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

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

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

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

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

对于GsonBuilder详见:

 http://google-gson.googlecode.com/svn/tags/1.2.3/docs/javadocs/com/google/gson/GsonBuilder.html

 

 

*注:TestBean就是一个带id、name、birthday的javabean，就不在这里贴代码了