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我在使用 Java 的 JFreeChart 时遇到了一些问题。我正在从远程数据库中检索数据，以使它们显示在我的应用程序的面板中。

  1. 问题：当我获取数据时，它不会直接显示在面板上。我必须最小化和最大化表单才能加载数据。

  2. 我需要这些数据每分钟刷新一次。我在考虑一个Timer，但我真的不知道如何整合它。

以下是部分代码：

import java.io.BufferedReader;
import java.net.Socket;
import java.io.IOException;
import java.io.InputStreamReader;
import java.util.List;
import java.util.ArrayList;
import javax.swing.JPanel;

public class GetRequest implements Runnable{

    public BufferedReader _input = null;
    public Socket clientSocket = null;
    public DrawChart draw;
    public List<Double> values_1, values_2, values_3, values_4;
    public JPanel _panel;

    public GetRequest(Socket socket, JPanel panel){
        clientSocket = socket;
        draw = new DrawChart();
        _panel = panel;
        values_1 = new ArrayList<Double>();
        values_2 = new ArrayList<Double>();
        values_3 = new ArrayList<Double>();
    }

    @Override
    public void run(){
        while(true){

            try{
                _input = new BufferedReader(
                    new InputStreamReader(clientSocket.getInputStream ()));
                String line = _input.readLine ();

                String[] clineComat = line.split (",");
                for(int i = 0 ;i<clineComat.length;i++){

                    String[] clineSemiComa_ = clineComat[i].split (";");
                    System.out.println(">"+clineComat[i]);
                    values_1.add (Double.parseDouble (clineSemiComa_[0])+1);
                    values_2.add (Double.parseDouble (clineSemiComa_[1])+1);
                    values_3.add (Double.parseDouble (clineSemiComa_[2]));
                }

                EventQueue.invokeLater (new Runnable(){
                public void run(){
                    draw.displayPie (_panel, values_1, values_2, values_3);
                }
            });
            }
            catch(IOException e){e.printStackTrace ();}
        }
    }}

这是 DrawChart.java 的代码

import  org.jfree.chart.ChartFactory;
import  org.jfree.chart.ChartPanel;
import  org.jfree.chart.JFreeChart;
import  org.jfree.data.general.DefaultPieDataset;
import javax.swing.JPanel;
import java.awt.BorderLayout;
import org.jfree.chart.plot.PlotOrientation;
import java.awt.Dimension;
import org.jfree.data.category.DefaultCategoryDataset;
import org.jfree.data.category.CategoryDataset;
import java.util.List;
import java.lang.Float;
import java.util.Timer;
import java.util.TimerTask;

public class DrawChart {

    public void displayPie(JPanel jpanel, List<Double> values_1, List<Double> values_2, List<Double> values_3) {

        CategoryDataset data = createDataset(values_1, values_2, values_3);
        //create a chart...
        JFreeChart chart=ChartFactory.createBarChart ("", null, null, data, PlotOrientation.VERTICAL, true, true, false);
        chart = ChartFactory.createLineChart ("", null, null, data, PlotOrientation.VERTICAL, true, true, false);

        //create and display a frame...
        ChartPanel panel=new ChartPanel(chart);
        panel.setPreferredSize (new Dimension(700,300));
        jpanel.setLayout(new java.awt.BorderLayout());
        jpanel.add (panel, BorderLayout.CENTER);
        jpanel.setVisible(true);
        }

    public static CategoryDataset createDataset(List<Double> a, List<Double> b, List<Double> c) {

        String series1 = "Series1";
        String series2 = "Series2";
        String series3 = "Series3";

        final DefaultCategoryDataset dataset = new DefaultCategoryDataset();

        if(a.size () != 0 && b.size () != 0 && c.size () != 0 ) {

            for(int i=0;i<a.size ();i++) {
                dataset.addValue(a.get (i), series1, i+1+"");
            }

            for(int i=0;i<b.size ();i++) {
                dataset.addValue(b.get (i), series2, i+1+"");
            }

            for(int i=0;i<c.size ();i++) {
                dataset.addValue(c.get (i), series3, i+1+"");
            }

        }

        return dataset;
    }
}

我该如何解决这个问题？有没有人做过类似的？谢谢

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1 回答 1

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我可能忽略了一个 JFreeChart 问题，但是在 Swing 中绘图必须发生在事件调度线程上。相反，您的呼叫displayPie()来自Runnable. GetRequest常见的补救措施包括：

于 2012-07-27T20:56:01.583 回答