xStream對JSON也有非常好的支持,它提供了2個模型驅動。用這2個驅動可以完成Java對象到JSON的相互轉換。使用JettisonMappedXmlDriver驅動,將Java對象轉換成json,需要添加jettison.jar
一、準備工作
1、 下載jar包、及官方資源
xStream的jar下載地址:
官方的示例很全,官方參考示例:http://xstream.codehaus.org/tutorial.html
添加xstream-1.3.1.jar文件到工程中,就可以開始下面的工作
- /**
- * <b>function:</b>XStream結合JettisonMappedXmlDriver驅動,轉換Java對象到JSON
- * 需要添加jettison jar
- * @author hoojo
- * @createDate Nov 27, 2010 1:23:18 PM
- */
- @Test
- public void writeEntity2JETTSON() {
- failRed("=======JettisonMappedXmlDriver===JavaObject >>>> JaonString=========");
- xstream = new XStream(new JettisonMappedXmlDriver());
- xstream.setMode(XStream.NO_REFERENCES);
- xstream.alias("student", Student.class);
- fail(xstream.toXML(bean));
- }
運行後結果如下:
=======JettisonMappedXmlDriver===JavaObject >>>> JaonString=========
- {"student":{"id":1,"name":"jack","email":"[email protected]","address":"china","birthday":[{},"2010-11-22"]}}
JSON的轉換和XML的轉換用法一樣,只是創建XStream需要傳遞一個參數,這個參數就是xml到JSON映射轉換的驅動。這裏會降到兩個驅動,分別是JettisonMappedXmlDriver、JsonHierarchicalStreamDriver。
2、 JsonHierarchicalStreamDriver完成Java對象到JSON的轉換
- /**
- * <b>function:</b>用XStream結合JsonHierarchicalStreamDriver驅動
- * 轉換java對象爲JSON字符串
- * @author hoojo
- * @createDate Nov 27, 2010 1:16:46 PM
- */
- @Test
- public void writeEntiry2JSON() {
- failRed("======JsonHierarchicalStreamDriver====JavaObject >>>> JaonString=========");
- xstream = new XStream(new JsonHierarchicalStreamDriver());
- //xstream.setMode(XStream.NO_REFERENCES);
- xstream.alias("student", Student.class);
- failRed("-------Object >>>> JSON---------");
- fail(xstream.toXML(bean));
- //failRed("========JsonHierarchicalStreamDriver==刪除根節點=========");
- //刪除根節點
- xstream = new XStream(new JsonHierarchicalStreamDriver() {
- public HierarchicalStreamWriter createWriter(Writer out) {
- return new JsonWriter(out, JsonWriter.DROP_ROOT_MODE);
- }
- });
- //xstream.setMode(XStream.NO_REFERENCES);
- xstream.alias("student", Student.class);
- fail(xstream.toXML(bean));
- }
運行後結果如下:
======JsonHierarchicalStreamDriver====JavaObject >>>> JaonString=========
-------Object >>>> JSON---------
- {"student": {
- "id": 1,
- "name": "jack",
- "email": "[email protected]",
- "address": "china",
- "birthday": {
- "birthday": "2010-11-22"
- }
- }}
- {
- "id": 1,
- "name": "jack",
- "email": "[email protected]",
- "address": "china",
- "birthday": {
- "birthday": "2010-11-22"
- }
- }
使用JsonHierarchicalStreamDriver轉換默認會給轉換後的對象添加一個根節點,但是在構建JsonHierarchicalStreamDriver驅動的時候,你可以重寫createWriter方法,刪掉根節點。
看上面的結果,一個是默認帶根節點的JSON對象,它只是將類名作爲一個屬性,將對象作爲該屬性的一個值。而另一個沒有帶根屬性的JSON就是通過重寫createWriter方法完成的。
3、 將List集合轉換成JSON字符串
- @Test
- public void writeList2JSON() {
- failRed("======JsonHierarchicalStreamDriver====JavaObject >>>> JaonString=========");
- JsonHierarchicalStreamDriver driver = new JsonHierarchicalStreamDriver();
- xstream = new XStream(driver);
- //xstream = new XStream(new JettisonMappedXmlDriver());//轉換錯誤
- //xstream.setMode(XStream.NO_REFERENCES);
- xstream.alias("student", Student.class);
- List<Student> list = new ArrayList<Student>();
- list.add(bean);//add
- bean = new Student();
- bean.setAddress("china");
- bean.setEmail("[email protected]");
- bean.setId(2);
- bean.setName("tom");
- Birthday day = new Birthday("2010-11-22");
- bean.setBirthday(day);
- list.add(bean);//add
- bean = new Student();
- bean.setName("jack");
- list.add(bean);//add
- fail(xstream.toXML(list));
- //failRed("========JsonHierarchicalStreamDriver==刪除根節點=========");
- //刪除根節點
- xstream = new XStream(new JsonHierarchicalStreamDriver() {
- public HierarchicalStreamWriter createWriter(Writer out) {
- return new JsonWriter(out, JsonWriter.DROP_ROOT_MODE);
- }
- });
- xstream.alias("student", Student.class);
- fail(xstream.toXML(list));
- }
運行後結果如下
======JsonHierarchicalStreamDriver====JavaObject >>>> JaonString=========
- ##{"list": [
- {
- "id": 1,
- "name": "jack",
- "email": "[email protected]",
- "address": "china",
- "birthday": {
- "birthday": "2010-11-22"
- }
- },
- {
- "id": 2,
- "name": "tom",
- "email": "[email protected]",
- "address": "china",
- "birthday": {
- "birthday": "2010-11-22"
- }
- },
- {
- "id": 0,
- "name": "jack"
- }
- ]}
- #[
- {
- "id": 1,
- "name": "jack",
- "email": "[email protected]",
- "address": "china",
- "birthday": {
- "birthday": "2010-11-22"
- }
- },
- {
- "id": 2,
- "name": "tom",
- "email": "[email protected]",
- "address": "china",
- "birthday": {
- "birthday": "2010-11-22"
- }
- },
- {
- "id": 0,
- "name": "jack"
- }
- ]
上面的list1是使用JsonHierarchicalStreamDriver 轉換的,當然你也可以使用JettisonMappedXmlDriver驅動進行轉換;用JettisonMappedXmlDriver轉換後,你會發現格式不同而且沒有根屬性。
4、 Map轉換json
- @Test
- public void writeMap2JSON() {
- failRed("======JsonHierarchicalStreamDriver==== Map >>>> JaonString=========");
- xstream = new XStream(new JsonHierarchicalStreamDriver());
- //xstream = new XStream(new JettisonMappedXmlDriver());
- xstream.alias("student", Student.class);
- Map<String, Student> map = new HashMap<String, Student>();
- map.put("No.1", bean);//put
- bean = new Student();
- bean.setAddress("china");
- bean.setEmail("[email protected]");
- bean.setId(2);
- bean.setName("tom");
- bean.setBirthday(new Birthday("2010-11-21"));
- map.put("No.2", bean);//put
- bean = new Student();
- bean.setName("jack");
- map.put("No.3", bean);//put
- fail(xstream.toXML(map));
- //failRed("========JsonHierarchicalStreamDriver==刪除根節點=========");
- //刪除根節點
- xstream = new XStream(new JsonHierarchicalStreamDriver() {
- public HierarchicalStreamWriter createWriter(Writer out) {
- return new JsonWriter(out, JsonWriter.DROP_ROOT_MODE);
- }
- });
- xstream.alias("student", Student.class);
- fail(xstream.toXML(map));
- }
運行後結果如下:
======JsonHierarchicalStreamDriver==== Map >>>> JaonString=========
- {"map": [
- [
- "No.3",
- {
- "id": 0,
- "name": "jack"
- }
- ],
- [
- "No.1",
- {
- "id": 1,
- "name": "jack",
- "email": "[email protected]",
- "address": "china",
- "birthday": {
- "birthday": "2010-11-22"
- }
- }
- ],
- [
- "No.2",
- {
- "id": 2,
- "name": "tom",
- "email": "[email protected]",
- "address": "china",
- "birthday": {
- "birthday": "2010-11-21"
- }
- }
- ]
- ]}
- [
- [
- "No.3",
- {
- "id": 0,
- "name": "jack"
- }
- ],
- [
- "No.1",
- {
- "id": 1,
- "name": "jack",
- "email": "[email protected]",
- "address": "china",
- "birthday": {
- "birthday": "2010-11-22"
- }
- }
- ],
- [
- "No.2",
- {
- "id": 2,
- "name": "tom",
- "email": "[email protected]",
- "address": "china",
- "birthday": {
- "birthday": "2010-11-21"
- }
- }
- ]
- ]
5、 將JSON轉換java對象
- /**
- * <b>function:</b>JsonHierarchicalStreamDriver可以將簡單的json字符串轉換成java對象,list、map轉換不成功;
- * JsonHierarchicalStreamDriver讀取JSON字符串到java對象出錯
- * @author hoojo
- * @createDate Nov 27, 2010 1:22:26 PM
- * @throws JSONException
- */
- @Test
- public void readJSON2Object() throws JSONException {
- String json = "{\"student\": {" +
- "\"id\": 1," +
- "\"name\": \"haha\"," +
- "\"email\": \"email\"," +
- "\"address\": \"address\"," +
- "\"birthday\": {" +
- "\"birthday\": \"2010-11-22\"" +
- "}" +
- "}}";
- //JsonHierarchicalStreamDriver讀取JSON字符串到java對象出錯,但JettisonMappedXmlDriver可以
- xstream = new XStream(new JettisonMappedXmlDriver());
- xstream.alias("student", Student.class);
- fail(xstream.fromXML(json).toString());
- //JettisonMappedXmlDriver轉換List集合出錯,但JsonHierarchicalStreamDriver可以轉換正確
- //JettisonMappedXmlDriver 轉換的字符串 {"list":{"student":[{"id":1,"name":"haha","email":"email","address":"address","birthday":[{},"2010-11-22"]}]},"student":{"id":2,"name":"tom","email":"[email protected]","address":"china","birthday":[{},"2010-11-22"]}}
- json = "{\"list\": [{" +
- "\"id\": 1," +
- "\"name\": \"haha\"," +
- "\"email\": \"email\"," +
- "\"address\": \"address\"," +
- "\"birthday\": {" +
- "\"birthday\": \"2010-11-22\"" +
- "}" +
- "},{" +
- "\"id\": 2," +
- "\"name\": \"tom\"," +
- "\"email\": \"[email protected]\"," +
- "\"address\": \"china\"," +
- "\"birthday\": {" +
- "\"birthday\": \"2010-11-22\"" +
- "}" +
- "}]}";
- System.out.println(json);//用js轉換成功
- List list = (List) xstream.fromXML(json);
- System.out.println(list.size());//0好像轉換失敗
- }
運行後結果如下:
- haha#1#address#2010-11-22#email
- {"list": [{"id": 1,"name": "haha","email": "email","address": "address","birthday": {"birthday": "2010-11-22"}},
- {"id": 2,"name": "tom","email": "[email protected]","address": "china","birthday": {"birthday": "2010-11-22"}}]}
- 0
JSON到Java的轉換是fromXML方法