在Java swing中，如何绘制折线图、饼状图、条形图？

Java Swing提供了Java2D API来绘制2D图形，可以用它来绘制折线图、饼状图、条形图等。下面分别介绍一下绘制这三种图表的方法。

1. 折线图

绘制折线图可以使用Java Swing中的JFreeChart库。这个库提供了各种类型的图表，包括折线图、饼状图、条形图等。以下是一个简单的绘制折线图的例子：

import javax.swing.*;
import org.jfree.chart.*;
import org.jfree.data.xy.*;

public class LineChartExample extends JFrame {
    public LineChartExample() {
        JFreeChart chart = ChartFactory.createXYLineChart(
            "Line Chart Example",
            "X Axis",
            "Y Axis",
            createDataset(),
            PlotOrientation.VERTICAL,
            true,
            true,
            false
        );
        
        ChartPanel panel = new ChartPanel(chart);
        setContentPane(panel);
    }
    
    private XYDataset createDataset() {
        XYSeries series = new XYSeries("Data");
        series.add(1, 2);
        series.add(2, 3);
        series.add(3, 1);
        series.add(4, 5);
        series.add(5, 2);
        
        XYSeriesCollection dataset = new XYSeriesCollection();
        dataset.addSeries(series);
        
        return dataset;
    }
    
    public static void main(String[] args) {
        LineChartExample example = new LineChartExample();
        example.setSize(500, 500);
        example.setVisible(true);
    }
}

2. 饼状图

绘制饼状图可以使用Java Swing中的Java2D API。以下是一个简单的绘制饼状图的例子：

import javax.swing.*;
import java.awt.*;
import java.awt.geom.*;

public class PieChartExample extends JFrame {
    public PieChartExample() {
        JPanel panel = new JPanel() {
            @Override
            public void paintComponent(Graphics g) {
                super.paintComponent(g);
                Graphics2D g2d = (Graphics2D) g;
                
                double total = 100;
                double[] values = {20, 30, 15, 35};
                Color[] colors = {Color.RED, Color.BLUE, Color.GREEN, Color.ORANGE};
                
                double start = 0;
                for (int i = 0; i < values.length; i++) {
                    double angle = values[i] / total * 360;
                    g2d.setColor(colors[i]);
                    g2d.fill(new Arc2D.Double(100, 100, 300, 300, start, angle, Arc2D.PIE));
                    start += angle;
                }
            }
        };
        
        setContentPane(panel);
    }
    
    public static void main(String[] args) {
        PieChartExample example = new PieChartExample();
        example.setSize(500, 500);
        example.setVisible(true);
    }
}

3. 条形图

绘制条形图可以使用Java Swing中的Java2D API。以下是一个简单的绘制条形图的例子：

import javax.swing.*;
import java.awt.*;
import java.awt.geom.*;

public class BarChartExample extends JFrame {
    public BarChartExample() {
        JPanel panel = new JPanel() {
            @Override
            public void paintComponent(Graphics g) {
                super.paintComponent(g);
                Graphics2D g2d = (Graphics2D) g;
                
                double[] values = {20, 30, 15, 35};
                Color[] colors = {Color.RED, Color.BLUE, Color.GREEN, Color.ORANGE};
                
                double x = 100;
                double y = 100;
                double width = 50;
                double height = 0;
                for (int i = 0; i < values.length; i++) {
                    height = values[i];
                    g2d.setColor(colors[i]);
                    g2d.fill(new Rectangle2D.Double(x, y, width, height));
                    x += width + 10;
                }
            }
        };
        
        setContentPane(panel);
    }
    
    public static void main(String[] args) {
        BarChartExample example = new BarChartExample();
        example.setSize(500, 500);
        example.setVisible(true);
    }
}