Java：将JSON结构反序列化为Map< String，Object> [英] Java: Deserializing JSON structure to Map<String, Object>

问题描述

我有一个JSON字符串，我想转换为Map结构，其中Object是基本类型的Java版本（即String，Int，Double），Map。或一个列表。

我用于测试的示例字符串是：

 code> {\ cases\ ：[{\ documents\ ：[{\ files\ ：[{\ name\ ：\ 一个。 pdf\}]}]}]}
  

这应该读作一系列案例每个都有一系列文件，每个文件都有一个文件数组，每个文件都有一个名字

我尝试过Google的Gson，但是

  Gson gson = new Gson（）; 
列表< Map< String，Object>> results = gson.fromJson（dictString，List.class）; 
  

给我：

  com.google.gson.JsonParseException：JsonDeserializer com.google.gson.DefaultTypeAdapters$CollectionTypeAdapter@561777b1无法反序列化json对象{case：[{documents：[{files：[ {name：a.pdf}]}]}]}给定类型接口java.util.List 
  

我试过Jackson，但是

 列表< Map< String，Object>> result =（List< Map< String，Object>）new ObjectMapper（）。readValue（dictString，List.class）; 
  

给了我：

  org.codehaus.jackson.map.JsonMappingException：无法反序列化java.util.List中的实例，从[OBJECT令牌
] [Source：java.io.StringReader@1c5aebd9;行：1，列：1] 
  

你有什么建议吗？或者是为了正确使用上述任何一种，还是给我需要的另一个解析器？

干杯

Nik

解决方案

根据您的描述，这听起来像您的定义不匹配。它像这样的东西应该是这样的：列表<列表< String>>>

更多的手册，但看看这里：

http：/ /json.org/java/

这将给你一个比自己解析字符串更容易使用的JSONObject，但是你仍然必须钻入它并手动构建您的地图。一半半解决方案。

I've got a JSON string that I want to convert to a Map structure where Object is either a Java version of a basic type (i.e. String, Int, Double), a Map. or a List.

The sample string I'm using for my tests is:

"{\"cases\":[{\"documents\":[{\"files\":[{\"name\":\"a.pdf\"}]}]}]}"

This should read as an array of cases that each have an array of documents, that each have an array of files, that each have a name

I've tried Google's Gson, but

Gson gson = new Gson();
List<Map<String, Object>> results = gson.fromJson(dictString, List.class);

gives me:

com.google.gson.JsonParseException: The JsonDeserializer com.google.gson.DefaultTypeAdapters$CollectionTypeAdapter@561777b1 failed to deserialize json object {"cases":[{"documents":[{"files":[{"name":"a.pdf"}]}]}]} given the type interface java.util.List

and I tried Jackson, but

List<Map<String, Object>> results = (List<Map<String, Object>>) new ObjectMapper().readValue(dictString, List.class);

gave me:

org.codehaus.jackson.map.JsonMappingException: Can not deserialize instance of java.util.List out of START_OBJECT token
 at [Source: java.io.StringReader@1c5aebd9; line: 1, column: 1]

Do you have any suggestions? Either for how to use either of the above correctly, or for another parser that gives me what I want?

Cheers

Nik

解决方案

Given your description, it sounds like your definition doesn't match up. It dounds like it should be something like: List<List<list<String>>>

It's a bit more manual but have a look here:

http://json.org/java/

This will give you a JSONObject that is much easier to use than parsing the string yourself, but you will still have to drill into it and manually build your map. Kind of a half and half solution.

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