在项目中用Jackson完成json和对象之间的转换,可以完成把对象序列化之后,存入redis,设置超时间,完成用户的登陆。
1. 在maven的pom文件中引入jackson.jar
<dependency> <groupId>org.codehaus.jackson</groupId> <artifactId>jackson-mapper-asl</artifactId> <version>1.9.12</version> </dependency>
2. 封装一个单独的JsonUtil类,提高可用性
@Slf4j public class JsonUtil { private static ObjectMapper objectMapper = new ObjectMapper(); static { //对象的所有字段全部列入 objectMapper.setSerializationInclusion(JsonSerialize.Inclusion.ALWAYS); // 取消默认转换timestamps形式 objectMapper.configure(SerializationConfig.Feature.WRITE_DATE_KEYS_AS_TIMESTAMPS,false); //忽略空bean转json的错误 objectMapper.configure(SerializationConfig.Feature.FAIL_ON_EMPTY_BEANS,false); //日期格式统一为以下格式 objectMapper.setDateFormat(new SimpleDateFormat(DateTimeUtil.STANDARD_FORMAT)); //忽略在json字符串中存在,在java属性中不存在的情况。防止错误 objectMapper.configure(DeserializationConfig.Feature.FAIL_ON_UNKNOWN_PROPERTIES,false); } // 把对象转化为json字符串 public static <T> String obj2String(T obj){ if (obj==null){ return null; } try { return obj instanceof String ? (String) obj :objectMapper.writeValueAsString(obj); } catch (Exception e) { log.warn("Parse object to String error",e); return null; } } // 返回格式化之后的字符串 public static <T> String obj2StringPretty(T obj){ if (obj==null){ return null; } try { return obj instanceof String ? (String) obj :objectMapper.writerWithDefaultPrettyPrinter().writeValueAsString(obj); } catch (Exception e) { log.warn("Parse object to String error",e); return null; } } public static <T> T string2Obj(String str,Class <T>clazz){ if (StringUtils.isEmpty(str)||clazz ==null){ return null; } try { return clazz.equals(String.class)?(T)str:objectMapper.readValue(str,clazz); }catch (Exception e){ log.warn("Parse str to object error",e); return null; } } public static <T> T string2Obj(String str, TypeReference<T> reference){ if (StringUtils.isEmpty(str)||reference ==null){ return null; } try { return (T) (reference.getType().equals(String.class)?(T)str:objectMapper.readValue(str,reference)); }catch (Exception e){ log.warn("Parse str to object error",e); return null; } } public static <T> T string2Obj(String str,Class<?> collectionClass,Class<?>...elecmentClassess){ JavaType javatype= objectMapper.getTypeFactory().constructParametricType(collectionClass,elecmentClassess); try { return objectMapper.readValue(str,javatype); }catch (Exception e){ log.warn("Parse str to object error",e); return null; } } }