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;
    }

    publicvoid setData(String data) {
        this.data = data;
    }

    public Map<String, String> getMap() {
        return map;
    }

    publicvoid 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
    publicvoid 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");
            }
        });
    }