我有 3 個 API GET 調(diào)用。我的方法面臨的問題是，應(yīng)用程序能夠從兩個 API 成功獲取數(shù)據(jù)，并且我也能夠在 UI 上顯示它。但是，對于第三次 API 調(diào)用，由于以下錯誤，之前顯示的數(shù)據(jù)消失了，這很糟糕。D/Volley: [380] BasicNetwork.logSlowRequests: HTTP response for request=<[ ] http://example.com/api/search/getTwitterData?limit=10&tag=JavaScript 0x865f5dc2 NORMAL 3> [lifetime=6683], [size=10543], [rc=200], [retryCount=0]如何使用 Volley 進行并發(fā) API GET 調(diào)用而不丟失 UI 上的數(shù)據(jù)。有人可以指導(dǎo)我嗎？這是我的代碼的摘錄。
4 回答
Helenr
TA貢獻1780條經(jīng)驗 獲得超4個贊
問題是您每次都會初始化適配器，這就是為什么一旦新的 API 調(diào)用您的數(shù)據(jù)就會丟失。我更喜歡下面的方法，這樣可以幫助您，在 ArrayList 中添加數(shù)據(jù)并通知適配器，
在onCreate中添加這一行，
staggeredGridAdapter = new StaggeredGridAdapter(StaggeredSearchActivity.this, dataset);
recyclerView.setAdapter(staggeredGridAdapter);
API回調(diào)響應(yīng)的變化：
...
dataset.add(new StaggeredCustomCard(user, userpost, postdate));
循環(huán)后添加以下行
staggeredGridAdapter.notifyDataSetChanged();
適配器的變化
private ArrayList<StaggeredCustomCard> dataSet;
private Context context;
public MyAdapter(ArrayList<StaggeredCustomCard> dataSet, Context context) {
this.data = data;
this.context = context;
}
注意：不要在適配器上創(chuàng)建新對象。
MYYA
TA貢獻1868條經(jīng)驗 獲得超4個贊
這種方法沒有多大意義。一旦您從三個端點之一收到響應(yīng)，您似乎每次都會創(chuàng)建一個新的適配器并將其附加到回收器并使用隨機的“notifyDataSetChanged”...
也許可以考慮使用具有處理業(yè)務(wù)登錄的服務(wù)層和網(wǎng)絡(luò)層的 ViewModel。
當(dāng)網(wǎng)絡(luò)方法之一的回調(diào)從端點響應(yīng)時，ViewModel 更新/發(fā)布 MutableLiveData>...合并三部分數(shù)據(jù)。
該活動只是觀察 ViewModel 的 MutableLiveData 并使用 DiffUtil 來更新回收器中的外觀/卡片。
縹緲止盈
TA貢獻2041條經(jīng)驗 獲得超4個贊
最好的方法是在 onCreate 方法的 StaggeredSearchActivity 中注冊您的 LiveData 并像您一樣監(jiān)聽數(shù)據(jù)庫更改。在每個成功響應(yīng)中，將其結(jié)果保存到?jīng)]有 LiveData 的數(shù)據(jù)庫中。onCreate方法中的LiveData會被觸發(fā)。
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main2);
ViewModel viewModel = ViewModelProviders.of(this, factory).get(ViewModel.class);
viewModel.getEntity().observe(this, entity -> {
if (entity != null) {
adapter.notifyDataSetChanged(entity );
}
});
requestQueue = Volley.newRequestQueue(this);
Intent intent = getIntent();
String searchText = intent.getStringExtra("searchText");
// Three concurrent API GET Calls
getMediumData(searchText);
getExampleData(searchText);
getGoogleData(searchText);
recyclerView = findViewById(R.id.staggered_recycler_view);
staggeredGridLayoutManager = new StaggeredGridLayoutManager(2, LinearLayoutManager.VERTICAL);
recyclerView.setLayoutManager(staggeredGridLayoutManager);
}
ArrayList<StaggeredCustomCard> dataset = new ArrayList<>();
private void getMediumData(String searchText) {
progressBar = findViewById(R.id.progressBar);
progressBar.setVisibility(View.VISIBLE);
String url = UrlConstants.getUrl() + searchText;
JsonObjectRequest jsonObjectRequest = new JsonObjectRequest
(Request.Method.GET, url, null, new Response.Listener<JSONObject>() {
@Override
public void onResponse(JSONObject response) {
StaggeredCustomCardDAO.insert();
// TODO just insert to dataBase
}
}, new Response.ErrorListener() {
@Override
public void onErrorResponse(VolleyError error) {
// TODO: Handle error
progressBar.setVisibility(View.INVISIBLE);
}
});
jsonObjectRequest.setRetryPolicy(new
DefaultRetryPolicy(
DefaultRetryPolicy.DEFAULT_TIMEOUT_MS * 15,
DefaultRetryPolicy.DEFAULT_MAX_RETRIES,
DefaultRetryPolicy.DEFAULT_BACKOFF_MULT));
requestQueue.add(jsonObjectRequest);
}
private void getExampleData(String searchText) {
JsonArrayRequest jsonArrayRequest = new JsonArrayRequest
(Request.Method.GET, url, null, new Response.Listener<JSONArray>() {
@Override
public void onResponse(JSONArray response) {
try {
// TODO just insert to dataBase
StaggeredCustomCardDAO.insert();
} catch (
JSONException e) {
e.printStackTrace();
}
}
}, new Response.ErrorListener() {
@Override
public void onErrorResponse(VolleyError error) {
}
});
jsonArrayRequest.setRetryPolicy(new DefaultRetryPolicy(
DefaultRetryPolicy.DEFAULT_TIMEOUT_MS * 15,
DefaultRetryPolicy.DEFAULT_MAX_RETRIES,
DefaultRetryPolicy.DEFAULT_BACKOFF_MULT));
requestQueue.add(jsonArrayRequest);
}
private void getGoogleData(String searchText) {
JsonObjectRequest jsonObjectRequest = new JsonObjectRequest
(Request.Method.GET, url, null, new Response.Listener<JSONObject>() {
@Override
public void onResponse(JSONObject response) {
// TODO just insert to dataBase
StaggeredCustomCardDAO.insert();
}
}, new Response.ErrorListener() {
@Override
public void onErrorResponse(VolleyError error) {
}
});
jsonObjectRequest.setRetryPolicy(new DefaultRetryPolicy(
DefaultRetryPolicy.DEFAULT_TIMEOUT_MS * 15,
DefaultRetryPolicy.DEFAULT_MAX_RETRIES,
DefaultRetryPolicy.DEFAULT_BACKOFF_MULT));
requestQueue.add(jsonObjectRequest);
}
class ViewModel extends androidx.lifecycle.ViewModel {
private LiveData<StaggeredCustomCard> entity;
public ViewModel(Repository repository) {
entity = repository.getNetworkData();
}
public LiveData<StaggeredCustomCard> getEntity() {
return entity;
}
}
class Repository {
LiveData<StaggeredCustomCard> getNetworkData() {
LiveData<StaggeredCustomCard> localeData = StaggeredCustomCardDAO .getLocaleData();//... todo Read from data base
return localeData;
}
@Dao
public interface StaggeredCustomCardDAO {
@Query("Select * from tbl_staggeredCustomCard ")
LiveData<StaggeredCustomCard> getLocaleData();
@Insert(onConflict = OnConflictStrategy.REPLACE)
void insert(List<StaggeredCustomCard> items);
}
}
達令說
TA貢獻1821條經(jīng)驗 獲得超6個贊
第一種方法：首先我建議您創(chuàng)建一個中央請求隊列。
public class AppController extends Application {
public static final String TAG = AppController.class
.getSimpleName();
private RequestQueue mRequestQueue;
private static AppController mInstance;
@Override
public void onCreate() {
super.onCreate();
mInstance = this;
}
public static synchronized AppController getInstance() {
return mInstance;
}
public RequestQueue getRequestQueue() {
if (mRequestQueue == null) {
mRequestQueue = Volley.newRequestQueue(getApplicationContext());
}
return mRequestQueue;
}
public <T> void addToRequestQueue(Request<T> req, String tag) {
// set the default tag if tag is empty
req.setTag(TextUtils.isEmpty(tag) ? TAG : tag);
getRequestQueue().add(req);
}
public <T> void addToRequestQueue(Request<T> req) {
req.setTag(TAG);
getRequestQueue().add(req);
}
public void cancelPendingRequests(Object tag) {
if (mRequestQueue != null) {
mRequestQueue.cancelAll(tag);
}
}
}
然后將您想要的請求添加到隊列中
// Adding request to request queue
AppController.getInstance().addToRequestQueue(jsonObjReq);
第二種方式：創(chuàng)建一個Generic Volley類和一個接口，使用接口來獲取成功和失敗響應(yīng)。
步驟 1 創(chuàng)建一個單獨的 Volley 類 步驟 2 創(chuàng)建一個用于訪問 volley 類響應(yīng)的接口 步驟 3 為該類創(chuàng)建新對象并發(fā)送所需參數(shù) new PostVolleyJsonRequest(TestVolley.this, TestVolley.this(interfcae), "Submit", url ，參數(shù)）；
類的上下文 用于發(fā)送成功和失敗響應(yīng)的接口 成功時識別的請求類型 url（強制） GET 的參數(shù)（可選） 不需要 通用 volley 類
public class PostVolleyJsonRequest {
private String type;
private Activity act;
private VolleyJsonRespondsListener volleyJsonRespondsListener;
private String networkurl;
private JSONObject jsonObject = null;
private JSONObject params;
public PostVolleyJsonRequest(Activity act, VolleyJsonRespondsListener volleyJsonRespondsListener, String type, String netnetworkUrl,JSONObject params) {
this.act = act;
this.volleyJsonRespondsListener = volleyJsonRespondsListener;
this.type = type;
this.networkurl = netnetworkUrl;
this.params = params;
sendRequest();
}
private void sendRequest() {
Log.d("url", "url" + networkurl);
JsonObjectRequest jsObjRequest = new JsonObjectRequest(Request.Method.POST,networkurl,params,
new Response.Listener<JSONObject>() {
@Override
public void onResponse(JSONObject response) {
Log.e("response", "response " + response);
volleyJsonRespondsListener.onSuccessJson(response, type);
}
},
new Response.ErrorListener() {
@Override
public void onErrorResponse(VolleyError error) {
try {
NetworkResponse response = error.networkResponse;
Log.e("response", "response " + response);
if (response != null) {
int code = response.statusCode;
String errorMsg = new String(response.data);
Log.e("response", "response" + errorMsg);
try {
jsonObject = new JSONObject(errorMsg);
} catch (JSONException e) {
e.printStackTrace();
}
String msg = jsonObject.optString("message");
volleyJsonRespondsListener.onFailureJson(code, msg);
} else {
String errorMsg = error.getMessage();
volleyJsonRespondsListener.onFailureJson(0, errorMsg);
}
} catch (Exception e) {
e.printStackTrace();
}
}
});
jsObjRequest.setRetryPolicy(new DefaultRetryPolicy(
600000,
DefaultRetryPolicy.DEFAULT_MAX_RETRIES,
DefaultRetryPolicy.DEFAULT_BACKOFF_MULT));
RequestQueue requestqueue = Volley.newRequestQueue(act);
requestqueue.add(jsObjRequest);
}
}
Use the interface to get responds message
public interface VolleyJsonRespondsListener {
public void onSuccessJson(JSONObject result, String type);
public void onFailureJson(int responseCode, String responseMessage);
}
在您想要包含多個請求的班級中
public class TestVolley extends AppCompatActivity implements VolleyJsonRespondsListener{
//Your class code goes here
//network request
try {
//parameters
//Context,Interface,Type(to indentify your responds),URL,parameter for your request
//request 1
new PostVolleyJsonRequest(TestVolley.this, TestVolley.this, "Submit", url, params);
//request 2
new PostVolleyJsonRequest(TestVolley.this, TestVolley.this, "AccessData", url_2, params_2);
} catch (Exception e) {
e.printStackTrace()
}
//Methods from Interface
@Override
public void onSuccessJson(JSONObject result, String type) {
//Based on the Type you send get the responds and parse it
switch (type) {
case "Submit":
try {
parseSubmit(result);
} catch (Exception e) {
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