一个小白问题，ajax与后台交互

Question

学习中，使用ssh，前端用了jquery，不是获取不到返回值，就是error，请问如何解决。
java代码：

 private String msg = "Operation is Error!!!";
    private String name;
    private String pwd;

    public void login() {
        System.out.println("用户：" + name + "，登录");
        if (name == null || "".equals(name.trim()) || pwd == null || "".equals(pwd.trim())) {
            msg = "name and password cannot be null";
        }
        msg = "Welcome~~~~~~~~~~";
    }

    public void setName(String name) {
        this.name = name;
    }

    public void setPwd(String pwd) {
        this.pwd = pwd;
    }

    public String getMsg() {
        return msg;
    }

struts代码：

 <package name="l" extends="json-default">
        <action name="login" class="LoginAction" method="login">
            <result type="json">
                <param name="includeProperties">msg</param>
            </result>
        </action>
</package>

js代码：

 $.ajax({
            url:"login",
            type:"post",
            data:{"name":name,"pwd":pwd},
            dataType:"json",
            error:function(){
                alert("OMG");
            },
            success:function(data){
                alert("hi");
                alert(data);
});

Answer 1

$.ajax({
type: 'POST',
url: url,
data: data,
success: success,
dataType: dataType
});