Jackson Annotations 简明教程

Jackson Annotations - @JsonPropertyOrder

@JsonPropertyOrder 允许在序列化 JSON 对象时保留指定的顺序。

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
}