Java Reflection for capturing parameters from JavaScript for RESTful web services?

I am using Struts 2-REST plugin for web services for my web app. It uses backbone.js to retrieve and display data from the services. However, I am struggling on how to capture the parameters from the collection.fetch() method to the server-side (Java). It is somehow similar how it is applied in AJAX.

For example:

Example #1

fetchStudents : function() {
    this.fetch({
      data : {
        packet : JSON.stringify({
          type : "retrieveAllStudents",
          data : {}
        })
      },
      type : 'POST',
      success : function(collection, response, options) {
        console.log('SUCCESS: all students fetched');
      }
    });
  }

Example #2:

fetchStudentById : function(studentId) {
    this.fetch({
      data : {
        packet : JSON.stringify({
          type : "retrieveStudentById",
          data : {
              studentId : studentId
            }
        })
      },
      type : 'POST',
      success : function(collection, response, options) {
        console.log('SUCCESS: student#' + studentId + ' fetched');
      }
    });
  }

Based on the examples above, parameter type refers to name of method to be called, whilst data is for the parameter/s of the method to be called.

For example# 1, it will be calling method retrieveAllStudents(); and example #2 will be calling retrieveStudentById(studentId) method.

Would it be advisable if I will use Java Reflections? Based on my research, its performance is slow, isn't it? If any, are there alternatives for Reflections?