Json和Guava Multimap
Json和Guava Multimap
提问于 2020-04-02 10:05:45
我想创建一个multimap，将其转换为JSON，然后再返回。这里的问题是，单个值仍然显示为集合/数组。
这是我有的东西
ObjectMapper objectMapper = new ObjectMapper();
objectMapper.registerModule(new GuavaModule());
Multimap<String, String> map = ArrayListMultimap.create();
map.put("Cheesecake", "mummy");
map.put("Cookie", "PHPSESSID=298zf09hf012fh2; csrftoken=u32t4o3tb3gg43");
map.put("Cookie", "yummy_cookie=choco; tasty_cookie=strawberry");
System.out.println(map);
System.out.println("---");
String json = objectMapper.writeValueAsString(map);
System.out.println("JSON:");
System.out.println(json);
System.out.println("---");
JsonNode node = objectMapper.readTree(json);
Multimap<String, String> multimap = objectMapper.readValue(
objectMapper.treeAsTokens(node),
objectMapper.getTypeFactory().constructMapLikeType(
Multimap.class, String.class, String.class));
System.out.println(multimap);输出：
{Cookie=[PHPSESSID=298zf09hf012fh2; csrftoken=u32t4o3tb3gg43, yummy_cookie=choco; tasty_cookie=strawberry], Cheesecake=[mummy]}
---
JSON:
{"Cookie":["PHPSESSID=298zf09hf012fh2; csrftoken=u32t4o3tb3gg43","yummy_cookie=choco; tasty_cookie=strawberry"],"Cheesecake":["mummy"]}
---
{Cookie=[PHPSESSID=298zf09hf012fh2; csrftoken=u32t4o3tb3gg43, yummy_cookie=choco; tasty_cookie=strawberry], Cheesecake=[mummy]}我想要这样的东西：
JSON:
{"Cookie":["PHPSESSID=298zf09hf012fh2; csrftoken=u32t4o3tb3gg43","yummy_cookie=choco; tasty_cookie=strawberry"],"Cheesecake":"mummy"}
//or even better
JSON:
{"Cookie":"PHPSESSID=298zf09hf012fh2; csrftoken=u32t4o3tb3gg43","Cookie":"yummy_cookie=choco; tasty_cookie=strawberry","Cheesecake":"mummy"}所以“妈妈”是json数组中的一个字符串值。
知道怎么归档吗？
回答 1
Stack Overflow用户
发布于 2020-04-02 15:02:02
您可以使用Multimpap#asMap()视图并使用SerializationFeature.WRITE_SINGLE_ELEM_ARRAYS_UNWRAPPED对其进行序列化，以实现所需格式中的第一个。请注意，您需要DeserializationFeature.ACCEPT_SINGLE_VALUE_AS_ARRAY来反序列化类似于地图的对象，如下所示：
ObjectMapper objectMapper = new ObjectMapper();
objectMapper.registerModule(new GuavaModule());
objectMapper.enable(DeserializationFeature.ACCEPT_SINGLE_VALUE_AS_ARRAY);
objectMapper.enable(SerializationFeature.WRITE_SINGLE_ELEM_ARRAYS_UNWRAPPED);
Multimap<String, String> map = ArrayListMultimap.create();
map.put("Cheesecake", "mummy");
map.put("Cookie", "PHPSESSID=298zf09hf012fh2; csrftoken=u32t4o3tb3gg43");
map.put("Cookie", "yummy_cookie=choco; tasty_cookie=strawberry");
System.out.println(map);
System.out.println("---");
String json = objectMapper.writeValueAsString(map.asMap());
System.out.println("JSON:");
System.out.println(json);
System.out.println("---");
JsonNode node = objectMapper.readTree(json);
Multimap<String, String> multimap = objectMapper.readValue(
objectMapper.treeAsTokens(node),
objectMapper.getTypeFactory().constructMapLikeType(
Multimap.class, String.class, String.class));
System.out.println(multimap);输出：
{Cookie=[PHPSESSID=298zf09hf012fh2; csrftoken=u32t4o3tb3gg43, yummy_cookie=choco; tasty_cookie=strawberry], Cheesecake=[mummy]}
---
JSON:
{"Cookie":["PHPSESSID=298zf09hf012fh2; csrftoken=u32t4o3tb3gg43","yummy_cookie=choco; tasty_cookie=strawberry"],"Cheesecake":"mummy"}
---
{Cookie=[PHPSESSID=298zf09hf012fh2; csrftoken=u32t4o3tb3gg43, yummy_cookie=choco; tasty_cookie=strawberry], Cheesecake=[mummy]}如果要序列化和反序列化第二种所需的格式，则需要编写自定义杰克逊序列化程序/反序列化程序。
页面原文内容由Stack Overflow提供。腾讯云小微IT领域专用引擎提供翻译支持
原文链接：
https://stackoverflow.com/questions/60989018
复制相关文章
相似问题
腾讯云开发者
