如何通過下載更新javafx標籤

Question

我正在開發一個下載管理器。我無法更新標籤。我試圖用run()方法下載更新標籤，但發生異常。我如何更新Label.Where我寫更新標籤和ProgressBar的代碼。

import javafx.application.*; 
import javafx.stage.*; 
import javafx.scene.*; 
import javafx.scene.control.*; 
import javafx.scene.layout.*; 
import javafx.geometry.*; 
import javafx.scene.effect.*; 
import javafx.scene.paint.*; 
import javafx.event.*; 
import javafx.scene.image.*; 
import java.util.*; 
import java.io.*; 
import java.net.*; 
import java.util.*; 
import java.io.*; 
import java.net.*; 
public class DownloadFile implements Runnable 
{ 
Thread thread; 
private static final int BUFFER_SIZE=1024; 
public final int DOWNLOADING=0; 
public final int PAUSED=1; 
public final int COMPLETE=2; 
public final int CANCELLED=3; 
public final int ERROR=4; 
private URL url; 
private int size; 
private int downloaded; 
private int status; 
static int check=0; 
Stage dStage; 
Label fileNameLabel; 
Label fileNameValueLabel; 
Label statusLabel; 
Label statusValueLabel; 
Label fileSizeLabel; 
Label fileSizeValueLabel; 
Label downloadedLabel; 
Label downloadedValueLabel; 
Label speedLabel; 
Label speedValueLabel; 
Label timeRemainingLabel; 
Label timeRemainingValueLabel; 
ProgressBar downloadingProgressBar; 
public void startStage() 
{ 
    dStage=new Stage(); 
    dStage.setResizable(false); 
    dStage.getIcons().add(new Image("images\\webdownloadmanager.png")); 
    dStage.setTitle("Friends Download Manager"); 
    BorderPane root=new BorderPane(); 
    root.setPadding(new Insets(10, 10, 10, 10)); 
    Scene dScene=new Scene(root,520,250); 
    dStage.setScene(dScene); 
    Label titleLabel=new Label(" Download Status "); 
    titleLabel.setStyle("-fx-background-color:#FFFFFF;"); 
    GridPane gpCenter=new GridPane(); 
    gpCenter.setPadding(new Insets(10, 10, 10, 10)); 
    gpCenter.setStyle("-fx-background-color:#FFFFFF;"); 
    fileNameLabel =new Label("File Name"); 
    fileNameValueLabel=new Label(); 
    statusLabel =new Label("Status"); 
    statusValueLabel =new Label(); 
    fileSizeLabel =new Label("File size"); 
    fileSizeValueLabel =new Label(); 
    downloadedLabel =new Label("Downloaded"); 
    downloadedValueLabel =new Label(); 
    speedLabel =new Label("Speed"); 
    speedValueLabel =new Label(); 
    timeRemainingLabel =new Label("Time Remaining "); 
    timeRemainingValueLabel =new Label(); 
    gpCenter.add(fileNameLabel,0,0); 
    gpCenter.add(fileNameValueLabel,2,0); 
    gpCenter.add(statusLabel ,0,3); 
    gpCenter.add(statusValueLabel ,2,3); 
    gpCenter.add(fileSizeLabel ,0,4); 
    gpCenter.add(fileSizeValueLabel ,2,4); 
    gpCenter.add(downloadedLabel ,0,5); 
    gpCenter.add(downloadedValueLabel ,2,5); 
    gpCenter.add(speedLabel ,0,6); 
    gpCenter.add(speedValueLabel ,2,6); 
    gpCenter.add(timeRemainingLabel ,0,7); 
    gpCenter.add(timeRemainingValueLabel ,2,7); 
    AnchorPane anchorPaneBottom=new AnchorPane(); 
    VBox vb=new VBox(); 
    HBox progressBarHB=new HBox(); 
    progressBarHB.setPadding(new Insets(10, 0, 30, 0)); 
    downloadingProgressBar=new ProgressBar(); 
    downloadingProgressBar.prefWidthProperty().bind(root.widthProperty().subtract(20)); 
    progressBarHB.getChildren().add(downloadingProgressBar); 
    vb.getChildren().addAll(progressBarHB); 
    HBox labelHB=new HBox(); 
    Label message=new Label("Whould you like to perform ?"); 
    labelHB.getChildren().add(message); 
    HBox buttonHB=new HBox(); 
    buttonHB.setSpacing(20); 
    Button startPauseButton=new Button("Start"); 
    startPauseButton.setPrefWidth(80); 
    Button cancelButton=new Button("Cancel"); 
    cancelButton.setPrefWidth(80); 
    buttonHB.getChildren().addAll(startPauseButton,cancelButton); 
    anchorPaneBottom.getChildren().addAll(vb,labelHB,buttonHB); 
    AnchorPane.setTopAnchor(buttonHB, 40.0); 
     AnchorPane.setRightAnchor(buttonHB,30.0); 
    AnchorPane.setLeftAnchor(labelHB,40.0); 
    AnchorPane.setTopAnchor(labelHB,40.0); 
     AnchorPane.setTopAnchor(vb, 0.0); 
    root.setTop(titleLabel); 
    root.setCenter(gpCenter); 
    root.setBottom(anchorPaneBottom); 
    dStage.show(); 
    dStage.setOnCloseRequest(new EventHandler<WindowEvent>() 
    { 
     public void handle(WindowEvent we) 
     { /* 
      if(WebDownloadManager.check==0) 
       Platform.exit(); 
      else 
       check--; 
      */ 
     } 
    });  
} 
public DownloadFile(URL url) 
{ 
    this.url=url; 
    size=-1; 
    downloaded=0; 
    status=DOWNLOADING; 
    startStage(); 
    fileNameValueLabel.setText(getFileName(url).toString()); 
    statusValueLabel.setText("Waiting.."); 
    fileSizeValueLabel.setText(getSize()+""); 
    downloadedValueLabel.setText("0.00 MB ("+getProgress()+" %)"); 
    speedValueLabel.setText("450.123 KB/sec"); 
    timeRemainingValueLabel.setText("1 hr "); 
    download(); 
} 
public String getUrl() 
{ 
    return url.toString(); 
} 
public int getSize() 
{ 
    return size; 
} 
public float getProgress() 
{ 
    float tf=(downloaded/size)*100; 
    return tf; 

} 
public int getStatus() 
{ 
    return status; 
} 
public void pause() 
{ 
    status=PAUSED; 
} 
public void resume() 
{ 
    status=DOWNLOADING; 
    download(); 
} 
public void cancel() 
{ 
    status=CANCELLED; 
} 
private void error() 
{ 
    status=ERROR; 
} 
private void download() 
{ 
    thread=new Thread(this); 
    thread.start(); 
} 
private String getFileName(URL url) 
{ 
    String fileName=url.getFile(); 
    String str=fileName.substring(fileName.lastIndexOf('/')+1).replace("%20"," "); 
    return str; 
} 
public void run() 
{ 

    RandomAccessFile file=null; 
    InputStream stream=null; 
    try 
    { 
     HttpURLConnection conn=(HttpURLConnection)url.openConnection(); 
     conn.setRequestProperty("Range","bytes="+downloaded+"-"); 
     conn.connect(); 
     if(conn.getResponseCode()/100!=2) 
     { 
      error(); 
     } 
     int contentLength=conn.getContentLength(); 
     if(contentLength<1) 
     { 
      error(); 
     } 
     if(size==-1) 
     { 
      size=contentLength; 
     } 

     file=new RandomAccessFile(getFileName(url),"rw"); 
     file.seek(downloaded); 
     stream=conn.getInputStream(); 
     while(status==DOWNLOADING) 
     { 
      statusValueLabel.setText("Running.."); 
      byte buffer[]; 
      if(size-downloaded>BUFFER_SIZE) 
      { 
       buffer=new byte[BUFFER_SIZE]; 
      } 
      else 
      { 
       buffer=new byte[size-downloaded]; 
      } 
      int read=stream.read(buffer); 
      if(read== -1) 
      { 
       break; 
      } 
      file.write(buffer,0,read); 
      downloaded+=read; 

     } 
     if(status==DOWNLOADING) 
     { 
      status=COMPLETE; 
     } 
    } 
    catch(Exception exp) 
    { 
     error(); 
     System.out.println("Error :"+exp); 
    } 
    finally 
    { 
     if(file!=null) 
     { 
      try 
      { 
       file.close(); 
      } 
      catch(Exception e) 
      { 

      } 
     } 
     if(stream!=null) 
     { 
      try 
      { 
       stream.close(); 
      } 
      catch(Exception exp) 
      { 

      } 
     } 
    } 
} 

}

Answer 1

不能FX線程以外更新JavaFX的元素。你需要做的是：

Platform.runLater(new Runnable(updateMethod());