常用JSON工具類JsonUtil封裝
阿新 • • 發佈：2019-01-01
前言
專案中經常會有String轉Object以及Object轉Json字串的需求，故封裝一個常用Json工具類
Maven依賴
<dependency>
<groupId>org.codehaus.jackson</groupId>
<artifactId>jackson-mapper-asl</artifactId>
<version>1.9.13</version>
</dependency>如果專案沒有使用Maven可以直接下載jar包
↓↓↓
package com.suddev.util;
import org.apache.commons.lang3.StringUtils;
import org.codehaus.jackson.map.DeserializationConfig;
import org.codehaus.jackson.map.ObjectMapper;
import org.codehaus.jackson.map.SerializationConfig;
import org.codehaus.jackson.map.annotate.JsonSerialize.Inclusion;
import 測試程式碼
case1 obj轉json
public static void main(String[] args) {
User user = new User();
user.setUsername("suddev");
user.setId(123);
String s = JsonUtil.obj2String(user);
System.out.println(s);
}
case2 輸出美化後的json字串
public static void main(String[] args) {
User user = new User();
user.setUsername("suddev");
user.setId(123);
String s = JsonUtil1.obj2StringPretty(user);
System.out.println(s);
}
case3 json字串轉obj
public static void main(String[] args) {
String s = "{\"id\":123,\"username\":\"suddev\"}";
User user = JsonUtil.string2Obj(s,User.class);
}
case4 使用TypeReference轉換複雜物件
public static void main(String[] args) {
User u1 = new User();
u1.setUsername("aaa");u1.setId(1);
User u2 = new User();
u2.setUsername("bbb");u2.setId(2);
List<User> userList = Lists.newArrayList();
userList.add(u1);userList.add(u2);
String userListStr = JsonUtil.obj2StringPretty(userList);
List<User> userListObj = JsonUtil.string2Obj(userListStr, new TypeReference<List<User>>() {});
}
case5 更簡單直接的複雜物件轉換方法
public static void main(String[] args) {
User u1 = new User();
u1.setUsername("aaa");u1.setId(1);
User u2 = new User();
u2.setUsername("bbb");u2.setId(2);
List<User> userList = Lists.newArrayList();
userList.add(u1);userList.add(u2);
String userListStr = JsonUtil.obj2StringPretty(userList);
// List<User> userListObj = JsonUtil.string2Obj(userListStr, new TypeReference<List<User>>() {});
// 依次傳入集合以及集合中物件型別的class
List<User> userListObj2 = JsonUtil.string2Obj(userListStr,List.class,User.class);
}
方便專案中使用將System.out替換為log的版本
/**
* Jackson工具類
*
* @author suddev
* @create 2017-11-25 2:18 PM
**/
@Slf4j
public class JsonUtil {
private static ObjectMapper objectMapper = new ObjectMapper();
static {
// 物件欄位全部列入
objectMapper.setSerializationInclusion(Inclusion.NON_DEFAULT);
// 取消預設轉換timestamps形式
objectMapper.configure(SerializationConfig.Feature.WRITE_DATES_AS_TIMESTAMPS,false);
// 忽略空bean轉json的錯誤
objectMapper.configure(SerializationConfig.Feature.FAIL_ON_EMPTY_BEANS,false);
// 統一日期格式yyyy-MM-dd HH:mm:ss
objectMapper.setDateFormat(new SimpleDateFormat(DateTimeUtil.STANDARD_FORMAT));
// 忽略在json字串中存在,但是在java物件中不存在對應屬性的情況
objectMapper.configure(DeserializationConfig.Feature.FAIL_ON_UNKNOWN_PROPERTIES,false);
}
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;
}
}
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 (IOException e) {
log.warn("Parse String to Object error",e);
return null;
}
}
public static <T> T string2Obj(String str, TypeReference<T> typeReference){
if (StringUtils.isEmpty(str) || typeReference == null){
return null;
}
try {
return (T)(typeReference.getType().equals(String.class)? str :objectMapper.readValue(str,typeReference));
} catch (IOException e) {
log.warn("Parse String to Object error",e);
return null;
}
}
public static <T> T string2Obj(String str,Class<?> collectionClass,Class<?>... elementClasses){
JavaType javaType = objectMapper.getTypeFactory().constructParametricType(collectionClass,elementClasses);
try {
return objectMapper.readValue(str,javaType);
} catch (IOException e) {
log.warn("Parse String to Object error",e);
return null;
}
}
}