Struts2中通过Ajax传递json数据

<?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"> ???<filter> ???????<filter-name>struts-prepare</filter-name> ???????<filter-class>org.apache.struts2.dispatcher.filter.StrutsPrepareFilter</filter-class> ???</filter> ???<filter> ???????<filter-name>struts-execute</filter-name> ???????<filter-class>org.apache.struts2.dispatcher.filter.StrutsExecuteFilter</filter-class> ???</filter>
 ???<filter-mapping> ???????<filter-name>struts-prepare</filter-name> ???????<url-pattern>/*</url-pattern> ???</filter-mapping> ???<filter-mapping> ???????<filter-name>struts-execute</filter-name> ???????<url-pattern>/*</url-pattern> ???</filter-mapping></web-app>

<?xml version="1.0" encoding="UTF-8" ?><!DOCTYPE struts PUBLIC ???????"-//Apache Software Foundation//DTD Struts Configuration 2.5//EN" ???????"http://struts.apache.org/dtds/struts-2.5.dtd"><struts> ???<package name="Login" extends="struts-default,json-default"> <!-- 需要继承struts-default和json-default --> ???????<action name="login"> ???????????<result>/login.jsp</result> ???????</action> ???????<action name="loginaction" class="com.hpe.struts.LoginAction"> ???????????<result type="json"><!-- 返回的数据类型为json --> ???????????????<param name="res">data</param><!-- 这个地方的data就是在LoginAction中定义的data，它必须要有getter、setter，这样就可以将data传递到前台页面上，LoginAction类中所有具有getter的字段都会被封装到一个类中，传递到前台　　{"data":"{\"msg\":\"登录成功！\",\"status\":\"1\"}","mmp":2000} --> ???????????</result> ???????</action> ???</package></struts> 

public class LoginAction extends ActionSupport implements ServletRequestAware { ???private HttpServletRequest request; ???private Map<String, String> map = new HashMap<String, String>(); ???private String data; ???public String getData() { ???????return data; ???} ???public void setData(String data) { ???????this.data = data; ???} ???public Map<String, String> getMap() { ???????return map; ???} ???public void setMap(Map<String, String> map) { ???????this.map = map; ???} ???UserService service = new UserService(); ???public String execute() throws IOException {
　　　　　// 获取HttpSession对象 ???????HttpSession session = ServletActionContext.getRequest().getSession();
　　　　　// 获取用户输入的验证码　 ???????String veryCode = request.getParameter("veryCode").toString(); ???????try { ???????????// 判断验证码
　　　　　　　// 获取session中的验证码 ???????????Object code = session.getAttribute("verycode"); ???????????if (code == null || !veryCode.toLowerCase().equals(code.toString().toLowerCase())) {
　　　　　　　　　　// 保存状态码和状态信息 ???????????????map.put("status", "0"); ???????????????map.put("msg", "验证码错误！");
　　　　　　　　　　// 将Map对象装换为JSONObject对象，然后转换为String类型，保存，并传递至前台页面 ???????????????data = JSONObject.fromObject(map).toString();
　　　　　　　　　 return SUCCESS; ???????????} ???????????// 判断用户名和密码
　　　　　　 ?String name = request.getParameter("name").toString();
 　　　　　　 String pwd = request.getParameter("pwd").toString();
　　　　　　 ?User u = service.login(name, pwd); ???????????if (u != null) { ???????????????session.setAttribute("user", u); ???????????????map.put("status", "1"); ???????????????map.put("msg", "登录成功！"); ???????????????data = JSONObject.fromObject(map).toString(); ???????????} else { ???????????????map.put("status", "-1"); ???????????????map.put("msg", "用户名或密码错误！"); ???????????????data = JSONObject.fromObject(map).toString(); ???????????} ???????} catch (SQLException e) { ???????????map.put("status", "-2"); ???????????map.put("msg", "登录异常：" + e.getMessage()); ???????????data = JSONObject.fromObject(map).toString(); ???????} ??????return SUCCESS; ???} ???@Override ???public void setServletRequest(HttpServletRequest request) { ???????this.request = request; ???}}

function login() { ???????var name = $(‘#name‘).val(); ???????var pwd = $(‘#pwd‘).val(); ???????var vcode = $(‘#vcode‘).val(); ???????$.ajax({ ???????????url : "/MyEasyBuy/loginaction", ???????????type : "post", ???????????data : { ???????????????"name" : name, ???????????????"pwd" : pwd, ???????????????"veryCode" : vcode ???????????}, ???????????dataType : "json", ???????????success : function(res) {// 此时获取到的res是一个Object类型的对象 ???????????????// 将对象转化为json字符串 ???????????????alert(JSON.stringify(res));// {"data":"{\"msg\":\"登录成功！\",\"status\":\"1\"}"} ???????????????// res对象的data属性 ???????????????alert(res.data);// {"msg":"登录成功！","status":"1"} ???????????????// 将res对象的data属性转化为json对象 ???????????????var obj = eval("(" + res.data + ")"); ???????????????alert(obj.msg);// 登录成功！ ???????????????// 错误 ???????????????// var obj2 = eval("{" + res.data + "}"); ???????????????// alert(obj2.msg); ???????????????// alert(res.data.msg); // undefined ???????????????// alert(JSON.parse(res.data).msg);// 登录成功！ ???????????????// res已经是一个对象，不能再次将其转换为json对象 ???????????????// alert(JSON.parse(res)); // 将json字符串转换为json对象 ???????????}, ???????????err : function() { ???????????????alert("error"); ???????????} ???????}); ???}