package com.utils;
import java.awt.Color;
import java.awt.Font;
import java.awt.Graphics;
import java.awt.image.BufferedImage;
import java.util.Random;
import javax.imageio.ImageIO;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import javax.servlet.http.HttpSession;
public class RandomValidateCode {
 public static final String RANDOMCODEKEY = "randomcode_key";//放到session中的key
 private Random random = new Random();
 private String randString = "0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZ";//隨機產(chǎn)生的字符串
 private int width = 80;//圖片寬
 private int height = 26;//圖片高
 private int lineSize = 40;//干擾線數(shù)量
 private int stringNum = 4;//隨機產(chǎn)生字符數(shù)量
 /**
  * 生成隨機圖片
  */
 public void getRandcode(HttpServletRequest request,
   HttpServletResponse response) {
  HttpSession session = request.getSession();
  //BufferedImage類是具有緩沖區(qū)的Image類,Image類是用于描述圖像信息的類
  BufferedImage image = new BufferedImage(width,height,BufferedImage.TYPE_INT_BGR);
  //產(chǎn)生Image對象的Graphics對象,改對象可以在圖像上進行各種繪制操作
  Graphics g = image.getGraphics();
  g.fillRect(0, 0, width, height);
  g.setFont(new Font("Times New Roman",Font.ROMAN_BASELINE,18));
  g.setColor(getRandColor(160, 200));
  //繪制干擾線
  for(int i=0;i<=lineSize;i++){
   drowLine(g);
  }
  //繪制隨機字符
  String randomString = "";
  for(int i=1;i<=stringNum;i++){
   randomString=drowString(g,randomString,i);
  }
  session.removeAttribute(RANDOMCODEKEY);
  session.setAttribute(RANDOMCODEKEY, randomString);
  g.dispose();
  try {
   //將內(nèi)存中的圖片通過流動形式輸出到客戶端
   ImageIO.write(image, "JPEG", response.getOutputStream());
  } catch (Exception e) {
   e.printStackTrace();
  }
 }
 /*
  * 獲得字體
  */
 private Font getFont(){
  return new Font("Fixedsys",Font.CENTER_BASELINE,18);
 }
 /*
  * 獲得顏色
  */
 private Color getRandColor(int fc,int bc){
  if(fc > 255)
   fc = 255;
  if(bc > 255)
   bc = 255;
  int r = fc + random.nextInt(bc-fc-16);
  int g = fc + random.nextInt(bc-fc-14);
  int b = fc + random.nextInt(bc-fc-18);
  return new Color(r,g,b);
 }
 /*
  * 繪制字符串
  */
 private String drowString(Graphics g,String randomString,int i){
  g.setFont(getFont());
  g.setColor(new Color(random.nextInt(101),random.nextInt(111),random.nextInt(121)));
  String rand = String.valueOf(getRandomString(random.nextInt(randString.length())));
  randomString +=rand;
  g.translate(random.nextInt(3), random.nextInt(3));
  g.drawString(rand, 13*i, 16);
  return randomString;
 }
 /*
  * 繪制干擾線
  */
 private void drowLine(Graphics g){
  int x = random.nextInt(width);
  int y = random.nextInt(height);
  int xl = random.nextInt(13);
  int yl = random.nextInt(15);
  g.drawLine(x, y, x+xl, y+yl);
 }
 /*
  * 獲取隨機的字符
  */
 public String getRandomString(int num){
  return String.valueOf(randString.charAt(num));
 }
}

 /**
 * 獲取生成驗證碼顯示到 UI 界面
 * @param request
 * @param response
 * @throws ServletException
 * @throws IOException
 */
 @RequestMapping(value="/checkCode")
 public void checkCode(HttpServletRequest request, HttpServletResponse response)
   throws ServletException, IOException {
 //設置相應類型,告訴瀏覽器輸出的內(nèi)容為圖片
  response.setContentType("image/jpeg");
  //設置響應頭信息，告訴瀏覽器不要緩存此內(nèi)容
  response.setHeader("pragma", "no-cache");
  response.setHeader("Cache-Control", "no-cache");
  response.setDateHeader("Expire", 0);
  RandomValidateCode randomValidateCode = new RandomValidateCode();
  try {
   randomValidateCode.getRandcode(request, response);//輸出圖片方法
  } catch (Exception e) {
   e.printStackTrace();
  }
 }

<img src="checkCode" alt="" width="100" height="32" class="passcode" style="height:43px;cursor:pointer;" onclick="this.src=this.src+'?'">