java - 将字符串转换为数组再转换为 Observable 中的对象

Question

我正在尝试使用 CloseableHttpAsyncClient要从端点读取，将字符串编码为对象(使用 javax.json)，然后将对象上的数组转换为它的各个组件:

CloseableHttpAsyncClient client = HttpAsyncClientBuilder.create().setDefaultCredentialsProvider(provider).build();

client.start();

Observable<ObservableHttpResponse> observable = ObservableHttp.createRequest(HttpAsyncMethods.createGet(uri), client)
            .toObservable();

Observable<JsonArray> shareable = observable.flatMap(response -> response.getContent().map(bb -> {
        String stringVal = new String(bb);
        StringReader reader = new StringReader(stringVal);
        JsonObject jobj = Json.createReader(reader).readObject();
        return jobj.getJsonArray("elements");
    })).share();

我需要获取Json数组，然后过滤数组的对象:

Observable<JsonObject> firstStream = shareable.filter(item -> item.getString("type").equals("TYPE_1"));
Observable<JsonObject> secondStream = shareable.filter(item -> item.getString("type").equals("TYPE_2"));
Observable<JsonObject> thirdStream = shareable.filter(item -> item.getString("type").equals("TYPE_3"));

如何转换 Observable<JsonArray>进入 ObservableJsonObject> ？

因为它是异步的，所以我不能使用 forEach 创建某种数组来缓冲数据。

更新:

所以考虑使用 CloseableHttpAsyncClient 可能不是我想要实现的最佳解决方案 - 我今天早上意识到(在所有事情的淋浴间)我正在尝试异步处理数据然后进行异步电话。

理想情况下，调用 CloseableHttpClient(同步)并将数据传递给 Observable 进行过滤将是一种更理想的方法(我不需要第一次调用来管理多个 http 调用)。

    CloseableHttpClient client = HttpClientBuilder.create().setDefaultCredentialsProvider(provider).build();

    StringBuffer result = new StringBuffer();

    try {
        HttpGet request = new HttpGet(uri);
        HttpResponse response = client.execute(request);

        BufferedReader rd = new BufferedReader(
                new InputStreamReader(response.getEntity().getContent()));

        String line;
        while ((line = rd.readLine()) != null) {
            result.append(line);
        }
    } catch(ClientProtocolException cpe) { } catch(IOException ioe) {  }

    StringReader reader = new StringReader(result.toString());
    JsonObject jobj = Json.createReader(reader).readObject();
    JsonArray elements = jobj.getJsonArray("elements");

    List<JsonObject> objects = elements.getValuesAs(JsonObject.class);


    Observable<JsonObject> shareable = Observable.from(objects).share();

    Observable<JsonObject> firstStream = shareable.filter(item -> item.getString("type").equals("TYPE_1"));
    Observable<JsonObject> secondStream = shareable.filter(item -> item.getString("type").equals("TYPE_2"));
    Observable<JsonObject> thirdStream = shareable.filter(item -> item.getString("type").equals("TYPE_3"));


    firstStream.subscribe(record -> {
        //connect to SOTS/Facebook and store the results
        ByteArrayOutputStream baos = new ByteArrayOutputStream();
        Json.createWriter(baos).writeObject(record);
        System.out.println(baos.toString());
    });

    secondStream.subscribe(record -> {
        ByteArrayOutputStream baos = new ByteArrayOutputStream();
        Json.createWriter(baos).writeObject(record);
        System.out.println(baos.toString());
    });

    thirdStream.subscribe(record -> {
        ByteArrayOutputStream baos = new ByteArrayOutputStream();
        Json.createWriter(baos).writeObject(record);
        System.out.println(baos.toString());
    });

Answer 1

试试这段代码:

    String myjson = "{\"elements\": [{\"text\":\"Obj1\"},{\"text\":\"Obj2\"}, {\"text\":\"Obj3\"}]}";

    Observable.just(myjson)
            .map(jsonStr -> new StringReader(myjson))
            .map(reader -> Json.createReader(reader).readObject())
            .map(jobj -> jobj.getJsonArray("elements"))
            .map(elements -> elements.toArray(new JsonObject[elements.size()]))
            .flatMap(jsonObjects -> Observable.from(jsonObjects))
            .subscribe(
                    (jsonObject) -> System.out.println(jsonObject.getString("text")),
                    throwable -> throwable.printStackTrace(),
                    () -> System.out.println("On complete"));

结果:

07-22 12:19:22.362 8032-8032/com.mediamanagment.app I/System.out﹕ Obj1
07-22 12:19:22.362 8032-8032/com.mediamanagment.app I/System.out﹕ Obj2
07-22 12:19:22.362 8032-8032/com.mediamanagment.app I/System.out﹕ Obj3

注意:
您应该使用此依赖项:

compile 'org.glassfish:javax.json:1.0.4'

取而代之的是:

compile 'javax.json:javax.json-api:1.0'

如果您将使用 'javax.json:javax.json-api:1.0'，您将得到 javax.json.JsonException: Provider org.glassfish.json.JsonProviderImpl not found在步骤:

.map(reader -> Json.createReader(reader).readObject())

因此，请使用'org.glassfish:javax.json:1.0.4'

更新:此外，而不是

.flatMap(jsonObjects -> Observable.from(jsonObjects))

您可以使用flatMapIterable( ):

.flatMapIterable(jsonObjects -> jsonObjects)