将json字符串转换为列表或映射 [英] Convert json string to list or map

问题描述

  [{projectFileId：8547，
projectId：8235，
fileName：1，
application：Excel，
复杂度：NORMAL，
 pageCount：2，
targetLanguages：ar-SA，
Id：8547
}，
 {projectFileId：8450 ，
projectId：8235，
fileName：Capacity Calculator.pptx，
application：Powerpoint，
complexity：NORMAL ，
pageCount：100，
targetLanguages：ar-LB，ar-SA，
Id：8450
} 
 
 
 
 
 $ b 
我想将此字符串转换为数组列表或映射，以便可以迭代通过它并获取字段值。 您可以使用     rel =nofollow>  GSON 库。只需使用  Gson＃fromJson（） 方法将JSON字符串转换为Java对象。
 
 
 
示例代码：
 
 
  BufferedReader reader = new BufferedReader（new FileReader（new File（ json.txt）））; 
 Gson gson = new Gson（）; 
 Type type = new TypeToken< ArrayList< Map< String，String>>>（）{} .getType（）; 
 ArrayList< Map< String，String>> data = gson.fromJson（reader，type）; 
 
 //从对象转换回JSON字符串
 System.out.println（new GsonBuilder（）。setPrettyPrinting（）。create（）。toJson（data））; 
  
 
 
 
 
 
 
你可以创建一个POJO类来直接转换它到POJO类对象的列表，以便于访问它。
 
 
 
示例代码： 
 
 
  class PojectDetail {
 private String projectFileId; 
 private String projectId; 
私人字符串文件名; 
私有字符串应用程序; 
私有字符串复杂度; 
私人字符串pageCount; 
 private String targetLanguages; 
私人字符串ID; 
 // getter& setter 
} 
 
 Gson gson = new Gson（）; 
 Type type = new TypeToken< ArrayList< PojectDetail>>（）{} .getType（）; 
 ArrayList< PojectDetail> data = gson.fromJson（reader，type）; 
  
 
I get a json string in server side as follow
[     {"projectFileId":"8547",
       "projectId":"8235",
       "fileName":"1",
       "application":"Excel",
       "complexity":"NORMAL",
       "pageCount":"2",
       "targetLanguages":" ar-SA",
       "Id":"8547"
      },
      {"projectFileId":"8450",
       "projectId":"8235",
       "fileName":"Capacity Calculator.pptx",
       "application":"Powerpoint",
       "complexity":"NORMAL",
       "pageCount":"100",
       "targetLanguages":" ar-LB, ar-SA",
       "Id":"8450"
      }
]
I want to convert this string into an arraylist or map whichever possible so that I can iterate over it and get the field values. 
解决方案
You can use GSON library. Simply use Gson#fromJson() method to convert JSON string into Java Object.


sample code:
BufferedReader reader = new BufferedReader(new FileReader(new File("json.txt")));
Gson gson = new Gson();
Type type = new TypeToken<ArrayList<Map<String, String>>>() {}.getType();
ArrayList<Map<String, String>> data = gson.fromJson(reader, type);

// convert back to JSON string from object
System.out.println(new GsonBuilder().setPrettyPrinting().create().toJson(data));




You can create a POJO class to convert it directly into List of POJO clas object to access it easily.

sample code:
class PojectDetail{
    private String projectFileId;
    private String projectId;
    private String fileName;
    private String application;
    private String complexity;
    private String pageCount;
    private String targetLanguages;
    private String Id;
    // getter & setter
}

Gson gson = new Gson();
Type type = new TypeToken<ArrayList<PojectDetail>>() {}.getType();
ArrayList<PojectDetail> data = gson.fromJson(reader, type);


                        
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