Rxjava 3，retrofit2和多次调用问题

时间：2020-04-28 21:33:06

标签： android retrofit2 android-room rx-java3

我在实现RxJava3 / Retrofit2时遇到麻烦，我需要完成的是：

总体思路是将云数据库同步到设备上的SqLite DB（房间）。 DB可能变大，大约有100,000个寄存器或更多，因此同步过程可能需要一些时间，我的第一个尝试是在一个请求中完成并获取所有寄存器，然后将它们保存到SqLite（Room），但这在某些情况下会，具体取决于设备生成的一些内存不足异常，因此在进行了一些研究之后，我发现RxJava是答案，并且还实现了一些API调用分页。

  1. 首先，我试图进行概念验证，以发出第一个Retrofit调用并显示活动的响应，但是我无法使其正常工作，我被卡住了！

这是我得到的错误： java.lang.ClassCastException: io.reactivex.rxjava3.internal.observers.LambdaObserver cannot be cast to io.reactivex.rxjava3.core.Observable

  1. 我想做的就是在这里寻求帮助；第一次调用时，我可以获取注册总数并定义页数，并在此基础上发送多个Retrofit请求，每当我收到响应（列表 ）时，保存它们到房间。

遵循一些代码

渐变

//Retrofit
implementation 'com.squareup.retrofit2:retrofit:2.8.1'
implementation 'com.squareup.retrofit2:converter-gson:2.8.1'
//Retrofit2 Adapter for RxJava 3
implementation "com.github.akarnokd:rxjava3-retrofit-adapter:3.0.0"
//okhttp3 Logging Interceptor
implementation "com.squareup.okhttp3:logging-interceptor:4.5.0"
//RxJava
implementation "io.reactivex.rxjava3:rxjava:3.0.2"
implementation 'io.reactivex.rxjava3:rxandroid:3.0.

分类项

public class Item {
    private String epc;
    private String barcode;
    private String name;
    private String description;
    private String brand;
    @SerializedName("serial_number")
    private String serialNumber;
    private double cost;
    @SerializedName("fk_item_state")
    private int status;
    @SerializedName("fk_category")
    private int category;
    @SerializedName("fk_location")
    private int location;
    private String parent;
    @SerializedName("responsable")
    private String responsible;
    @SerializedName("purchase_date")
    private String purchaseDate;
    @SerializedName("creation_date")
    private String creationDate;
    @SerializedName("last_update")
    private String lastUpdate;
    @SerializedName("inventory_date")
    private String inventoryDate;
    @SerializedName("last_seen")
    private String lastSeen;
...

ItemSyncDetails类

public class ItemSyncDetails {
    @SerializedName("CurrentPage")
    int currentPage;
    @SerializedName("PageCount")
    int pageCount;
    @SerializedName("PageSize")
    int pageSize;
    @SerializedName("RecordCount")
    int recordCount;
    @SerializedName("Results")
    List<Item> mItemList;
...

界面FrekuencyApi 

import io.reactivex.rxjava3.core.Observable;
import retrofit2.http.GET;
import retrofit2.http.Query;

public interface FrekuencyApi {

    @GET("item")
    Observable<ItemSyncDetails> getItemsPageDetails(
            @Query("pageSize") Integer pageSize,
            @Query("currentPage") Integer currentPage,
            @Query("sortBy") Integer sortBy
    );
...

MainActivity类

import io.reactivex.rxjava3.android.schedulers.AndroidSchedulers;
import io.reactivex.rxjava3.core.Observable;
import io.reactivex.rxjava3.disposables.CompositeDisposable;
import io.reactivex.rxjava3.schedulers.Schedulers;
import okhttp3.Interceptor;
import okhttp3.OkHttpClient;
import okhttp3.Request;
import okhttp3.logging.HttpLoggingInterceptor;
import retrofit2.Retrofit;
import retrofit2.converter.gson.GsonConverterFactory;
...

public class MainActivity extends AppCompatActivity {

    private TextView tvResult;
    private Button send;
    private ProgressDialog mProgressDialog;
    private ItemSyncDetails mItemSyncDetails;
    private List<Item> mItemsList;
    private CompositeDisposable disposables = new CompositeDisposable();
    private FrekuencyApi frekuencyApi;
    private Retrofit retrofit;
    private int mNumPages;
    private CompositeDisposable compositeDisposable;
    private HttpLoggingInterceptor logging;

    private static final String TAG = "MainActivity";
    private Object handleResults;


    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);

        tvResult = findViewById(R.id.tv_result);
        send = findViewById(R.id.btnSend);
        mItemSyncDetails = new ItemSyncDetails();
        mProgressDialog = new ProgressDialog(this);

        mItemsList = new ArrayList<Item>();

        HttpLoggingInterceptor interceptor = new HttpLoggingInterceptor();
        interceptor.setLevel(HttpLoggingInterceptor.Level.BODY);
        OkHttpClient client = new OkHttpClient.Builder()
                .addInterceptor(interceptor)
                .addNetworkInterceptor(new Interceptor() {
                    @Override
                    public okhttp3.Response intercept(Chain chain) throws IOException {
                        Request request = chain.request().newBuilder()
                                .build();
                        return chain.proceed(request);
                    }
                }).build();

        retrofit = new Retrofit.Builder()
                .baseUrl("http://192.168.1.10:82/api/v1.0/")
                .client(client)
                .addCallAdapterFactory(RxJava3CallAdapterFactory.create())
                .addConverterFactory(GsonConverterFactory.create())
                .build();

        send.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                //TODO: EVENTO AL HACER CLICK EN BOTON
                getRecordsCount();
            }
        });
    }

    private void getRecordsCount(){
        FrekuencyApi frekuencyApi = retrofit.create(FrekuencyApi.class);
        Observable<ItemSyncDetails> observable = (Observable<ItemSyncDetails>) frekuencyApi.getRecordsCount(1,1,1)
                .subscribeOn(Schedulers.io())
                .retry(3)
                .observeOn(AndroidSchedulers.mainThread())
                .subscribe(this::HandleResults, this::handleError );
    }

    private void HandleResults(ItemSyncDetails itemSyncDetails) {
        this.mItemSyncDetails = itemSyncDetails;
        int pageSize = 100;
        int numPages = itemSyncDetails.getPageCount()/pageSize;
        if (itemSyncDetails.getRecordCount() < pageSize || itemSyncDetails.getRecordCount()%pageSize != 0){
            numPages++;
        }
        this.mNumPages = numPages;
        tvResult.append("Page size: " + pageSize + "\n");
        tvResult.append("Page number: " + this.mNumPages + "\n");
        tvResult.append("Total items: " + itemSyncDetails.getRecordCount() + "\n");
    }

    private void handleError(Throwable throwable) {
        Log.e("Observer", ""+ throwable.toString());
        Toast.makeText(this, "ERROR DE CONEXION",
                Toast.LENGTH_LONG).show();
    }
...

错误日志

D/AndroidRuntime: Shutting down VM
E/AndroidRuntime: FATAL EXCEPTION: main
    Process: com.frekuency.retrofitapptest, PID: 9120
    java.lang.ClassCastException: io.reactivex.rxjava3.internal.observers.LambdaObserver cannot be cast to io.reactivex.rxjava3.core.Observable
        at com.frekuency.retrofitapptest.views.MainActivity.getRecordsCount(MainActivity.java:110)
        at com.frekuency.retrofitapptest.views.MainActivity.access$000(MainActivity.java:39)
        at com.frekuency.retrofitapptest.views.MainActivity$2.onClick(MainActivity.java:98)
        at android.view.View.performClick(View.java:5273)
        at android.view.View$PerformClick.run(View.java:21315)
        at android.os.Handler.handleCallback(Handler.java:743)
        at android.os.Handler.dispatchMessage(Handler.java:95)
        at android.os.Looper.loop(Looper.java:150)
        at android.app.ActivityThread.main(ActivityThread.java:5659)
        at java.lang.reflect.Method.invoke(Native Method)
        at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:822)
        at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:712)
D/OkHttp: --> GET http://192.168.1.10:82/api/v1.0/item?pageSize=1&currentPage=1&sortBy=1
    --> END GET
I/Process: Sending signal. PID: 9120 SIG: 9
I/System: core_booster, getBoosterConfig = false

json--http://192.168.1.10:82/api/v1.0/item?pageSize=1&currentPage=1&sortBy=1 

{
  Results: [
  {
    epc: "202020202020202030303031",
    barcode: "0001",
    name: "Televisor Samnsung",
    description: "0001",
    creation_date: "2020-02-26T10:55:06",
    last_update: "2020-02-26T10:55:06",
    last_seen: "2020-02-26T10:55:06",
    brand: "Samnsung",
    serial_number: "0001",
    parent: "",
    fk_category: 1,
    responsable: "",
    purchase_date: "2020-02-26T10:55:06",
    cost: 0,
    fk_location: 1008,
    fk_item_state: 1,
    inventory_date: "2020-02-26T10:55:06"
  }
 ],
 CurrentPage: 1,
 PageCount: 65565,
 PageSize: 1,
 RecordCount: 65565
}

在此先感谢您的帮助。

我对MainActivity类做了一些更改

public class MainActivity extends AppCompatActivity {
...
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);

        tvResult = findViewById(R.id.tv_result);
        send = findViewById(R.id.btnSend);
        mItemSyncDetails = new ItemSyncDetails();
        mProgressDialog = new ProgressDialog(this);

        mItemsList = new ArrayList<Item>();

        HttpLoggingInterceptor interceptor = new HttpLoggingInterceptor();
        interceptor.setLevel(HttpLoggingInterceptor.Level.BODY);
        OkHttpClient client = new OkHttpClient.Builder()
                .addInterceptor(interceptor)
                .addNetworkInterceptor(new Interceptor() {
                    @Override
                    public okhttp3.Response intercept(Chain chain) throws IOException {
                        Request request = chain.request().newBuilder()
                                .build();
                        return chain.proceed(request);
                    }
                }).build();

        retrofit = new Retrofit.Builder()
                .baseUrl("http://192.168.1.10:82/api/v1.0/")
                .client(client)
                .addCallAdapterFactory(RxJava3CallAdapterFactory.create())
                .addConverterFactory(GsonConverterFactory.create())
                .build();

        send.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
              showProgressDialog("Items");
              getRecordsCount();
            }
        });
    }

private void getRecordsCount(){
    retrofit.create(FrekuencyApi.class)
    .getRecordsCount(1,1,1)
            .subscribeOn(Schedulers.io())
            .retry(3)
            .observeOn(AndroidSchedulers.mainThread())
            .subscribe(this::HandleResults, this::handleError,this::getNumPagesHandlerComplete );
}

private void HandleResults(ItemSyncDetails itemSyncDetails) {
    this.mItemSyncDetails = itemSyncDetails;
    int pageSize = 100;
    int numPages = itemSyncDetails.getRecordCount()/pageSize;
    if (itemSyncDetails.getRecordCount() < pageSize || itemSyncDetails.getRecordCount()%pageSize != 0){
        numPages++;
    }
    this.mNumPages = numPages;
    tvResult.append("Tamaño de pagina: " + pageSize + "\n");
    tvResult.append("Numero de paginas: " + this.mNumPages + "\n");
    tvResult.append("Numero total de registros: " + itemSyncDetails.getRecordCount() + "\n");
}

private void getNumPagesHandlerComplete() {
    getAllRecords(mNumPages);
}

private void getAllRecords(int numPages){
    frekuencyApi = retrofit.create(FrekuencyApi.class);
    //numPages: total of pages are the number of times to send the request to API
    Observable.range(1, numPages)
    .concatMap(i -> frekuencyApi.getItemsPageDetails(100,i,1))
            .subscribeOn(Schedulers.newThread())
            .observeOn(AndroidSchedulers.mainThread())
            .subscribe(this::getAllHandleResults, this::handleError,this::handleComplete);
}

private void getAllHandleResults(ItemSyncDetails itemSyncDetails) {
    //TODO: Should it be the right place to save data to DB?
    //Get the progress
    int tmp = getProgress(itemSyncDetails.getPageCount(),
            itemSyncDetails.getCurrentPage(),itemSyncDetails.getPageSize());
    //Update ProgressDialog Progress
    mProgressDialog.setProgress(tmp);
    tvResult.setText("Progreso: "+ tmp + "%\n");
    if (itemSyncDetails.getCurrentPage() == itemSyncDetails.getPageCount()){
        //Showing on screen when last request is done
        tvResult.append("******************\n");
        tvResult.append(itemSyncDetails.getItemList().toString());
        tvResult.append("******************\n");
    }
}

private void handleComplete() {
    //when the last request finished
    tvResult.append("\nProceso de Sincronizacion terminado con exito!");
    closeProgressDialog();
}

private void handleError(Throwable throwable) {
    Log.e("Observer", ""+ throwable.toString());
    tvResult.append("\n******************\n");
    tvResult.append("ERROR DE CONEXION...\n");
    tvResult.append(throwable.toString());
    Toast.makeText(this, "ERROR DE CONEXION",
            Toast.LENGTH_LONG).show();
    closeProgressDialog();
}
...

对MainActivity类进行更改后，基本上有两种方法getRecordsCount（）和getAllRecords（int numPages），每个方法都会触发一个RX Java调用过程，第一个方法调用一个Retrofit调用，并基于该方法的答案第一次调用，调用第二个方法，它将向API发送（n）个请求，其中n是参数numPages，我使用了一个progressDialog进行更新，当孔处理完成时，progressDialog是close（）。在第一个RX Java调用完成的onComplete方法上，它调用了第二个RX Java方法，这时我需要的是：

  1. 如何在一个Rx Java进程中而不是两个调用中将其改进为更优雅的代码？
  2. 我正在考虑在getAllHandleResults（）方法上对数据库进行Room插入调用以获取列表，这是向DB插入的正确位置吗？
  3. 现在，我在getAllHandleResults（）方法上使用concatMap，据我所知，此运算符按顺序执行Retrofit调用，我这样做是因为在尝试RX Java + Retrofit之前，使用Volley + Room + LiveData + ViewModel + AsyncTask，我确实注意到数据库插入一次完成，此操作比Retrofit Call慢，并且一次插入操作需要等待上一次插入完成，所以现在我有使用Room + LiveData + ViewModel + AsyncTask的数据库部分，因此，当从onNext方法调用插入方法（此操作发生在主线程上）时，插入操作将在后台线程中的AsyncTask上执行，您是否有什么建议吗？ DB可以使用RX Java完成吗？您是否有一些网页可以获取相关信息？再次感谢您的帮助。

0 个答案:

没有答案
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