Java 中 Jackson @JsonInclude 註解的重要性?


Jackson @JsonInclude 註解可用於在特定條件下排除類的屬性欄位,並且可以使用 JsonInclude.Include 列舉定義它。JsonInclude.Include 列舉包含 "ALWAYS", "NON_DEFAULT", "NON_EMPTY" and "NON_NULL" 這幾個常量,以確定是否排除屬性(欄位)。

語法

public static enum JsonInclude.Include extends Enum<JSonInclude.Include>

示例

import com.fasterxml.jackson.annotation.*;
import com.fasterxml.jackson.databind.*;
import java.io.*;
public class JsonIncludeTest {
   public static void main(String args[]) throws IOException {
      ObjectMapper objectMapper = new ObjectMapper();
      Employee emp = new Employee();
      String jsonString = objectMapper.writerWithDefaultPrettyPrinter().writeValueAsString(emp);
      System.out.println(jsonString);
   }
}
// Employee class
@JsonInclude(JsonInclude.Include.NON_EMPTY)
class Employee {
   public int empId = 115;
   public String empName = null;
   @Override
   public String toString() {
      return "Employee{" +
             "empId=" + empId +
             ", empName='" + empName + '\'' +
             '}';
   }
}

輸出

{
   "empId" : 115
}

更新時間: 2020-07-07

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