Let a mthod in RestControl return a json string

The get method of EmpControl

package com.hy.empcloud;

import java.util.List;

import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.http.MediaType;
import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.PathVariable;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RequestMethod;
import org.springframework.web.bind.annotation.RestController;
import org.springframework.web.client.RestTemplate;

@RestController
public class EmpControl {
    @Autowired
    EmpService service;
    
    @Autowired
    RestTemplate restTemplate;
    
    @GetMapping("/test")
    public String test() {
        return "Hello";
    }

    @GetMapping("/emp/{id}")
    public Emp get(@PathVariable Long id) throws Exception{
        return this.service.find(id);
    }
    
    @RequestMapping(value="/all",method=RequestMethod.GET,produces=MediaType.APPLICATION_JSON_VALUE)
    public List<Emp> get() {
        return this.service.getAll();
    }
}

Visit url and it's returned value

[{"id":1,"name":"Andy","age":41},{"id":2,"name":"刘德华","age":42},{"id":3,"name":"Bill","age":43},{"id":4,"name":"比尔","age":44}]

--END--

2019年8月24日21点09分