如何在多维JSON字符串中包含变量？

{
  "name": "{{name}}",
  "age": {{age}},
  "address": {
    "street": "{{address.street}}",
    "city": "{{address.city}}",
    "country": "{{address.country}}"
  }
}

{
  "name": "",
  "age": 0,
  "address": {
    "street": "",
    "city": "",
    "country": ""
  }
}

String name = "John";
int age = 30;
String street = "123 Main St";
String city = "New York";
String country = "USA";

String jsonString = "{\n" +
    "  \"name\": \"" + name + "\",\n" +
    "  \"age\": " + age + ",\n" +
    "  \"address\": {\n" +
    "    \"street\": \"" + street + "\",\n" +
    "    \"city\": \"" + city + "\",\n" +
    "    \"country\": \"" + country + "\"\n" +
    "  }\n" +
    "}";