如何在 Java 中使用 Jackson 對映多種日期格式?
Jackson是一個基於 Java 的庫,它可以用來將 Java 物件轉換為 JSON,以及將 JSON 轉換為 Java 物件。我們可以使用@JsonFormat 註解在 Jackson 庫中對映多種日期格式,它是一個通用註解,用於配置屬性值的序列化細節。@JsonFormat有三個重要的欄位:shape、pattern和timezone。shape欄位可以定義用於序列化的結構(JsonFormat.Shape.NUMBER 和 JsonFormat.Shape.STRING),pattern欄位可用於序列化和反序列化。對於日期,模式包含SimpleDateFormat相容的定義,最後,timezone欄位可用於序列化,預設值為系統預設時區。
語法
@Target(value={ANNOTATION_TYPE,FIELD,METHOD,PARAMETER,TYPE}) @Retention(value=RUNTIME) public @interface JsonFormat
示例
import java.io.*; import java.util.Date; import com.fasterxml.jackson.annotation.JsonFormat; import com.fasterxml.jackson.databind.ObjectMapper; public class JacksonDateformatTest { final static ObjectMapper mapper = new ObjectMapper(); public static void main(String[] args) throws Exception { JacksonDateformatTest jacksonDateformat = new JacksonDateformatTest(); jacksonDateformat.dateformat(); } public void dateformat() throws Exception { String json = "{\"createDate\":\"1980-12-08\"," + "\"createDateGmt\":\"1980-12-08 3:00 PM GMT+1:00\"}"; Reader reader = new StringReader(json); Employee employee = mapper.readValue(reader, Employee.class); System.out.println(employee); } } // Employee class class Employee implements Serializable { @JsonFormat(shape = JsonFormat.Shape.STRING, pattern = "yyyy-MM-dd", timezone = "IST") private Date createDate; @JsonFormat(shape = JsonFormat.Shape.STRING, pattern = "yyyy-MM-dd HH:mm a z", timezone = "IST") private Date createDateGmt; public Date getCreateDate() { return createDate; } public void setCreateDate(Date createDate) { this.createDate = createDate; } public Date getCreateDateGmt() { return createDateGmt; } public void setCreateDateGmt(Date createDateGmt) { this.createDateGmt = createDateGmt; } @Override public String toString() { return "Employee [\ncreateDate=" + createDate + ", \ncreateDateGmt=" + createDateGmt + "\n]"; } }
輸出
Employee [ createDate=Mon Dec 08 00:00:00 IST 1980, createDateGmt=Mon Dec 08 07:30:00 IST 1980 ]
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