差異處

這裏顯示兩個版本的差異處。

--- java:jackson:annotation:jsonserialize:convertdate [2016/03/11 00:12]
tony
+++ java:jackson:annotation:jsonserialize:convertdate [2023/06/25 09:48]
@@ 行 1: / 行 1: @@
-{{tag>java jackson}}
-====== Convert the Date format to ISO8601 ======
-===== Problem =====
-在做Rest API的輸出處理時，一定會遇到日期要顯示的格式，而日期也伴隨著timezone的問題。要顯示成甚麼樣子的格式，就看各個應用程式的需求。一開始是想仿效臉書轉為unix time，後來再為這問題爭論不休；最後我在study後，認為ISO8601比較符合我們需求，就決定為我們的顯示格式。
-===== How to? =====
-預設使用Jackson去做Date的轉換，會輸出為unix time。如果要達到我們的目的，可透過@JsonSerialize設定對應序列化的物件；而要接收使用者輸入轉為對應物件的話，可透過@JsonDeserialize設定對應反序列化物件。
-==== Object with JsonSerialize and JsonDeserialize annotation ====
-<code java>
-public class Event {
-	@JsonSerialize(using=ISO8601DateSerializer.class)
-	@JsonDeserialize(using=ISO8601DateDeserializer.class)
-	private Date date;
-	private String message;
-	public Date getDate(){
-		return date;
-	}
-	public void setDate(Date date){
-		this.date = date;
-	}
-        // ... skip
-}
-</code>
-==== ISO8601DateSerializer for Date ====
-<code java>
-public class ISO8601DateSerializer extends StdSerializer<Date> {
-	private static final long serialVersionUID = 1L;
-	public ISO8601DateSerializer() {
-		super(Date.class);
-	}
-	@Override
-	public void serialize(Date date, JsonGenerator json,
-			SerializerProvider provider) throws IOException,
-			JsonGenerationException {
-		DateFormat df = StdDateFormat.getISO8601Format(
-				TimeZone.getTimeZone("UTC"), Locale.getDefault());
-		String out = df.format(date);
-		json.writeString(out);
-	}
-}
-</code>
-==== ISO8601DateDeserializer for Date ====
-<code java>
-public class ISO8601DateDeserializer extends StdDeserializer<Date> {
-	private static final long serialVersionUID = 1L;
-	public ISO8601DateDeserializer() {
-        super(Date.class);
-    }
-	@Override
-	public Date deserialize(JsonParser parser, DeserializationContext context)
-			throws IOException, JsonProcessingException {
-		try {
-			DateFormat df = StdDateFormat.getISO8601Format(
-					TimeZone.getTimeZone("UTC"), Locale.getDefault());
-			return df.parse(parser.getText());
-		} catch (Exception e) {
-			return null;
-		}
-	}
-}
-</code>
-==== Convert to Json ====
-簡單寫一個測試案例，去驗證序列化後再反序列化的內容會一致:
-<code java>
-	@Test
-	public void testDateWithAnnotation() throws Exception {
-		ObjectMapper mapper = new ObjectMapper();
-		Date d = new Date();
-		Event e = new Event();
-		e.setDate(d);
-		String ret = mapper.writeValueAsString(e);
-		System.out.println(ret);
-		Event newEvent = mapper.readValue(ret, Event.class);
-		assertEquals(d.getTime(), newEvent.getDate().getTime());
-	}
-</code>
-output:
-<code>
-{"date":"2016-03-10T15:40:11.869+0000","message":null}
-</code>
-==== Apply to all Date fields ====
-上面所敘述的是透過在欄位宣告@JsonSerialize，來達到我們的目的。如果想要讓每一個擁有Date的bean物件都能使用這個格式，可以透過Jackson所提供的Module功能，去設定對應物件的Serializer與Deserializer:
-<code java>
-ObjectMapper mapper = new ObjectMapper();
-SimpleModule m = new SimpleModule();
-m.addSerializer(Date.class, new ISO8601DateSerializer());
-m.addDeserializer(Date.class, new ISO8601DateDeserializer());
-mapper.registerModule(m);
-</code>
-===== Reference =====
-  * [[http://stackoverflow.com/questions/5471379/ways-to-convert-unix-linux-time-to-windows-time|ways-to-convert-unix-linux-time-to-windows-time]]
-  * [[https://zh.wikipedia.org/wiki/ISO_8601|ISO8601]]
-  * [[http://nbsoftsolutions.com/blog/designing-a-rest-api-unix-time-vs-iso-8601|Designing a REST API: Unix time vs ISO-8601]]
-=====    =====
-----
-\\
-~~DISQUS~~