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Gson学习

google gson学习

关键字: json gson java

Gson网址http://code.google.com/p/google-gson/

1.简单的处理list和map

Gson gson = new Gson();
List testList = new ArrayList();
testList.add("first");
testList.add("second");
String listToJson = gson.toJson(testList);
System.out.println(listToJson);     
//prints ["first","second"]
 
Map testMap = new HashMap();
testMap.put("id", "id.first");
testMap.put("name","name.second");
String mapToJson = gson.toJson(testMap);
System.out.println(mapToJson);  
//prints {"id":"id.first","name":"name.second"}

2.处理带泛型的集合

List<TestBean> testBeanList = new ArrayList<TestBean>();
TestBean testBean = new TestBean();
testBean.setId("id");
testBean.setName("name");
testBeanList.add(testBean);
         
java.lang.reflect.Type type = new com.google.gson.reflect.TypeToken<List<TestBean>>() {
}.getType();
String beanListToJson = gson.toJson(testBeanList,type);
System.out.println(beanListToJson);
//prints [{"id":"id","name":"name"}]
         
List<TestBean> testBeanListFromJson = gson.fromJson(beanListToJson, type);
System.out.println(testBeanListFromJson);
//prints [TestBean@1ea5671[id=id,name=name,birthday=<null>]]

map等其他集合类型同上

3.Date类型转化

先写工具类

工具类

 1    1. import java.lang.reflect.Type;  
 2    2.   
 3    3. import com.google.gson.JsonDeserializationContext;  
 4    4. import com.google.gson.JsonDeserializer;  
 5    5. import com.google.gson.JsonElement;  
 6    6. import com.google.gson.JsonParseException;  
 7    7.   
 8    8. public class UtilDateDeserializer implements JsonDeserializer<java.util.Date> {  
 9    9.   
10   10.     @Override  
11   11.     public java.util.Date deserialize(JsonElement json, Type typeOfT, JsonDeserializationContext context)  
12   12.             throws JsonParseException {  
13   13.         return new java.util.Date(json.getAsJsonPrimitive().getAsLong());  
14   14.     }  
15   15. }

代码

 1   1. import java.lang.reflect.Type;  
 2   2.   
 3   3. import com.google.gson.JsonElement;  
 4   4. import com.google.gson.JsonPrimitive;  
 5   5. import com.google.gson.JsonSerializationContext;  
 6   6. import com.google.gson.JsonSerializer;  
 7   7.   
 8   8. public class UtilDateSerializer implements JsonSerializer<java.util.Date> {  
 9   9.   
10  10.     @Override  
11  11.     public JsonElement serialize(java.util.Date src, Type typeOfSrc,     
12  12.             JsonSerializationContext context) {     
13  13.         return new JsonPrimitive(src.getTime());     
14  14.     }     
15  15.   
16  16. }

序列化

 1   1. /** 
 2   2.      * 序列化方法 
 3   3.      * @param bean 
 4   4.      * @param type 
 5   5.      * @return 
 6   6.      */  
 7   7.     public static String bean2json(Object bean, Type type) {  
 8   8.         Gson gson = new GsonBuilder().registerTypeAdapter(java.util.Date.class, new UtilDateSerializer())  
 9   9.                 .setDateFormat(DateFormat.LONG).create();  
10  10.         return gson.toJson(bean);  
11  11.     }  
12  12.   
13  13.     /** 
14  14.      * 反序列化方法 
15  15.      * @param json 
16  16.      * @param type 
17  17.      * @return 
18  18.      */  
19  19.     public static <T> T json2bean(String json, Type type) {  
20  20.         Gson gson = new GsonBuilder().registerTypeAdapter(java.util.Date.class, new UtilDateDeserializer())  
21  21.                 .setDateFormat(DateFormat.LONG).create();  
22  22.         return gson.fromJson(json, type);  
23  23.     }

现在开始测试

 1# List<TestBean> testBeanList = new ArrayList<TestBean>();  
 2# TestBean testBean = new TestBean();  
 3# testBean.setId("id");  
 4# testBean.setName("name");  
 5# testBean.setBirthday(new java.util.Date());  
 6# testBeanList.add(testBean);  
 7#   
 8# java.lang.reflect.Type type = new com.google.gson.reflect.TypeToken<List<TestBean>>() {  
 9# }.getType();  
10# String beanListToJson = bean2json(testBeanList, type);  
11# System.out.println("beanListToJson:" + beanListToJson);  
12# //prints [{"id":"id","name":"name","birthday":1256531559390}]  
13#   
14# List<TestBean> testBeanListFromJson = json2bean(beanListToJson, type);  
15# System.out.println(testBeanListFromJson);  
16# //prints [TestBean@77a7f9[id=id,name=name,birthday=Mon Oct 26 12:39:05 CST 2009]]