SWT:定期更新 GUI [英] SWT: Periodically update GUI

问题描述

我有一个 SWT GUI，它显示从数据库中获取的列表.我希望它做的是定期更新 GUI，这将涉及清除 shell 中的所有内容并再次运行 populateList() 方法.我为此尝试了几种建议的策略，但 GUI 永远不会更新.我最近的尝试是使用 display.asyncexec 创建一个线程来处理这个问题.这似乎给了我一个无效的线程访问错误.

I have an SWT GUI which displays a list taken from a database. What I would like for it to do is to periodically update the GUI, which would involve clearing everything in the shell and running the populateList() method again. I have tried several suggested strategies for this, but the GUI never updates. My latest attempt is using display.asyncexec to create a thread to handle this. This appears to give me an invalid thread access error.

这是我的代码:

package display;
import java.io.IOException;
import java.io.StringReader;
import java.util.ArrayList;
import java.util.Timer;
import java.util.TimerTask;

import object_models.Request;
import util.RestClient.RequestMethod;
import org.eclipse.swt.SWT;
import org.eclipse.swt.graphics.Color;
import org.eclipse.swt.graphics.Font;
import org.eclipse.swt.graphics.Image;
import org.eclipse.swt.graphics.Point;
import org.eclipse.swt.layout.GridData;
import org.eclipse.swt.layout.GridLayout;
import org.eclipse.swt.layout.RowData;
import org.eclipse.swt.layout.RowLayout;
import org.eclipse.swt.widgets.Composite;
import org.eclipse.swt.widgets.Control;
import org.eclipse.swt.widgets.Display;
import org.eclipse.swt.widgets.Label;
import org.eclipse.swt.widgets.Shell;
import org.xmlpull.v1.XmlPullParser;
import org.xmlpull.v1.XmlPullParserException;
import org.xmlpull.v1.XmlPullParserFactory;


import util.RestClient;


public class StoragePickupDisplay {

    protected Shell shell;


    private ArrayList<Request> pendingRequests;
    /**
     * Launch the application.
     * @param args
     */
    public static void main(String[] args) {
        try {
            StoragePickupDisplay window = new StoragePickupDisplay();
            window.open();
        } catch (Exception e) {
            e.printStackTrace();
        }
    }

    /**
     * Open the window.
     * @throws InterruptedException 
     */
    public void open() throws InterruptedException {
        Display display = Display.getDefault();
        createContents();
        populateList();
        shell.open();
        shell.layout();

        while (!shell.isDisposed()) {
            if (!display.readAndDispatch()) {
                display.sleep();
            }



        display.asyncExec(new Runnable() {
            public void run() {
              populateList();
            }
          });
        Thread.sleep(1000);

        }
    }

    /**
     * Create contents of the window.
     */
    protected void createContents() {
        shell = new Shell();
        //shell.setMaximized(true);

        //shell.setFullScreen(true);
        shell.setText("Request Pickup");
        shell.setMaximized(true);


        GridLayout gridLayout= new GridLayout(1,false);

        shell.setLayout(gridLayout);




    }
    protected void populateList(){


        pendingRequests=new ArrayList<Request>();

        RestClient client = new RestClient("http://XXXXXX:8080/StorageWebService/rest/operations/getPendingRequests");

        try {
            client.Execute(RequestMethod.GET);
        } catch (Exception e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        }

        String response = client.getResponse();


        pendingRequests= parseResponse(response);



        for(Request request: pendingRequests){
            Composite row = new Composite(shell,SWT.NONE);

            GridLayout gridLayout = new GridLayout(4,true);
            gridLayout.marginTop=5;
            row.setLayout(gridLayout);
            row.setLayoutData(new GridData(SWT.FILL, SWT.BEGINNING, true, false));


            Composite left = new Composite(row,SWT.NONE);
            left.setLayout(new GridLayout(2,false));
            left.setLayoutData(new GridData(SWT.FILL, SWT.BEGINNING, true, false));

            Label label = new Label(left,SWT.LEFT);
            label.setText(""+request.getId());

            label.setFont(new Font(Display.getDefault(),"Arial",30, SWT.NONE));
            label.setLayoutData(new GridData(SWT.FILL, SWT.BEGINNING, false, false));


            label = new Label(left,SWT.LEFT);
            label.setText(request.getNickname());
            label.setFont(new Font(Display.getDefault(),"Arial",30, SWT.NONE));
            label.setLayoutData(new GridData(SWT.FILL, SWT.BEGINNING, true, false));

            label = new Label(row,SWT.LEFT);
            label.setText(""+request.getNumberCompleted()+" of "+request.getNumberItems()+" Picked");
            label.setFont(new Font(Display.getDefault(),"Arial",30, SWT.NONE));
            label.setLayoutData(new GridData(SWT.FILL, SWT.BEGINNING, true, false));

            label = new Label(row,SWT.LEFT);
            label.setText("Estimated Wait Time:");
            label.setFont(new Font(Display.getDefault(),"Arial",30, SWT.NONE));
            label.setLayoutData(new GridData(SWT.FILL, SWT.BEGINNING, true, false));



            Label separator = new Label(shell, SWT.HORIZONTAL|SWT.SEPARATOR|SWT.PUSH);

            GridData gridData = new GridData(SWT.FILL, SWT.BEGINNING, true, false);
            //gridData.horizontalSpan=4;
            separator.setLayoutData(gridData);



        }

    }
    public ArrayList<Request> parseResponse(String response){
        ArrayList<Request> list = new ArrayList<Request>();
        try {



            XmlPullParser parser = XmlPullParserFactory.newInstance().newPullParser();
            parser.setInput(new StringReader(response));

            int eventType = parser.getEventType();


            Request curRequest = new Request();


            while (eventType != XmlPullParser.END_DOCUMENT) {
                if (eventType == XmlPullParser.START_TAG) {
                    String name = parser.getName();
                    if (name.equalsIgnoreCase("id")) {
                        String text = parser.nextText();
                        curRequest.setId(Integer.parseInt(text));

                    }
                    if (name.equalsIgnoreCase("nickname")) {
                        String text = parser.nextText();
                        curRequest.setNickname(text);

                    }
                    if (name.equalsIgnoreCase("numberCompleted")) {
                        String text = parser.nextText();
                        curRequest.setNumberCompleted(Integer.parseInt(text));

                    }
                    if (name.equalsIgnoreCase("numberItems")) {
                        String text = parser.nextText();
                        curRequest.setNumberItems(Integer.parseInt(text));

                    }
                    if (name.equalsIgnoreCase("status")) {
                        String text = parser.nextText();
                        curRequest.setStatus(Integer.parseInt(text));

                    }

                }

                if (eventType == XmlPullParser.END_TAG) {
                    if (parser.getName().equalsIgnoreCase("Request")) {
                        list.add(curRequest);
                        curRequest = new Request();
                    }
                }
                eventType = parser.next();
            }

        } catch (XmlPullParserException e) {

            e.printStackTrace();
        } catch (IOException e) {

            e.printStackTrace();
        }

        return list;

    }




}

推荐答案

正如 Liam15 已经提到的，您应该启动一个不同的线程.否则，您将阻止 UI，它会变得无响应.线程应处理数据获取，然后同步或异步更新 UI.

As Liam15 has already mentioned, you should start a different thread. Otherwise you will block the UI and it will become unresponsive. The thread should handle the data acquisition and then update the UI synchronously or asynchronously.

以下是您的 open() 方法的示例:

Here is an example how your open() method could look like:

public void open() throws InterruptedException {
    Display display = Display.getDefault();
    createContents();
    shell.open();

    Thread updateThread = new Thread() {
        public void run() {
            while (true) {
                final ArrayList<Request> pendingRequests = getPendingRequests();
                Display.getDefault().syncExec(new Runnable() {

                    @Override
                    public void run() {
                        populateList(pendingRequests);
                    }
                });

                try {
                    Thread.sleep(1000);
                } catch (InterruptedException e) {
                    e.printStackTrace();
                }
            }
        }
    };
    // background thread
    updateThread.setDaemon(true);
    updateThread.start();

    while (!shell.isDisposed()) {
        if (!display.readAndDispatch()) {
            display.sleep();
        }
    }
}

为了清除 shell 并更新 shell 内容，您可以将以下代码行添加到 populateList() 方法中.

In order to clear the shell and update the shell contents, you can add the following lines of code to your populateList() method.

在方法的开头添加:

Control[] oldControls = shell.getChildren();

在方法末尾添加:

for (Control oldControl : oldControls) {
    oldControl.dispose();
}
shell.layout();

这篇关于SWT:定期更新 GUI的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！