验证码的变换

//验证码
    public String imageCode() throws IOException{
      //获得验证码随机数
      String code = ImageUtil1.getRandomCode(4);
      BufferedImage img = ImageUtil1.createImage(code);
      ValueStackUtil.setSessionAttribute("imgCode", code);
      ImageIO.write(img, "png", ServletActionContext.getResponse().getOutputStream());
      return null;
    }




点击验证码变换


    <tr>
      <td valign="middle" align="right">
        验证码:
        <img id="num" src="<s:url value='/user/user_imageCode'/>" οnclick='this.src=this.src+"?c="+Math.random()'/>
      </td>
      <td valign="middle" align="left">
        <input id="code" type="text" required="true" class="inputgri" name="code" />
      </td>
    </tr>






点击换一张更换验证码
    <script type="text/javascript">
      function fun(){
          var img1 = document.getElementById("num");
          img1.src = "<s:url value='/user/user_imageCode'/>;" + new Date();
                  } 
    </script>




    <tr>
      <td valign="middle" align="right">
      验证码:
        <img id="num" src="<s:url value='/user/user_imageCode'/>" />
          <a href="javascript:void(0)" οnclick="fun()">换一张</a>
      </td>


      <td valign="middle" align="left">
        <input type="text" class="inputgri" name="code" />
      </td>
    </tr>


  验证码的util方法：

public class ImageUtil {
  public static String getRandomCode(int n){
    String str = "1234567890ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz";
    int len = str.length();
    StringBuffer sb = new StringBuffer();
    Random r = new Random();
    for(int i=0;i<n;i++){
      sb.append(str.charAt(r.nextInt(len)));
    }
    return sb.toString();
  }


   public static BufferedImage createImage(String securityCode){


          int codeLength = securityCode.length();//验证码长度


          int fontSize = 20;//字体大小


          int fontWidth = fontSize+1;


          //图片宽高


          int width = codeLength*fontWidth+60;
          int height = fontSize*2;
          //图片


          BufferedImage image = new BufferedImage(width, height, BufferedImage.TYPE_INT_RGB);


          Graphics2D g = image.createGraphics();


          g.setColor(Color.WHITE);//设置背景色


          g.fillRect(0, 0, width, height);//填充背景


          g.setColor(Color.LIGHT_GRAY);//设置边框颜色


          g.setFont(new Font("Courier New", Font.BOLD, height-2));//边框字体样式


          g.drawRect(0, 0,0, 0);//绘制边框


          //绘制噪点


          Random rand = new Random();


          g.setColor(Color.LIGHT_GRAY);


          for (int i = 0; i < codeLength*6; i++) {


              int x = rand.nextInt(width);


              int y = rand.nextInt(height);


              g.drawRect(x, y, 1, 1);//绘制1*1大小的矩形


          }


          //绘制验证码


          int codeY = height-10;


          g.setColor(new Color(19,148,246));


          g.setFont(new Font("Georgia", Font.BOLD, fontSize));
          for(int i=0;i<codeLength;i++){
            double deg=new Random().nextDouble()*20;
            g.rotate(Math.toRadians(deg), i*16+13,codeY-7.5);
              g.drawString(String.valueOf(securityCode.charAt(i)), i*16+5, codeY);
              g.rotate(Math.toRadians(-deg), i*16+13,codeY-7.5);
          }
         
          g.dispose();//关闭资源


          return image;


      }
  
}