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或欄位,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
}
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