If I would like to do conversation with Java Bean to JSON and JSON to Java Bean, any library can be used?
How-To
Add dependency to your pom.xml
<dependency> <groupId>org.codehaus.jackson</groupId> <artifactId>jackson-mapper-asl</artifactId> <version>1.9.13</version> </dependency>
Create an User bean for test:
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 | package albert.practice.json; import java.io.Serializable; import lombok.Data; import lombok.ToString; @Data @ToString public class User implements Serializable { private static final long serialVersionUID = 1L; private String id; private String login; private String mail; } |
Test code is as bellows:
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 | package albert.practice.json; import java.io.IOException; import java.util.ArrayList; import java.util.List; import org.codehaus.jackson.JsonGenerationException; import org.codehaus.jackson.JsonParseException; import org.codehaus.jackson.map.JsonMappingException; import org.codehaus.jackson.map.ObjectMapper; import org.codehaus.jackson.type.TypeReference; import lombok.extern.slf4j.Slf4j; @Slf4j public class JacksonTest { public static void main(String[] args) { JacksonTest test = new JacksonTest(); String jsonString = test.convertOjbectToJson(); List<User> users = test.convertJsonToObject(jsonString); for (User user : users) { log.debug("user = " + user.toString()); } } public List<User> convertJsonToObject(String jsonString) { ObjectMapper mapper = new ObjectMapper(); List<User> users = new ArrayList<User>(); try { users = mapper.readValue(jsonString, new TypeReference<List<User>>() { }); } catch (JsonParseException e) { e.printStackTrace(); } catch (JsonMappingException e) { e.printStackTrace(); } catch (IOException e) { e.printStackTrace(); } return users; } public String convertOjbectToJson() { List<User> users = createUsers(); String jsonString = ""; ObjectMapper mapper = new ObjectMapper(); try { jsonString = mapper.writeValueAsString(users); } catch (JsonGenerationException e) { e.printStackTrace(); } catch (JsonMappingException e) { e.printStackTrace(); } catch (IOException e) { e.printStackTrace(); } log.debug("jsonString = " + jsonString); return jsonString; } private List<User> createUsers() { User albert = new User(); albert.setId("1"); albert.setLogin("albert"); albert.setMail("albert@gmail.com"); User mandy = new User(); mandy.setId("2"); mandy.setLogin("mandy"); mandy.setMail("mandy@gmail.com"); User verio = new User(); verio.setId("3"); verio.setLogin("verio"); verio.setMail("verio@gmail.com"); List<User> users = new ArrayList<User>(); users.add(albert); users.add(mandy); users.add(verio); return users; } } |
print log:
1 2 3 4 | 2016-06-01 15:35:39.630 [main] DEBUG albert.practice.json.JacksonTest - jsonString = [{"id":"1","login":"albert","mail":"albert@gmail.com"},{"id":"2","login":"mandy","mail":"mandy@gmail.com"},{"id":"3","login":"verio","mail":"verio@gmail.com"}] 2016-06-01 15:35:39.670 [main] DEBUG albert.practice.json.JacksonTest - user = User(id=1, login=albert, mail=albert@gmail.com) 2016-06-01 15:35:39.670 [main] DEBUG albert.practice.json.JacksonTest - user = User(id=2, login=mandy, mail=mandy@gmail.com) 2016-06-01 15:35:39.670 [main] DEBUG albert.practice.json.JacksonTest - user = User(id=3, login=verio, mail=verio@gmail.com) |
Reference
[1] http://www.mkyong.com/java/how-to-convert-java-object-to-from-json-jackson/
[2] https://stackoverflow.com/questions/28821715/java-lang-classcastexception-java-util-linkedhashmap-cannot-be-cast-to-com-test
