JSON工具类总结

json与类对象互相转化及map等相互转换，Jackson框架

private JSONUtils() {}public static ObjectMapper om;static {om = new ObjectMapper();om.configure(DeserializationConfig.Feature.ACCEPT_SINGLE_VALUE_AS_ARRAY,false);}/** * 类对象转换成JSON字符串 *  * @param obj * @return */public static String toJSON(Object obj) {try {return om.writeValueAsString(obj);} catch (Exception e) {e.printStackTrace();}return null;}/** * JSON字符串转换成类对象 *  * @param <T> * @param json * @param t * @return */public static <T> T toBean(String json, Class<T> t) {try {return om.readValue(json, t);} catch (Exception e) {e.printStackTrace();}return null;}/** * JSON字符串转换成Map对象 */// public static Map<String, List<String>> toMap(String json) {// try {// return om.readValue(json, new TypeReference<Map<String, List<String>>>()// {// });// } catch (Exception e) {// e.printStackTrace();// }// return null;// }public static Map<String, Object> toMap(String json) {try {return om.readValue(json, new TypeReference<Map<String, Object>>() {});} catch (Exception e) {e.printStackTrace();}return null;}/** * JSON转换为集合 */public static List<Map<String, List<String>>> toList(String json) {try {return om.readValue(json,new TypeReference<List<Map<String, List<String>>>>() {});} catch (Exception e) {e.printStackTrace();}return null;}public static void main(String[] args) {List<Map<String, List<String>>> list = new ArrayList<Map<String, List<String>>>();Map<String, List<String>> map = new HashMap<String, List<String>>();map.put("bbb", new ArrayList<String>());map.get("bbb").add("hello");map.put("aaa", new ArrayList<String>());list.add(map);String json = toJSON(list);System.out.println(json);list = toList(json);System.out.println(list.get(0).size());}