JSON工具类总结

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());

}