问找不到http://localhost:8080/login - NetworkError: 404

EN

    <servlet>
    <description></description>
    <display-name>LoginServlet</display-name>
    <servlet-name>LoginServlet</servlet-name>
    <servlet-class>com.login.LoginServlet</servlet-class>

  </servlet>
  <servlet-mapping>
    <servlet-name>LoginServlet</servlet-name>
    <url-pattern>/login</url-pattern>
  </servlet-mapping>

function Login(){
    console.log("in login function");
    var userId=$('#username').val();
    var pass=$('#password').val();

    if(userId=="" || pass==""){
        alert("UserId or Password cannot be blank!");
        document.getElementById("username").focus();
    }else{
        var url='/login';
        var dataString= 'action=login&userId='+userId+'&pass='+pass;
        $.ajax({
            type: 'POST',
            url: url,
            data: dataString,
            success: function (data){
                var loggedIn=data.html();
                console.log(loggedIn + " " + data);
                $('#loggedIn').val(loggedIn);
                $('#loggedIn').show();
            }
            });
    }