Hey there! Let's tackle your request step by step. First, note that XML-based implementation is feasible for Android apps, but for Swing's JButton, we'll need to build a custom extension class since Swing doesn't support native XML styling for these specific gradient effects.

1. Android Platform: XML + Minimal Code (Gradient Stroke via XML, Gradient Text with Tiny Code) #

We can handle the gradient stroke entirely with XML, and use a small snippet of code for the gradient text (since Android's XML can't directly define gradient text colors).

Step 1: Define Gradient Stroke Drawable #

Create a drawable file res/drawable/gradient_stroke_button.xml for the button's background and stroke:

<shape xmlns:android="http://schemas.android.com/apk/res/android"
    android:shape="rectangle">
    <!-- Optional rounded corners -->
    <corners android:radius="8dp"/>
    <!-- Solid background (adjust to your needs) -->
    <solid android:color="#FFFFFF"/>
    <!-- Gradient stroke: reference a color gradient -->
    <stroke
        android:width="2dp"
        android:color="@color/gradient_stroke"/>
</shape>

Step 2: Define Gradient Color for Stroke #

Create a color state list res/color/gradient_stroke.xml to handle pressed/default states:

<selector xmlns:android="http://schemas.android.com/apk/res/android">
    <item android:state_pressed="true">
        <gradient
            android:startColor="#FF6E40"
            android:endColor="#FFC107"
            android:angle="0"/>
    </item>
    <item>
        <gradient
            android:startColor="#FF4081"
            android:endColor="#3F51B5"
            android:angle="0"/>
    </item>
</selector>

Step 3: Add Button to Layout #

In your activity layout XML, reference the drawable as the button's background:

<Button
    android:id="@+id/gradient_btn"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:text="Gradient Button"
    android:background="@drawable/gradient_stroke_button"/>

Step 4: Add Gradient Text (Code Snippet) #

Since Android XML can't directly set gradient text, add this to your activity's onCreate method:

Button gradientBtn = findViewById(R.id.gradient_btn);
// Create a horizontal linear gradient for text
LinearGradient textGradient = new LinearGradient(
    0, 0, gradientBtn.getWidth(), 0,
    Color.parseColor("#FF4081"),
    Color.parseColor("#3F51B5"),
    Shader.TileMode.CLAMP
);
// Apply the gradient to the button's text paint
gradientBtn.getPaint().setShader(textGradient);

2. Swing Platform: Custom JButton Extension Class #

Swing doesn't support XML-based styling for gradient stroke/text, so we'll build a custom JButton by overriding its painting methods.

Step 1: Build the Custom GradientButton Class #

import javax.swing.*;
import java.awt.*;
import java.awt.geom.RoundRectangle2D;

public class GradientButton extends JButton {
    // Customizable gradient and styling parameters
    private Color strokeStart = new Color(255, 64, 129);
    private Color strokeEnd = new Color(63, 81, 181);
    private Color textStart = new Color(255, 64, 129);
    private Color textEnd = new Color(63, 81, 181);
    private int strokeWidth = 2;
    private int borderRadius = 8;

    public GradientButton(String text) {
        super(text);
        // Disable default painting to avoid overriding our custom work
        setOpaque(false);
        setContentAreaFilled(false);
        setBorderPainted(false);
        setFocusPainted(false); // Optional: remove focus outline
    }

    @Override
    protected void paintComponent(Graphics g) {
        Graphics2D g2d = (Graphics2D) g.create();
        // Enable anti-aliasing for smoother edges
        g2d.setRenderingHint(RenderingHints.KEY_ANTIALIASING, RenderingHints.VALUE_ANTIALIAS_ON);

        // Draw a solid background (adjust color as needed)
        g2d.setColor(Color.WHITE);
        g2d.fill(new RoundRectangle2D.Float(0, 0, getWidth(), getHeight(), borderRadius, borderRadius));

        // Draw gradient text
        FontMetrics metrics = g2d.getFontMetrics();
        int textX = (getWidth() - metrics.stringWidth(getText())) / 2;
        int textY = (getHeight() - metrics.getHeight()) / 2 + metrics.getAscent();

        LinearGradientPaint textGradient = new LinearGradientPaint(
                textX, textY, textX + metrics.stringWidth(getText()), textY,
                new float[]{0f, 1f},
                new Color[]{textStart, textEnd}
        );
        g2d.setPaint(textGradient);
        g2d.drawString(getText(), textX, textY);

        g2d.dispose();
        super.paintComponent(g);
    }

    @Override
    protected void paintBorder(Graphics g) {
        Graphics2D g2d = (Graphics2D) g.create();
        g2d.setRenderingHint(RenderingHints.KEY_ANTIALIASING, RenderingHints.VALUE_ANTIALIAS_ON);

        // Draw gradient stroke
        LinearGradientPaint strokeGradient = new LinearGradientPaint(
                0, 0, getWidth(), 0,
                new float[]{0f, 1f},
                new Color[]{strokeStart, strokeEnd}
        );
        g2d.setPaint(strokeGradient);
        g2d.setStroke(new BasicStroke(strokeWidth));
        // Offset stroke to avoid clipping edges
        g2d.draw(new RoundRectangle2D.Float(strokeWidth/2f, strokeWidth/2f,
                getWidth() - strokeWidth, getHeight() - strokeWidth,
                borderRadius, borderRadius));

        g2d.dispose();
    }

    // Optional: Add setter methods to customize colors/styling at runtime
    public void setStrokeColors(Color start, Color end) {
        this.strokeStart = start;
        this.strokeEnd = end;
        repaint();
    }

    public void setTextColors(Color start, Color end) {
        this.textStart = start;
        this.textEnd = end;
        repaint();
    }
}

Step 2: Use the Custom Button in Your Swing App #

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

public class GradientButtonDemo extends JFrame {
    public GradientButtonDemo() {
        setTitle("Gradient Button Demo");
        setSize(300, 200);
        setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        setLayout(new FlowLayout());

        GradientButton myBtn = new GradientButton("Custom Gradient Button");
        // Optional: Adjust colors dynamically
        // myBtn.setStrokeColors(new Color(255, 110, 64), new Color(255, 193, 7));
        // myBtn.setTextColors(new Color(255, 110, 64), new Color(255, 193, 7));
        add(myBtn);
    }

    public static void main(String[] args) {
        // Run on Swing's event dispatch thread
        SwingUtilities.invokeLater(() -> new GradientButtonDemo().setVisible(true));
    }
}

内容的提问来源于stack exchange，提问作者Rahul Mishra