java - 安卓 : Notified when all Async calls are completed

Question

我被困在一个实现中。我正在开发一个 Android 应用程序，我在其中集成了第 3 方 SDK(库)并调用其 API。 SDK的函数调用实际上是Async调用(库调用的WebAPI调用)给出一个响应(成功或失败)。

现在，我试图通过代码来解释这种情况。

for (................) {
    AsyncAPICall (SuccessListener { 
        onSuccess() {
            for (................) {
                AsyncAPICall (SuccessListener { 
                    onSuccess() {
                        for (................) {
                            AsyncAPICall (SuccessListener, ErrorListener);
                        }
                    }
                }, ErrorListener);
            }
        }
    }, ErrorListener);
}

我想要通知或回调，或者被通知所有异步调用都已完成。异步调用在不同的线程中运行，并且由于 for 循环，许多调用将同时完成。

是否有任何机制可以在所有异步调用收到响应或我需要手动执行某些操作后通知我？

有什么帮助吗？

Answer 1

@Khushbu Shah，我更新了我的答案，它有点变化:)(它很长)。
为了确保它正常工作，我创建了一个独立的工作示例并使用此 API 进行测试:https://jsonplaceholder.typicode.com/posts/1

private final Retrofit retrofit = new Retrofit.Builder()
            .baseUrl("https://jsonplaceholder.typicode.com/posts/")
            .addConverterFactory(GsonConverterFactory.create())
            .addCallAdapterFactory(RxJavaCallAdapterFactory.create())
            .build();

    private final RestPostsService restPostsService = retrofit.create(RestPostsService.class);

    private Observable<Posts> getPostById(int id) {
        return restPostsService.getPostsById(id);
    }

解决方案一:在顺序调用多个任务时使用，前一个任务的结果永远是下一个任务的输入

getPostById(1)
                .concatMap(posts1 -> {
                    //get post 1 success
                    return getPostById(posts1.getId() + 1);
                })
                .concatMap(posts2 -> {
                    //get post 2 success
                    return getPostById(posts2.getId() + 1);
                })
                .concatMap(posts3 -> {
                    //get post 3success
                    return getPostById(posts3.getId() + 1);
                })
                .subscribeOn(Schedulers.io())
                .observeOn(AndroidSchedulers.mainThread())
                .subscribe(finalPosts -> {
                    //get post 4 success
                    Toast.makeText(this, "Final result: " + finalPosts.getId() + " - " + finalPosts.getTitle(),
                            Toast.LENGTH_LONG).show();
                });

解决方案2:在顺序调用多个任务时使用，之前任务的所有结果作为最终任务的输入(例如:上传头像后和封面图片，调用 api 以使用这些图片 URL 创建新用户):

Observable
                .zip(getPostById(1), getPostById(2), getPostById(3), (posts1, posts2, posts3) -> {
                    //this method defines how to zip all separate results into one
                    return posts1.getId() + posts2.getId() + posts3.getId();
                })
                .flatMap(finalPostId -> {
                    //after get all first three posts, get the final posts,
                    // the final posts-id is sum of these posts-id
                    return getPostById(finalPostId);
                })
                .subscribeOn(Schedulers.io())
                .observeOn(AndroidSchedulers.mainThread())
                .subscribe(finalPosts -> {
                    Toast.makeText(this, "Final posts: " + finalPosts.getId() + " - " + finalPosts.getTitle(),
                            Toast.LENGTH_SHORT).show();
                });

AndroidManifest

 <uses-permission android:name="android.permission.INTERNET"/>

root build.gradle

// Top-level build file where you can add configuration options common to all sub-projects/modules.

buildscript {
    repositories {
        jcenter()
    }
    dependencies {
        classpath 'com.android.tools.build:gradle:2.3.3'
        classpath 'me.tatarka:gradle-retrolambda:3.2.0'
        classpath 'me.tatarka.retrolambda.projectlombok:lombok.ast:0.2.3.a2'

        // NOTE: Do not place your application dependencies here; they belong
        // in the individual module build.gradle files
    }

    // Exclude the version that the android plugin depends on.
    configurations.classpath.exclude group: 'com.android.tools.external.lombok'
}

allprojects {
    repositories {
        jcenter()
    }
}

task clean(type: Delete) {
    delete rootProject.buildDir
}

app/build.gradle

apply plugin: 'me.tatarka.retrolambda'
apply plugin: 'com.android.application'

android {
    compileSdkVersion 26
    buildToolsVersion "26.0.1"
    defaultConfig {
        applicationId "app.com.rxretrofit"
        minSdkVersion 15
        targetSdkVersion 26
        versionCode 1
        versionName "1.0"
        testInstrumentationRunner "android.support.test.runner.AndroidJUnitRunner"
    }
    buildTypes {
        release {
            minifyEnabled false
            proguardFiles getDefaultProguardFile('proguard-android.txt'), 'proguard-rules.pro'
        }
    }

    compileOptions {
        sourceCompatibility JavaVersion.VERSION_1_8
        targetCompatibility JavaVersion.VERSION_1_8
    }
}

dependencies {
    compile fileTree(dir: 'libs', include: ['*.jar'])
    androidTestCompile('com.android.support.test.espresso:espresso-core:2.2.2', {
        exclude group: 'com.android.support', module: 'support-annotations'
    })
    compile 'com.android.support:appcompat-v7:26.+'
    compile 'com.android.support.constraint:constraint-layout:1.0.2'
    testCompile 'junit:junit:4.12'

    provided 'org.projectlombok:lombok:1.16.6'
    compile 'com.squareup.retrofit2:retrofit:2.3.0'
    compile 'com.squareup.retrofit2:converter-gson:2.3.0'
    compile 'com.squareup.retrofit2:adapter-rxjava:2.3.0'
    compile 'io.reactivex:rxandroid:1.2.1'
}

模型

package app.com.rxretrofit;
import com.google.gson.annotations.SerializedName;
/**
 * -> Created by Think-Twice-Code-Once on 11/26/2017.
 */
public class Posts {
    @SerializedName("userId")
    private int userId;
    @SerializedName("id")
    private int id;
    @SerializedName("title")
    private String title;
    @SerializedName("body")
    private String body;
    public int getUserId() {
        return userId;
    }
    public void setUserId(int userId) {
        this.userId = userId;
    }
    public int getId() {
        return id;
    }
    public void setId(int id) {
        this.id = id;
    }
    public String getTitle() {
        return title;
    }
    public void setTitle(String title) {
        this.title = title;
    }
    public String getBody() {
        return body;
    }
    public void setBody(String body) {
        this.body = body;
    }
}

RestPostService.java

package app.com.rxretrofit;

import retrofit2.http.GET;
import retrofit2.http.Path;
import rx.Observable;

/**
 * -> Created by Think-Twice-Code-Once on 11/26/2017.
 */

public interface RestPostsService {

    @GET("{id}")
    Observable<Posts> getPostsById(@Path("id") int id);
}

顺便说一下，使用Rx + Retrofit + Dagger + MVP 模式 是一个很好的组合。