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Jackson Annotations – @JsonAnyGetter
@JsonAnyGetter allows a getter method to return Map which is then used to serialize the additional properties of JSON in the similar fashion as other properties.
Example without @JsonAnyGetter
import java.io.IOException; import java.util.HashMap; import java.util.Map; import com.fasterxml.jackson.databind.ObjectMapper; public class JacksonTester { public static void main(String args[]){ ObjectMapper mapper = new ObjectMapper(); try{ Student student = new Student(); student.add("Name", "Mark"); student.add("RollNo", "1"); String jsonString = mapper .writerWithDefaultPrettyPrinter() .writeValueAsString(student); System.out.println(jsonString); } catch (IOException e) { e.printStackTrace(); } } } class Student { private Map<String, String> properties; public Student(){ properties = new HashMap<>(); } public Map<String, String> getProperties(){ return properties; } public void add(String property, String value){ properties.put(property, value); } }
Output
{ "properties" : { "RollNo" : "1", "Name" : "Mark" } }
Example with @JsonAnyGetter
import java.io.IOException; import java.util.HashMap; import java.util.Map; import com.fasterxml.jackson.annotation.JsonAnyGetter; import com.fasterxml.jackson.databind.ObjectMapper; public class JacksonTester { public static void main(String args[]){ ObjectMapper mapper = new ObjectMapper(); try{ Student student = new Student(); student.add("Name", "Mark"); student.add("RollNo", "1"); String jsonString = mapper .writerWithDefaultPrettyPrinter() .writeValueAsString(student); System.out.println(jsonString); } catch (IOException e) { e.printStackTrace(); } } } class Student { private Map<String, String> properties; public Student(){ properties = new HashMap<>(); } @JsonAnyGetter public Map<String, String> getProperties(){ return properties; } public void add(String property, String value){ properties.put(property, value); } }
Output
{ "RollNo" : "1", "Name" : "Mark" }
Jackson Annotations – @JsonGetter
@JsonGetter allows a specific method to be marked as getter method.
Example without @JsonGetter
import java.io.IOException; import com.fasterxml.jackson.databind.ObjectMapper; public class JacksonTester { public static void main(String args[]){ ObjectMapper mapper = new ObjectMapper(); try { Student student = new Student("Mark", 1); String jsonString = mapper .writerWithDefaultPrettyPrinter() .writeValueAsString(student); System.out.println(jsonString); } catch (IOException e) { e.printStackTrace(); } } } class Student { private String name; private int rollNo; public Student(String name, int rollNo){ this.name = name; this.rollNo = rollNo; } public String getStudentName(){ return name; } public int getRollNo(){ return rollNo; } }
Output
{ "studentName" : "Mark", "rollNo" : 1 }
Example with @JsonGetter
import java.io.IOException; import com.fasterxml.jackson.databind.ObjectMapper; import com.fasterxml.jackson.annotation.JsonGetter; public class JacksonTester { public static void main(String args[]){ ObjectMapper mapper = new ObjectMapper(); try { Student student = new Student("Mark", 1); String jsonString = mapper .writerWithDefaultPrettyPrinter() .writeValueAsString(student); System.out.println(jsonString); } catch (IOException e) { e.printStackTrace(); } } } class Student { private String name; private int rollNo; public Student(String name, int rollNo){ this.name = name; this.rollNo = rollNo; } @JsonGetter public String getStudentName(){ return name; } public int getRollNo(){ return rollNo; } }
Output
{ "name" : "Mark", "rollNo" : 1 }
Jackson Annotations – @JsonPropertyOrder
@JsonPropertyOrder allows a specific order to be preserved while serializing a JSON object.
Example without @JsonPropertyOrder
import java.io.IOException; import com.fasterxml.jackson.databind.ObjectMapper; public class JacksonTester { public static void main(String args[]){ ObjectMapper mapper = new ObjectMapper(); try { Student student = new Student("Mark", 1); String jsonString = mapper .writerWithDefaultPrettyPrinter() .writeValueAsString(student); System.out.println(jsonString); } catch (IOException e) { e.printStackTrace(); } } } class Student { private String name; private int rollNo; public Student(String name, int rollNo) { this.name = name; this.rollNo = rollNo; } public String getName(){ return name; } public int getRollNo(){ return rollNo; } }
Output
{ "name" : "Mark", "rollNo" : 1 }
Example @JsonPropertyOrder
import java.io.IOException; import com.fasterxml.jackson.databind.ObjectMapper; import com.fasterxml.jackson.annotation.JsonPropertyOrder; public class JacksonTester { public static void main(String args[]){ ObjectMapper mapper = new ObjectMapper(); try { Student student = new Student("Mark", 1); String jsonString = mapper .writerWithDefaultPrettyPrinter() .writeValueAsString(student); System.out.println(jsonString); } catch (IOException e) { e.printStackTrace(); } } } @JsonPropertyOrder({ "rollNo", "name" }) class Student { private String name; private int rollNo; public Student(String name, int rollNo){ this.name = name; this.rollNo = rollNo; } public String getName(){ return name; } public int getRollNo(){ return rollNo; } }
Output
{ "name" : "Mark", "rollNo" : 1 }
Jackson Annotations – @JsonRawValue
@JsonRawValue allows to serialize a text without escaping or without any decoration.
Example without @JsonRawValue
import java.io.IOException; import com.fasterxml.jackson.databind.ObjectMapper; public class JacksonTester { public static void main(String args[]){ ObjectMapper mapper = new ObjectMapper(); try { Student student = new Student("Mark", 1, "{"attr":false}"); String jsonString = mapper .writerWithDefaultPrettyPrinter() .writeValueAsString(student); System.out.println(jsonString); } catch (IOException e) { e.printStackTrace(); } } } class Student { private String name; private int rollNo; private String json; public Student(String name, int rollNo, String json){ this.name = name; this.rollNo = rollNo; this.json = json; } public String getName(){ return name; } public int getRollNo(){ return rollNo; } public String getJson(){ return json; } }
Output
{ "name" : "Mark", "rollNo" : 1, "json" : {"attr":false} }
Example with @JsonRawValue
import java.io.IOException; import com.fasterxml.jackson.databind.ObjectMapper; import com.fasterxml.jackson.annotation.JsonRawValue; public class JacksonTester { public static void main(String args[]){ ObjectMapper mapper = new ObjectMapper(); try { Student student = new Student("Mark", 1, "{"attr":false}"); String jsonString = mapper .writerWithDefaultPrettyPrinter() .writeValueAsString(student); System.out.println(jsonString); } catch (IOException e) { e.printStackTrace(); } } } class Student { private String name; private int rollNo; @JsonRawValue private String json; public Student(String name, int rollNo, String json) { this.name = name; this.rollNo = rollNo; this.json = json; } public String getName(){ return name; } public int getRollNo(){ return rollNo; } public String getJson(){ return json; } }
Output
{ "name" : "Mark", "rollNo" : 1, "json" : {"attr":false} }
Jackson Annotations – @JsonValue
@JsonValue allows to serialize an entire object using its single method.
Example @JsonValue
import java.io.IOException; import com.fasterxml.jackson.annotation.JsonValue; import com.fasterxml.jackson.databind.ObjectMapper; public class JacksonTester { public static void main(String args[]){ ObjectMapper mapper = new ObjectMapper(); try { Student student = new Student("Mark", 1); String jsonString = mapper .writerWithDefaultPrettyPrinter() .writeValueAsString(student); System.out.println(jsonString); } catch (IOException e) { e.printStackTrace(); } } } class Student { private String name; private int rollNo; public Student(String name, int rollNo){ this.name = name; this.rollNo = rollNo; } public String getName(){ return name; } public int getRollNo(){ return rollNo; } @JsonValue public String toString(){ return "{ name : " + name + " }"; } }
Output
"{ name : Mark }"
Jackson Annotations – @JsonRootName
@JsonRootName allows to have a root node specified over the JSON. We need to enable wrap root value as well.
Example @JsonRootName
import java.io.IOException; import com.fasterxml.jackson.annotation.JsonRootName; import com.fasterxml.jackson.databind.ObjectMapper; import com.fasterxml.jackson.databind.SerializationFeature; public class JacksonTester { public static void main(String args[]){ ObjectMapper mapper = new ObjectMapper(); try { Student student = new Student("Mark", 1); mapper.enable(SerializationFeature.WRAP_ROOT_VALUE); String jsonString = mapper .writerWithDefaultPrettyPrinter() .writeValueAsString(student); System.out.println(jsonString); } catch (IOException e) { e.printStackTrace(); } } } @JsonRootName(value = "student") class Student { private String name; private int rollNo; public Student(String name, int rollNo){ this.name = name; this.rollNo = rollNo; } public String getName(){ return name; } public int getRollNo(){ return rollNo; } }
Output
{ "student" : { "name" : "Mark", "rollNo" : 1 } }
Jackson Annotations – @JsonSerialize
@JsonSerialize is used to specify custom serializer to marshall the json object.
Example with @JsonSerialize
import java.io.IOException; import java.text.ParseException; import java.text.SimpleDateFormat; import java.util.Date; import com.fasterxml.jackson.core.JsonGenerator; import com.fasterxml.jackson.databind.ObjectMapper; import com.fasterxml.jackson.databind.SerializerProvider; import com.fasterxml.jackson.databind.annotation.JsonSerialize; import com.fasterxml.jackson.databind.ser.std.StdSerializer; public class JacksonTester { public static void main(String args[]) throws ParseException { ObjectMapper mapper = new ObjectMapper(); SimpleDateFormat dateFormat = new SimpleDateFormat("dd-MM-yyyy"); try { Student student = new Student("Mark", 1, dateFormat.parse("20-11-1984")); String jsonString = mapper .writerWithDefaultPrettyPrinter() .writeValueAsString(student); System.out.println(jsonString); } catch (IOException e) { e.printStackTrace(); } } } class Student { private String name; private int rollNo; @JsonSerialize(using = CustomDateSerializer.class) private Date dateOfBirth; public Student(String name, int rollNo, Date dob){ this.name = name; this.rollNo = rollNo; this.dateOfBirth = dob; } public String getName(){ return name; } public int getRollNo(){ return rollNo; } public Date getDateOfBirth(){ return dateOfBirth; } } class CustomDateSerializer extends StdSerializer<Date> { private static final long serialVersionUID = 1L; private static SimpleDateFormat formatter = new SimpleDateFormat("dd-MM-yyyy"); public CustomDateSerializer() { this(null); } public CustomDateSerializer(Class<Date> t) { super(t); } @Override public void serialize(Date value, JsonGenerator generator, SerializerProvider arg2) throws IOException { generator.writeString(formatter.format(value)); } }
Output
{ "name" : "Mark", "rollNo" : 1, "dateOfBirth" : "20-11-1984" }
Jackson Annotations – @JsonCreator
@JsonCreator is used to fine tune the constructor or factory method used in deserialization. We”ll be using @JsonProperty as well to achieve the same. In the example below, we are matching an json with different format to our class by defining the required property names.
Example @JsonCreator
import java.io.IOException; import java.text.ParseException; import com.fasterxml.jackson.annotation.JsonCreator; import com.fasterxml.jackson.annotation.JsonProperty; import com.fasterxml.jackson.databind.ObjectMapper; public class JacksonTester { public static void main(String args[]) throws ParseException{ String json = "{"id":1,"theName":"Mark"}"; ObjectMapper mapper = new ObjectMapper(); try { Student student = mapper .readerFor(Student.class) .readValue(json); System.out.println(student.rollNo +", " + student.name); } catch (IOException e) { e.printStackTrace(); } } } class Student { public String name; public int rollNo; @JsonCreator public Student(@JsonProperty("theName") String name, @JsonProperty("id") int rollNo){ this.name = name; this.rollNo = rollNo; } }
Output
1, Mark
Jackson Annotations – @JacksonInject
@JacksonInject is used when a property value is to be injected instead of being parsed from Json input. In the example below, we are inserting a value into object instead of parsing from the Json.
Example @JacksonInject
import java.io.IOException; import java.text.ParseException; import com.fasterxml.jackson.annotation.JacksonInject; import com.fasterxml.jackson.databind.InjectableValues; import com.fasterxml.jackson.databind.ObjectMapper; public class JacksonTester { public static void main(String args[]) throws ParseException{ String json = "{"name":"Mark"}"; InjectableValues injectableValues = new InjectableValues.Std() .addValue(int.class, 1); ObjectMapper mapper = new ObjectMapper(); try { Student student = mapper .reader(injectableValues) .forType(Student.class) .readValue(json); System.out.println(student.rollNo +", " + student.name); } catch (IOException e) { e.printStackTrace(); } } } class Student { public String name; @JacksonInject public int rollNo; }
Output
1, Mark
Jackson Annotations – @JsonAnySetter
@JsonAnySetter allows a setter method to use Map which is then used to deserialize the additional properties of JSON in the similar fashion as other properties.
Example @JsonAnySetter
import java.io.IOException; import java.util.HashMap; import java.util.Map; import com.fasterxml.jackson.annotation.JsonAnySetter; import com.fasterxml.jackson.databind.ObjectMapper; public class JacksonTester { public static void main(String args[]){ ObjectMapper mapper = new ObjectMapper(); String jsonString = "{"RollNo" : "1","Name" : "Mark"}"; try { Student student = mapper.readerFor(Student.class).readValue(jsonString); System.out.println(student.getProperties().get("Name")); System.out.println(student.getProperties().get("RollNo")); } catch (IOException e) { e.printStackTrace(); } } } class Student { private Map<String, String> properties; public Student(){ properties = new HashMap<>(); } public Map<String, String> getProperties(){ return properties; } @JsonAnySetter public void add(String property, String value){ properties.put(property, value); } }
Output
Mark 1
Jackson Annotations – @JsonSetter
@JsonSetter allows a specific method to be marked as setter method.
Example @JsonSetter
import java.io.IOException; import com.fasterxml.jackson.annotation.JsonSetter; import com.fasterxml.jackson.databind.ObjectMapper; public class JacksonTester { public static void main(String args[]){ ObjectMapper mapper = new ObjectMapper(); String jsonString = "{"rollNo":1,"name":"Marks"}"; try { Student student = mapper.readerFor(Student.class).readValue(jsonString); System.out.println(student.name); } catch (IOException e) { e.printStackTrace(); } } } class Student { public int rollNo; public String name; @JsonSetter("name") public void setTheName(String name) { this.name = name; } }
Output
Marks
Jackson Annotations – @JsonDeserialize
@JsonDeserialize is used to specify custom deserializer to unmarshall the json object.
Example @JsonDeserialize
import java.io.IOException; import java.text.ParseException; import java.text.SimpleDateFormat; import java.util.Date; import com.fasterxml.jackson.core.JsonParser; import com.fasterxml.jackson.core.JsonProcessingException; import com.fasterxml.jackson.databind.DeserializationContext; import com.fasterxml.jackson.databind.ObjectMapper; import com.fasterxml.jackson.databind.annotation.JsonDeserialize; import com.fasterxml.jackson.databind.deser.std.StdDeserializer; public class JacksonTester { public static void main(String args[]) throws ParseException{ ObjectMapper mapper = new ObjectMapper(); String jsonString = "{"name":"Mark","dateOfBirth":"20-12-1984"}"; try { Student student = mapper .readerFor(Student.class) .readValue(jsonString); System.out.println(student.dateOfBirth); } catch (IOException e) { e.printStackTrace(); } } } class Student { public String name; @JsonDeserialize(using = CustomDateDeserializer.class) public Date dateOfBirth; } class CustomDateDeserializer extends StdDeserializer<Date> { private static final long serialVersionUID = 1L; private static SimpleDateFormat formatter = new SimpleDateFormat("dd-MM-yyyy"); public CustomDateDeserializer() { this(null); } public CustomDateDeserializer(Class<Date> t) { super(t); } @Override public Date deserialize(JsonParser parser, DeserializationContext context) throws IOException, JsonProcessingException { String date = parser.getText(); try { return formatter.parse(date); } catch (ParseException e) { e.printStackTrace(); } return null; } }
Output
Thu Dec 20 00:00:00 IST 1984
Jackson Annotations – @JsonEnumDefaultValue
@JsonEnumDefaultValue is used to deserialize an unknown enum value using a default value.
Example @JsonEnumDefaultValue
import java.io.IOException; import java.text.ParseException; import com.fasterxml.jackson.annotation.JsonEnumDefaultValue; import com.fasterxml.jackson.databind.DeserializationFeature; import com.fasterxml.jackson.databind.ObjectMapper; public class JacksonTester { public static void main(String args[]) throws ParseException{ ObjectMapper mapper = new ObjectMapper(); mapper.enable(DeserializationFeature.READ_UNKNOWN_ENUM_VALUES_USING_DEFAULT_VALUE); String jsonString = ""abc""; try { LETTERS value = mapper.readValue(jsonString, LETTERS.class); System.out.println(value); } catch (IOException e) { e.printStackTrace(); } } } enum LETTERS { A, B, @JsonEnumDefaultValue UNKNOWN }
Output
UNKNOWN
Jackson Annotations – @JsonIgnoreProperties
@JsonIgnoreProperties is used at class level to mark a property or list of properties to be ignored.
Example – @JsonIgnoreProperties
import java.io.IOException; import com.fasterxml.jackson.annotation.JsonIgnoreProperties; import com.fasterxml.jackson.databind.ObjectMapper; public class JacksonTester { public static void main(String args[]) { ObjectMapper mapper = new ObjectMapper(); try { Student student = new Student(1,11,"1ab","Mark"); String jsonString = mapper .writerWithDefaultPrettyPrinter() .writeValueAsString(student); System.out.println(jsonString); } catch (IOException e) { e.printStackTrace(); } } } @JsonIgnoreProperties({ "id", "systemId" }) class Student { public int id; public String systemId; public int rollNo; public String name; Student(int id, int rollNo, String systemId, String name){ this.id = id; this.systemId = systemId; this.rollNo = rollNo; this.name = name; } }
Output
{ "rollNo" : 11, "name" : "Mark" }
Jackson Annotations – @JsonIgnore
@JsonIgnore is used at field level to mark a property or list of properties to be ignored.
Example – @JsonIgnore
import java.io.IOException; import com.fasterxml.jackson.annotation.JsonIgnore; import com.fasterxml.jackson.databind.ObjectMapper; public class JacksonTester { public static void main(String args[]){ ObjectMapper mapper = new ObjectMapper(); try{ Student student = new Student(1,11,"1ab","Mark"); String jsonString = mapper .writerWithDefaultPrettyPrinter() .writeValueAsString(student); System.out.println(jsonString); } catch (IOException e) { e.printStackTrace(); } } } class Student { public int id; @JsonIgnore public String systemId; public int rollNo; public String name; Student(int id, int rollNo, String systemId, String name){ this.id = id; this.systemId = systemId; this.rollNo = rollNo; this.name = name; } }
Output
{ "id" : 1, "rollNo" : 11, "name" : "Mark" }
Jackson Annotations – @JsonIgnoreType
@JsonIgnoreType is used at mark a property of special type to be ignored.
Example – @JsonIgnoreType
import java.io.IOException; import com.fasterxml.jackson.annotation.JsonIgnoreType; import com.fasterxml.jackson.databind.ObjectMapper; public class JacksonTester { public static void main(String args[]){ ObjectMapper mapper = new ObjectMapper(); try { Student student = new Student(1,11,"1ab","Mark"); String jsonString = mapper .writerWithDefaultPrettyPrinter() .writeValueAsString(student); System.out.println(jsonString); } catch (IOException e) { e.printStackTrace(); } } } class Student { public int id; @JsonIgnore public String systemId; public int rollNo; public Name nameObj; Student(int id, int rollNo, String systemId, String name){ this.id = id; this.systemId = systemId; this.rollNo = rollNo; nameObj = new Name(name); } @JsonIgnoreType class Name { public String name; Name(String name){ this.name = name; } } }
Output
{ "id" : 1, "systemId" : "1ab", "rollNo" : 11 }
Jackson Annotations – @JsonInclude
@JsonInclude is used at exclude properties having null/empty or default values.
Example – @JsonInclude
import java.io.IOException; import com.fasterxml.jackson.annotation.JsonInclude; import com.fasterxml.jackson.databind.ObjectMapper; public class JacksonTester { public static void main(String args[]){ ObjectMapper mapper = new ObjectMapper(); try { Student student = new Student(1,null); String jsonString = mapper .writerWithDefaultPrettyPrinter() .writeValueAsString(student); System.out.println(jsonString); } catch (IOException e) { e.printStackTrace(); } } } @JsonInclude(JsonInclude.Include.NON_NULL) class Student { public int id; public String name; Student(int id,String name){ this.id = id; this.name = name; } }
Output
{ "id" : 1 }
Jackson Annotations – @JsonAutoDetect
@JsonAutoDetect can be used to include properties which are not accessible otherwise.
Example – @JsonAutoDetect
import java.io.IOException; import com.fasterxml.jackson.annotation.JsonAutoDetect; import com.fasterxml.jackson.databind.ObjectMapper; public class JacksonTester { public static void main(String args[]){ ObjectMapper mapper = new ObjectMapper(); try{ Student student = new Student(1,"Mark"); String jsonString = mapper .writerWithDefaultPrettyPrinter() .writeValueAsString(student); System.out.println(jsonString); } catch (IOException e) { e.printStackTrace(); } } } @JsonAutoDetect(fieldVisibility = JsonAutoDetect.Visibility.ANY) class Student { private int id; private String name; Student(int id,String name) { this.id = id; this.name = name; } }
Output
{ "id" : 1, "name" : "Mark" }
Jackson Annotations – @JsonTypeInfo
@JsonTypeInfo is used to indicate details of type information which is to be included in serialization and de-serialization.
Example – @JsonTypeInfo
import java.io.IOException; import com.fasterxml.jackson.annotation.JsonSubTypes; import com.fasterxml.jackson.annotation.JsonTypeInfo; import com.fasterxml.jackson.annotation.JsonTypeInfo.As; import com.fasterxml.jackson.annotation.JsonTypeName; import com.fasterxml.jackson.databind.ObjectMapper; public class JacksonTester { public static void main(String args[]) throws IOException { Shape shape = new JacksonTester.Circle("CustomCircle", 1); String result = new ObjectMapper() .writerWithDefaultPrettyPrinter() .writeValueAsString(shape); System.out.println(result); String json = "{"name":"CustomCircle","radius":1.0, "type":"circle"}"; Circle circle = new ObjectMapper().readerFor(Shape.class).readValue(json); System.out.println(circle.name); } @JsonTypeInfo(use = JsonTypeInfo.Id.NAME, include = As.PROPERTY, property = "type") @JsonSubTypes({ @JsonSubTypes.Type(value = Square.class, name = "square"), @JsonSubTypes.Type(value = Circle.class, name = "circle") }) static class Shape { public String name; Shape(String name){ this.name = name; } } @JsonTypeName("square") static class Square extends Shape { public double length; Square(){ this(null,0.0); } Square(String name, double length){ super(name); this.length = length; } } @JsonTypeName("circle") static class Circle extends Shape { public double radius; Circle(){ this(null,0.0); } Circle(String name, double radius) { super(name); this.radius = radius; } } }
Output
{ "type" : "circle", "name" : "CustomCircle", "radius" : 1.0 } CustomCircle
Jackson Annotations – @JsonSubTypes
@JsonSubTypes is used to indicate subtypes of types annotated.
Example – @JsonSubTypes
import java.io.IOException; import com.fasterxml.jackson.annotation.JsonSubTypes; import com.fasterxml.jackson.annotation.JsonTypeInfo; import com.fasterxml.jackson.annotation.JsonTypeInfo.As; import com.fasterxml.jackson.annotation.JsonTypeName; import com.fasterxml.jackson.databind.ObjectMapper; public class JacksonTester { public static void main(String args[]) throws IOException{ Shape shape = new JacksonTester.Circle("CustomCircle", 1); String result = new ObjectMapper() .writerWithDefaultPrettyPrinter() .writeValueAsString(shape); System.out.println(result); String json = "{"name":"CustomCircle","radius":1.0, "type":"circle"}"; Circle circle = new ObjectMapper().readerFor(Shape.class).readValue(json); System.out.println(circle.name); } @JsonTypeInfo(use = JsonTypeInfo.Id.NAME, include = As.PROPERTY, property = "type") @JsonSubTypes({ @JsonSubTypes.Type(value = Square.class, name = "square"), @JsonSubTypes.Type(value = Circle.class, name = "circle") }) static class Shape { public String name; Shape(String name) { this.name = name; } } @JsonTypeName("square") static class Square extends Shape { public double length; Square(){ this(null,0.0); } Square(String name, double length){ super(name); this.length = length; } } @JsonTypeName("circle") static class Circle extends Shape { public double radius; Circle(){ this(null,0.0); } Circle(String name, double radius){ super(name); this.radius = radius; } } }
Output
{ "type" : "circle", "name" : "CustomCircle", "radius" : 1.0 } CustomCircle
Jackson Annotations – @JsonTypeName
@JsonTypeName is used to set type names to be used for annotated class.
Example – @JsonTypeName
import java.io.IOException; import com.fasterxml.jackson.annotation.JsonSubTypes; import com.fasterxml.jackson.annotation.JsonTypeInfo; import com.fasterxml.jackson.annotation.JsonTypeInfo.As; import com.fasterxml.jackson.annotation.JsonTypeName; import com.fasterxml.jackson.databind.ObjectMapper; public class JacksonTester { public static void main(String args[]) throws IOException { Shape shape = new JacksonTester.Circle("CustomCircle", 1); String result = new ObjectMapper() .writerWithDefaultPrettyPrinter() .writeValueAsString(shape); System.out.println(result); String json = "{"name":"CustomCircle","radius":1.0, "type":"circle"}"; Circle circle = new ObjectMapper().readerFor(Shape.class).readValue(json); System.out.println(circle.name); } @JsonTypeInfo(use = JsonTypeInfo.Id.NAME, include = As.PROPERTY, property = "type") @JsonSubTypes({ @JsonSubTypes.Type(value = Square.class, name = "square"), @JsonSubTypes.Type(value = Circle.class, name = "circle") }) static class Shape { public String name; Shape(String name){ this.name = name; } } @JsonTypeName("square") static class Square extends Shape { public double length; Square(){ this(null,0.0); } Square(String name, double length){ super(name); this.length = length; } } @JsonTypeName("circle") static class Circle extends Shape { public double radius; Circle(){ this(null,0.0); } Circle(String name, double radius){ super(name); this.radius = radius; } } }
Output
{ "type" : "circle", "name" : "CustomCircle", "radius" : 1.0 } CustomCircle
Jackson Annotations – @JsonProperty
@JsonProperty is used to mark non-standard getter/setter method to be used with respect to json property.
Example – @JsonProperty
import java.io.IOException; import com.fasterxml.jackson.annotation.JsonProperty; import com.fasterxml.jackson.databind.ObjectMapper; public class JacksonTester { public static void main(String args[]) throws IOException { ObjectMapper mapper = new ObjectMapper(); String json = "{"id" : 1}"; Student student = mapper.readerFor(Student.class).readValue(json); System.out.println(student.getTheId()); } } class Student { private int id; Student(){} Student(int id){ this.id = id; } @JsonProperty("id") public int getTheId() { return id; } @JsonProperty("id") public void setTheId(int id) { this.id = id; } }
Output
1
Jackson Annotations – @JsonFormat
@JsonFormat is used to specify format while serialization or de-serialization. It is mostly used with Date fields.
Example – @JsonFormat
import java.io.IOException; import java.text.ParseException; import java.text.SimpleDateFormat; import java.util.Date; import com.fasterxml.jackson.annotation.JsonFormat; import com.fasterxml.jackson.databind.ObjectMapper; public class JacksonTester { public static void main(String args[]) throws IOException, ParseException { ObjectMapper mapper = new ObjectMapper(); SimpleDateFormat simpleDateFormat = new SimpleDateFormat("dd-MM-yyyy"); Date date = simpleDateFormat.parse("20-12-1984"); Student student = new Student(1, date); String jsonString = mapper .writerWithDefaultPrettyPrinter() .writeValueAsString(student); System.out.println(jsonString); } } class Student { public int id; @JsonFormat(shape = JsonFormat.Shape.STRING, pattern = "dd-MM-yyyy") public Date birthDate; Student(int id, Date birthDate){ this.id = id; this.birthDate = birthDate; } }
Output
{ "id" : 1, "birthDate" : "19-12-1984" }
Jackson Annotations – @JsonUnwrapped
@JsonUnwrapped is used to unwrap values of objects during serialization or de-serialization.
Example – @JsonUnwrapped
import java.io.IOException; import java.text.ParseException; import java.text.SimpleDateFormat; import java.util.Date; import com.fasterxml.jackson.annotation.JsonUnwrapped; import com.fasterxml.jackson.databind.ObjectMapper; public class JacksonTester { public static void main(String args[]) throws IOException, ParseException{ ObjectMapper mapper = new ObjectMapper(); SimpleDateFormat simpleDateFormat = new SimpleDateFormat("dd-MM-yyyy"); Date date = simpleDateFormat.parse("20-12-1984"); Student.Name name = new Student.Name(); name.first = "Jane"; name.last = "Doe"; Student student = new Student(1, name); String jsonString = mapper .writerWithDefaultPrettyPrinter() .writeValueAsString(student); System.out.println(jsonString); } } class Student { public int id; @JsonUnwrapped public Name name; Student(int id, Name name){ this.id = id; this.name = name; } static class Name { public String first; public String last; } }
Output
{ "id" : 1, "first" : "Jane", "last" : "Doe" }
Jackson Annotations – @JsonView
@JsonView is used to control values to be serialized or not.
Example – @JsonView
import java.io.IOException; import java.text.ParseException; import com.fasterxml.jackson.annotation.JsonView; import com.fasterxml.jackson.databind.ObjectMapper; public class JacksonTester { public static void main(String args[]) throws IOException, ParseException { ObjectMapper mapper = new ObjectMapper(); Student student = new Student(1, "Mark", 12); String jsonString = mapper .writerWithDefaultPrettyPrinter() .withView(Views.Public.class) .writeValueAsString(student); System.out.println(jsonString); } } class Student { @JsonView(Views.Public.class) public int id; @JsonView(Views.Public.class) public String name; @JsonView(Views.Internal.class) public int age; Student(int id, String name, int age) { this.id = id; this.name = name; this.age = age; } } class Views { static class Public {} static class Internal extends Public {} }
Output
{ "id" : 1, "name" : "Mark" }
Jackson Annotations – @JsonManagedReference
@JsonManagedReferences and JsonBackReferences are used to display objects with parent child relationship. @JsonManagedReferences is used to refer to parent object and @JsonBackReferences is used to mark child objects.
Example – @JsonManagedReferences
import java.io.IOException; import java.text.ParseException; import java.util.ArrayList; import java.util.List; import com.fasterxml.jackson.annotation.JsonBackReference; import com.fasterxml.jackson.annotation.JsonManagedReference; import com.fasterxml.jackson.databind.ObjectMapper; public class JacksonTester { public static void main(String args[]) throws IOException, ParseException { ObjectMapper mapper = new ObjectMapper(); Student student = new Student(1, "Mark"); Book book1 = new Book(1,"Learn HTML", student); Book book2 = new Book(1,"Learn JAVA", student); student.addBook(book1); student.addBook(book2); String jsonString = mapper .writerWithDefaultPrettyPrinter() .writeValueAsString(book1); System.out.println(jsonString); } } class Student { public int rollNo; public String name; @JsonBackReference public List<Book> books; Student(int rollNo, String name){ this.rollNo = rollNo; this.name = name; this.books = new ArrayList<Book>(); } public void addBook(Book book){ books.add(book); } } class Book { public int id; public String name; Book(int id, String name, Student owner){ this.id = id; this.name = name; this.owner = owner; } @JsonManagedReference public Student owner; }
Output
{ "id" : 1, "name" : "Learn HTML", "owner" : { "rollNo" : 1, "name" : "Mark" } }
Jackson Annotations – @JsonBackReference
@JsonManagedReferences and JsonBackReferences are used to display objects with parent child relationship. @JsonManagedReferences is used to refer to parent object and @JsonBackReferences is used to mark child objects.
Example – @JsonBackReferences
import java.io.IOException; import java.text.ParseException; import java.util.ArrayList; import java.util.List; import com.fasterxml.jackson.annotation.JsonBackReference; import com.fasterxml.jackson.annotation.JsonManagedReference; import com.fasterxml.jackson.databind.ObjectMapper; public class JacksonTester { public static void main(String args[]) throws IOException, ParseException { ObjectMapper mapper = new ObjectMapper(); Student student = new Student(1, "Mark"); Book book1 = new Book(1,"Learn HTML", student); Book book2 = new Book(1,"Learn JAVA", student); student.addBook(book1); student.addBook(book2); String jsonString = mapper .writerWithDefaultPrettyPrinter() .writeValueAsString(book1); System.out.println(jsonString); } } class Student { public int rollNo; public String name; @JsonBackReference public List<Book> books; Student(int rollNo, String name){ this.rollNo = rollNo; this.name = name; this.books = new ArrayList<Book>(); } public void addBook(Book book){ books.add(book); } } class Book { public int id; public String name; Book(int id, String name, Student owner) { this.id = id; this.name = name; this.owner = owner; } @JsonManagedReference public Student owner; }
Output
{ "id" : 1, "name" : "Learn HTML", "owner" : { "rollNo" : 1, "name" : "Mark" } }
Jackson Annotations – @JsonIdentityInfo
@JsonIdentityInfo is used when objects have parent child relationship. @JsonIdentityInfo is used to indicate that object identity will be used during serialization/de-serialization.
Example – @JsonIdentityInfo
import java.io.IOException; import java.text.ParseException; import java.util.ArrayList; import java.util.List; import com.fasterxml.jackson.annotation.JsonIdentityInfo; import com.fasterxml.jackson.annotation.ObjectIdGenerators; import com.fasterxml.jackson.databind.ObjectMapper; public class JacksonTester { public static void main(String args[]) throws IOException, ParseException{ ObjectMapper mapper = new ObjectMapper(); Student student = new Student(1,13, "Mark"); Book book1 = new Book(1,"Learn HTML", student); Book book2 = new Book(2,"Learn JAVA", student); student.addBook(book1); student.addBook(book2); String jsonString = mapper .writerWithDefaultPrettyPrinter() .writeValueAsString(book1); System.out.println(jsonString); } } @JsonIdentityInfo( generator = ObjectIdGenerators.PropertyGenerator.class, property = "id") class Student { public int id; public int rollNo; public String name; public List<Book> books; Student(int id, int rollNo, String name){ this.id = id; this.rollNo = rollNo; this.name = name; this.books = new ArrayList<Book>(); } public void addBook(Book book){ books.add(book); } } @JsonIdentityInfo( generator = ObjectIdGenerators.PropertyGenerator.class, property = "id") class Book{ public int id; public String name; Book(int id, String name, Student owner){ this.id = id; this.name = name; this.owner = owner; } public Student owner; }
Output
{ "id" : 1, "name" : "Learn HTML", "owner" : { "id" : 1, "rollNo" : 13, "name" : "Mark", "books" : [ 1, { "id" : 2, "name" : "Learn JAVA", "owner" : 1 } ] } }
Jackson Annotations – @JsonFilter
@JsonFilter is used to apply filter during serialization/de-serialization like which properties are to be used or not.
Example – @JsonFilter
import java.io.IOException; import java.text.ParseException; import com.fasterxml.jackson.annotation.JsonFilter; import com.fasterxml.jackson.databind.ObjectMapper; import com.fasterxml.jackson.databind.ser.FilterProvider; import com.fasterxml.jackson.databind.ser.impl.SimpleBeanPropertyFilter; import com.fasterxml.jackson.databind.ser.impl.SimpleFilterProvider; public class JacksonTester { public static void main(String args[]) throws IOException, ParseException { ObjectMapper mapper = new ObjectMapper(); Student student = new Student(1,13, "Mark"); FilterProvider filters = new SimpleFilterProvider() .addFilter( "nameFilter", SimpleBeanPropertyFilter.filterOutAllExcept("name")); String jsonString = mapper.writer(filters) .withDefaultPrettyPrinter() .writeValueAsString(student); System.out.println(jsonString); } } @JsonFilter("nameFilter") class Student { public int id; public int rollNo; public String name; Student(int id, int rollNo, String name) { this.id = id; this.rollNo = rollNo; this.name = name; } }
Output
{ "name" : "Mark" }
Jackson Annotations – Custom Annotation
We can create custom annotation easily using @JacksonAnnotationsInside annotation.
Example – Custom Annotation
import java.io.IOException; import java.lang.annotation.Retention; import java.lang.annotation.RetentionPolicy; import java.text.ParseException; import com.fasterxml.jackson.annotation.JacksonAnnotationsInside; import com.fasterxml.jackson.annotation.JsonInclude; import com.fasterxml.jackson.annotation.JsonInclude.Include; import com.fasterxml.jackson.annotation.JsonPropertyOrder; import com.fasterxml.jackson.databind.ObjectMapper; public class JacksonTester { public static void main(String args[]) throws IOException, ParseException { ObjectMapper mapper = new ObjectMapper(); Student student = new Student(1,13, "Mark"); String jsonString = mapper .writerWithDefaultPrettyPrinter() .writeValueAsString(student); System.out.println(jsonString); } } @CustomAnnotation class Student { public int id; public int rollNo; public String name; public String otherDetails; Student(int id, int rollNo, String name){ this.id = id; this.rollNo = rollNo; this.name = name; } } @Retention(RetentionPolicy.RUNTIME) @JacksonAnnotationsInside @JsonInclude(value = Include.NON_NULL) @JsonPropertyOrder({ "rollNo", "id", "name" }) @interface CustomAnnotation {}
Output
{ "rollNo" : 13, "id" : 1, "name" : "Mark" }
Jackson Annotations – Mixin
Mixin Annotation is a way to associate annotations without modifying the target class. See the example below −
Example – Mixin Annotation
import java.io.IOException; import com.fasterxml.jackson.annotation.JsonIgnoreType; import com.fasterxml.jackson.databind.MapperFeature; import com.fasterxml.jackson.databind.ObjectMapper; public class JacksonTester { public static void main(String args[]) { ObjectMapper mapper = new ObjectMapper(); try { Student student = new Student(1,11,"1ab","Mark"); String jsonString = mapper .writerWithDefaultPrettyPrinter() .writeValueAsString(student); System.out.println(jsonString); ObjectMapper mapper1 = new ObjectMapper(); mapper1.addMixIn(Name.class, MixInForIgnoreType.class); jsonString = mapper1 .writerWithDefaultPrettyPrinter() .writeValueAsString(student); System.out.println(jsonString); } catch (IOException e) { e.printStackTrace(); } } } class Student { public int id; public String systemId; public int rollNo; public Name nameObj; Student(int id, int rollNo, String systemId, String name) { this.id = id; this.systemId = systemId; this.rollNo = rollNo; nameObj = new Name(name); } } class Name { public String name; Name(String name){ this.name = name; } } @JsonIgnoreType class MixInForIgnoreType {}
Output
{ "id" : 1, "systemId" : "1ab", "rollNo" : 11, "nameObj" : { "name" : "Mark" } } { "id" : 1, "systemId" : "1ab", "rollNo" : 11 }
Jackson Annotations – Disable
We can disable jackson annotations using disable() function of ObjectMapper.
Example – Disabling Annotation
import java.io.IOException; import com.fasterxml.jackson.annotation.JsonIgnoreType; import com.fasterxml.jackson.databind.MapperFeature; import com.fasterxml.jackson.databind.ObjectMapper; public class JacksonTester { public static void main(String args[]){ ObjectMapper mapper = new ObjectMapper(); try{ Student student = new Student(1,11,"1ab","Mark"); String jsonString = mapper .writerWithDefaultPrettyPrinter() .writeValueAsString(student); System.out.println(jsonString); ObjectMapper mapper1 = new ObjectMapper(); mapper1.disable(MapperFeature.USE_ANNOTATIONS); jsonString = mapper1 .writerWithDefaultPrettyPrinter() .writeValueAsString(student); System.out.println(jsonString); } catch (IOException e) { e.printStackTrace(); } } } class Student { public int id; public String systemId; public int rollNo; public Name nameObj; Student(int id, int rollNo, String systemId, String name){ this.id = id; this.systemId = systemId; this.rollNo = rollNo; nameObj = new Name(name); } } @JsonIgnoreType class Name { public String name; Name(String name){ this.name = name; } }
Output
{ "id" : 1, "systemId" : "1ab", "rollNo" : 11 } { "id" : 1, "systemId" : "1ab", "rollNo" : 11, "nameObj" : { "name" : "Mark" } }
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