[英]Json jackson : can't parse a json a file
我正在嘗試解析JSON文件並將其存儲在列表中。 我收到此錯誤:com.fasterxml.jackson.databind.JsonMappingException:無法從START_OBJECT令牌中反序列化java.util.ArrayList實例
這是我的JSON文件
{ "budgetList":[
{
"label":"Salary Tim",
"category":"Monthly Income",
"real":1590,
"estimated":1590,
"date":"",
"month":"",
"year":"",
"type":"Income"
},
{
"label":"Salary Tom",
"category":"Monthly Income",
"real":1540,
"estimated":1540,
"date":"",
"month":"",
"year":"",
"type":"Income"
}
]
}
這是我的代碼
預算 :
public class Budget {
private String label;
private String category;
private int real;
private int estimated;
private Date date;
private int year;
private String type;
....
....
}
我的服務:
List<Budget> budgets = objectMapper.readValue(new File("src/main/resources/json/new_exercise.json"), TypeFactory.defaultInstance().constructCollectionType(List.class,
Budget.class));
我哪里錯了?
提前致謝。
代碼是
ObjectMapper objectMapper = new ObjectMapper();
List<Budget> budgets = null;
JsonNode node = objectMapper.readTree(new File("src/main/resources/json/new_exercise.json"));
node = node.get("budgetList");
TypeReference<List<Budget>> typeRef = new TypeReference<List<Budget>>(){};
budgets = objectMapper.readValue(node.traverse(), typeRef);
可以使用GSON庫嗎? 很簡單
Reader reader = new InputStreamReader(new FileInputStream(“ / opt / file.json”));
Gson gson = gsonBuilder.create();
列出listBudget = gson.fromJson(閱讀器,新的TypeToken>(){} .getType());
我認為唯一的問題是Date和整數解析器when為空。 但是您可以注冊適配器,例如:
GsonBuilder gsonBuilder = new GsonBuilder(); gsonBuilder.registerTypeAdapter(Date.class, new JsonDeserializer<Date>() { DateFormat df = new SimpleDateFormat("yyyy-MM-dd HH:mm"); public Date deserialize(final JsonElement json, final Type typeOfT, final JsonDeserializationContext context) throws JsonParseException { try { return df.parse(json.getAsString()); } catch (ParseException e) { return null; } } });
Reader reader = new InputStreamReader(new FileInputStream(“ / opt / file.json”)); Gson gson = gsonBuilder.create();
列出listBudget = gson.fromJson(閱讀器,新的TypeToken>(){} .getType());
它對您有用嗎?,別忘了驗證您的json。 ”
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