java 生成验证码

//在有些网站的注册和登录的时候会要用到验证码,是这样生成的

import java.awt.BorderLayout;
import java.awt.Color;
import java.awt.Font;
import java.awt.Graphics;
import java.awt.Graphics2D;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.awt.event.MouseAdapter;
import java.awt.event.MouseEvent;
import java.util.Random;

import javax.swing.JButton;
import javax.swing.JFrame;
import javax.swing.JLabel;

import cn.com.csuinfosoft.window.CenterWindow;

/**
 * 产生验证码
 * @author 黄根华 
 */
public class ValidateCodeImage extends JFrame {

  public ValidateCodeImage() {
    this.setSize(100, 120);
    final ValidateCodeLabel codeLabel = new ValidateCodeLabel();
    final JLabel codeTitle = new JLabel(codeLabel.getCode());
    JButton codeButton = new JButton("改变下");
    codeButton.addActionListener(new ActionListener() {
      public void actionPerformed(ActionEvent e) {
        codeTitle.setText(codeLabel.changeCode());
      }
    });
    // 用户点击图片也可以改变形状
    codeLabel.setMouseListener(new ValidateCodeListener() {
      public void codeChange(String code) {
        codeTitle.setText(codeLabel.changeCode());
      }
    });
    this.add(codeTitle, BorderLayout.NORTH);
    this.add(codeLabel, BorderLayout.CENTER);
    this.add(codeButton, BorderLayout.SOUTH);
    this.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
    CenterWindow.centerWindow(this);
  }

  public static void main(String[] args) {
    new ValidateCodeImage().setVisible(true);
  }

  class ValidateCodeLabel extends JLabel {
    /** 可能产生的字符 中文会有乱码 */
    private final static String CODES = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789";
    /** 要产生验证码长度 */
    private final static int RANDCODELENGTH = 5;
    /** 每个字符宽度 px */
    private final static int EACHCODELENGTH = 15;
    /** 左边空隙 系数 */
    private final static double LEFT = 0.2;
    /** 顶部空隙 系数 */
    private final static double HEAD = 0.7;
    /** 总共产生多少的噪声点，线 */
    private final static int NOISECOUNT = 20;
    /** 混乱系数 */
    private final static double RANDOMFACTOR = 0.3;

    private Color backGround, noise, line;
    private String randCode;
    private Random random = new Random();

    public ValidateCodeLabel() {
      this.backGround = new Color(240, 243, 248);
      generateCode();
    }

    public ValidateCodeLabel(Color backGround, Color noise, Color line) {
      this.backGround = backGround;
      this.noise = noise;
      this.line = line;
      generateCode();
    }

    public void setMouseListener(final ValidateCodeListener listener) {
      this.addMouseListener(new MouseAdapter() {
        public void mouseClicked(MouseEvent e) {
          generateCode();
          listener.codeChange(randCode);
        }
      });
    }

    protected void paintComponent(Graphics g) {
      createValidateImage(g, randCode);
    }

    // Graphics 用于绘画 相当于MFC里面的CDC
    private void createValidateImage(Graphics g, String randCode) {
      Graphics2D graphic = (Graphics2D) g;

      // 设定背景色
      graphic.setColor(backGround);
      int width = this.getWidth();
      int height = this.getHeight();
      graphic.fillRect(0, 0, width, height);

      // 设定字体
      graphic.setFont(new Font("Times New Roman", Font.PLAIN, 18));

      for (int index = 0; index < randCode.length(); index++) {
        // 将认证码显示到图象中
        graphic.setColor(new Color(random.nextInt(255), random.nextInt(123),
            random.nextInt(123)));
        double radian = generateRadian();
        graphic.rotate(radian, width / 2, height / 2);
        graphic.drawString(String.valueOf(randCode.charAt(index)),
            ((int) (EACHCODELENGTH * index + width * LEFT)),
            (int) (height * HEAD));
        graphic.rotate(-radian, width / 2, height / 2);
      }

      // 干扰线
      if (line != null) {
        g.setColor(line);
        for (int count = 0; count < NOISECOUNT; count++) {
          int x = random.nextInt(width - 12);
          int y = random.nextInt(height - 12);
          int xl = random.nextInt(12);
          int yl = random.nextInt(12);
          g.drawLine(x, y, x + xl, y + yl);
        }
      };

      // 噪声点
      if (noise != null) {
        graphic.setColor(noise);
        for (int count = 0; count < NOISECOUNT; count++) {
          g.fillArc(random.nextInt(width - 3), random.nextInt(height - 3), 3,
              3, 0, 360);
        }
      };

      // 图象生效
      graphic.dispose();
    }

    // 随机数
    private double generateRadian() {
      return random.nextDouble() * RANDOMFACTOR;
    }

    // 验证码产生
    private void generateCode() {
      StringBuffer code = new StringBuffer();
      for (int index = 0; index < RANDCODELENGTH; index++) {
        int randomNuber = random.nextInt(CODES.length());
        code.append(CODES.substring(randomNuber, randomNuber + 1));
      }
      this.randCode = code.toString();
      this.repaint();
    }

    /**
     * 改变生成的验证码
     *
     * @return
     */
    public String changeCode() {
      generateCode();
      return this.randCode.toLowerCase();
    }

    /**
     * 得到当前生成的验证码
     *
     * @return
     */
    public String getCode() {
      return this.randCode.toLowerCase();
    }
  }
  /**
   * 用户点击了图片后的回调方法 作用类似于actionListener
   *
   * @author lonelybell
   *
   */
  class ValidateCodeListener {
    public void codeChange(String code) {}
  }
}