Java:带有重复键的Json使用Jackson进行映射 [英] Java : Json with duplicate keys to map using Jackson
问题描述
我有一个json文件,它具有相同的键值,但值不同,如下所示:
{
domains: {
A:{
name:a,
type:a1
},
B:{
name:r,
type:g1
},
A:{
name:b,
type:b1
}
}
}
来自外部系统。
如何将 json转换为java map 对象并访问该键的不同值:A
我正在使用类似下面,
map = mapper.readValue(json,new TypeReference< HashMap< String,String>>(){}) ;
这将返回具有唯一键的映射。但是我需要一个map对象来保存来自json文件的所有数据。
无论如何要实现这一点?
我同意@fge的评论。
但是,如果你真的坚持解决这个问题,你可以将子类 HashMap
(或任何其他的 Map
),覆盖它的 put
方法,使用任何你想要的机制处理重复。只要确保你的 Map
具有一个无参数构造函数。
Guava也可以有一个数据类型,重复( Multimap
?)。如果是这样,你会想要使用杰克逊的Guava模块: https://github.com/FasterXML/jackson -datatype-guava
I have a json file with same key but different values as follows,
{
"domains" : {
"A" : {
"name" : "a",
"type" : "a1"
},
"B" :{
"name" : "r",
"type" : "g1"
},
"A" : {
"name" : "b",
"type" : "b1"
}
}
}
which is coming from external system. How to convert the json to java map object and access the different values of the key: A
I am using something like below,
map = mapper.readValue(json, new TypeReference<HashMap<String,String>>(){});
which returns a map with unique keys. But I need a map object to hold all the data from json file.
Anyway to achieve this?
I agree with comments by @fge.
But if you really insists on solving this, you could sub-class HashMap
(or any other Map
), override its put
method, and handle duplicates using whatever mechanism you want. Just make sure your Map
has a no-arguments constructor.
Guava may also have a datatype that would allow retaining duplicates (Multimap
?). If so, you will want to use Jackson's Guava module: https://github.com/FasterXML/jackson-datatype-guava
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