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JSON-B for CZJUG

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Slides from my and Roman Grigoriadi presentation for Czech Java User Group (CZJUG).

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JSON-B for CZJUG

  1. 1. Copyright © 2015, Oracle and/or its affiliates. All rights reserved. JSONB introduction and comparison with other frameworks Dmitry Kornilov JSON-B spec lead @m0mus Roman Grigoriadi JSON-B RI lead engineer @bravehorsie
  2. 2. Copyright © 2015, Oracle and/or its affiliates. All rights reserved. | Safe Harbor Statement The following is intended to outline our general product direction. It is intended for information purposes only, and may not be incorporated into any contract. It is not a commitment to deliver any material, code, or functionality, and should not be relied upon in making purchasing decisions. The development, release, and timing of any features or functionality described for Oracle’s products remains at the sole discretion of Oracle. 2
  3. 3. Copyright © 2015, Oracle and/or its affiliates. All rights reserved. 3 Program Agenda 1. What is JSON-B 2. JSR-367 status 3. Default mapping 4. Customized mapping 5. Demo application 6. JSON-B RI 7. Q&A
  4. 4. Copyright © 2015, Oracle and/or its affiliates. All rights reserved. 4 • JSON Binding is a standard • It’s about converting Java objects to and from JSON documents • JSON Binding = JSON-B = JSONB = JSR 367 What is JSON Binding? 4
  5. 5. Copyright © 2015, Oracle and/or its affiliates. All rights reserved. 5 What is JSON Binding? 5 public class Customer { public int id; public String firstName; public String lastName; …. } Customer e = new Customer(); e.id = 1; e.firstName = “John”; e.lastName = “Doe”; { "id": 1, "firstName" : "John", "lastName" : "Doe", } Java JSON
  6. 6. Copyright © 2015, Oracle and/or its affiliates. All rights reserved. 6 What is JSON Binding? 6 public class Customer { public int id; public String firstName; public String lastName; …. } Customer e = new Customer(); e.id = 1; e.firstName = “John”; e.lastName = “Doe”; { "id": 1, "firstName" : "John", "lastName" : "Doe", } Java JSON JSON-B
  7. 7. Copyright © 2015, Oracle and/or its affiliates. All rights reserved. 7 • Genson • Gson • Jackson • … Alternatives 7
  8. 8. Copyright © 2015, Oracle and/or its affiliates. All rights reserved. | JSON-B Standard 8
  9. 9. Copyright © 2015, Oracle and/or its affiliates. All rights reserved. 99 Java Community Process • JSR-367 • JSR status and updates • Expert group
  10. 10. Copyright © 2015, Oracle and/or its affiliates. All rights reserved. 1010 Specification and API Project • Hosted on java.net • Spec in pdf format • Git repository • Wiki • Bug tracker • Mailing lists
  11. 11. Copyright © 2015, Oracle and/or its affiliates. All rights reserved. 1111 Participate! users@jsonb-spec.java.net
  12. 12. Copyright © 2015, Oracle and/or its affiliates. All rights reserved. 1212 Reference Implementation • eclipselink.org/jsonb • Mirror on GitHub
  13. 13. Copyright © 2015, Oracle and/or its affiliates. All rights reserved. 1313 Summary • JCP Page https://www.jcp.org/en/jsr/detail?id=367 • Specification Project Home: https://java.net/projects/jsonb-spec • API sources & samples: https://java.net/projects/jsonb-spec/sources/git/show/api • Specification in pdf: https://java.net/projects/jsonb-spec/sources/git/content/spec/spec.pdf • Reference implementation: http://eclipselink.org/jsonb
  14. 14. Copyright © 2015, Oracle and/or its affiliates. All rights reserved. | JSON-B Default Mapping 14
  15. 15. Copyright © 2015, Oracle and/or its affiliates. All rights reserved. 1515 Default Mapping • No configuration, no annotations • The scope: – Basic Types – Specific JDK Types – Dates – Classes – Collections/Arrays – Enumerations – JSON-P import javax.json.bind.Jsonb; import javax.json.bind.JsonbBuilder; // Create with default config Jsonb jsonb = JsonbBuilder.create();
  16. 16. Copyright © 2015, Oracle and/or its affiliates. All rights reserved. • toJson(…) • fromJson(…) 1616 JSON-B Engine String toJson(Object object); String toJson(Object object, Type runtimeType); void toJson(Object object, Writer writer); void toJson(Object object, Type runtimeType, Writer appendable); void toJson(Object object, OutputStream stream); void toJson(Object object, Type runtimeType, OutputStream stream); <T> T fromJson(String str, Class<T> type); <T> T fromJson(String str, Type runtimeType); <T> T fromJson(Reader readable, Class<T> type); <T> T fromJson(Reader readable, Type runtimeType); <T> T fromJson(InputStream stream, Class<T> type); <T> T fromJson(InputStream stream, Type runtimeType);
  17. 17. Copyright © 2015, Oracle and/or its affiliates. All rights reserved. 1717 Default Mapping – Basic Types • java.lang.String • java.lang.Character • java.lang.Byte (byte) • java.lang.Short (short) • java.lang.Integer (int) • java.lang.Long (long) • java.lang.Float (float) • java.lang.Double (double) • java.lang.Boolean (boolean)
  18. 18. Copyright © 2015, Oracle and/or its affiliates. All rights reserved. 1818 Default Mapping – Basic Types • java.lang.String • java.lang.Character • java.lang.Byte (byte) • java.lang.Short (short) • java.lang.Integer (int) • java.lang.Long (long) • java.lang.Float (float) • java.lang.Double (double) • java.lang.Boolean (boolean) Serialization: toString() Deserialization: parseXXX()
  19. 19. Copyright © 2015, Oracle and/or its affiliates. All rights reserved. 1919 • java.lang.String • java.lang.Character • java.lang.Byte (byte) • java.lang.Short (short) • java.lang.Integer (int) • java.lang.Long (long) • java.lang.Float (float) • java.lang.Double (double) • java.lang.Boolean (boolean) Default Mapping – Basic Types “string” ’u0041’ (byte) 1 (short) 1 (int) 1 1L 1.2f 1.2 true “string” “A” 1 1 1 1 1.2 1.2 true
  20. 20. Copyright © 2015, Oracle and/or its affiliates. All rights reserved. 2020 Default Mapping – Specific Types • java.math.BigInteger • java.math.BigDecimal • java.net.URL • java.net.URI • java.util.Optional • java.util.OptionalInt • java.util.OptionalLong • java.util.OptionalDouble
  21. 21. Copyright © 2015, Oracle and/or its affiliates. All rights reserved. • java.math.BigInteger • java.math.BigDecimal • java.net.URL • java.net.URI • java.util.Optional • java.util.OptionalInt • java.util.OptionalLong • java.util.OptionalDouble 2121 Default Mapping – Specific Types Serialization: toString() Deserialization: Single argument constructor
  22. 22. Copyright © 2015, Oracle and/or its affiliates. All rights reserved. 2222 Default Mapping – Specific Types • java.math.BigInteger • java.math.BigDecimal • java.net.URL • java.net.URI • java.util.Optional • java.util.OptionalInt • java.util.OptionalLong • java.util.OptionalDouble Serialization: toString() Deserialization: Single argument constructor • Represented by its value if not empty • Considered null if empty
  23. 23. Copyright © 2015, Oracle and/or its affiliates. All rights reserved. 2323 Optional Types OptionalInt.of(1) OptionalInt.empty() JSON-B 1 Genson {"asInt": 1, "present": true} Gson {”value": 1, "present": true} Jackson 1 JSON-B null Genson - Gson {”value": 0, "present": false} Jackson null
  24. 24. Copyright © 2015, Oracle and/or its affiliates. All rights reserved. 2424 Default Mapping – Dates java.util.Date ISO_DATE_TIME java.util.Calendar, java.util.GregorianCalendar ISO_DATE if to time information present, otherwise ISO_DATE_TIME Java.util.TimeZone, java.util.SimpleTimeZone NormalizedCustomId (see TimeZone javadoc) java.time.Instant ISO_INSTANT java.time.LocalDate ISO_LOCAL_DATE java.time.LocalTime ISO_LOCAL_TIME java.time.LocalDateTime ISO_LOCAL_DATE_TIME java.time.ZonedDateTime ISO_ZONED_DATE_TIME java.time.OffsetDateTime ISO_OFFSET_DATE_TIME java.time.OffsetTime ISO_OFFSET_TIME java.time.ZoneId NormalizedZoneId as specified in ZoneId javadoc java.time.ZoneOffset NormalizedZoneId as specified in ZoneOffset javadoc java.time.Duration ISO 8601 seconds based representation java.time.Period ISO 8601 period representation
  25. 25. Copyright © 2015, Oracle and/or its affiliates. All rights reserved. 2525 SimpleDateFormat sdf = new SimpleDateFormat("dd.MM.yyyy"); Date date = sdf.parse("08.03.2016"); Default Mapping – Date Sample JSON-B “2016-03-08T00:00:00” Genson 1457391600000 Gson "Mar 8, 2016 12:00:00 AM” Jackson 1457391600000
  26. 26. Copyright © 2015, Oracle and/or its affiliates. All rights reserved. 2626 Default Mapping – Calendar Sample Calendar cal = Calendar.getInstance(); cal.clear(); cal.set(2016, 3, 8); JSON-B “2016-03-08” Genson 1457391600000 Gson {"year":2016, "month":3, "dayOfMonth":8, "hourOfDay":0, "minute":0, "second": 0} Jackson 1457391600000
  27. 27. Copyright © 2015, Oracle and/or its affiliates. All rights reserved. 2727 Default Mapping – Classes • Public and protected nested and static nested classes • Anonymous classes (serialization only) • Inheritance is supported • Default no-argument constructor is required for deserialization
  28. 28. Copyright © 2015, Oracle and/or its affiliates. All rights reserved. 2828 Default Mapping – Fields • Final fields are serialized • Static fields are skipped • Transient fields are skipped • Null fields are skipped • Lexicographical order • Parent class fields are serialized before child class fields
  29. 29. Copyright © 2015, Oracle and/or its affiliates. All rights reserved. 2929 Fields Order Comparison class Parent { public int parentB = 2; public int parentA = 1; } class Child extends Parent { public int childB = 4; public int childA = 3; } JSON-B {"parentA":1,"parentB":2, "childA":3, "childB":4} Genson {"childA":3, "childB":4, "parentA":1,"parentB":2} Gson {"childB":4, "childA":3, "parentB":2,"parentA":1} Jackson {"parentB":2,"parentA":1, "childB":4, "childA":3}
  30. 30. Copyright © 2015, Oracle and/or its affiliates. All rights reserved. 3030 Default Mapping – Scope and Field Access Strategy Serialization • Existing fields with public getters • Public fields with no getters • Public getter/setter pair without a corresponding field Deserialization • Existing fields with public setters • Public fields with no setters • Public getter/setter pair without a corresponding field
  31. 31. Copyright © 2015, Oracle and/or its affiliates. All rights reserved. 3131 Scope and Field Access Strategy – JSON-B public class Foo { public final int publicFinalField; private final int privateFinalField; public static int publicStaticField; public int publicWithNoGetter; public int publicWithPrivateGetter; public Integer publicNullField = null; private int privateWithNoGetter; private int privateWithPublicGetter; public int getNoField() {}; public void setNoField(int value) {}; } { "publicFinalField": 1, "publicWithNoGetter": 1, "privateWithPublicGetter": 1, "noField": 1 }
  32. 32. Copyright © 2015, Oracle and/or its affiliates. All rights reserved. 3232 Scope and Field Access Strategy – Genson public class Foo { public final int publicFinalField; private final int privateFinalField; public static int publicStaticField; public int publicWithNoGetter; public int publicWithPrivateGetter; public Integer publicNullField = null; private int privateWithNoGetter; private int privateWithPublicGetter; public int getNoField() {}; public void setNoField(int value) {}; } { "publicFinalField": 1, "publicWithNoGetter": 1, "publicWithPrivateGetter": 1, "publicNullField": null, "privateWithPublicGetter": 1, "noField": 1 }
  33. 33. Copyright © 2015, Oracle and/or its affiliates. All rights reserved. 3333 Scope and Field Access Strategy – Gson public class Foo { public final int publicFinalField; private final int privateFinalField; public static int publicStaticField; public int publicWithNoGetter; public int publicWithPrivateGetter; public Integer publicNullField = null; private int privateWithNoGetter; private int privateWithPublicGetter; public int getNoField() {}; public void setNoField(int value) {}; } { "publicFinalField": 1, "privateFinalField": 1, "publicWithNoGetter": 1, "publicWithPrivateGetter": 1, "privateWithNoGetter": 1, "privateWithPublicGetter": 1, }
  34. 34. Copyright © 2015, Oracle and/or its affiliates. All rights reserved. 3434 Scope and Field Access Strategy – Jackson public class Foo { public final int publicFinalField; private final int privateFinalField; public static int publicStaticField; public int publicWithNoGetter; public int publicWithPrivateGetter; public Integer publicNullField = null; private int privateWithNoGetter; private int privateWithPublicGetter; public int getNoField() {}; public void setNoField(int value) {}; } { "publicFinalField": 1, "publicWithNoGetter": 1, "publicWithPrivateGetter": 1, "publicNullField": null, "privateWithPublicGetter": 1, "noField": 1 }
  35. 35. Copyright © 2015, Oracle and/or its affiliates. All rights reserved. 3535 Scope and Field Access Strategy – Summary Framework Respects getters/setters Respects getter/setter visibility Not public fields Virtual fields JSON-B Yes Yes No Yes Genson Yes No No Yes Gson No No Yes No Jackson Yes No No Yes
  36. 36. Copyright © 2015, Oracle and/or its affiliates. All rights reserved. 3636 // Array int[] intArray = {1, 2, 3}; jsonb.toJson(intArray); // [1,2,3] // Collection Collection<Object> list = new ArrayList<>(); list.add(1); list.add(2); list.add(null); jsonb.toJson(list); // [1,2,null] // Map Map<String, Object> map = new LinkedHashMap<>(); map.put("first", 1); map.put("second", 2); jsonb.toJson(map); // {"first":1,"second":2} Arrays/Collections • Collection • Map • Set • HashSet • NavigableSet • SortedSet • TreeSet • LinkedHashSet • TreeHashSet • HashMap • NavigableMap • SortedMap • TreeMap • LinkedHashMap • TreeHashMap • List • ArrayList • LinkedList • Deque • ArrayDeque • Queue • PriorityQueue • EnumSet • EnumMap
  37. 37. Copyright © 2015, Oracle and/or its affiliates. All rights reserved. 3737 JSON-P Types • javax.json.JsonArray • javax.json.JsonStructure • javax.json.JsonValue • javax.json.JsonPointer • javax.json.JsonString • javax.json.JsonNumber
  38. 38. Copyright © 2015, Oracle and/or its affiliates. All rights reserved. 3838 JSON-P Types • javax.json.JsonArray • javax.json.JsonStructure • javax.json.JsonValue • javax.json.JsonPointer • javax.json.JsonString • javax.json.JsonNumber Serialization: javax.json.JsonWriter Deserialization: javax.json.JsonReader
  39. 39. Copyright © 2015, Oracle and/or its affiliates. All rights reserved. 3939 JsonBuilderFactory f = Json.createBuilderFactory(null); JsonObject jsonObject = f.createObjectBuilder() .add(“name", "Jason") .add(“city", "Prague") .build(); JSON-P Sample { "name": "Jason", ”city": ”Prague" }
  40. 40. Copyright © 2015, Oracle and/or its affiliates. All rights reserved. 4040 JSON-P Types Support in Other Frameworks • Genson: – Support added in JSR353Bundle • Gson – No JSON-P support • Jackson – Support added in JSR353Module
  41. 41. Copyright © 2015, Oracle and/or its affiliates. All rights reserved. | Customized Mapping 41
  42. 42. Copyright © 2015, Oracle and/or its affiliates. All rights reserved. 4242 JSON-B Engine Configuration JsonbConfig config = new JsonbConfig() .withFormatting(…) .withNullValues(…) .withEncoding(…) .withStrictIJSON(…) .withPropertyNamingStrategy(…) .withPropertyOrderStrategy(…) .withPropertyVisibilityStrategy(…) .withAdapters(…) .withBinaryDataStrategy(…); Jsonb jsonb = JsonbBuilder.newBuilder() .withConfig(…) .withProvider(…) .build(); • Annotations • Runtime configuration – JsonbConfig – JsonbBuilder
  43. 43. Copyright © 2015, Oracle and/or its affiliates. All rights reserved. 4343 Customizations • Property names • Property order • Ignoring properties • Null handling • Custom instantiation • Fields visibility • Adapters • Date/Number Formats • Binary Encoding
  44. 44. Copyright © 2015, Oracle and/or its affiliates. All rights reserved. 4444 Property Name Customization • JSON-B: – @JsonbProperty (Field, Method) • Genson: – @JsonProperty (Field, Method) – Use GensonBuilder().rename() method • Gson: – @SerializedName (Field) • Jackson: – @JsonProperty (Field, Method)
  45. 45. Copyright © 2015, Oracle and/or its affiliates. All rights reserved. 4545 Custom Mapping - Property Names public class Customer { public int id; public String firstName; } { "id": 1, "firstName": "Jason" }
  46. 46. Copyright © 2015, Oracle and/or its affiliates. All rights reserved. 4646 Custom Mapping - Property Names public class Customer { private int id; @JsonbProperty("name") private String firstName; } public class Customer { public int id; public String firstName; @JsonbProperty("name") public String getFirstName() { return firstName; } } { "id": 1, "name": "Jason" }
  47. 47. Copyright © 2015, Oracle and/or its affiliates. All rights reserved. 4747 Custom Mapping - Property Names public class Customer { public int id; public String firstName; @JsonbProperty(“getter-name") String getFirstName() { return firstName; } @JsonbProperty(“setter-name") void setFirstName(String str) { this.firstName = str; } } Serialization: { "id": 1, “getter-name": "Jason" } Deserialization: { "id": 1, “setter-name": "Jason" }
  48. 48. Copyright © 2015, Oracle and/or its affiliates. All rights reserved. 4848 Property Naming Strategy • Supported naming strategies – IDENTITY (myMixedCaseProperty) – LOWER_CASE_WITH_DASHES (my-mixed-case-property) – LOWER_CASE_WITH_UNDERSCORES (my_mixed_case_property) – UPPER_CAMEL_CASE (MyMixedCaseProperty) – UPPER_CAMEL_CASE_WITH_SPACES (My Mixed Case Property) – CASE_INSENSITIVE (mYmIxEdCaSePrOpErTy) – Or a custom implementation • JsonbConfig().withPropertyNamingStrategy(…):
  49. 49. Copyright © 2015, Oracle and/or its affiliates. All rights reserved. • Genson – GensonBuilder.with(PropertyNameResolver… resolvers) • Gson: – GsonBuilder.setFieldNamingPolicy(FieldNamingPolicy policy) • Jackson – ObjectMapper.setPropertyNamingStrategy(PropertyNamingStrategy pns) 4949 Property Naming Strategy
  50. 50. Copyright © 2015, Oracle and/or its affiliates. All rights reserved. 5050 Property Order Strategy • Strategies: – LEXICOGRAPHICAL (A-Z) – ANY – REVERSE (Z-A) • Compile Time: – @JsonbPropertyOrder on class • Runtime: – withPropertyOrderStrategy(…) @JsonbPropertyOrder(ANY) public class Foo { public int bar2; public int bar1; }
  51. 51. Copyright © 2015, Oracle and/or its affiliates. All rights reserved. • Compile Time: – Transient modifier – @JsonbTransient annotation – PropertyVisibilityStrategy interface – @JsonbVisibility annotation • Runtime: – withPropertyVisibilityStrategy(…) 5151 Ignoring Properties and Visibility Customization public class Foo { public transient int skipped; @JsonbTransient public int alsoSkipped; } @JsonbVisibility(MyStrategy.class) public class Bar { private int field1; private int field2; }
  52. 52. Copyright © 2015, Oracle and/or its affiliates. All rights reserved. • Genson – @JsonIgnore annotation – Include(…) and exclude(…) methods in GensonBuilder class • Gson: – @Exposed annotation – ExclusionStrategy interface • Jackson – @JsonIgnore annotation on field – @JsonIgnoreProperties annotation on class – Filters and mix-ins 5252 Ignoring Properties in Other Frameworks
  53. 53. Copyright © 2015, Oracle and/or its affiliates. All rights reserved. • Null fields are skipped by default • Compile Time: – @JsonbNillable annotation • Runtime: – JsonbConfig().withNullValues(true) 5353 Null Handling public class Customer { public int id = 1; @JsonbNillable public String name = null; }
  54. 54. Copyright © 2015, Oracle and/or its affiliates. All rights reserved. 5454 Null Handling in Other Frameworks Framework Serializes nulls by default Null Handling JSON-B No @JsonbNillable Genson Yes GensonBuilder.setSkipNull(true) Gson No GsonBuilder.serializeNulls() Jackson Yes @JsonInclude(JsonInclude.Include.NON_NULL) ObjectMapper.setSerializationInclusion(JsonInclude.Include.NON_NULL);
  55. 55. Copyright © 2015, Oracle and/or its affiliates. All rights reserved. 5555 Custom Instantiation public class Customer { public int id; public String name; @JsonbCreator public static Customer getFromDb(int id) { return CustomerDao.getByPrimaryKey(id); } } public class Order { public int id; public Customer customer; } { "id": 1, "customer": { "id": 2 } }
  56. 56. Copyright © 2015, Oracle and/or its affiliates. All rights reserved. • JAXB inspired JsonbAdapter interface • @JsonbTypeAdapter annotation • JsonbConfig().withAdapters(JsonbAdapter… adapters); 5656 Adapters
  57. 57. Copyright © 2015, Oracle and/or its affiliates. All rights reserved. • Genson – Converter interface – JAXB adapters support with JAXBBundle • Gson: – TypeAdapter interface • Jackson – External serializers – Mix-In annotations 5757 Adapters in Other Frameworks
  58. 58. Copyright © 2015, Oracle and/or its affiliates. All rights reserved. 5858 Date/Number Format public class FormatTest { public Date defaultDate; @JsonbDateFormat("dd.MM.yyyy") public Date formattedDate; public BigDecimal defaultNumber; @JsonbNumberFormat(“#0.00") public BigDecimal formattedNumber; } { “defaultDate”: “2015-07-26T23:00:00", “formattedDate”: ”26.07.2015", “defaultNumber": 1.2, “formattedNumber": 1.20 }
  59. 59. Copyright © 2015, Oracle and/or its affiliates. All rights reserved. | Date/Number Formats in other Frameworks • Genson – @JsonDateFormat annotation – GensonBuilder.setDateFormat(dateFormat) • Gson: – GsonBuilder.setDateFormat • Jackson – @JsonFormat annotation – objectMapper.setDateFormat(myDateFormat);
  60. 60. Copyright © 2015, Oracle and/or its affiliates. All rights reserved. 6060 Binary Data Encoding • BYTE (default) • BASE_64 • BASE_64_URL JsonbConfig config = new JsonbConfig() .withBinaryDataStrategy(BinaryDataStrategy.BASE_64); Jsonb jsonb = JsonbBuilder.create(config); String json = jsonb.toJson(obj);
  61. 61. Copyright © 2015, Oracle and/or its affiliates. All rights reserved. 6161 I-JSON • I-JSON (”Internet JSON”) is a restricted profile of JSON – https://tools.ietf.org/html/draft-ietf-json-i-json-06 • JSON-B fully supports I-JSON by default with three exceptions: – JSON Binding does not restrict the serialization of top-level JSON texts that are neither objects nor arrays. The restriction should happen at application level. – JSON Binding does not serialize binary data with base64url encoding. – JSON Binding does not enforce additional restrictions on dates/times/duration. • Configuration: withStrictIJSONSerializationCompliance
  62. 62. Copyright © 2015, Oracle and/or its affiliates. All rights reserved. | JSON-B RI 62
  63. 63. Copyright © 2015, Oracle and/or its affiliates. All rights reserved. | JSON-B Demo Application • https://github.com/bravehorsie/jsonb-demo.git • Client server web application • Subject is JSON object, constructed and managed in JavaScript • Demonstrates: –Default and customized mappings –@JsonbProperty annotation –Adapters –Virtual properties handling
  64. 64. Copyright © 2015, Oracle and/or its affiliates. All rights reserved. 6464 JSON-B Demo Model public class Hero { @JsonbProperty("hero_name") private String name; @JsonbProperty("hero_class") private HeroClass heroClass; @JsonbTypeAdapter(ItemsAdapter.class) @JsonbProperty("hero_items") private Map<ItemSlot, Item> items = new HashMap<>(); @JsonbProperty("total_strength") public Long getTotalStrength() { return getTotalStat("strength"); } @JsonbProperty("total_vitality") public Long getTotalVitality() { return getTotalStat("vitality"); } … } public class ItemSlot { private final Long id; // Head, Shoulders, Chest, Boots, etc. private final String name; } public class Item { // Tyrael's might, Butcher's Carver private String name; private List<Stat> stats; ... } public class Stat { // Strength, Vitality private String name; private Integer value; ... }
  65. 65. Copyright © 2015, Oracle and/or its affiliates. All rights reserved. 6565 JSON-B Demo Servlet @Override protected void doPost(HttpServletRequest httpRequest, HttpServletResponse httpResponse) throws ServletException, IOException { // Unmarshall json to Request object with Hero inside. Request request = jsonb.fromJson(httpRequest.getInputStream(), Request.class); Hero hero = request.getHero(); // Generate combat log and loot. CombatLog combatLog = combatEngine.generateCombatLog(hero); combatEngine.generateLoot(hero); // Marshall our hero back to JSON object. jsonb.toJson(new Response(hero, combatLog), Response.class, httpResponse.getOutputStream()); }
  66. 66. Copyright © 2015, Oracle and/or its affiliates. All rights reserved. | JSON-B Scope and Concurrency • Thread safe • Optimal when instance is created per “class model” or per configuration. public class MyRestWsDao { private final Jsonb jsonb; public MyRestWsDao() { JsonbBuilder.create(config); } public Response callBusiness(Request req) { String reqPayload = jsonb.toJson(req); String respPayload = transport.send(reqPayload); return jsonb.fromJson( respPayload, Response.class); } }
  67. 67. Copyright © 2015, Oracle and/or its affiliates. All rights reserved. | Type Resolution and Generics • There is no type info in JSON document. • Type resolution by field / method type declaration { ”fileld1": ”value1", “field2": ”value2” } jsonb.fromJson(json, Pojo.class); public class Pojo { private Box box; }
  68. 68. Copyright © 2015, Oracle and/or its affiliates. All rights reserved. | Type Resolution and Generics • Generic types are resolved by field bounds // Example 1 private List<Box> boxList; // Example 2 public class Pojo<X> { private GenericPojo<Integer> integerGenericPojo; } public class GenericPojo<X> { private List<X> x; }
  69. 69. Copyright © 2015, Oracle and/or its affiliates. All rights reserved. | Type Resolution and Generics • Generic types for root type must be passed to JSONB • Deserialization into interfaces is not supported (besides known types as Map, List, Set, etc..) public class GenericBox<X> { private List<X> xList; private X x; } jsonb.fromJson(json, new GenericBox<BigDecimal>() {}.getClass()); public class IncompatibleClass { public Serializable something; }
  70. 70. Copyright © 2015, Oracle and/or its affiliates. All rights reserved. | JSON-B Adapters • JSON-B runtime conversion of one type to another (in addition to pre- process conversion) • Customizing types, which you can’t modify (don’t own sources) • Conversion is needed for just a part of domain model • Inspired by JAXB XmlAdapter
  71. 71. Copyright © 2015, Oracle and/or its affiliates. All rights reserved. 7171 JSON-B Adapter Sample public class User { private Long id; private String email; private String userName; private String firstName; private String surName; } { “email”: ”f.pokorny@centrum.cz", “firstName": “Frantisek", “id”: 123, “userName": “frantaUser", “surName”: ”Pokorny" }
  72. 72. Copyright © 2015, Oracle and/or its affiliates. All rights reserved. 7272 JSON-B Adapter Sample public class AdaptedUser { @JsonbProperty("USER_ID") private Long id; } { “USER_ID”: 123 }
  73. 73. Copyright © 2015, Oracle and/or its affiliates. All rights reserved. 7373 JSON-B Adapter Sample public class UserAdapter implements JsonbAdapter<User, AdaptedUser> { @Inject private UserService userService; @Override public AdaptedUser adaptToJson(User obj) throws Exception { return new AdaptedUser(obj.getId()); } @Override public User adaptFromJson(AdaptedUser obj) throws Exception { User user = userService.findById(obj.getId()); return user; } }
  74. 74. Copyright © 2015, Oracle and/or its affiliates. All rights reserved. 7474 JSON-B Adapter Sample public class Hero { ... @JsonbTypeAdapter(ItemsAdapter.class) private Map<ItemSlot, Item> items = new HashMap<>(); ... } public class ItemSlot { private final Long id; private final String name; ... } public class Item { private String name; private List<Stat> stats; ... }
  75. 75. Copyright © 2015, Oracle and/or its affiliates. All rights reserved. 7575 JSON-B Adapter Sample public class ItemsAdapter implements JsonbAdapter<Map<ItemSlot, Item>, Map<String, Item>> { @Override public Map<String, Item> adaptToJson(Map<ItemSlot, Item> obj) throws Exception { final Map<String, Item> result = new HashMap<>(); for (Map.Entry<ItemSlot, Item> entry : obj.entrySet()) { result.put(entry.getKey().getName(), entry.getValue()); } return result; } @Override public Map<ItemSlot, Item> adaptFromJson(Map<String, Item> obj) throws Exception { final Map<ItemSlot, Item> result = new HashMap<>(); for (Map.Entry<String, Item> entry : obj.entrySet()) { ItemSlotEnum slotEnum = ItemSlotEnum.valueOf(entry.getKey()); result.put(new ItemSlot(slotEnum.getId(), slotEnum.name()), entry.getValue()); } return result; } }
  76. 76. Copyright © 2015, Oracle and/or its affiliates. All rights reserved. | What’s Next • Serializers / Deserializers with access to low level JSON-P API • Polymorphism (@JsonbPolymorphic / PolymorphicAdapter)
  77. 77. Copyright © 2015, Oracle and/or its affiliates. All rights reserved. 7777 Participate! users@jsonb-spec.java.net
  78. 78. Copyright © 2015, Oracle and/or its affiliates. All rights reserved. | Q&A 78

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