java生成图片验证码实例代码

@Controller
public class ImgVerifyCode extends HttpServlet {
 
  /**
   *
   */
  private static final long serialVersiOnUID= 1L;
 
  /**
   * 验证码图片的宽度。
   */
  private int width = 70;
 
  /**
   * 验证码图片的高度。
   */
  private int height =30;
 
  /**
   * 验证码字符个数
   */
  private int codeCount = 5;
 
  /**
   * xx
   */
  private int xx = 0;
 
  /**
   * 字体高度
   */
  private int fontHeight;
 
  /**
   * codeY
   */
  private int codeY;
 
  /**
   * codeSequence
   */
   String[] codeSequence = { "1" , "2" , "3" , "4" , "5" ,"6","7","8","9","A","a","B","b","c","C"
       ,"D","d","E","e","F","f","G","g","z","X","Q","v"};
 
  /**
   * 初始化验证图片属性
   */
  public void init() throws ServletException {
    // 从web.xml中获取初始信息
    // 宽度
    String strWidth =width+"";
    // 高度
    String strHeight = height+"";
    // 字符个数
    String strCodeCount = codeCount+"";
 
    // 将配置的信息转换成数值
    try {
      if (strWidth != null && strWidth.length() != 0) {
        width = Integer.parseInt(strWidth);
      }
      if (strHeight != null && strHeight.length() != 0) {
        height = Integer.parseInt(strHeight);
      }
      if (strCodeCount != null && strCodeCount.length() != 0) {
        codeCount = Integer.parseInt(strCodeCount);
      }
    } catch (NumberFormatException e) {
      e.printStackTrace();
    }
 
    xx = width / (codeCount + 2); //生成随机数的水平距离
    fOntHeight= height - 12;   //生成随机数的数字高度
    codeY = height - 8;      //生成随机数的垂直距离
 
  }
 
 
  protected String images(HttpServletRequest req, HttpServletResponse resp)
      throws ServletException,IOException {
    init();
    // 定义图像buffer
    BufferedImage buffImg = new BufferedImage(width, height,
        BufferedImage.TYPE_INT_RGB);
    Graphics2D gd = buffImg.createGraphics();
 
    // 创建一个随机数生成器类
    Random random = new Random();
 
    // 将图像填充为白色
    gd.setColor(Color.WHITE);
    gd.fillRect(0, 0, width, height);
 
    // 创建字体，字体的大小应该根据图片的高度来定。
    Font fOnt= new Font("Fixedsys", Font.PLAIN, fontHeight);
    // 设置字体。
    gd.setFont(font);
 
    // 画边框。
    gd.setColor(Color.BLACK);
    gd.drawRect(0, 0, width - 1, height - 1);
 
    // 随机产生4条干扰线，使图象中的认证码不易被其它程序探测到。
    gd.setColor(Color.BLACK);
    for (int i = 0; i <4; i++) {
      int x = random.nextInt(width);
      int y = random.nextInt(height);
      int xl = random.nextInt(12);
      int yl = random.nextInt(12);
      gd.drawLine(x, y, x + xl, y + yl);
    }
 
    // randomCode用于保存随机产生的验证码，以便用户登录后进行验证。
    StringBuffer randomCode = new StringBuffer();
    int red = 0, green = 0, blue = 0;
 
    // 随机产生codeCount数字的验证码。
    for (int i = 0; i