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1、关于Ajax交互的步骤
1.1 获取到xmlhttprequest
1.2 设置xmlhttprequest的onreadystatechange响应事件
1.3 准备获取ajax请求 xmlhttp.open("POST", "AjaxServerlet", true);
1.4 设置消息头为表单形式,模仿表单的POSt提交xmlhttp.setRequestHeader("Content-type","application/x-www-form-urlencoded");
1.5 发送ajax请求xmlhttp.send("age=18&name=zhang"); //Ajax的POST请求,参数是通过xmlhttp.send()方法携带的
1.6 处理Ajax交互获取到的数据,具体的处理在xmlhttprequest的onreadystatechange响应事件中实现
2、Ajax与Java的Servlet通过POSt交互
2.1 html代码
<body> <button id="mybtn">点击</button> <div id="myAjax"></div> </body>2.2 JavaScript代码
<script type="text/javascript">
//1、获取到xmlhttprequest
function getXmlhttp() {
var xmlhttp;
if (window.XMLHttpRequest) { // code for IE7+, Firefox, Chrome, Opera, Safari
xmlhttp = new XMLHttpRequest();
} else { // code for IE6, IE5
xmlhttp = new ActiveXObject("Microsoft.XMLHTTP");
}
return xmlhttp;
}
window.onload = function() {
document.getElementById('mybtn').onclick = function() {
//1、获取到xmlhttprequest 对象
var xmlhttp = getXmlhttp();
//2、xmlhttprequest的响应事件
xmlhttp.onreadystatechange = function() {
if (xmlhttp.readyState == 4 && xmlhttp.status == 200) {
//5、操作获取到的信息
//5.1ajax返回的数据,转换为javascript对象
// 5.1.1 利用eval实现转换
var ajaxResult = eval("(" + xmlhttp.responseText + ")");
//5.1.2 利用jquery的方法,对于jQuery.parseJSON(),键值必须为双引号
/* var ajaxResult = jQuery.parseJSON(xmlhttp.responseText); */
alert(ajaxResult)
//5.2获取JavaScript对象的属性
var age = ajaxResult.age;
var name = ajaxResult.name;
//5.3获取到页面的DIV,并设置内容
var mydiv = document.getElementById("myAjax");
mydiv.innerHTML = "name:" + name + "," + "age:" + age;
}
}
//3、准备获取ajax请求
//3.1 对于get请求,带参数的方式,直接在open函数的请求地址带上参数
xmlhttp.open("POST", "AjaxServerlet", true);
//4、发送ajax请求
xmlhttp.setRequestHeader("Content-type",
"application/x-www-form-urlencoded");
xmlhttp.send("age=18&name=zhang");
};
}
</script> 2.3 style代码
<style type="text/css">
#myAjax {
width: 400px;
height: 400px;
border: 1px dashed red;
text-align: center; /* div中的文字水平方向居中显示 */
line-height: 400px; /*这个和div的高度相同,div中的文字就会垂直方向居中显示 */
font-size: 16px;
font-weight: bold;
}
</style> 2.4 AjaxServerlet.java代码
public class AjaxServerlet extends HttpServlet {
public void doGet(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException {
String age = request.getParameter("age");
String name = request.getParameter("name");
Person person = new Person(name, age);
String personJSON = "{\"name" + "\":\"" + name + "\"," + "\"age"
+ "\":" + age + "}";
System.out.println(personJSON);
response.getWriter().write(personJSON);
}
public void doPost(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException {
doGet(request, response);
}
}
2.5 web.xml代码
<servlet> <servlet-name>AjaxServerlet</servlet-name> <servlet-class>com.ajax.com.AjaxServerlet</servlet-class> </servlet> <servlet-mapping> <servlet-name>AjaxServerlet</servlet-name> <url-pattern>/AjaxServerlet</url-pattern> </servlet-mapping> <welcome-file-list> <welcome-file>index.html</welcome-file> </welcome-file-list>
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原文地址：http://blog.csdn.net/zbw18297786698/article/details/51330357
