Jackson ObjectMapper使用Json字符串键反序列化Map

Question

The task is create correct Json string representation. There are Map that may contains value that Json string. During write this map to string mapper escape new line and quote Json.

private String getJson() throws JsonProcessingException {
    ObjectMapper mapper = new ObjectMapper();
    Map<String, String> map = new HashMap<>();
    map.put("key1", "val1");
    map.put("key2", "val2");
    return mapper.writerWithDefaultPrettyPrinter().writeValueAsString(map);
}

return:

{
  "key1" : "val1",
  "key2" : "val2"
}

Code

public String test() throws JsonProcessingException {
    ObjectMapper mapper = new ObjectMapper();
    Map<String, String> map = new HashMap<>();
    map.put("information", getJson());
    String result = mapper.writeValueAsString(map);
    System.out.println(result);
    return result; 
}

return

{"information":"{\r\n  \"key1\" : \"val1\",\r\n  \"key2\" : \"val2\"\r\n}"}

But is it possible for test() method return String like:

{
  "information": {
    "key1": "val1",
    "key2": "val2"
  }
}

Thanks

Answer 1

Problem in console output. Map has value as string. If you want formmating output you can put map with "key1", "key2" in your map with key "information" and call mapper.writerWithDefaultPrettyPrinter().writeValueAsString(map)

Answer 2

You have to convert JSON back to map before putting it to "information" map. In your code it is treated just as a string not a map. So you have to update your test() method to something like this:

public static String test() throws IOException {
    ObjectMapper mapper = new ObjectMapper();
    TypeReference<HashMap<String, String>> typeRef = new TypeReference<HashMap<String, String>>() {};
    Map<String, String> oldMap = mapper.readValue(getJson(), typeRef);

    Map<String, Map<String, String>> map = new HashMap<>();
    map.put("information", oldMap);

    String result = mapper.writerWithDefaultPrettyPrinter().writeValueAsString(map);
    System.out.println(result);
    return result; 
}

And the outptut is

{
  "information" : {
    "key1" : "val1",
    "key2" : "val2"
  }
}