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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

 

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.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());
    }

}

 

/**
     * 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

 

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>

 

 

 对于GsonBuilder详见:

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