为什么JavaFX中的onSuseded（…）方法不是第一次调用？

我正在尝试从服务器加载数据。然后通过JavaFX视图显示加载的数据。我使用一个服务来执行网络操作，我使用ApacheHttpClient来实现这一点。起初，我认为这个bug与网络有关。我已经做了一些穴居人式的调试，并逐渐意识到错误与服务有关。奇怪的是，服务在第二次运行时调用onSucceeded（）方法（不同的实例，我没有重新启动服务）。我无法理解为什么服务只在第二次调用onSucceeded（）方法

下面是我为执行网络操作而实现的服务类

public class HttpClientService extends Service<String> {

    private static final String TAG = HttpClientService.class.getName();
    private static final Logger logger = Logger.getLogger(TAG);

    private ObjectProperty<URL> url = new SimpleObjectProperty<>();
    private ObservableList<NameValuePair> parameters = FXCollections.observableArrayList();

    public HttpClientService(String url, Map<String, String> map) throws MalformedURLException {
        setUrl(new URL(url));
        for (String name : map.keySet()) {
            String value = map.get(name);
            parameters.add(new BasicNameValuePair(name, value));
        }
    }

    public HttpClientService(String url, NameValuePair ... parameters) throws MalformedURLException {
        setUrl(new URL(url));
        getParameters().addAll(parameters);
    }

    public HttpClientService(URL url, NameValuePair ... parameters) {
        setUrl(url);
        getParameters().addAll(parameters);
    }

    protected Task<String> createTask() {
        return new HttpClientTask(getUrl(), getParameters());
    }

    public URL getUrl() {
        return url.get();
    }

    public ObjectProperty<URL> urlProperty() {
        return url;
    }

    public void setUrl(URL url) {
        this.url.set(url);
    }

    public ObservableList<NameValuePair> getParameters() {
        return parameters;
    }

    public void setParameters(ObservableList<NameValuePair> parameters) {
        this.parameters = parameters;
    }

    @Override
    protected void succeeded() {
        System.out.println("## Successful...");
    }

    @Override
    protected void failed() {
        Throwable exception = getException();

        System.out.println("Error: Failed to download guest profiles.");
        exception.printStackTrace();
    }

    @Override
    protected void cancelled() {
        System.out.println("HttpClientService was stopped.");
    }

    @Override
    protected void running() {
        logger.log(Level.INFO, "Running service...");
    }
}

公共类HttpClientService扩展服务{
私有静态最终字符串标记=HttpClientService.class.getName（）；
专用静态最终记录器=Logger.getLogger（标记）；
private ObjectProperty url=新的SimpleObjectProperty（）；
私有ObservableList参数=FXCollections.observableArrayList（）；
公共HttpClientService（字符串url、映射映射）引发错误的异常{
setUrl（新URL（URL））；
for（字符串名称：map.keySet（））{
字符串值=map.get（名称）；
添加（新的BasicNameValuePair（名称、值））；
}
}
公共HttpClientService（字符串url、NameValuePair…参数）引发畸形的异常{
setUrl（新URL（URL））；
getParameters（）.addAll（参数）；
}
公共HttpClientService（URL、NameValuePair…参数）{
setUrl（url）；
getParameters（）.addAll（参数）；
}
受保护的任务createTask（）{
返回新的HttpClientTask（getUrl（），getParameters（））；
}
公共URL getUrl（）{
返回url.get（）；
}
公共对象属性urlProperty（）{
返回url；
}
公共无效设置URL（URL）{
this.url.set（url）；
}
公共可观察列表getParameters（）{
返回参数；
}
公共void setParameters（ObservableList参数）{
此参数=参数；
}
@凌驾
受保护的无效已成功（）{
System.out.println（“成功…”）；
}
@凌驾
受保护的void失败（）{
Throwable exception=getException（）；
System.out.println（“错误：未能下载来宾配置文件。”）；
异常。printStackTrace（）；
}
@凌驾
受保护的作废已取消（）{
System.out.println（“HttpClientService已停止”）；
}
@凌驾
受保护的空运行（）{
logger.log（Level.INFO，“正在运行的服务…”）；
}
}

下面是调用服务并将数据注入视图的方法

private void loadBlocks() {
    try {
        // TODO: Get the property identifier and set!
        Integer propertyIdentifier = 1;

        Map<String, String> parameters = new HashMap<>();
        parameters.put("property", propertyIdentifier.toString());

        HttpClientService service = new HttpClientService(UrlPath.ADMINISTRATION_PROPERTY_BLOCK_LIST_ALL, parameters);
        service.setOnSucceeded(workerStateEvent -> {
            logger.log(Level.INFO, "Successfully loaded blocks");

            try {
                String result = (String)workerStateEvent.getSource().getValue();
                logger.log(Level.INFO, result);

                List<Block> blocks = mapper.readValue(result, new TypeReference<ArrayList<Block>>(){});

                ObservableList<Block> items = blocksTableView.getItems();
                items.clear();
                items.addAll(blocks);

                NotificationHelper.postNotification(eventBus, "Successfully loaded blocks", 500);
            }
            catch (IOException exception) {
                exception.printStackTrace();
            }
        });
        service.stateProperty().addListener((observableValue, state, t1) -> System.out.println(t1));
        service.start();
    }
    catch (MalformedURLException exception) {
        exception.printStackTrace();
    }
}

private void加载块（）{
试一试{
//TODO:获取属性标识符并设置！
整数propertyIdentifier=1；
映射参数=新的HashMap（）；
parameters.put（“property”，propertyIdentifier.toString（））；
HttpClientService服务=新的HttpClientService（UrlPath.ADMINISTRATION\u PROPERTY\u BLOCK\u LIST\u ALL，参数）；
service.setOnSucceed（workerStateEvent->{
logger.log（Level.INFO，“已成功加载块”）；
试一试{
字符串结果=（字符串）workerStateEvent.getSource（）.getValue（）；
logger.log（Level.INFO，result）；
List blocks=mapper.readValue（结果，new TypeReference（）{}）；
ObservableList items=blocksTableView.getItems（）；
items.clear（）；
项目。添加所有（块）；
postNotification（事件总线，“成功加载块”，500）；
}
捕获（IOException异常）{
异常。printStackTrace（）；
}
});
service.stateProperty（）.addListener（（observeValue，state，t1）->System.out.println（t1））；
service.start（）；
}
捕获（畸形异常异常）{
异常。printStackTrace（）；
}
}

这是应用程序的日志

SCHEDULED
RUNNING
Nov 10, 2018 2:28:26 PM com.onecube.pms.client.service.HttpClientService running
INFO: Running service...
Nov 10, 2018 2:28:26 PM com.onecube.pms.client.task.HttpClientTask call
INFO: [Content-Type: application/x-www-form-urlencoded,Content-Length: 10,Chunked: false]
14:28:26.778 [Thread-3] DEBUG org.apache.http.client.protocol.RequestAddCookies - CookieSpec selected: default
14:28:26.794 [Thread-3] DEBUG org.apache.http.client.protocol.RequestAuthCache - Auth cache not set in the context
14:28:26.796 [Thread-3] DEBUG org.apache.http.impl.conn.PoolingHttpClientConnectionManager - Connection request: [route: {}->http://localhost:8080][total kept alive: 0; route allocated: 0 of 100; total allocated: 0 of 200]
14:28:26.809 [Thread-3] DEBUG org.apache.http.impl.conn.PoolingHttpClientConnectionManager - Connection leased: [id: 0][route: {}->http://localhost:8080][total kept alive: 0; route allocated: 1 of 100; total allocated: 1 of 200]
14:28:26.810 [Thread-3] DEBUG org.apache.http.impl.execchain.MainClientExec - Opening connection {}->http://localhost:8080
14:28:26.829 [Thread-3] DEBUG org.apache.http.impl.conn.DefaultHttpClientConnectionOperator - Connecting to localhost/127.0.0.1:8080
14:28:26.830 [Thread-3] DEBUG org.apache.http.impl.conn.DefaultHttpClientConnectionOperator - Connection established 127.0.0.1:63671<->127.0.0.1:8080
14:28:26.831 [Thread-3] DEBUG org.apache.http.impl.execchain.MainClientExec - Executing request POST /administration/property/block/listAll HTTP/1.1
14:28:26.831 [Thread-3] DEBUG org.apache.http.impl.execchain.MainClientExec - Target auth state: UNCHALLENGED
14:28:26.834 [Thread-3] DEBUG org.apache.http.impl.execchain.MainClientExec - Proxy auth state: UNCHALLENGED
14:28:26.836 [Thread-3] DEBUG org.apache.http.headers - http-outgoing-0 >> POST /administration/property/block/listAll HTTP/1.1
14:28:26.836 [Thread-3] DEBUG org.apache.http.headers - http-outgoing-0 >> Content-Length: 10
14:28:26.836 [Thread-3] DEBUG org.apache.http.headers - http-outgoing-0 >> Content-Type: application/x-www-form-urlencoded
14:28:26.836 [Thread-3] DEBUG org.apache.http.headers - http-outgoing-0 >> Host: localhost:8080
14:28:26.836 [Thread-3] DEBUG org.apache.http.headers - http-outgoing-0 >> Connection: Keep-Alive
14:28:26.836 [Thread-3] DEBUG org.apache.http.headers - http-outgoing-0 >> User-Agent: Apache-HttpClient/4.5.6 (Java/11.0.1)
14:28:26.836 [Thread-3] DEBUG org.apache.http.headers - http-outgoing-0 >> Accept-Encoding: gzip,deflate
14:28:26.837 [Thread-3] DEBUG org.apache.http.wire - http-outgoing-0 >> "POST /administration/property/block/listAll HTTP/1.1[\r][\n]"
14:28:26.837 [Thread-3] DEBUG org.apache.http.wire - http-outgoing-0 >> "Content-Length: 10[\r][\n]"
14:28:26.837 [Thread-3] DEBUG org.apache.http.wire - http-outgoing-0 >> "Content-Type: application/x-www-form-urlencoded[\r][\n]"
14:28:26.837 [Thread-3] DEBUG org.apache.http.wire - http-outgoing-0 >> "Host: localhost:8080[\r][\n]"
14:28:26.837 [Thread-3] DEBUG org.apache.http.wire - http-outgoing-0 >> "Connection: Keep-Alive[\r][\n]"
14:28:26.837 [Thread-3] DEBUG org.apache.http.wire - http-outgoing-0 >> "User-Agent: Apache-HttpClient/4.5.6 (Java/11.0.1)[\r][\n]"
14:28:26.837 [Thread-3] DEBUG org.apache.http.wire - http-outgoing-0 >> "Accept-Encoding: gzip,deflate[\r][\n]"
14:28:26.837 [Thread-3] DEBUG org.apache.http.wire - http-outgoing-0 >> "[\r][\n]"
14:28:26.838 [Thread-3] DEBUG org.apache.http.wire - http-outgoing-0 >> "property=1"
14:28:26.845 [Thread-3] DEBUG org.apache.http.wire - http-outgoing-0 << "HTTP/1.1 200 [\r][\n]"
14:28:26.846 [Thread-3] DEBUG org.apache.http.wire - http-outgoing-0 << "Content-Type: application/json;charset=UTF-8[\r][\n]"
14:28:26.846 [Thread-3] DEBUG org.apache.http.wire - http-outgoing-0 << "Transfer-Encoding: chunked[\r][\n]"
14:28:26.846 [Thread-3] DEBUG org.apache.http.wire - http-outgoing-0 << "Date: Sat, 10 Nov 2018 08:58:26 GMT[\r][\n]"
14:28:26.846 [Thread-3] DEBUG org.apache.http.wire - http-outgoing-0 << "[\r][\n]"
14:28:26.846 [Thread-3] DEBUG org.apache.http.wire - http-outgoing-0 << "2[\r][\n]"
14:28:26.846 [Thread-3] DEBUG org.apache.http.wire - http-outgoing-0 << "[][\r][\n]"
14:28:26.846 [Thread-3] DEBUG org.apache.http.wire - http-outgoing-0 << "0[\r][\n]"
14:28:26.846 [Thread-3] DEBUG org.apache.http.wire - http-outgoing-0 << "[\r][\n]"
14:28:26.850 [Thread-3] DEBUG org.apache.http.headers - http-outgoing-0 << HTTP/1.1 200 
14:28:26.850 [Thread-3] DEBUG org.apache.http.headers - http-outgoing-0 << Content-Type: application/json;charset=UTF-8
java.lang.Throwable
    at com.onecube.pms.client.task.HttpClientTask.call(HttpClientTask.java:81)
    at com.onecube.pms.client.task.HttpClientTask.call(HttpClientTask.java:32)
    at javafx.concurrent.Task$TaskCallable.call(Task.java:1425)
    at java.base/java.util.concurrent.FutureTask.run(FutureTask.java:264)
    at javafx.concurrent.Service.lambda$executeTask$6(Service.java:725)
    at java.base/java.security.AccessController.doPrivileged(Native Method)
    at javafx.concurrent.Service.lambda$executeTask$7(Service.java:724)
    at java.base/java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1128)
    at java.base/java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:628)
    at java.base/java.lang.Thread.run(Thread.java:834)
14:28:26.850 [Thread-3] DEBUG org.apache.http.headers - http-outgoing-0 << Transfer-Encoding: chunked
14:28:26.850 [Thread-3] DEBUG org.apache.http.headers - http-outgoing-0 << Date: Sat, 10 Nov 2018 08:58:26 GMT
14:28:26.856 [Thread-3] DEBUG org.apache.http.impl.execchain.MainClientExec - Connection can be kept alive indefinitely
14:28:26.860 [Thread-3] DEBUG org.apache.http.impl.conn.PoolingHttpClientConnectionManager - Connection [id: 0][route: {}->http://localhost:8080] can be kept alive indefinitely
14:28:26.861 [Thread-3] DEBUG org.apache.http.impl.conn.DefaultManagedHttpClientConnection - http-outgoing-0: set socket timeout to 0
14:28:26.861 [Thread-3] DEBUG org.apache.http.impl.conn.PoolingHttpClientConnectionManager - Connection released: [id: 0][route: {}->http://localhost:8080][total kept alive: 1; route allocated: 1 of 100; total allocated: 1 of 200]
SCHEDULED
RUNNING
Nov 10, 2018 2:28:43 PM com.onecube.pms.client.service.HttpClientService running
INFO: Running service...
Nov 10, 2018 2:28:43 PM com.onecube.pms.client.task.HttpClientTask call
INFO: [Content-Type: application/x-www-form-urlencoded,Content-Length: 10,Chunked: false]
14:28:43.429 [Thread-4] DEBUG org.apache.http.client.protocol.RequestAddCookies - CookieSpec selected: default
14:28:43.430 [Thread-4] DEBUG org.apache.http.client.protocol.RequestAuthCache - Auth cache not set in the context
14:28:43.431 [Thread-4] DEBUG org.apache.http.impl.conn.PoolingHttpClientConnectionManager - Connection request: [route: {}->http://localhost:8080][total kept alive: 0; route allocated: 0 of 100; total allocated: 0 of 200]
14:28:43.431 [Thread-4] DEBUG org.apache.http.impl.conn.PoolingHttpClientConnectionManager - Connection leased: [id: 1][route: {}->http://localhost:8080][total kept alive: 0; route allocated: 1 of 100; total allocated: 1 of 200]
14:28:43.431 [Thread-4] DEBUG org.apache.http.impl.execchain.MainClientExec - Opening connection {}->http://localhost:8080
14:28:43.431 [Thread-4] DEBUG org.apache.http.impl.conn.DefaultHttpClientConnectionOperator - Connecting to localhost/127.0.0.1:8080
14:28:43.432 [Thread-4] DEBUG org.apache.http.impl.conn.DefaultHttpClientConnectionOperator - Connection established 127.0.0.1:63675<->127.0.0.1:8080
14:28:43.432 [Thread-4] DEBUG org.apache.http.impl.execchain.MainClientExec - Executing request POST /administration/property/block/listAll HTTP/1.1
14:28:43.432 [Thread-4] DEBUG org.apache.http.impl.execchain.MainClientExec - Target auth state: UNCHALLENGED
14:28:43.433 [Thread-4] DEBUG org.apache.http.impl.execchain.MainClientExec - Proxy auth state: UNCHALLENGED
14:28:43.433 [Thread-4] DEBUG org.apache.http.headers - http-outgoing-1 >> POST /administration/property/block/listAll HTTP/1.1
14:28:43.434 [Thread-4] DEBUG org.apache.http.headers - http-outgoing-1 >> Content-Length: 10
14:28:43.434 [Thread-4] DEBUG org.apache.http.headers - http-outgoing-1 >> Content-Type: application/x-www-form-urlencoded
14:28:43.434 [Thread-4] DEBUG org.apache.http.headers - http-outgoing-1 >> Host: localhost:8080
14:28:43.434 [Thread-4] DEBUG org.apache.http.headers - http-outgoing-1 >> Connection: Keep-Alive
14:28:43.434 [Thread-4] DEBUG org.apache.http.headers - http-outgoing-1 >> User-Agent: Apache-HttpClient/4.5.6 (Java/11.0.1)
14:28:43.434 [Thread-4] DEBUG org.apache.http.headers - http-outgoing-1 >> Accept-Encoding: gzip,deflate
14:28:43.434 [Thread-4] DEBUG org.apache.http.wire - http-outgoing-1 >> "POST /administration/property/block/listAll HTTP/1.1[\r][\n]"
14:28:43.434 [Thread-4] DEBUG org.apache.http.wire - http-outgoing-1 >> "Content-Length: 10[\r][\n]"
14:28:43.434 [Thread-4] DEBUG org.apache.http.wire - http-outgoing-1 >> "Content-Type: application/x-www-form-urlencoded[\r][\n]"
14:28:43.434 [Thread-4] DEBUG org.apache.http.wire - http-outgoing-1 >> "Host: localhost:8080[\r][\n]"
14:28:43.434 [Thread-4] DEBUG org.apache.http.wire - http-outgoing-1 >> "Connection: Keep-Alive[\r][\n]"
14:28:43.434 [Thread-4] DEBUG org.apache.http.wire - http-outgoing-1 >> "User-Agent: Apache-HttpClient/4.5.6 (Java/11.0.1)[\r][\n]"
14:28:43.434 [Thread-4] DEBUG org.apache.http.wire - http-outgoing-1 >> "Accept-Encoding: gzip,deflate[\r][\n]"
14:28:43.435 [Thread-4] DEBUG org.apache.http.wire - http-outgoing-1 >> "[\r][\n]"
14:28:43.435 [Thread-4] DEBUG org.apache.http.wire - http-outgoing-1 >> "property=1"
java.lang.Throwable
    at com.onecube.pms.client.task.HttpClientTask.call(HttpClientTask.java:81)
    at com.onecube.pms.client.task.HttpClientTask.call(HttpClientTask.java:32)
    at javafx.concurrent.Task$TaskCallable.call(Task.java:1425)
    at java.base/java.util.concurrent.FutureTask.run(FutureTask.java:264)
    at javafx.concurrent.Service.lambda$executeTask$6(Service.java:725)
    at java.base/java.security.AccessController.doPrivileged(Native Method)
    at javafx.concurrent.Service.lambda$executeTask$7(Service.java:724)
    at java.base/java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1128)
    at java.base/java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:628)
    at java.base/java.lang.Thread.run(Thread.java:834)
Nov 10, 2018 2:28:43 PM com.onecube.pms.client.controller.administration.room.ManageBlocksController lambda$loadBlocks$2
INFO: Successfully loaded blocks
Nov 10, 2018 2:28:43 PM com.onecube.pms.client.controller.administration.room.ManageBlocksController lambda$loadBlocks$2
INFO: []
14:28:43.444 [Thread-4] DEBUG org.apache.http.wire - http-outgoing-1 << "HTTP/1.1 200 [\r][\n]"
14:28:43.449 [Thread-4] DEBUG org.apache.http.wire - http-outgoing-1 << "Content-Type: application/json;charset=UTF-8[\r][\n]"
14:28:43.449 [Thread-4] DEBUG org.apache.http.wire - http-outgoing-1 << "Transfer-Encoding: chunked[\r][\n]"
14:28:43.449 [Thread-4] DEBUG org.apache.http.wire - http-outgoing-1 << "Date: Sat, 10 Nov 2018 08:58:43 GMT[\r][\n]"
14:28:43.449 [Thread-4] DEBUG org.apache.http.wire - http-outgoing-1 << "[\r][\n]"
14:28:43.449 [Thread-4] DEBUG org.apache.http.wire - http-outgoing-1 << "2[\r][\n]"
14:28:43.449 [Thread-4] DEBUG org.apache.http.wire - http-outgoing-1 << "[][\r][\n]"
14:28:43.449 [Thread-4] DEBUG org.apache.http.wire - http-outgoing-1 << "0[\r][\n]"
14:28:43.449 [Thread-4] DEBUG org.apache.http.wire - http-outgoing-1 << "[\r][\n]"
14:28:43.450 [Thread-4] DEBUG org.apache.http.headers - http-outgoing-1 << HTTP/1.1 200 
14:28:43.450 [Thread-4] DEBUG org.apache.http.headers - http-outgoing-1 << Content-Type: application/json;charset=UTF-8
14:28:43.450 [Thread-4] DEBUG org.apache.http.headers - http-outgoing-1 << Transfer-Encoding: chunked
14:28:43.451 [Thread-4] DEBUG org.apache.http.headers - http-outgoing-1 << Date: Sat, 10 Nov 2018 08:58:43 GMT
14:28:43.452 [Thread-4] DEBUG org.apache.http.impl.execchain.MainClientExec - Connection can be kept alive indefinitely
14:28:43.453 [Thread-4] DEBUG org.apache.http.impl.conn.PoolingHttpClientConnectionManager - Connection [id: 1][route: {}->http://localhost:8080] can be kept alive indefinitely
14:28:43.453 [Thread-4] DEBUG org.apache.http.impl.conn.DefaultManagedHttpClientConnection - http-outgoing-1: set socket timeout to 0
14:28:43.453 [Thread-4] DEBUG org.apache.http.impl.conn.PoolingHttpClientConnectionManager - Connection released: [id: 1][route: {}->http://localhost:8080][total kept alive: 1; route allocated: 1 of 100; total allocated: 1 of 200]
## Successful...
SUCCEEDED

预定
跑步
2018年11月10日下午2:28:26 com.onecube.pms.client.service.HttpClientService正在运行
信息：正在运行服务。。。
2018年11月10日下午2:28:26 com.onecube.pms.client.task.HttpClientTask呼叫
信息：[内容类型：application/x-www-form-urlencoded，内容长度：10，分块：false]
14:28:26.778[Thread-3]DEBUG org.apache.http.client.protocol.RequestAddCookies-CookieSpec selected:默认值
14:28:26.794[Thread-3]调试org.apache.http.client.protocol.RequestAuthCache-未在上下文中设置Auth缓存
14:28:26.796[Thread-3]DEBUG org.apache.http.impl.conn.PoolighttpClientConnectionManager-连接请求：[路由：{}->http://localhost:8080][保持活动状态的总数：0；分配的路由：0/100；分配的总数：0/200]
14:28:26.809[Thread-3]DEBUG org.apache.http.impl.conn.PoolighttpClientConnectionManager-已租用的连接：[id:0][路由：{}->http://localhost:8080][保持活动状态的总数：0；分配的路由：100个中的1个；分配的总数：200个中的1个]
14:28:26.810[Thread-3]DEBUG org.apache.http.impl.execchain.MainClientExec-打开连接{}->http://localhost:8080
14:28:26.829[Thread-3]调试org.apache.http.impl.conn.DefaultHttpClientConnectionOperator-连接到本地主机/127.0.0.1:8080
14:28:26.830[Thread-3]DEBUG org.apache.http.impl.conn.DefaultHttpClientConnectionOperator-连接已建立127.0.0.1:63671127.0.0.1:8080
14:28:26.831[Thread-3]DEBUG org.apache.http.impl.execchain.MainClientExec-执行请求POST/administration/property/block/listAll http/1.1
14:28:26.831[Thread-3]DEBUG org.apache.http.impl.execchain.MainClientExec-目标身份验证状态：未被质询
14:28:26.834[Thread-3]DEBUG org.apache.http.impl.execchain.MainClientExec-代理身份验证状态：未被质询
14:28:26.836[Thread-3]DEBUG org.apache.http.headers-http-outing-0>>POST/administration/property/block/listAll http/1.1
14:28: