public class JSONUtils {
    private static Gson gson = null;

    static {
        if (gson == null) {
            gson = new Gson();
        }
    }

    private JSONUtils() {
    }

    /**
     * 轉成json
     *
     * @param object
     * @return
     */
    public static String GsonString(Object object) {
        String gsonString 
 
= null;
        if (gson != null) {
            gsonString = gson.toJson(object);
        }
        return gsonString;
    }

    /**
     * 轉成bean
     *
     * @param gsonString
     * @param cls
     * @return
     */
    public static <T> T GsonToBean(String gsonString, Class<T> cls) {
        T t 
 
= null;
        if (gson != null) {
            t = gson.fromJson(gsonString, cls);
        }
        return t;
    }

    /**
     * 轉成list
     * 泛型在編譯期類型被擦除導致報錯
     *
     * @param gsonString
     * @param cls
     * @return
     */
    public static <T> List<T> GsonToList(String gsonString, Class<T> cls) {
        List
 
<T> list = null;
        if (gson != null) {
            list = gson.fromJson(gsonString, new TypeToken<List<T>>() {
            }.getType());
        }
        return list;
    }

    /**
     * 轉成list
     * 解決泛型問題
     *
     * @param json
     * @param cls
     * @param <T>
     * @return
     */
    public <T> List<T> jsonToList(String json, Class<T> cls) {
        Gson gson = new Gson();
        List<T> list = new ArrayList<T>();
        JsonArray array = new JsonParser().parse(json).getAsJsonArray();
        for (final JsonElement elem : array) {
            list.add(gson.fromJson(elem, cls));
        }
        return list;
    }

    /**
     * 轉成list中有map的
     *
     * @param gsonString
     * @return
     */
    public static <T> List<Map<String, T>> GsonToListMaps(String gsonString) {
        List<Map<String, T>> list = null;
        if (gson != null) {
            list = gson.fromJson(gsonString,
                    new TypeToken<List<Map<String, T>>>() {
                    }.getType());
        }
        return list;
    }

    /**
     * 轉成map的
     *
     * @param gsonString
     * @return
     */
    public static <T> Map<String, T> GsonToMaps(String gsonString) {
        Map<String, T> map = null;
        if (gson != null) {
            map = gson.fromJson(gsonString, new TypeToken<Map<String, T>>() {
            }.getType());
        }
        return map;
    }


}

JSON轉換