extjs ajax java简单精美验证码实现 有图

前端：利用ExtJs的autoEl功能加载图片。

     var imgCheckValid = new Ext.create('Ext.Component',{
         width: 70, //图片宽度
         height: 45, //图片高度
         margin:'5',
         id:"imd_imgCheckValid",
         autoEl: {
             tag: 'img',    //指定为img标签
             src: 'Code/genCodeImg.do?'    //指定url路径
         },
         listeners: {
             render: function(component){
                   component.getEl().on('click', function(e){
                      this.dom.src = 'Code/genCodeImg.do?'+(new Date().getTime());  // autoEl不会自动加载，只有设置了不同的src才会加载
                 });
              }
         }
     });

小编心得：autoEl会自动加载，要实现点击验证码刷新，登录失败刷新，方法是给请求的url加上时间戳。所以刷新验证码只要在需要刷新的时候重新设置加上时间戳的src即可。

疑问解答：为什么只是给了src一个路径，并没有给图片地址，页面能显示图片呢？

目前不是很清楚：猜想它是根据给的链接，自动从response中获得二进制资源。明确的是我会向response中写入流

后台：struts,spring配置

struts:

     <!-- 客户端 -->
     <package name="Code" extends="json" namespace="/Code">
         <action name="genCodeImg" class="codeAction" method="genCodeImg">
             <result name="success" type="json">
                 <param name="root">responseJson</param>
             </result>
         </action>
     </package>

spring:

<!-- 验证码生成器--> <bean id="codeAction" class="com.sinsche.i.action.impl.CodeAction" scope="prototype"></bean>

后台：

 import java.awt.Color;
 import java.awt.Font;
 import java.awt.Graphics;
 import java.awt.image.BufferedImage;
 import java.util.Map;
 import java.util.Random;

 import javax.imageio.ImageIO;
 import javax.servlet.ServletOutputStream;
 import javax.servlet.http.HttpServletResponse;

 import org.apache.struts2.ServletActionContext;

 import com.common.core.st2.action.BaseAction;
 import com.opensymphony.xwork2.ActionContext;
 import com.sinsche.i.action.ICodeAction;

 public class CodeAction extends BaseAction implements  ICodeAction {
     /**
      *
      */
     private static final long serialVersionUID = 6865491407475710154L;
     private boolean success;
     private String message;
     // 图片的宽度。
     private int width = 70;
     // 图片的高度。
     private int height = 45;
     // 验证码字符个数
     private int codeCount = 4;
     // 验证码干扰线数
     private int lineCount = 20;
     // 验证码图片Buffer
     private BufferedImage buffImg = null;
     Random random = new Random();
     public String genCodeImg() throws Exception {
         HttpServletResponse resp = ServletActionContext.getResponse();
         int fontWidth = width / codeCount;// 字体的宽度
         int fontHeight = height - 5;// 字体的高度
         int codeY = height - 8;

         // 图像buffer
         buffImg = new BufferedImage(width, height, BufferedImage.TYPE_INT_RGB);
         Graphics g = buffImg.getGraphics();
         // Graphics2D g = buffImg.createGraphics();
         // 设置背景色
         g.setColor(getRandColor(200, 250));
         g.fillRect(0, 0, width, height);

         // 设置字体
         // Font font1 = getFont(fontHeight);
         Font font = new Font("Fixedsys", Font.BOLD, fontHeight);
         g.setFont(font);

         // 设置干扰线
         for (int i = 0; i < lineCount; i++) {
             int xs = random.nextInt(width);
             int ys = random.nextInt(height);
             int xe = xs + random.nextInt(width);
             int ye = ys + random.nextInt(height);
 //            g.setColor(getRandColor(1, 255));
             shear(g,1,20,getRandColor(1, 255));
             g.drawLine(xs, ys, xe, ye);
         }

         // 添加噪点
         float yawpRate = 0.01f;// 噪声率
         int area = (int) (yawpRate * width * height);
         for (int i = 0; i < area; i++) {
             int x = random.nextInt(width);
             int y = random.nextInt(height);

             buffImg.setRGB(x, y, random.nextInt(255));
         }

         String str1 = randomStr(codeCount);// 得到随机字符
         for (int i = 0; i < codeCount; i++) {
             String strRand = str1.substring(i, i + 1);
             g.setColor(getRandColor(1, 255));
             // g.drawString(a,x,y);
             // a为要画出来的东西，x和y表示要画的东西最左侧字符的基线位于此图形上下文坐标系的 (x, y) 位置处

             g.drawString(strRand, i * fontWidth + 3, codeY);
         }

         // 将四位数字的验证码保存到Session中。
         Map<String, Object> map = ActionContext.getContext().getSession();
         System.out.print(str1);
         map.put("code", str1.toString());
         // 禁止图像缓存。
         resp.setHeader("Pragma", "no-cache");
         resp.setHeader("Cache-Control", "no-cache");
         resp.setDateHeader("Expires", 0);

         resp.setContentType("image/jpeg");

         // 将图像输出到Servlet输出流中。
         ServletOutputStream sos = resp.getOutputStream();
         ImageIO.write(buffImg, "jpeg", sos);
         sos.close();

         return null;
     }

     // 得到随机字符
     private String randomStr(int n) {
         String str1 = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz1234567890";
         String str2 = "";
         int len = str1.length() - 1;
         double r;
         for (int i = 0; i < n; i++) {
             r = (Math.random()) * len;
             str2 = str2 + str1.charAt((int) r);
         }
         return str2;
     }

     // 得到随机颜色
     private Color getRandColor(int fc, int bc) {// 给定范围获得随机颜色
         if (fc > 255)
             fc = 255;
         if (bc > 255)
             bc = 255;
         int r = fc + random.nextInt(bc - fc);
         int g = fc + random.nextInt(bc - fc);
         int b = fc + random.nextInt(bc - fc);
         return new Color(r, g, b);
     }

 //    /**
 //     * 产生随机字体
 //     */
 //    private Font getFont(int size) {
 //        Font font[] = new Font[5];
 //        font[0] = new Font("Ravie", Font.PLAIN, size);
 //        font[1] = new Font("Antique Olive Compact", Font.PLAIN, size);
 //        font[2] = new Font("Fixedsys", Font.PLAIN, size);
 //        font[3] = new Font("Wide Latin", Font.PLAIN, size);
 //        font[4] = new Font("Gill Sans Ultra Bold", Font.PLAIN, size);
 //        return font[random.nextInt(5)];
 //    }

     // 扭曲方法
     private void shear(Graphics g, int w1, int h1, Color color) {
         shearX(g, w1, h1, color);
         shearY(g, w1, h1, color);
     }

     private void shearX(Graphics g, int w1, int h1, Color color) {

         int period = random.nextInt(2);

         boolean borderGap = true;
         int frames = 1;
         int phase = random.nextInt(2);

         for (int i = 0; i < h1; i++) {
             double d = (double) (period >> 1) * Math.sin((double) i / (double) period + (6.2831853071795862D * (double) phase) / (double) frames);
             g.copyArea(0, i, w1, 1, (int) d, 0);
             if (borderGap) {
                 g.setColor(color);
                 g.drawLine((int) d, i, 0, i);
                 g.drawLine((int) d + w1, i, w1, i);
             }
         }

     }

     private void shearY(Graphics g, int w1, int h1, Color color) {

         int period = random.nextInt(40) + 10; // 50;

         boolean borderGap = true;
         int frames = 20;
         int phase = 7;
         for (int i = 0; i < w1; i++) {
             double d = (double) (period >> 1) * Math.sin((double) i / (double) period + (6.2831853071795862D * (double) phase) / (double) frames);
             g.copyArea(i, 0, 1, h1, 0, (int) d);
             if (borderGap) {
                 g.setColor(color);
                 g.drawLine(i, (int) d, i, 0);
                 g.drawLine(i, (int) d + h1, i, h1);
             }

         }

     }

     public BufferedImage getBuffImg() {
         return buffImg;
     }
     @Override
     public String list() throws Exception {
         return null;
     }

     @Override
     public String create() throws Exception {
         return null;
     }

     @Override
     public String update() throws Exception {
         return null;
     }

     @Override
     public String delete() throws Exception {
         return null;
     }

     @Override
     public String listByPage() throws Exception {
         return null;
     }

     public boolean isSuccess() {
         return success;
     }

     public void setSuccess(boolean success) {
         this.success = success;
     }

     public String getMessage() {
         return message;
     }

     public void setMessage(String message) {
         this.message = message;
     }

 }

效果：