Java: Convert JSON to DTO Object

Use Jakson

U can convert JSON to DTO and back automatically with ObjectMapper:

• Convert Java object to JSON, writeValue(...)
• Convert JSON to Java object, readValue(...)
• Convert JSON to List of Java objects, readValues(...)

U can use field with different name with @JsonProperty(...) annotation.
U can skip unneeded properties with the following method: configure(DeserializationFeature.FAIL_ON_UNKNOWN_PROPERTIES, false);

Convert JSON to DTO

Java

public class JsonToDtoTest {

   String usersJSON = "[" +
                         "{" +
                            "\"userId\":\"23746376473L\"," +
                            "\"username\":\"Joe\"," +
                            "\"phone\":\"43287377\"," +
                            "\"created\":\"2016-01-21T10:40:04.623Z\"" +
                         "}," +
                         "{" +
                            "\"userId\":\"23746376473L\"," +
                            "\"username\":\"Joe\"," +
                            "\"phone\":\"43287377\"," +
                            "\"created\":\"2016-01-21T10:40:04.623Z\"" +
                         "}]";

   class UserDto {

     @JsonProperty("userId")
     Long id;
     String username;

     public Long getId() { return id; }

     public void setId(Long id) {
         this.id = id;
     }

     public String getUsername() { return username; }

     public void setUsername(String username) {
         this.username = username;
     }

     @Override
     public String toString() {
         return "UserDto { id=" + id + "username=" + username + "};"
     }
   }

   @Test
   public void testParseJSON() throws Exception {
     ObjectMapper mapper = new ObjectMapper();
     mapper.configure(DeserializationFeature.FAIL_ON_UNKNOWN_PROPERTIES, false);

     ObjectReader reader = mapper.reader(UserDto.class);
     MappingIterator elements = reader.readValues(usersJSON);
     UserDto user = elements.next();
     Assert.assertEquals("23746376473L", user.getId());
     Assert.assertEquals("Joe", user.getUsername());
   }
 }
 
 
 

Deserialize an array of objects

Java

...
JavaType type = mapper.getTypeFactory().constructCollectionType(List.class, UserDto.class);
List users = mapper.readValue(usersJSON, type);

see Also

• Generate POJOb from JSON or JSON-Schema
• Github - Jackson-Annotations
• Mkyong - How to convert Java object to / from JSON (Jackson)
• All Http Status Codes
• Spring 4 API - HttpStatus
• Java EE 7 API - Response.Status
• Apache Commons - HttpStatus
• REST (Restful Web Services)
• Themeleaf - Offsite
• Web Resource Optimizer for Java
• Wro4j - Github
• Keynote: Top JS frmeworks 2015