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?

I can use this JSON data in a JSP page, how you want to use it? Using ajax call? — Naman Gala
– Naman Gala, Commented Sep 8, 2015 at 5:01
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. — Raman Shrivastava
– Raman Shrivastava, Commented Sep 8, 2015 at 5:04
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? — Raman Shrivastava
– Raman Shrivastava, Commented Sep 8, 2015 at 5:19

Naman Gala · Accepted Answer · 2015-09-08 05:20:29Z

1

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;
}

answered Sep 8, 2015 at 5:20

Naman Gala

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1 Comment

Nikhil Bharadwaj Over a year ago

,Thanks.That helped a lot.

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