Converting JSON data to Java object

user_127160 0
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I want to be able to access properties from a JSON string within my Java action method. The string is available by simply saying myJsonString = object.getJson(). Below is an example of what the string can look like:

{
    'title': 'ComputingandInformationsystems',
    'id': 1,
    'children': 'true',
    'groups': [{
        'title': 'LeveloneCIS',
        'id': 2,
        'children': 'true',
        'groups': [{
            'title': 'IntroToComputingandInternet',
            'id': 3,
            'children': 'false',
            'groups': []
        }]
    }]
}

In this string every JSON object contains an array of other JSON objects. The intention is to extract a list of IDs where any given object possessing a group property that contains other JSON objects. I looked at Google's Gson as a potential JSON plugin. Can anyone offer some form of guidance as to how I can generate Java from this JSON string?

jackson gson json java
14 Answers

Oddly, the only decent JSON processor mentioned so far has been GSON.

Here are more good choices:

  • Jackson (Github) -- powerful data binding (JSON to/from POJOs), streaming (ultra fast), tree model (convenient for untyped access)
  • Flex-JSON -- highly configurable serialization

EDIT (Aug/2013):

One more to consider:

  • Genson -- functionality similar to Jackson, aimed to be easier to configure by developer
user_595010

The easiest way is that you can use this softconvertvalue method which is a custom method in which you can convert jsonData into your specific Dto class. 

Dto response = softConvertValue(jsonData, Dto.class);


public static <T> T softConvertValue(Object fromValue, Class<T> toValueType) 
{
    ObjectMapper objMapper = new ObjectMapper();
    return objMapper
        .configure(DeserializationFeature.FAIL_ON_UNKNOWN_PROPERTIES, false)
        .convertValue(fromValue, toValueType);
}
user_53800380

Pass your JSON file in this way, it will return the object.

File file = new File("D:\\Coding\\tickets\\temp.json");
ObjectMapper om = new ObjectMapper();
Profile profile = om.readValue(file, new TypeReference<Profile>() {});
user_18625900 

        <!-- GSON -->
        <dependency>
            <groupId>com.google.code.gson</groupId>
            <artifactId>gson</artifactId>
            <version>2.8.7</version>
        </dependency>

  @Test
    void readListJsonFromFileTest() throws IOException {

        Type type = new TypeToken<List<SimplePojo>>(){}.getType();

        String fromJsonFile = readFromJsonFile("json/simplePojoJsonList.json");

        List<SimplePojo> pojoList = gson.fromJson(fromJsonFile, type);

        Assertions.assertNotNull(pojoList);
    }

    @Test
    void readJsonFromFileTest() throws IOException {

        Type type = new TypeToken<SimplePojo>(){}.getType();

        String fromJsonFile = readFromJsonFile("json/simplePojoJson.json");

        SimplePojo simplePojo = gson.fromJson(fromJsonFile, type);

        Assertions.assertNotNull(simplePojo);
    }

     String readFromJsonFile(String pathToJson) throws IOException {

        InputStream resource = new ClassPathResource(pathToJson).getInputStream();

        String json = StreamUtils.copyToString(resource, StandardCharsets.UTF_8);

        return json;
    }
user_120939750
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