json 用Jackson得到数组的大小

dsekswqp  于 2023-01-22  发布在  其他
关注(0)|答案(3)|浏览(142)

I've the below data in a json file.

{  
   "product":"Data",
   "data":{  
      "zip":[  
         {  
            "codeValue":"12345",
            "distance":[  
               {  
                  "5":"a c"
               },
               {  
                  "2":"z c"
               }
            ]
         },
         {  
            "codeValue":"60089",
            "distance":[  
               {  
                  "5":"a c"
               },
               {  
                  "2":"z c"
               }
            ]
         }
      ]
   }
}

and I'm trying to print the zip size using the below code.

public void getJsonResponse() throws Exception {
    String text = getTheData();
    System.out.println(text);
    ObjectMapper objMap = new ObjectMapper();
    Map<String, Object> map = objMap.readValue(text, new TypeReference<Map<String, Object>>() {
    });

    String mainMap = map.get("product").toString();
    String getData = map.get("data").toString();
    Map<String, Object> map1 = objMap.readValue(getData, new TypeReference<Map<String, Object>>() {
    });
    List zip = (List) map1.get("zip");
    System.out.println(zip.size());
}

here instead of sysout on zip.size() , if I used mainMap , I get the output as Data, but when I use zip.size() , I get some exception as
Exception in thread "main" com.fasterxml.jackson.core.JsonParseException: Unexpected character ('z' (code 122)): was expecting double-quote to start field name at [Source: java.io.StringReader@60f82f98; line: 1, column: 3] at com.fasterxml.jackson.core.JsonParser._constructError(JsonParser.java:1524) at com.fasterxml.jackson.core.base.ParserMinimalBase._reportError(ParserMinimalBase.java:557) at com.fasterxml.jackson.core.base.ParserMinimalBase._reportUnexpectedChar(ParserMinimalBase.java:475) at com.fasterxml.jackson.core.json.ReaderBasedJsonParser._handleOddName(ReaderBasedJsonParser.java:1293) at com.fasterxml.jackson.core.json.ReaderBasedJsonParser._parseName(ReaderBasedJsonParser.java:1190) at com.fasterxml.jackson.core.json.ReaderBasedJsonParser.nextToken(ReaderBasedJsonParser.java:612) at com.fasterxml.jackson.databind.deser.std.MapDeserializer._readAndBindStringMap(MapDeserializer.java:412) at com.fasterxml.jackson.databind.deser.std.MapDeserializer.deserialize(MapDeserializer.java:312) at com.fasterxml.jackson.databind.deser.std.MapDeserializer.deserialize(MapDeserializer.java:26) at com.fasterxml.jackson.databind.ObjectMapper._readMapAndClose(ObjectMapper.java:2993) at com.fasterxml.jackson.databind.ObjectMapper.readValue(ObjectMapper.java:2105) at onlyJava.JsonDataCAll.getJsonResponse(JsonDataCAll.java:24) at onlyJava.Test.main(Test.java:13)
please let me know where have I gone wrong and how can I fix this.

snz8szmq

snz8szmq1#

String getData = map.get("data").toString();

这不会返回JSON,因此会出现异常。您将得到类似于{zip=[{...
而是将您的语句从

Map<String, Object> map1 = objMap.readValue(getData, new TypeReference<Map<String, Object>>() {
        });

Map<String, Object> map1 = (Map<String, Object>) map.get("data");
wgxvkvu9

wgxvkvu92#

您进行了可以跳过的转换。请尝试以下操作:

Map data = (Map) map.get("data");
List zip = (List) data.get("zip");
System.out.println(zip.size());
w6lpcovy

w6lpcovy3#

强制转换为数组节点

import com.fasterxml.jackson.databind.node.ArrayNode;

ArrayNode zip = (ArrayNode)data.get("zip");
System.out.println(zip.size());

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