Ajax实战项目1 验证用户的唯一性 环境（Ajax+struts2）

验证用户的唯一性

Ajax验证用户名是否存在

步骤：

<?xml version="1.0" encoding="UTF-8"?>
<web-app xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns="http://xmlns.jcp.org/xml/ns/javaee" xsi:schemaLocation="http://xmlns.jcp.org/xml/ns/javaee http://xmlns.jcp.org/xml/ns/javaee/web-app_3_1.xsd" id="WebApp_ID" version="3.1">
<display-name>Ajax</display-name>
<welcome-file-list>
<welcome-file>login.jsp</welcome-file>
</welcome-file-list>
<filter>
<filter-name>struts2</filter-name>
<filter-class>org.apache.struts2.dispatcher.ng.filter.StrutsPrepareAndExecuteFilter</filter-class>
</filter>
<filter-mapping>
<filter-name>struts2</filter-name>
<url-pattern>/*</url-pattern>
</filter-mapping>
</web-app>

<script type="text/javascript">
function checkUserName() {
var name = document.getElementById("name").value;
//alert(name);

if (name == "") {
document.getElementById("namemsg").innerHTML = "<font color='red'>用户名不能为空</font>";
return ;
}
var xmlHttp ;
if(window.XMLHttpRequest) {
xmlHttp = new XMLHttpRequest() ;
} else {
xmlHttp = new ActiveXObject("Microsoft.XMLHTTP") ;
}
//alert("readState状态:"+xmlHttp.readyState+"status:状态:"+xmlHttp.status) ;
xmlHttp.onreadystatechange = function () {
//alert("readState状态:"+xmlHttp.readyState+"status:状态:"+xmlHttp.status) ;
if (xmlHttp.readyState == 4 && xmlHttp.status == 200) {
//alert("xmlHttp.responseText:"+xmlHttp.responseText) ;
if(xmlHttp.responseText == "true") {
document.getElementById("namemsg").innerHTML = "<font color='red'>该用户名已经注册！</font>" ;
}else{
document.getElementById("namemsg").innerHTML = "<font color='#99CC66'>该用户名可用！</font>" ;
}
}
}

xmlHttp.open("get", "user_isexist?name="+name, true) ;
//xmlhttp.setRequestHeader("Content-type","application/x-www-form-urlencoded") ;
xmlHttp.send() ;
}
</script>

<div class="row">
<h1>Ajax验证用户的唯一性</h1>
<form action="">
名字：
<input type="text" id="name" name="name" id="name" onblur="checkUserName();" />
<span id="namemsg"></span>
<br><br>
<input type="submit" value="submit">
</form>
</div>

public void isexist() {
boolean isexist = getName().equals("张三") ;
try {
PrintWriter w = response.getWriter();
w.print(isexist);
w.flush();
w.close();
} catch (IOException e) {
e.printStackTrace();
}
}

<?xml version="1.0" encoding="UTF-8" ?>
<!DOCTYPE struts PUBLIC
"-//Apache Software Foundation//DTD Struts Configuration 2.3//EN"
"http://struts.apache.org/dtds/struts-2.3.dtd">

<struts>

<constant name="struts.enable.DynamicMethodInvocation" value="true" />
<constant name="struts.ui.theme" value="simple" />
<constant name="struts.devMode" value="true" />

<package name="default" namespace="/" extends="struts-default">
<action name="user_*" class="com.ddge.action.UserAction" method="{1}">
<result name="error">/login.jsp</result>
</action>
</package>

</struts>

总结