e.printStackTrace();
}
HttpHeaders headers = new HttpHeaders();
headers.setContentType(MediaType.IMAGE_PNG);
headers.setContentLength(image.length);
return new HttpEntity<>(image, headers);
} catch (IOException ignored) {
}
return null;
}
答案 0 :(得分：2)
我不知道服务器端的要求是什么，但对于移动应用程序，分配给应用程序的内存非常有限。你可能发送的位图必须是几千字节，当它被接收时，你将它存储在String或字节数组中，然后将它写在一个字符串中。 这会占用应用程序的大量内存，也会产生性能问题。
作为替代方法，您可以在json字符串中提供服务器中图像的url，然后将该url传递给某些Imagehelper / Lazyloading库（如Volley）的方法。
答案 1 :(得分：0)
我终于能够通过从Picaso加载图像并从服务器端发送图像的URL来解决问题。
代码：
Picasso.with（view.getContext（））
Picasso.load(StaticRestTemplate.baseURL+"restaurantimage/"+restaurantList.get(RestaurantList.restoProfilePicture))
.config(Bitmap.Config.RGB_565)
.fit()
.centerInside()
.into(restoImage);