@JsonDeserialize anotasi digunakan untuk mengisytiharkan penyahserialisasi tersuai apabila menyahsiri JSON ke dalam objek Java. Kami boleh melaksanakan deserializer tersuai dengan melanjutkan kelas StdDeserializer menggunakan jenis generik Pekerja, dan perlu mengatasi kaedah deserialize() kelas StdDeserializer .
@Target(value={ANNOTATION_TYPE,METHOD,FIELD,TYPE,PARAMETER}) @Retention(value=RUNTIME) public @interface JsonDeserialize
Dalam program berikut, kita boleh menggunakan @JsonDeserialize anotasi untuk melaksanakan deserializer tersuai
import java.io.*; import com.fasterxml.jackson.core.*; import com.fasterxml.jackson.databind.*; import com.fasterxml.jackson.databind.annotation.*; import com.fasterxml.jackson.databind.deser.std.*; public class JsonDeSerializeAnnotationTest { public static void main (String[] args) throws JsonProcessingException, IOException { Employee emp = new Employee(115, "Adithya"); ObjectMapper mapper = new ObjectMapper(); String jsonString = mapper.writeValueAsString(emp); emp = mapper.readValue(jsonString, Employee.class); System.out.println(emp); } } // CustomDeserializer class class CustomDeserializer extends StdDeserializer<Employee> { public CustomDeserializer(Class<Employee> t) { super(t); } public CustomDeserializer() { this(Employee.class); } @Override public Employee deserialize(JsonParser jp, DeserializationContext dc) throws IOException, JsonProcessingException { int id = 0; String name = null; JsonToken currentToken = null; while((currentToken = jp.nextValue()) != null) { switch(currentToken) { case VALUE_NUMBER_INT: if(jp.getCurrentName().equals("id")) { id = jp.getIntValue(); } break; case VALUE_STRING: switch(jp.getCurrentName()) { case "name": name = jp.getText(); break; default: break; } break; default: break; } } return new Employee(id, name); } } // Employee class @JsonDeserialize(using=CustomDeserializer.class)<strong> </strong>class Employee { private int id; private String name; public Employee(int id, String name) { this.id = id; this.name = name; } public int getId() { return id; } public String getName() { return name; } @Override public String toString() { StringBuilder sb = new StringBuilder("ID: ").append(this.id).append("\nName: ").append(this.name); return sb.toString(); } }
ID: 115 Name: Adithya
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