我几乎不熟悉android并且正在与asyncTask斗争。
我想要的是将相应的图像添加到地图上的标记。 此地图上的每个条目都有自己的图像，必须通过json从服务器加载。
图像加载工作正常但我没有得到正确的工作流程来获取我需要一个条目的图像。
到目前为止，我有一个解决方案可以在for循环中加载异步任务，但这不能正确，因为应用程序拒绝继续执行43个任务并停止 “ECONNECTION TIMEOUT”
那么怎样才能让asynctask脱离循环？
希望有人可以帮忙吗？谢谢！
这是我的代码：
公共类MapsActivity扩展AppCompatActivity实现OnMapReadyCallback {
private GoogleMap mMap;
JSONArray contentJson;
String contentId;
String imageJsonUrl;
String userId;
Bitmap bmp;
LatLng latLng;
Marker m;
HashMap<Marker, String> hashMap;
int k = 0;
// check value for Request check
final int MY_LOCATION_REQUEST_CODE = 3;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_maps);
// Obtain the SupportMapFragment and get notified when the map is ready to be used.
SupportMapFragment mapFragment = (SupportMapFragment) getSupportFragmentManager()
.findFragmentById(R.id.map);
mapFragment.getMapAsync(this);
Toolbar myToolbar = (Toolbar) findViewById(R.id.my_toolbar);
setSupportActionBar(myToolbar);
getSupportActionBar().setDisplayShowTitleEnabled(false);
if(this.getIntent().getExtras() != null) {
try {
contentJson = new JSONArray(this.getIntent().getStringExtra("contentJson"));
// Log.v("TESTITEST", contentJson.toString());
} catch (JSONException e) {
Log.e("EXCEPTION", "unexpected JSON exception", e);
e.printStackTrace();
}
}
}
public boolean onCreateOptionsMenu(Menu menu) {
// Inflate the menu; this adds items to the action bar if it is present.
getMenuInflater().inflate(R.menu.menu_maps, menu);
return true;
}
public LatLng getLatLngPosition() {
return new LatLng(0, 0);
}
/**
* Manipulates the map once available.
* This callback is triggered when the map is ready to be used.
* This is where we can add markers or lines, add listeners or move the camera. In this case,
* we just add a marker near Sydney, Australia.
* If Google Play services is not installed on the device, the user will be prompted to install
* it inside the SupportMapFragment. This method will only be triggered once the user has
* installed Google Play services and returned to the app.
*/
@Override
public void onMapReady(GoogleMap googleMap) {
mMap = googleMap;
//Ask for Permission. If granted show my Location
if (ActivityCompat.checkSelfPermission(MapsActivity.this, Manifest.permission.ACCESS_FINE_LOCATION)
!= PackageManager.PERMISSION_GRANTED) {
// Check Permissions Now
ActivityCompat.requestPermissions(MapsActivity.this,
new String[]{Manifest.permission.ACCESS_FINE_LOCATION},
MY_LOCATION_REQUEST_CODE);
} else {
// permission has been granted, continue as usual
mMap.setMyLocationEnabled(true);
}
PlaceAutocompleteFragment autocompleteFragment = (PlaceAutocompleteFragment)
getFragmentManager().findFragmentById(R.id.place_autocomplete_fragment);
autocompleteFragment.setOnPlaceSelectedListener(new PlaceSelectionListener() {
@Override
public void onPlaceSelected(Place place) {
// TODO: Get info about the selected place.
LatLng selectedLocation = place.getLatLng();
mMap.animateCamera(CameraUpdateFactory.newLatLngZoom(selectedLocation, 10f));
}
@Override
public void onError(Status status) {
// TODO: Handle the error.
Log.i("PlaceSelectorError", "An error occurred: " + status);
}
});
LatLng bonn = new LatLng(50.7323, 7.1847);
LatLng cologne = new LatLng(50.9333333, 6.95);
//mMap.addMarker(new MarkerOptions().position(bonn).title("Marker in Bonn"));
// hash map for saving content id with marker
hashMap = new HashMap<Marker, String>();
if(contentJson != null) {
if (this.getIntent().getStringExtra("contentId") == null) {
// show all contents of my friends
try {
for (int i = 0; i < contentJson.length(); i++) {
JSONObject jsonInfo = contentJson.getJSONObject(i);
JSONArray contents = jsonInfo.getJSONArray("content");
// Log.v("contentslength", String.valueOf(contents.length()));
//get all contents of one user
for (int j = 0; j < contents.length(); j++) {
JSONObject eachcontent = contents.getJSONObject(j);
//Log.v("eachcontent", eachcontent.toString());
JSONObject location = eachcontent.getJSONObject("Location");
String contentId = eachcontent.getString("id");
String contentTitle = eachcontent.getString("title");
userId = eachcontent.getString("user_id");
latLng = new LatLng(Double.valueOf(location.getString("latitude")), Double.valueOf(location.getString("longitude")));
new MapImageLoadTask("http://192.168.63.35:1234/rest_app_users/getImage/", userId, contentId, contentTitle, latLng).execute();
Log.v("contentTitle", contentTitle);
//Log.v("m", m.toString());
//m = mMap.addMarker(new MarkerOptions().title(contentTitle).position(new LatLng(Double.valueOf(location.getString("latitude")), Double.valueOf(location.getString("longitude")))).icon(BitmapDescriptorFactory.fromBitmap(bmp)));
}
}
} catch (JSONException e) {
Log.e("Exception", "unexpected JSON exception", e);
e.printStackTrace();
}
}
else {
// if we only want to see a specific content
try {
for (int i = 0; i < contentJson.length(); i++) {
JSONObject jsonInfo = contentJson.getJSONObject(i);
JSONArray contents = jsonInfo.getJSONArray("content");
//get all contents of one user
for (int j = 0; j < contents.length(); j++) {
JSONObject eachcontent = contents.getJSONObject(j);
JSONObject location = eachcontent.getJSONObject("Location");
if(eachcontent.getString("id").equals(this.getIntent().getStringExtra("contentId"))) {
String contentId = eachcontent.getString("id");
String contentTitle = eachcontent.getString("title");
userId = eachcontent.getString("user_id");
latLng = new LatLng(Double.valueOf(location.getString("latitude")), Double.valueOf(location.getString("longitude")));
// Log.v("LATLNG", contentId);
new MapImageLoadTask("http://192.168.63.35:1234/rest_app_users/getImage/", userId, contentId, contentTitle, latLng).execute();
continue;
}
}
}
} catch (JSONException e) {
Log.e("LOGEDILOG", "unexpected JSON exception", e);
e.printStackTrace();
}
}
}
mMap.setOnMyLocationChangeListener(new GoogleMap.OnMyLocationChangeListener() {
@Override
public void onMyLocationChange(Location location) {
mMap.animateCamera(CameraUpdateFactory.newLatLngZoom(
new LatLng(location.getLatitude(), location.getLongitude()), 10f));
mMap.setOnMyLocationChangeListener(null);
}
});
mMap.setOnInfoWindowClickListener(new GoogleMap.OnInfoWindowClickListener() {
@Override
public void onInfoWindowClick(Marker marker) {
String id = hashMap.get(marker);
Log.v("BITMAP", bmp.toString());
try {
Context context = getApplicationContext();
Intent mapIntent = new Intent(getApplicationContext(), contentDetailActivity.class);
mapIntent.putExtra("contentId", id);
mapIntent.putExtra("contentJson", contentJson.toString());
mapIntent.putExtra("userId", userId);
String filename = "profileImage.png";
FileOutputStream stream = context.openFileOutput(filename, Context.MODE_PRIVATE);
bmp.compress(Bitmap.CompressFormat.PNG, 100, stream);
//Cleanup
stream.close();
mapIntent.putExtra("image", filename);
startActivity(mapIntent);
} catch (Exception e) {
e.printStackTrace();
}
}
});
}
public Marker[] addMarkers() {
return null;
}
/**
* lets you load Image from external source via url
*/
public class MapImageLoadTask extends AsyncTask<Void, Void, Bitmap> {
private final String LOG_TAG = MapImageLoadTask.class.getSimpleName();
String url, userId, contentId, title;
LatLng location;
BufferedReader reader = null;
public MapImageLoadTask(String url, String userId, String contentId, String title, LatLng location) {
this.url = url;
this.userId = userId;
this.contentId = contentId;
this.title = title;
this.location = location;
}
private String getImageUrlFromJson(String imageJson) throws JSONException {
JSONObject imageJsonOutput = new JSONObject(imageJson);
imageJsonUrl = imageJsonOutput.getString("imageUrl");
//Log.v(LOG_TAG, imageJsonUrl);
return imageJsonUrl;
}
@Override
protected Bitmap doInBackground(Void... params) {
String imageJson = null;
try {
URL urlConnection = new URL(url + userId);
HttpURLConnection connection = (HttpURLConnection) urlConnection
.openConnection();
connection.setDoInput(true);
connection.connect();
InputStream input = connection.getInputStream();
StringBuffer buffer = new StringBuffer();
if (input == null) {
// Nothing to do.
//forecastJsonStr = null;
return null;
}
reader = new BufferedReader(new InputStreamReader(input));
String line;
while ((line = reader.readLine()) != null) {
// Since it's JSON, adding a newline isn't necessary (it won't affect parsing)
// But it does make debugging a *lot* easier if you print out the completed
// buffer for debugging.
buffer.append(line + "\n");
}
if (buffer.length() == 0) {
return null;
}
imageJson = buffer.toString();
} catch (Exception e) {
e.printStackTrace();
}
try {
String jsonUrl = getImageUrlFromJson(imageJson);
URL url = new URL(jsonUrl);
bmp = BitmapFactory.decodeStream(url.openConnection().getInputStream());
return bmp;
}
catch(Exception e) {
e.printStackTrace();
}
return null;
}
@Override
protected void onPostExecute(Bitmap result) {
super.onPostExecute(result);
k +=1;
Log.v("COUNTER", String.valueOf(k));
m = mMap.addMarker(new MarkerOptions().title(title).position(location).icon(BitmapDescriptorFactory.fromBitmap(bmp)));
hashMap.put(m, contentId);
}
}
}
答案 0 :(得分：1)
您的问题可能是AsyncTask限制。在android.os.AsyncTask.java中你会看到核心大小和阻塞队列大小（128），应该使用asynctask的计数器并调试它（问题是，很多异步任务或其他）。
AsyncTask.java
public abstract class AsyncTask<Params, Progress, Result> {
private static final String LOG_TAG = "AsyncTask";
private static final int CPU_COUNT = Runtime.getRuntime().availableProcessors();
private static final int CORE_POOL_SIZE = CPU_COUNT + 1;
private static final int MAXIMUM_POOL_SIZE = CPU_COUNT * 2 + 1;
private static final int KEEP_ALIVE = 1;
private static final ThreadFactory sThreadFactory = new ThreadFactory() {
private final AtomicInteger mCount = new AtomicInteger(1);
public Thread newThread(Runnable r) {
return new Thread(r, "AsyncTask #" + mCount.getAndIncrement());
}
};
private static final BlockingQueue<Runnable> sPoolWorkQueue =
new LinkedBlockingQueue<Runnable>(128);
...}
更改代码使用缓冲区（RequestData）并仅使用一个异步任务。在onProgressUpdate
中更新每个publishProgress的Market实例
private GoogleMap mMap;
JSONArray contentJson;
String contentId;
String imageJsonUrl;
String userId;
Bitmap bmp;
LatLng latLng;
Marker m;
HashMap<Marker, String> hashMap;
int k = 0;
// check value for Request check
final int MY_LOCATION_REQUEST_CODE = 3;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_maps);
// Obtain the SupportMapFragment and get notified when the map is ready to be used.
SupportMapFragment mapFragment = (SupportMapFragment) getSupportFragmentManager()
.findFragmentById(R.id.map);
mapFragment.getMapAsync(this);
Toolbar myToolbar = (Toolbar) findViewById(R.id.my_toolbar);
setSupportActionBar(myToolbar);
getSupportActionBar().setDisplayShowTitleEnabled(false);
if(this.getIntent().getExtras() != null) {
try {
contentJson = new JSONArray(this.getIntent().getStringExtra("contentJson"));
// Log.v("TESTITEST", contentJson.toString());
} catch (JSONException e) {
Log.e("EXCEPTION", "unexpected JSON exception", e);
e.printStackTrace();
}
}
}
public boolean onCreateOptionsMenu(Menu menu) {
// Inflate the menu; this adds items to the action bar if it is present.
getMenuInflater().inflate(R.menu.menu_maps, menu);
return true;
}
public LatLng getLatLngPosition() {
return new LatLng(0, 0);
}
/**
* Manipulates the map once available.
* This callback is triggered when the map is ready to be used.
* This is where we can add markers or lines, add listeners or move the camera. In this case,
* we just add a marker near Sydney, Australia.
* If Google Play services is not installed on the device, the user will be prompted to install
* it inside the SupportMapFragment. This method will only be triggered once the user has
* installed Google Play services and returned to the app.
*/
@Override
public void onMapReady(GoogleMap googleMap) {
mMap = googleMap;
//Ask for Permission. If granted show my Location
if (ActivityCompat.checkSelfPermission(MapsActivity.this, Manifest.permission.ACCESS_FINE_LOCATION)
!= PackageManager.PERMISSION_GRANTED) {
// Check Permissions Now
ActivityCompat.requestPermissions(MapsActivity.this,
new String[]{Manifest.permission.ACCESS_FINE_LOCATION},
MY_LOCATION_REQUEST_CODE);
} else {
// permission has been granted, continue as usual
mMap.setMyLocationEnabled(true);
}
PlaceAutocompleteFragment autocompleteFragment = (PlaceAutocompleteFragment)
getFragmentManager().findFragmentById(R.id.place_autocomplete_fragment);
autocompleteFragment.setOnPlaceSelectedListener(new PlaceSelectionListener() {
@Override
public void onPlaceSelected(Place place) {
// TODO: Get info about the selected place.
LatLng selectedLocation = place.getLatLng();
mMap.animateCamera(CameraUpdateFactory.newLatLngZoom(selectedLocation, 10f));
}
@Override
public void onError(Status status) {
// TODO: Handle the error.
Log.i("PlaceSelectorError", "An error occurred: " + status);
}
});
LatLng bonn = new LatLng(50.7323, 7.1847);
LatLng cologne = new LatLng(50.9333333, 6.95);
//mMap.addMarker(new MarkerOptions().position(bonn).title("Marker in Bonn"));
// hash map for saving content id with marker
hashMap = new HashMap<Marker, String>();
if(contentJson != null) {
if (this.getIntent().getStringExtra("contentId") == null) {
// show all contents of my friends
try {
for (int i = 0; i < contentJson.length(); i++) {
JSONObject jsonInfo = contentJson.getJSONObject(i);
JSONArray contents = jsonInfo.getJSONArray("content");
// Log.v("contentslength", String.valueOf(contents.length()));
//get all contents of one user
for (int j = 0; j < contents.length(); j++) {
JSONObject eachcontent = contents.getJSONObject(j);
//Log.v("eachcontent", eachcontent.toString());
JSONObject location = eachcontent.getJSONObject("Location");
String contentId = eachcontent.getString("id");
String contentTitle = eachcontent.getString("title");
userId = eachcontent.getString("user_id");
latLng = new LatLng(Double.valueOf(location.getString("latitude")), Double.valueOf(location.getString("longitude")));
new MapImageLoadTask("http://192.168.63.35:1234/rest_app_users/getImage/", userId, contentId, contentTitle, latLng).execute();
Log.v("contentTitle", contentTitle);
//Log.v("m", m.toString());
//m = mMap.addMarker(new MarkerOptions().title(contentTitle).position(new LatLng(Double.valueOf(location.getString("latitude")), Double.valueOf(location.getString("longitude")))).icon(BitmapDescriptorFactory.fromBitmap(bmp)));
}
}
} catch (JSONException e) {
Log.e("Exception", "unexpected JSON exception", e);
e.printStackTrace();
}
}
else {
// if we only want to see a specific content
try {
List<RequestData> datas = new ArrayList<RequestData>();
for (int i = 0; i < contentJson.length(); i++) {
JSONObject jsonInfo = contentJson.getJSONObject(i);
JSONArray contents = jsonInfo.getJSONArray("content");
//get all contents of one user
for (int j = 0; j < contents.length(); j++) {
JSONObject eachcontent = contents.getJSONObject(j);
JSONObject location = eachcontent.getJSONObject("Location");
if(eachcontent.getString("id").equals(this.getIntent().getStringExtra("contentId"))) {
String contentId = eachcontent.getString("id");
String contentTitle = eachcontent.getString("title");
userId = eachcontent.getString("user_id");
latLng = new LatLng(Double.valueOf(location.getString("latitude")), Double.valueOf(location.getString("longitude")));
// Log.v("LATLNG", contentId);
RequestData data = new RequestData();
data.url = "http://192.168.63.35:1234/rest_app_users/getImage/";
data.userId = userId;
data.contentId = contentId;
data.contentTitle = contentTitle;
data.latlng = latlng;
datas.add(data);
//new MapImageLoadTask("http://192.168.63.35:1234/rest_app_users/getImage/", userId, contentId, contentTitle, latLng).execute();
continue;
}
}
}
new MapImageLoadTask(datas).execute();
} catch (JSONException e) {
Log.e("LOGEDILOG", "unexpected JSON exception", e);
e.printStackTrace();
}
}
}
mMap.setOnMyLocationChangeListener(new GoogleMap.OnMyLocationChangeListener() {
@Override
public void onMyLocationChange(Location location) {
mMap.animateCamera(CameraUpdateFactory.newLatLngZoom(
new LatLng(location.getLatitude(), location.getLongitude()), 10f));
mMap.setOnMyLocationChangeListener(null);
}
});
mMap.setOnInfoWindowClickListener(new GoogleMap.OnInfoWindowClickListener() {
@Override
public void onInfoWindowClick(Marker marker) {
String id = hashMap.get(marker);
Log.v("BITMAP", bmp.toString());
try {
Context context = getApplicationContext();
Intent mapIntent = new Intent(getApplicationContext(), contentDetailActivity.class);
mapIntent.putExtra("contentId", id);
mapIntent.putExtra("contentJson", contentJson.toString());
mapIntent.putExtra("userId", userId);
String filename = "profileImage.png";
FileOutputStream stream = context.openFileOutput(filename, Context.MODE_PRIVATE);
bmp.compress(Bitmap.CompressFormat.PNG, 100, stream);
//Cleanup
stream.close();
mapIntent.putExtra("image", filename);
startActivity(mapIntent);
} catch (Exception e) {
e.printStackTrace();
}
}
});
}
public Marker[] addMarkers() {
return null;
}
/**
* lets you load Image from external source via url
*/
static class RequestData{
public String url;
public String userId;
public String contentId;
public String contentTitle;
public LatLng latLng;
public Bitmap bmp;
}
public class MapImageLoadTask extends AsyncTask<Void, RequestData, Void> {
private final String LOG_TAG = MapImageLoadTask.class.getSimpleName();
BufferedReader reader = null;
List<RequestData> dataSet;
public MapImageLoadTask(List<RequestData> dataSet) {
this.dataSet = dataSet;
}
private String getImageUrlFromJson(String imageJson) throws JSONException {
JSONObject imageJsonOutput = new JSONObject(imageJson);
imageJsonUrl = imageJsonOutput.getString("imageUrl");
//Log.v(LOG_TAG, imageJsonUrl);
return imageJsonUrl;
}
@Override
protected Bitmap doInBackground(Void... params) {
for(RequestData item : dataSet){
String imageJson = null;
try {
URL urlConnection = new URL(url + userId);
HttpURLConnection connection = (HttpURLConnection) urlConnection
.openConnection();
connection.setDoInput(true);
connection.connect();
InputStream input = connection.getInputStream();
StringBuffer buffer = new StringBuffer();
if (input == null) {
// Nothing to do.
//forecastJsonStr = null;
return null;
}
reader = new BufferedReader(new InputStreamReader(input));
String line;
while ((line = reader.readLine()) != null) {
// Since it's JSON, adding a newline isn't necessary (it won't affect parsing)
// But it does make debugging a *lot* easier if you print out the completed
// buffer for debugging.
buffer.append(line + "\n");
}
if (buffer.length() == 0) {
return null;
}
imageJson = buffer.toString();
} catch (Exception e) {
e.printStackTrace();
}
try {
String jsonUrl = getImageUrlFromJson(imageJson);
URL url = new URL(jsonUrl);
bmp = BitmapFactory.decodeStream(url.openConnection().getInputStream());
//
item.bmp = bmp;
publishProgress(item);
}
catch(Exception e) {
e.printStackTrace();
}
}
return null;
}
protected void onPublishProgress(RequestData item){
k +=1;
Log.v("COUNTER", String.valueOf(k));
m = mMap.addMarker(new MarkerOptions().title(item.title).position(item.location).icon(BitmapDescriptorFactory.fromBitmap(item.bmp)));
hashMap.put(m, contentId);
}
@Override
protected void onPostExecute(Bitmap result) {
super.onPostExecute(result);
}
}
}