/* *前段 */

	 <script>
	 function changeImage(){
		var fullurl = '${ctx }/sync/data/getCode?version='+Math.random();
		var image = document.getElementById("imageid");
	        image.src = fullurl;
	 }
	 </script>

//後端 package com.becom.modules.syncdata.web; import java.awt.Color; import java.awt.Font; import java.awt.Graphics2D; import java.awt.image.BufferedImage; import java.io.FileOutputStream; import java.io.IOException; import java.io.OutputStream; import java.util.Random;

import javax.imageio.ImageIO;

/**

• 驗證碼生成器

• 轉載 https://www.cnblogs.com/yhtboke/p/5749126.html */ public class ValidateCode { // 圖片的寬度。 private int width = 160; // 圖片的高度。 private int height = 28; // 驗證碼字元個數 private int codeCount = 4; // 驗證碼干擾線數 private int lineCount = 150; // 驗證碼 private String code = null; // 驗證碼圖片Buffer private BufferedImage buffImg = null;

  private char[] codeSequence = { ‘A’, ‘B’, ‘C’, ‘D’, ‘E’, ‘F’, ‘G’, ‘H’, ‘I’, ‘J’, ‘K’, ‘L’, ‘M’, ‘N’, ‘P’, ‘Q’, ‘R’, ‘S’, ‘T’, ‘U’, ‘V’, ‘W’, ‘X’, ‘Y’, ‘Z’, ‘1’, ‘2’, ‘3’, ‘4’, ‘5’, ‘6’, ‘7’, ‘8’, ‘9’ };

  public ValidateCode() { this.createCode(); }

  /** *

  • @param width

  •        圖片寬
    

  • @param height

  •        圖片高
     
    

  */ public ValidateCode(int width, int height) { this.width = width; this.height = height; this.createCode(); }

  /** *

  • @param width

  •        圖片寬
    

  • @param height

  •        圖片高
    

  • @param codeCount

  •        字元個數
    

  • @param lineCount

  •        干擾線條數
    

  */ public ValidateCode(int width, int height, int codeCount, int lineCount) { this.width = width; this.height = height; this.codeCount = codeCount; this.lineCount = lineCount; this.createCode(); }

  public void createCode() { int x = 0, fontHeight = 0, codeY = 0; int red = 0, green = 0, blue = 0;

   x = width / (codeCount + 2);// 每個字元的寬度
   fontHeight = height - 2;// 字型的高度
   codeY = height - 4;
  
   // 影象buffer
   buffImg = new BufferedImage(width, height, BufferedImage.TYPE_INT_RGB);
   Graphics2D g = buffImg.createGraphics();
   // 生成隨機數
   Random random = new Random();
   // 將影象填充為白色
   g.setColor(Color.WHITE);
   g.fillRect(0, 0, width, height);
   // 建立字型
   Font font = new Font("Fixedsys", Font.BOLD, fontHeight);
   g.setFont(font);
   //干擾線
   for (int i = 0; i < lineCount; i++) {
       int xs = random.nextInt(width);
       int ys = random.nextInt(height);
       int xe = xs + random.nextInt(width / 8);
       int ye = ys + random.nextInt(height / 8);
       red = random.nextInt(255);
       green = random.nextInt(255);
       blue = random.nextInt(255);
       g.setColor(new Color(red, green, blue));
       g.drawLine(xs, ys, xe, ye);
   }
  
   // randomCode記錄隨機產生的驗證碼
   StringBuffer randomCode = new StringBuffer();
   // 隨機產生codeCount個字元的驗證碼。
   for (int i = 0; i < codeCount; i++) {
       String strRand = String.valueOf(codeSequence[random.nextInt(codeSequence.length)]);
       // 產生隨機的顏色值，讓輸出的每個字元的顏色值都將不同。
       red = random.nextInt(255);
       green = random.nextInt(255);
       blue = random.nextInt(255);
       g.setColor(new Color(red, green, blue));
       g.drawString(strRand, (i + 1) * x, codeY);
       // 將產生的四個隨機數組合在一起。
       randomCode.append(strRand);
   }
   // 將四位數字的驗證碼儲存到Session中。
   code = randomCode.toString();
  

  }

  public void write(String path) throws IOException { OutputStream sos = new FileOutputStream(path); this.write(sos); }

  public void write(OutputStream sos) throws IOException { ImageIO.write(buffImg, “png”, sos); sos.close(); }

  public BufferedImage getBuffImg() { return buffImg; }

  public String getCode() { return code; } }

  //控制層返回驗證碼流檔案 @RequestMapping("/getCode") public void getCode(HttpServletRequest reqeust, HttpServletResponse response) throws IOException {

   response.setContentType("image/jpeg");
   // 禁止影象快取。
   response.setHeader("Pragma", "no-cache");
   response.setHeader("Cache-Control", "no-cache");
   response.setDateHeader("Expires", 0);
  
   HttpSession session = reqeust.getSession();
  
   ValidateCode vCode = new ValidateCode(100, 28, 4, 100);
   session.setAttribute(Helper.SESSION_CHECKCODE, vCode.getCode());
   vCode.write(response.getOutputStream());
  

  }