How to convert list of Objects to JSON in Spring MVC and Hibernate?

Question

I'm Using Spring MVC and hibernate to fetch data from MySQL. In the controller class a ModelAndView method listEmployees is returning a MAP.The method is getting list of Employee objects from EmployeeService class. I want this method to take list of Employee Objects from Service class and covert it into JSON,or convert it into JSON and write that data in a JSON file so that I can use this JSON data in a JSP page.

@RequestMapping(value="/employees", method = RequestMethod.GET)  
 public @ResponseBody ModelAndView listEmployees() {  
  Map<String, Object> model = new HashMap<String, Object>();
  model.put("employees",prepareListofBean(employeeService.listEmployeess()));  
  return new ModelAndView("employeesList", model);  

 }

private List<EmployeeBean> prepareListofBean(List<Employee> employees){
        List<EmployeeBean> beans = null;
        if(employees != null && !employees.isEmpty()){
            beans = new ArrayList<EmployeeBean>();
            EmployeeBean bean = null;
            for(Employee employee : employees){
                bean = new EmployeeBean();
                bean.setName(employee.getEmpName());
                bean.setId(employee.getEmpId());
                bean.setAddress(employee.getEmpAddress());
                bean.setSalary(employee.getSalary());
                bean.setAge(employee.getEmpAge());
                beans.add(bean);
            }
        }
        return beans;
    }

EDIT

In this below method I tried GSON to convert list to JSON,but was getting null pointer Exception.

**@RequestMapping(value="/employees1", method = RequestMethod.GET)  
    public ModelAndView employeelist() {  

    Gson gson=new Gson();
    gson.toJson(employeeService.listEmployeess());

    ModelAndView modelAndView=new ModelAndView();
    modelAndView.addObject(gson);

    return modelAndView;

    }**

What could be the mistake in this above method?

Solution

You need to assign returned json value to String object and then pass it to ModelAndView. Refer Gson.toJson() and also make sure your class(EmployeeBean) is serializable.

@RequestMapping(value = "/employees1", method = RequestMethod.GET)
public ModelAndView employeelist() {
    Gson gson = new Gson();
    String json = gson.toJson(employeeService.listEmployeess());

    ModelAndView modelAndView = new ModelAndView();
    modelAndView.addObject(json);

    return modelAndView;
}

Comments

[Naman Gala]

I can use this JSON data in a JSP page, how you want to use it? Using ajax call?

[Raman Shrivastava]

There are many libraries built around this e.g. Jackson, GSON etc. Check those. Look for basic tutorials on them. And try posting your attempt rather than asking blind question.

[Nikhil Bharadwaj]

@Raman Shrivastava,please see my edit.

[Raman Shrivastava]

listEmployeess() - spelling is wrong based upon your method declaration in initial code. toJson() returns a String. Why are you not storing toJson()'s result in a String?

[Nikhil Bharadwaj]

,Thanks.That helped a lot.