1.将对象转换为JSON字符串，返回值为一个JSON字符串

public static String toJson(Object value) {try {return mapper.writeValueAsString(value);} catch (Exception e) {e.printStackTrace();}return null;}

2. 将JSON字符串转换为实体对象，返回值为实体对象

public static <T> T toObject(String json, Class<T> valueType) {Assert.hasText(json);Assert.notNull(valueType);try {SimpleDateFormat dateFormat = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss");mapper.setDateFormat(dateFormat);return mapper.readValue(json, valueType);} catch (Exception e) {e.printStackTrace();}return null;