只需加上我的几分钱来帮助你。
- 使用
background thread 从服务中获取数据，因为可能需要一些时间才能获得响应。在 JavaFX 应用程序线程上执行它可能会导致不良的用户体验。在这种情况下，Task 将为您提供帮助。
- 收到回复后，从中构造一个必要的
object / collection of object，您将使用它来更新场景图上的元素。
- 由于
JavaFX Application Thread 是您可以访问live scene graph 元素的唯一线程，因此您不能直接在后台线程中使用它们（使用它们将导致IllegalStateException）。您可以使用Platform.runLater 或调用task 的方法来更新JavaFX 场景图上的数据，这些方法保证会更新FX 应用程序线程上的状态，例如updateProgress(...)、updateMessage(...)、getValue(...) 等.
- 使用您在
Step-2 中构建的object / collection of object 创建（或更新）FX 场景图元素。
- 如果您有一个接受
ObservableList 作为其内容的控件（如TableView 或ListView），您只需绑定 内容和Task 的属性之一，即可更新它们会在执行期间/之后自动执行，具体取决于它们的使用情况。
- 但在你的情况下，既然你有
GridPane，所以我们可能需要更进一步，编写逻辑来创建控件并将它们添加到GridPane。
示例
我创建了一个使用服务的示例，解析 JSON 数据并从中创建一个GridPane。 JSON 中有 list of few people on StackOverflow 和他们的名字、他们的喜好（根据我）和 SO 上的个人资料图片。
它使用后台任务从服务加载 JSON 数据，使用任务的 setOnSucceeded(...) 处理程序将其传递给创建 GridPane 的 createGridPane(onservableList)。
GridPane 的其中一列包含相应人员的个人资料图片。由于下载这些图片可能需要一些时间，因此我为每个用户生成了 multiple threads 到 load the image。
您可以找到source code here。
它使用GSON 作为库将JSON 转换为POJO 类。
import com.google.common.reflect.TypeToken;
import com.google.gson.Gson;
import javafx.application.Application;
import javafx.collections.FXCollections;
import javafx.collections.ObservableList;
import javafx.concurrent.Task;
import javafx.concurrent.WorkerStateEvent;
import javafx.event.EventHandler;
import javafx.geometry.HPos;
import javafx.geometry.Insets;
import javafx.geometry.Pos;
import javafx.geometry.VPos;
import javafx.scene.Node;
import javafx.scene.Scene;
import javafx.scene.control.Button;
import javafx.scene.control.Label;
import javafx.scene.control.ScrollPane;
import javafx.scene.image.Image;
import javafx.scene.image.ImageView;
import javafx.scene.layout.*;
import javafx.stage.Stage;
import java.io.BufferedReader;
import java.io.InputStreamReader;
import java.net.URL;
import java.util.List;
import java.util.concurrent.ExecutorService;
import java.util.concurrent.Executors;
public class ConsumeJSON extends Application {
private ObservableList<PeopleOnSO> listOfPeople;
private static final String JSON_URL = "https://api.myjson.com/bins/3jwmh";
private static final String IMAGE_URL = "http://www.fontspring.com/presentation_20150512/images/ajax_loader_blue_512.gif";
private final ExecutorService executorService = Executors.newCachedThreadPool();
private Image loadImage;
@Override
public void start(Stage stage) throws Exception {
loadImage = new Image(IMAGE_URL);
VBox root = new VBox();
root.setAlignment(Pos.TOP_CENTER);
root.setPadding(new Insets(20));
root.setSpacing(20);
Button button = new Button("Fill GridPane");
root.getChildren().addAll(button);
button.setOnAction(e -> {
// Display loading image
ImageView loading = new ImageView(loadImage);
loading.setFitWidth(60);
loading.setFitHeight(60);
root.getChildren().add(loading);
executorService.submit(fetchList);
});
fetchList.setOnSucceeded(new EventHandler<WorkerStateEvent>() {
@Override
public void handle(WorkerStateEvent t) {
listOfPeople = FXCollections.observableArrayList(fetchList.getValue());
GridPane gridPane = createGridPane(listOfPeople);
//Remove Loading Image and add GridPane
root.getChildren().remove(1);
VBox.setVgrow(gridPane, Priority.ALWAYS);
root.getChildren().add(gridPane);
stage.sizeToScene();
}
});
ScrollPane scrollPane = new ScrollPane(root);
Scene scene = new Scene(scrollPane, 600, 500);
stage.setScene(scene);
stage.setTitle("Load Data from JSON");
stage.show();
stage.setOnCloseRequest(e -> {
executorService.shutdown();
});
}
public GridPane createGridPane(ObservableList<PeopleOnSO> listOfPeople){
GridPane gridPane = new GridPane();
gridPane.setAlignment(Pos.CENTER);
gridPane.setGridLinesVisible(true);
gridPane.setPadding(new Insets(20));
gridPane.setMinHeight(500);
gridPane.setMaxWidth(500);
//Create headings
Label nameHeading = new Label("Name");
nameHeading.setStyle("-fx-font-weight: bold");
Label likeHeading = new Label("Likes");
likeHeading.setStyle("-fx-font-weight: bold");
Label imageHeading = new Label("Image");
imageHeading.setStyle("-fx-font-weight: bold");
gridPane.add(nameHeading, 0, 0);
gridPane.add(likeHeading, 1, 0);
gridPane.add(imageHeading, 2, 0);
// Aligning at center
alignElements(nameHeading, likeHeading, imageHeading);
// Setting Constraints
for (int i = 0; i < 3; i++) {
ColumnConstraints column = new ColumnConstraints(150);
// column.setPercentWidth(80);
gridPane.getColumnConstraints().add(column);
}
for (int i = 0; i < listOfPeople.size(); i++) {
PeopleOnSO people = listOfPeople.get(i);
Label nameLabel = new Label(people.getName());
Label likeLabel = new Label(people.getLike());
ImageView imageView = new ImageView(loadImage);
imageView.setFitHeight(60);
imageView.setFitWidth(60);
//Thread for loading images later
FetchImage fetchImage = new FetchImage(people.getImageUrl());
fetchImage.setOnSucceeded(worker -> {
imageView.setImage((Image) fetchImage.getValue());
});
executorService.submit(fetchImage);
// Adding to GridPane and necessary configuration
gridPane.add(nameLabel, 0, i + 1);
gridPane.add(likeLabel, 1, i + 1);
gridPane.add(imageView, 2, i + 1);
//Aligning at center
alignElements(nameLabel, likeLabel, imageView);
gridPane.getRowConstraints().add(new RowConstraints(80));
}
return gridPane;
}
/**
* Align elements at the center
* @param nodes
*/
private void alignElements(Node ... nodes ) {
for(Node node : nodes) {
GridPane.setHalignment(node, HPos.CENTER);
GridPane.setValignment(node, VPos.CENTER);
}
}
/**
* Task to fetch details from JSONURL
* @param <V>
*/
private Task<List<PeopleOnSO>> fetchList = new Task() {
@Override
protected List<PeopleOnSO> call() throws Exception {
List<PeopleOnSO> list = null;
try {
Gson gson = new Gson();
list = new Gson().fromJson(readUrl(JSON_URL), new TypeToken<List<PeopleOnSO>>() {
}.getType());
} catch (Exception e) {
e.printStackTrace();
}
return list;
}
};
/**
* Task to fetch images for individual ImageViews
* @param <V>
*/
private class FetchImage<V> extends Task<Image> {
private String imageUrl;
public FetchImage(String imageUrl) {
this.imageUrl = imageUrl;
}
@Override
protected Image call() throws Exception {
Image image = new Image(imageUrl);
return image;
}
}
/**
* Read the URL and return the json data
* @param urlString
* @return
* @throws Exception
*/
private static String readUrl(String urlString) throws Exception {
BufferedReader reader = null;
try {
URL url = new URL(urlString);
reader = new BufferedReader(new InputStreamReader(url.openStream()));
StringBuffer buffer = new StringBuffer();
int read;
char[] chars = new char[1024];
while ((read = reader.read(chars)) != -1)
buffer.append(chars, 0, read);
return buffer.toString();
} finally {
if (reader != null)
reader.close();
}
}
private class PeopleOnSO {
private final String name;
private final String like;
private final String imageUrl;
public PeopleOnSO(String name, String like, String imageUrl){
this.name = new String(name);
this.like = new String(like);
this.imageUrl = new String(imageUrl);
}
public String getName() {
return name;
}
public String getLike() {
return like;
}
public String getImageUrl() {
return imageUrl;
}
}
public static void main(String[] args) {
launch(args);
}
}