java生成一个颜色渐变的进度条的代码实现

以下是一个简单的Java代码实现颜色渐变的进度条：

import java.awt.Color;
import java.awt.Dimension;
import java.awt.Graphics;
import javax.swing.JPanel;

public class GradientProgressBar extends JPanel {
  private int progress;
  
  public GradientProgressBar() {
    this.setPreferredSize(new Dimension(200, 20));
    this.progress = 0;
  }
  
  public void setProgress(int progress) {
    this.progress = progress;
    this.repaint();
  }
  
  public void paintComponent(Graphics g) {
    super.paintComponent(g);
    int width = this.getWidth() - 1;
    int height = this.getHeight() - 1;
    
    // 绘制外边框
    g.setColor(Color.BLACK);
    g.drawRect(0, 0, width, height);
    
    // 绘制进度条背景色
    g.setColor(new Color(255, 255, 255));
    g.fillRect(1, 1, width - 2, height - 2);
    
    // 计算进度条渐变色
    Color startColor = new Color(0, 255, 0);
    Color endColor = new Color(255, 0, 0);
    float ratio = (float)this.progress / (float)100;
    int red = (int)(endColor.getRed() * ratio + startColor.getRed() * (1 - ratio));
    int green = (int)(endColor.getGreen() * ratio + startColor.getGreen() * (1 - ratio));
    int blue = (int)(endColor.getBlue() * ratio + startColor.getBlue() * (1 - ratio));
    Color progressColor = new Color(red, green, blue);
    
    // 绘制进度条渐变色
    g.setColor(progressColor);
    int progressWidth = (int)((float)(width - 2) * ratio);
    g.fillRect(1, 1, progressWidth, height - 2);
  }
}

当然，具体的实现方式还要根据具体需求来做相应的调整。