差異處
這裏顯示兩個版本的差異處。
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java:jackson:helloworld [2016/02/17 23:16] tony [Source Object] |
java:jackson:helloworld [2023/06/25 09:48] |
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| - | {{tag>java jackson}} | ||
| - | ====== Jackson - Hello World ====== | ||
| - | ===== Introduction ===== | ||
| - | 本篇內容展示Jackson的基本功能-將物件轉為json與xml格式。由於內容簡單，看程式碼就知道該怎麼做，不多做說明。 | ||
| - | ===== Ivy.xml ===== | ||
| - | 相依函式庫使用以下四個項目: | ||
| - | <code xml> | ||
| - | <dependency org="com.fasterxml.jackson.core" name="jackson-core" rev="latest.integration" conf="default->default(*)" /> | ||
| - | <dependency org="com.fasterxml.jackson.core" name="jackson-annotations" rev="latest.integration" conf="default->default(*)" /> | ||
| - | <dependency org="com.fasterxml.jackson.core" name="jackson-databind" rev="latest.integration" conf="default->default(*)" /> | ||
| - | <dependency org="com.fasterxml.jackson.dataformat" name="jackson-dataformat-xml" rev="latest.integration" conf="default->default(*)" /> | ||
| - | </code> | ||
| - | ===== Source Object ===== | ||
| - | User類別是此範例中，要轉為json與xml格式的目標。在mID與mPasswd成員變數上，使用了JsonProperty annotation去描述結果要呈現的欄位名稱。以json為例，mID顯示的欄位名稱即為id；以xml為例，mID的標籤名稱為id: | ||
| - | <code java> | ||
| - | package org.tonylin.practice.jackson; | ||
| - | import com.fasterxml.jackson.annotation.JsonProperty; | ||
| - | |||
| - | public class User { | ||
| - | @JsonProperty(value="id") | ||
| - | private String mID; | ||
| - | |||
| - | @JsonProperty(value="passwd") | ||
| - | private String mPasswd; | ||
| - | |||
| - | public String getmID() { | ||
| - | return mID; | ||
| - | } | ||
| - | |||
| - | public void setID(String aID) { | ||
| - | this.mID = aID; | ||
| - | } | ||
| - | |||
| - | public String getPasswd() { | ||
| - | return mPasswd; | ||
| - | } | ||
| - | |||
| - | public void setPasswd(String aPasswd) { | ||
| - | this.mPasswd = aPasswd; | ||
| - | } | ||
| - | } | ||
| - | </code> | ||
| - | 這裡必須特別注意的是，Jackson會優先使用get method為欄位名稱。下面這個範例所輸出的ss值為test而不是test2，即使對ss加上@JsonProperty(value="ss")也是test: | ||
| - | <code java> | ||
| - | private String ss = "test2"; | ||
| - | |||
| - | public String getSS(){ | ||
| - | return "test"; | ||
| - | } | ||
| - | </code> | ||
| - | 一般的member宣告會使用m開頭，如果@JsonProperty的value和get method不同，就會導致同時輸出method欄位與@JsonProperty宣告的欄位: | ||
| - | <code java> | ||
| - | @JsonProperty(value="s1") | ||
| - | private String mss = "test2"; | ||
| - | |||
| - | public String getSS(){ | ||
| - | return "test"; | ||
| - | } | ||
| - | </code> | ||
| - | Output: | ||
| - | <code> | ||
| - | "ss":"test","s1":"test2" | ||
| - | </code> | ||
| - | ===== Convert to json ===== | ||
| - | <code java> | ||
| - | @Test | ||
| - | public void testJsonGenerator() throws IOException { | ||
| - | ObjectMapper mapper = new ObjectMapper(); | ||
| - | |||
| - | JsonGenerator generator = mapper.getFactory().createGenerator(System.out); | ||
| - | |||
| - | User u = new User(); | ||
| - | u.setID("user"); | ||
| - | u.setPasswd("123456"); | ||
| - | |||
| - | generator.writeObject(u); | ||
| - | } | ||
| - | </code> | ||
| - | Output: | ||
| - | <code> | ||
| - | {"id":"user","passwd":"123456"} | ||
| - | </code> | ||
| - | ===== Convert to xml ===== | ||
| - | <code java> | ||
| - | @Test | ||
| - | public void testXmlGenerator() throws IOException { | ||
| - | XmlMapper mapper = new XmlMapper(); | ||
| - | JsonGenerator generator = mapper.getFactory().createGenerator(System.out); | ||
| - | |||
| - | User u = new User(); | ||
| - | u.setID("user"); | ||
| - | u.setPasswd("123456"); | ||
| - | |||
| - | generator.writeObject(u); | ||
| - | } | ||
| - | </code> | ||
| - | Output: | ||
| - | <code xml> | ||
| - | <User xmlns=""><id>user</id><passwd>123456</passwd></User> | ||
| - | </code> | ||
| - | |||
| - | ===== ===== | ||
| - | ---- | ||
| - | \\ | ||
| - | ~~DISQUS~~ | ||
