How to implement custom serializer in Java using Jackson library?

The Jackson API provides many methods to process JSON data. By using Jackson API, we can convert Java objects to JSON strings and reconstruct objects from JSON strings. We can use the StdSerializer class to implement a custom serializer and need to override the serialize(T value, JsonGenerator gen, SerializerProvider provider) method. The first parameter value represents the value to be serialized (cannot be empty), and the second parameter gen represents the generator used to output the resulting Json content, and the third parameter provider represents the provider that can be used to obtain the serializer used to serialize the object value.

Grammar

public abstract void serialize(T value, JsonGenerator gen, SerializerProvider provider) throws IOException

Example

Translated into Chinese:

Example

import java.io.*;
import com.fasterxml.jackson.core.*;
import com.fasterxml.jackson.databind.*;
import com.fasterxml.jackson.databind.module.*;
import com.fasterxml.jackson.databind.ser.std.StdSerializer;
public class JacksonSerializeTest {
   public static void main(String[] args) throws Exception {
      JacksonSerializeTest test = new JacksonSerializeTest();
      test.serialize();
   }
   public void serialize() throws Exception {
      User user = new User();
      user.setFirstName("Raja");
      user.setLastName("Ramesh");
      ObjectMapper mapper = new ObjectMapper();
      SimpleModule module = new SimpleModule();
      module.addSerializer(User.class, new UserSerializer());
      mapper.registerModule(module);

      String jsonStr = mapper.writerWithDefaultPrettyPrinter().writeValueAsString(user); // pretty print
      System.out.println(jsonStr);
   }
}
// User class
class User implements Serializable {
   private String firstName;
   private String lastName;
   public String getFirstName() {
      return firstName;
   }
   public void setFirstName(String firstName) {
      this.firstName = firstName;
   }
   public String getLastName() {
      return lastName;
   }
   public void setLastName(String lastName) {
      this.lastName = lastName;
   }
}
// UserSerializer class
class UserSerializer extends StdSerializer<User> {
   public UserSerializer() {
      this(null);
   }
   public UserSerializer(Class<User> t) {
      super(t);
   }
<strong>   </strong>@Override
   public void serialize(User value, JsonGenerator jgen, SerializerProvider provider) throws       IOException, JsonProcessingException {
      jgen.writeStartObject();
      jgen.writeStringField("firstName", value.getFirstName());
      jgen.writeStringField("lastName", value.getLastName());
      jgen.writeEndObject();
   }
}

Output

{
 "firstName" : "Raja",
 "lastName" : "Ramesh"
}

The above is the detailed content of How to implement custom serializer in Java using Jackson library?. For more information, please follow other related articles on the PHP Chinese website!