js 异步请求

<p id="check">
	<label>验证码：</label>
	<input  class="vid" id="ValidateCode" name="ValidateCode"  type="text" value="" onblur="checkValidateCode()"/>
	<img id="checkcodeimg" src="<%=path %>/image.jsp" style="margin-left:10px;" width="74px" height="28px"  onclick="this.src='<%=path %>/image.jsp?date='+new Date();"/>
	<span id="codeSpan"></span>
</p>

image.jsp

 <%@ page contentType="image/jpeg" import="java.awt.*, java.awt.image.*,java.util.*,javax.imageio.*"%>
 <%!Color getRandColor(int fc, int bc) {
         Random random = new Random();
         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);
     }%>
 <%
     out.clear();//????resin???????tomacat??????
     out = pageContext.pushBody();
     response.setHeader("Pragma", "No-cache");
     response.setHeader("Cache-Control", "no-cache");
     response.setDateHeader("Expires", 0);

     int width = 60, height = 20;
     BufferedImage image = new BufferedImage(width, height,
             BufferedImage.TYPE_INT_RGB);

     Graphics g = image.getGraphics();
     Random random = new Random();

     g.setColor(getRandColor(200, 250));
     g.fillRect(0, 0, width, height);

     g.setFont(new Font("Times New Roman", Font.PLAIN, 18));

     g.setColor(getRandColor(160, 200));
     for (int i = 0; i < 155; i++) {
         int x = random.nextInt(width);
         int y = random.nextInt(height);
         int xl = random.nextInt(12);
         int yl = random.nextInt(12);
         g.drawLine(x, y, x + xl, y + yl);
     }

     String sRand = "";
     for (int i = 0; i < 4; i++) {
         String rand = String.valueOf(random.nextInt(10));
         sRand += rand;

         g.setColor(new Color(20 + random.nextInt(110), 20 + random.nextInt(110), 20 + random.nextInt(110)));
         g.drawString(rand, 13 * i + 6, 16);
     }
     // ??????SESSION
     session.setAttribute("rand", sRand);
     g.dispose();

     ImageIO.write(image, "JPEG", response.getOutputStream());
 %>

　　

实现jsp

  var xmlHttpRequest;
     //XmlHttpRequest对象
     function createXmlHttpRequest(){
         if(window.ActiveXObject){ //如果是IE
             return new ActiveXObject("Microsoft.XMLHTTP");
         }else if(window.XMLHttpRequest){ //非IE浏览器
             return new XMLHttpRequest();
         }
     }
      function checkValidateCode(){
         code = document.getElementById("ValidateCode").value.trim();
         var url = "user_validateCodeCheck.do?validateCode="+code;
         xmlHttpRequest = createXmlHttpRequest();
         xmlHttpRequest.onreadystatechange = HuiDiaoFun;
         xmlHttpRequest.open("post",url,true);
         xmlHttpRequest.send(null);
     }

     //回调函数
     function HuiDiaoFun(){
         if(xmlHttpRequest.readyState == 4 && xmlHttpRequest.status == 200){
             var resp = xmlHttpRequest.responseText;
             if (resp == "error") {
                 document.getElementById("codeSpan").innerHTML = "验证码错误！";
                 document.getElementById("codeSpan").style.color = "#FF0000";
             }else if(resp == "ok"){
                 document.getElementById("codeSpan").innerHTML = "";
             }
         }
     }  

 public class UserAction extends BaseAction{

     private String validateCode;

     public void validateCodeCheck(){
         String code = (String)getHttpSession().getAttribute("rand");
         System.out.println(code);
         if(StringUtils.isNoneEmpty(validateCode) && validateCode.equals(code)){
             ResponseUtil.writeUTF(getHttpResponse(), "ok");
         }else{
             ResponseUtil.writeUTF(getHttpResponse(), "error");
         }
     }

 }

 import java.io.IOException;
 import java.io.UnsupportedEncodingException;
 import java.util.Enumeration;
 import java.util.HashMap;
 import java.util.List;
 import java.util.Map;

 import javax.servlet.ServletContext;
 import javax.servlet.http.HttpServletRequest;
 import javax.servlet.http.HttpServletResponse;
 import javax.servlet.http.HttpSession;
 import javax.servlet.jsp.PageContext;

 import org.apache.struts2.ServletActionContext;
 import org.springframework.web.context.support.WebApplicationContextUtils;

 import com.opensymphony.xwork2.ActionSupport;

 /**
  * action基类，提供共用方法
  *
  *
  */
 public class BaseAction extends ActionSupport {

     public UnitService baseUnitService;
     public RoleService baseRoleService;
     public ConfigService baseConfigService;
     public ChannelService baseChannelService;
     public InfoService baseInfoService;
     public int pageSize=10;
     public int currPage=1;
     public int totalCount=0;
     public String pageStr;
     public String pageFuncId;
     public String showMessage;
     public String forwardUrl="";
     public int forwardSeconds=0;
     public String getForwardUrl() {
         return forwardUrl;
     }
     public void setForwardUrl(String forwardUrl) {
         this.forwardUrl = forwardUrl;
     }
     public int getForwardSeconds() {
         return forwardSeconds;
     }
     public void setForwardSeconds(int forwardSeconds) {
         this.forwardSeconds = forwardSeconds;
     }
     public int getPageSize() {
         return pageSize;
     }
     public void setPageSize(int pageSize) {
         this.pageSize = pageSize;
     }
     public int getCurrPage() {
         return currPage;
     }
     public void setCurrPage(int currPage) {
         this.currPage = currPage;
     }
     public HttpSession getHttpSession(){
         return ServletActionContext.getRequest().getSession();
     }
     public HttpServletRequest getHttpRequest(){
         return ServletActionContext.getRequest();
     }
     public HttpServletResponse getHttpResponse(){
         return ServletActionContext.getResponse();
     }
     public PageContext getPageContext(){
         return ServletActionContext.getPageContext();
     }
     public ServletContext getServletContext(){
         return ServletActionContext.getServletContext();
     }
     public Map<String, Object> getApplication(){
         return ServletActionContext.getContext().getApplication();
     }
     public String getBasePath(){
         String path = getHttpRequest().getContextPath();
         String basePath = getHttpRequest().getScheme()+"://"+getHttpRequest().getServerName()+":"+getHttpRequest().getServerPort()+path+"/";
         return basePath;
     }

     /**
      * 获取配置
      * @return
      */
     public Map<String, Object> getConfig(){
         if (getApplication().get("config")!=null) {
             return (Map<String, Object>)getApplication().get("config");
         }else {
             //重新生成
             return setConfig();
         }
     }
     /**
      * 获取配置值
      * @return
      */
     public String getConfigVal(String name){
         Map<String, Object> config=getConfig();
         if (config!=null && config.get(name)!=null) {
             return config.get(name).toString();
         }
         return "";
     }
     /**
      * 设置配置
      * @return
      */
     public Map<String, Object> setConfig(){
          baseConfigService = (ConfigService) getBean("configService");
         List<Config> configList=baseConfigService.find();
         Map<String, Object> config=new HashMap<String, Object>();
         if (configList!=null && configList.size()>0) {
             for (int i = 0; i < configList.size(); i++) {
                 config.put(configList.get(i).getCode(), configList.get(i).getConfigvalue());
             }
         }
         getApplication().put("config", config);
         return config;
     }
     public void write(String content,String charset){
         getHttpResponse().setCharacterEncoding(charset);
         getHttpResponse().setContentType("text/html;charset="+charset);
         try {
             getHttpResponse().getWriter().print(content);
         } catch (IOException e) {
             e.printStackTrace();
         }
     }
     /**
      * 判断是否为admin登录
      */
     public boolean isAdminLogin(){
         return "admin".equals(getLoginName());
     }
     /**
      * 判断是否为站点总管理员
      */
     public boolean isSiteAdmin(){
         if (getHttpSession().getAttribute("siteAdmin")!=null) {
             return (Boolean)getHttpSession().getAttribute("siteAdmin");
         }
         return false;
     }
     /**
      * 获取当前管理站点
      * @return
      */
     public Site getManageSite(){
         if (getHttpSession().getAttribute("manageSite")!=null) {
             //获取当前管理站点
             return (Site)getHttpSession().getAttribute("manageSite");
         }
         return null;
     }
     /**
      * 获取session中的当前登录用户名
      * @return
      */
     public String getLoginName(){
         if (getLoginAdmin()!=null) {
             return getLoginAdmin().getLoginname();
         }
         return "";
     }
     /**
      * 获取session中的当前登录用户
      * @return
      */
     public Users getLoginAdmin(){
         if (getHttpSession().getAttribute("loginAdmin")!=null) {
             return (Users)getHttpSession().getAttribute("loginAdmin");
         }
         return null;
     }
     /**
      * 获取session中的当前登录会员
      * @return
      */
     public Member getLoginMember(){
         if (getHttpSession().getAttribute("loginMember")!=null) {
             return (Member)getHttpSession().getAttribute("loginMember");
         }
         return null;
     }
     /**
      * 获取session中的当前登录会员组
      * @return
      */
     public Membergroup getLoginMembergroup(){
         if (getHttpSession().getAttribute("loginMembergroup")!=null) {
             return (Membergroup)getHttpSession().getAttribute("loginMembergroup");
         }
         return null;
     }
     /**
      * 获取session中的当前会员登录用户名
      * @return
      */
     public String getLoginMemberName(){
         if (getLoginMember()!=null) {
             return getLoginMember().getLoginname();
         }
         return "";
     }

     /**
      * 获取登录用户所属单位
      * @return
      */
     public List<Unit> getLoginUnits(){
         //先判断session是否存在
         HttpSession session=getHttpSession();
         if (session.getAttribute("loginUnits")!=null) {
             return (List<Unit>)session.getAttribute("loginUnits");
         }else {
             //不存在则重新提取
             baseUnitService = (UnitService) getBean("unitService");
             List<Unit> list = baseUnitService.findByUser(getLoginAdmin().getId());
             session.setAttribute("loginUnits", list);
             return list;
         }
     }
     /**
      * 获取登录用户所属单位组成的sql语句
      * 例:'','',''
      * @return
      */
     public String getLoginUnitIdsSql(){
         List<Unit> list=getLoginUnits();
         StringBuilder sb=new StringBuilder();
         if (list!=null && list.size()>0) {
             for (int i = 0; i < list.size(); i++) {
                 if (i>0) {
                     sb.append(",");
                 }
                 sb.append("'"+list.get(i).getId()+"'");
             }
         }
         return sb.toString();
     }
     /**
      * 获取登录用户所属角色
      * @return
      */
     public List<Roles> getLoginRoles(){
         //先判断session是否存在
         HttpSession session=getHttpSession();
         if (session.getAttribute("loginRoles")!=null) {
             return (List<Roles>)session.getAttribute("loginRoles");
         }else {
             //不存在则重新提取
             baseRoleService = (RoleService) getBean("roleService");
             List<Roles> list = baseRoleService.findByUser(getLoginAdmin().getId());
             session.setAttribute("loginRoles", list);
             return list;
         }
     }
     /**
      * 获取登录用户所属角色组成的sql语句
      * 例:'','',''
      * @return
      */
     public String getLoginRoleIdsSql(){
         List<Roles> list=getLoginRoles();
         StringBuilder sb=new StringBuilder();
         if (list!=null && list.size()>0) {
             for (int i = 0; i < list.size(); i++) {
                 if (i>0) {
                     sb.append(",");
                 }
                 sb.append("'"+list.get(i).getId()+"'");
             }
         }
         return sb.toString();
     }
     /**
      * 返回到通用信息提示页面
      * @param msg
      * @param url
      * @param seconds
      * @return
      */
     public String showMessage(String showMessage,String forwardUrl,int forwardSeconds){
         this.showMessage=showMessage;
         this.forwardUrl=forwardUrl;
         this.forwardSeconds=forwardSeconds;
         return "showMessage";
     }
     /**
      * 设置静态化参数
      * @param data
      * @throws UnsupportedEncodingException
      */
     public void setData(Map<String,Object> data,Site site) throws UnsupportedEncodingException{
         //传递site参数
         data.put("site", site);
         data.put("contextPath", getContextPath());
         data.put("contextPathNo", getContextPathNo());
         data.put("request_remoteAddr", getHttpRequest().getRemoteAddr());
         //获取参数并放入data
         Enumeration<String> paramNames=getHttpRequest().getParameterNames();
         if (paramNames!=null && paramNames.hasMoreElements()) {
             String name;
             while (paramNames.hasMoreElements()) {
                 name=paramNames.nextElement();
                 if (name!=null &&
                         !name.equals("site") &&
                         !name.equals("contextPath")&&
                         !name.equals("currChannelid")&&
                         !name.equals("currInfoid")) {
                     if(name.equals("key")){
                         String key = new String(getHttpRequest().getParameter(name).getBytes(),"UTF-8");
                         data.put(name, key);
                     }else{
                         data.put(name, getHttpRequest().getParameter(name));
                     }
                 }
             }
         }
         //如果有currChannelid参数则传递currChannel对象
         if (getHttpRequest().getParameter("currChannelid")!=null && getHttpRequest().getParameter("currChannelid").trim().length()>0) {
             baseChannelService = (ChannelService) getBean("channelService");
             data.put("currChannel",baseChannelService.findById(getHttpRequest().getParameter("currChannelid")));
         }
         //如果有currInfoid参数则传递currInfo对象
         if (getHttpRequest().getParameter("currInfoid")!=null && getHttpRequest().getParameter("currInfoid").trim().length()>0) {
             baseInfoService = (InfoService) getBean("infoService");
             data.put("currInfo",baseInfoService.findById(getHttpRequest().getParameter("currInfoid")));
         }
         //获取seesion中存放的变量
         Enumeration<String> sessionNames=getHttpSession().getAttributeNames();
         if (sessionNames!=null && sessionNames.hasMoreElements()) {
             String name;
             while (sessionNames.hasMoreElements()) {
                 name=sessionNames.nextElement();
                 if (name!=null) {
                     //session变量名称改为session_变量名，避免重名
                     data.put("session_"+name, getHttpSession().getAttribute(name));
                 }
             }
         }
     }
     public String getContextPath(){
         return getHttpRequest().getContextPath()+"/";
     }
     public String getContextPathNo(){
         return getHttpRequest().getContextPath()+"/";
     }
     public String getPageStr() {
         return pageStr;
     }
     public void setPageStr(String pageStr) {
         this.pageStr = pageStr;
     }
     public int getTotalCount() {
         return totalCount;
     }
     public void setTotalCount(int totalCount) {
         this.totalCount = totalCount;
     }
     public String getPageFuncId() {
         return pageFuncId;
     }
     public void setPageFuncId(String pageFuncId) {
         this.pageFuncId = pageFuncId;
     }
     public UnitService getBaseUnitService() {
         return baseUnitService;
     }
     public void setBaseUnitService(UnitService baseUnitService) {
         this.baseUnitService = baseUnitService;
     }
     public RoleService getBaseRoleService() {
         return baseRoleService;
     }
     public void setBaseRoleService(RoleService baseRoleService) {
         this.baseRoleService = baseRoleService;
     }
     public ConfigService getBaseConfigService() {
         return baseConfigService;
     }
     public void setBaseConfigService(ConfigService baseConfigService) {
         this.baseConfigService = baseConfigService;
     }
     public String getShowMessage() {
         return showMessage;
     }
     public void setShowMessage(String showMessage) {
         this.showMessage = showMessage;
     }

     public ChannelService getBaseChannelService() {
         return baseChannelService;
     }
     public void setBaseChannelService(ChannelService baseChannelService) {
         this.baseChannelService = baseChannelService;
     }
     public InfoService getBaseInfoService() {
         return baseInfoService;
     }
     public void setBaseInfoService(InfoService baseInfoService) {
         this.baseInfoService = baseInfoService;
     }

     public Object getBean(String bean) {
         return WebApplicationContextUtils.getWebApplicationContext(
                 ServletActionContext.getRequest().getSession().getServletContext()).getBean(bean);
     }
 }