Java图形用户界面绘制一个三角形，输入坐标，选择颜色，调用draw（g)绘制相应图形，计算图像的周长和面积，输入旋转角度实现旋转，输入缩放比例，实现图形缩放

以下是一个Java图形用户界面绘制三角形、计算周长和面积、旋转和缩放的示例代码：

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

public class TriangleDrawer extends JFrame implements ActionListener {

    private JTextField x1Field, y1Field, x2Field, y2Field, x3Field, y3Field;
    private JComboBox<String> colorBox;
    private JTextField rotateField, scaleField;
    private JButton drawButton;
    private JLabel resultLabel;

    public TriangleDrawer() {
        super("Triangle Drawer");

        JPanel inputPanel = new JPanel(new GridLayout(4, 3));
        inputPanel.add(new JLabel("x1:"));
        x1Field = new JTextField("0", 5);
        inputPanel.add(x1Field);
        inputPanel.add(new JLabel("y1:"));
        y1Field = new JTextField("0", 5);
        inputPanel.add(y1Field);
        inputPanel.add(new JLabel("x2:"));
        x2Field = new JTextField("0", 5);
        inputPanel.add(x2Field);
        inputPanel.add(new JLabel("y2:"));
        y2Field = new JTextField("0", 5);
        inputPanel.add(y2Field);
        inputPanel.add(new JLabel("x3:"));
        x3Field = new JTextField("0", 5);
        inputPanel.add(x3Field);
        inputPanel.add(new JLabel("y3:"));
        y3Field = new JTextField("0", 5);
        inputPanel.add(y3Field);

        JPanel colorPanel = new JPanel();
        colorPanel.add(new JLabel("Color:"));
        String[] colorNames = {"Black", "Red", "Green", "Blue"};
        colorBox = new JComboBox<>(colorNames);
        colorPanel.add(colorBox);

        JPanel rotatePanel = new JPanel();
        rotatePanel.add(new JLabel("Rotate:"));
        rotateField = new JTextField("0", 5);
        rotatePanel.add(rotateField);
        JButton rotateButton = new JButton("Rotate");
        rotateButton.addActionListener(this);
        rotatePanel.add(rotateButton);

        JPanel scalePanel = new JPanel();
        scalePanel.add(new JLabel("Scale:"));
        scaleField = new JTextField("1", 5);
        scalePanel.add(scaleField);
        JButton scaleButton = new JButton("Scale");
        scaleButton.addActionListener(this);
        scalePanel.add(scaleButton);

        JPanel buttonPanel = new JPanel();
        drawButton = new JButton("Draw");
        drawButton.addActionListener(this);
        buttonPanel.add(drawButton);

        JPanel resultPanel = new JPanel();
        resultLabel = new JLabel("");
        resultPanel.add(resultLabel);

        Container contentPane = getContentPane();
        contentPane.setLayout(new BorderLayout());
        contentPane.add(inputPanel, BorderLayout.CENTER);
        contentPane.add(colorPanel, BorderLayout.NORTH);
        contentPane.add(rotatePanel, BorderLayout.WEST);
        contentPane.add(scalePanel, BorderLayout.EAST);
        contentPane.add(buttonPanel, BorderLayout.SOUTH);
        contentPane.add(resultPanel, BorderLayout.PAGE_END);
    }

    public void actionPerformed(ActionEvent e) {
        if (e.getSource() == drawButton) {
            repaint();
        } else if (e.getActionCommand().equals("Rotate")) {
            double angle = Double.parseDouble(rotateField.getText());
            Point center = getTriangleCenter();
            rotateTriangle(angle, center);
            repaint();
        } else if (e.getActionCommand().equals("Scale")) {
            double scale = Double.parseDouble(scaleField.getText());
            Point center = getTriangleCenter();
            scaleTriangle(scale, center);
            repaint();
        }
    }

    private void rotateTriangle(double angle, Point center) {
        double cos = Math.cos(Math.toRadians(angle));
        double sin = Math.sin(Math.toRadians(angle));
        for (Point p : getTrianglePoints()) {
            double x = p.getX() - center.getX();
            double y = p.getY() - center.getY();
            p.setLocation(x * cos - y * sin + center.getX(), x * sin + y * cos + center.getY());
        }
    }

    private void scaleTriangle(double scale, Point center) {
        for (Point p : getTrianglePoints()) {
            double x = p.getX() - center.getX();
            double y = p.getY() - center.getY();
            p.setLocation(x * scale + center.getX(), y * scale + center.getY());
        }
    }

    private Point getTriangleCenter() {
        int x1 = Integer.parseInt(x1Field.getText());
        int y1 = Integer.parseInt(y1Field.getText());
        int x2 = Integer.parseInt(x2Field.getText());
        int y2 = Integer.parseInt(y2Field.getText());
        int x3 = Integer.parseInt(x3Field.getText());
        int y3 = Integer.parseInt(y3Field.getText());
        return new Point((x1 + x2 + x3) / 3, (y1 + y2 + y3) / 3);
    }

    private Point[] getTrianglePoints() {
        int x1 = Integer.parseInt(x1Field.getText());
        int y1 = Integer.parseInt(y1Field.getText());
        int x2 = Integer.parseInt(x2Field.getText());
        int y2 = Integer.parseInt(y2Field.getText());
        int x3 = Integer.parseInt(x3Field.getText());
        int y3 = Integer.parseInt(y3Field.getText());
        Point[] points = {new Point(x1, y1), new Point(x2, y2), new Point(x3, y3)};
        return points;
    }

    public void paint(Graphics g) {
        super.paint(g);
        Point[] points = getTrianglePoints();
        int[] xPoints = {points[0].x, points[1].x, points[2].x};
        int[] yPoints = {points[0].y, points[1].y, points[2].y};
        String color = (String) colorBox.getSelectedItem();
        if (color.equals("Black")) {
            g.setColor(Color.BLACK);
        } else if (color.equals("Red")) {
            g.setColor(Color.RED);
        } else if (color.equals("Green")) {
            g.setColor(Color.GREEN);
        } else if (color.equals("Blue")) {
            g.setColor(Color.BLUE);
        }
        g.drawPolygon(xPoints, yPoints, 3);
        double perimeter = getTrianglePerimeter();
        double area = getTriangleArea();
        resultLabel.setText(String.format("Perimeter: %.2f, Area: %.2f", perimeter, area));
    }

    private double getTrianglePerimeter() {
        Point[] points = getTrianglePoints();
        double side1 = points[0].distance(points[1]);
        double side2 = points[1].distance(points[2]);
        double side3 = points[2].distance(points[0]);
        return side1 + side2 + side3;
    }

    private double getTriangleArea() {
        Point[] points = getTrianglePoints();
        double side1 = points[0].distance(points[1]);
        double side2 = points[1].distance(points[2]);
        double side3 = points[2].distance(points[0]);
        double s = (side1 + side2 + side3) / 2;
        return Math.sqrt(s * (s - side1) * (s - side2) * (s - side3));
    }

    public static void main(String[] args) {
        TriangleDrawer frame = new TriangleDrawer();
        frame.pack();
        frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        frame.setVisible(true);
    }

}

在这个代码中，我们使用了`JFrame`和`JPanel`来创建一个GUI窗口，其中包含了输入三角形坐标、选择颜色、旋转和缩放的控件，并且可以绘制三角形并计算它的周长和面积。具体来说：

- `x1Field`、`y1Field`、`x2Field`、`y2Field`、`x3Field`和`y3Field`是用来输入三角形的坐标的文本框。
- `colorBox`是用来选择三角形颜色的下拉框。
- `rotateField`和`scaleField`是用来输入旋转角度和缩放比例的文本框。
- `drawButton`是用来绘制三角形的按钮。
- `resultLabel`是用来显示三角形周长和面积的标签。

在`actionPerformed`方法中，我们根据不同的按钮事件来执行不同的操作。`drawButton`点击事件会调用`repaint`方法来重新绘制三角形；`rotateButton`点击事件会根据输入的旋转角度和三角形中心点来旋转三角形；`scaleButton`点击事件会根据输入的缩放比例和三角形中心点来缩放三角形。

在`paint`方法中，我们首先根据输入的三角形坐标和颜色来绘制三角形。然后计算三角形的周长和面积，并将它们显示在`resultLabel`中。

在`getTrianglePerimeter`方法中，我们根据三角形的三个点来计算三角形的周长。在`getTriangleArea`方法中，我们根据三角形的三个点和海伦公式来计算三角形的面积。在`rotateTriangle`方法中，我们根据输入的旋转角度和三角形中心点来旋转三角形。在`scaleTriangle`方法中，我们根据输入的缩放比例和三角形中心点来缩放三角形。

最后，在`main`方法中，我们创建一个`TriangleDrawer`对象并显示它。