Gson简单使用

1.简单的处理list和map

Java代码
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"}  
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

Java代码
List<TestBean> testBeanList = new ArrayList<TestBean>();   
TestBean testBean = new TestBean();   
testBean.setId("id");   
testBean.setName("name");   
testBeanList.add(testBean);   
List<TestBean> testBeanList = new ArrayList<TestBean>();
TestBean testBean = new TestBean();
testBean.setId("id");
testBean.setName("name");
testBeanList.add(testBean);
Java代码
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>]]  
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



Java代码
import java.lang.reflect.Type;   
  
import com.google.gson.JsonDeserializationContext;   
import com.google.gson.JsonDeserializer;   
import com.google.gson.JsonElement;   
import com.google.gson.JsonParseException;   
  
public class UtilDateDeserializer implements JsonDeserializer<java.util.Date> {   
  
    @Override  
    public java.util.Date deserialize(JsonElement json, Type typeOfT, JsonDeserializationContext context)   
            throws JsonParseException {   
        return new java.util.Date(json.getAsJsonPrimitive().getAsLong());   
    }   
}  
import java.lang.reflect.Type;
import com.google.gson.JsonDeserializationContext;
import com.google.gson.JsonDeserializer;
import com.google.gson.JsonElement;
import com.google.gson.JsonParseException;
public class UtilDateDeserializer implements JsonDeserializer<java.util.Date> {
@Override
public java.util.Date deserialize(JsonElement json, Type typeOfT, JsonDeserializationContext context)
throws JsonParseException {
return new java.util.Date(json.getAsJsonPrimitive().getAsLong());
}
}

Java代码
import java.lang.reflect.Type;   
  
import com.google.gson.JsonElement;   
import com.google.gson.JsonPrimitive;   
import com.google.gson.JsonSerializationContext;   
import com.google.gson.JsonSerializer;   
  
public class UtilDateSerializer implements JsonSerializer<java.util.Date> {   
  
    @Override  
    public JsonElement serialize(java.util.Date src, Type typeOfSrc,      
            JsonSerializationContext context) {      
        return new JsonPrimitive(src.getTime());      
    }      
  
}  
import java.lang.reflect.Type;
import com.google.gson.JsonElement;
import com.google.gson.JsonPrimitive;
import com.google.gson.JsonSerializationContext;
import com.google.gson.JsonSerializer;
public class UtilDateSerializer implements JsonSerializer<java.util.Date> {
@Override
public JsonElement serialize(java.util.Date src, Type typeOfSrc,
JsonSerializationContext context) {
return new JsonPrimitive(src.getTime());
}
}

Java代码
/**  
     * 序列化方法  
     * @param bean  
     * @param type  
     * @return  
     */  
    public static String bean2json(Object bean, Type type) {   
        Gson gson = new GsonBuilder().registerTypeAdapter(java.util.Date.class, new UtilDateSerializer())   
                .setDateFormat(DateFormat.LONG).create();   
        return gson.toJson(bean);   
    }   
  
    /**  
     * 反序列化方法  
     * @param json  
     * @param type  
     * @return  
     */  
    public static <T> T json2bean(String json, Type type) {   
        Gson gson = new GsonBuilder().registerTypeAdapter(java.util.Date.class, new UtilDateDeserializer())   
                .setDateFormat(DateFormat.LONG).create();   
        return gson.fromJson(json, type);   
    }  
/**
* 序列化方法
* @param bean
* @param type
* @return
*/
public static String bean2json(Object bean, Type type) {
Gson gson = new GsonBuilder().registerTypeAdapter(java.util.Date.class, new UtilDateSerializer())
.setDateFormat(DateFormat.LONG).create();
return gson.toJson(bean);
}
/**
* 反序列化方法
* @param json
* @param type
* @return
*/
public static <T> T json2bean(String json, Type type) {
Gson gson = new GsonBuilder().registerTypeAdapter(java.util.Date.class, new UtilDateDeserializer())
.setDateFormat(DateFormat.LONG).create();
return gson.fromJson(json, type);
}



现在开始测试



Java代码
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]]  
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]]



后记：对于java.sql.Date的转化同上类似，写两个类用于其序列化和反序列化即可SQLDateDeserializer implements JsonDeserializer<java.sql.Date>

SQLDateSerializer implements JsonSerializer<java.sql.Date>