jsp
<img id="img" alt="验证码" src="${pageContext.request.contextPath }/validateservlet"><a href="javascript:change()">看不清,换一张</a>
<script type="text/javascript">
function change(){
var img = document.getElementById("img");
img.src="${pageContext.request.contextPath}/validateservlet?num="+Math.random();
}
$("#img").click(function(){
$("#img").attr("src","${pageContext.request.contextPath}/validateservlet?num="+Math.random());
})
</script>
servlet
ValidateCode code = new ValidateCode(120,40,4,20);
code.write(response.getOutputStream());
xml配置文件
<servlet>
<servlet-name>validateservlet</servlet-name>
<servlet-class>com.qf.demo1.ValidateServlet</servlet-class>
<load-on-startup>-1</load-on-startup>
</servlet>
<servlet-mapping>
<servlet-name>validateservlet</servlet-name>
<url-pattern>/validateservlet</url-pattern>
</servlet-mapping>