[英]Convert JSON string to json objects
我有一個返回的json字符串:
[{"TRAIN_JOURNEY_STAFF[],"ID":15,"EMAIL_ADDRESS":"jk@connectedrail.com","PASSWORD":"test","FIRST_NAME":"Joe","LAST_NAME":"Kevin","DATE_OF_BIRTH":"1996-04-20T00:00:00","GENDER":"Male","STAFF_ROLE":"Conductor","PHOTO":null},{new record..}]
這里有幾條記錄,我找不到將這個json字符串轉換為單個對象的方法。 我正在使用以下內容讀取數據:
StringBuffer response;
try (BufferedReader in = new BufferedReader(
new InputStreamReader(con.getInputStream()))) {
String inputLine;
response = new StringBuffer();
while ((inputLine = in.readLine()) != null) {
response.append(inputLine);
}
}
System.out.print(response.toString());
}
我已經嘗試過簡單的json庫,但是解析器將字符串混合在一起,這並不理想,因為我需要將數據逐行輸出到jtables。
任何幫助,將不勝感激。
使用GSON在下面解決了該問題。 非常感謝大家!
JsonElement jelement = new JsonParser().parse(response.toString());
JsonArray jarray = jelement.getAsJsonArray();
JsonObject jobject = jarray.get(0).getAsJsonObject();
System.out.println(jobject.get("FIRST_NAME"));
您可以使用如下形式:
public class ObjectSerializer {
private static ObjectMapper objectMapper;
@Autowired
public ObjectSerializer(ObjectMapper objectMapper) {
ObjectSerializer.objectMapper = objectMapper;
}
public static <T> T getObject(Object obj, Class<T> class1) {
String jsonObj = "";
T userDto = null;
try {
jsonObj = objectMapper.writeValueAsString(obj);
userDto = (T) objectMapper.readValue(jsonObj, class1);
System.out.println(jsonObj);
} catch (JsonProcessingException jpe) {
} catch (IOException e) {
e.printStackTrace();
}
return userDto;
}
將您的JSON對象傳遞給帶有類名的此方法alogn,它將把JSON數據設置為相應的類。
注意:類必須具有與要與其映射的JSON中相同的變量。
你基本上是這樣的:
[
{
"TRAIN_JOURNEY_STAFF":[
],
"ID":15,
"EMAIL_ADDRESS":"jk@connectedrail.com",
"PASSWORD":"test",
"FIRST_NAME":"Joe",
"LAST_NAME":"Kevin",
"DATE_OF_BIRTH":"1996-04-20T00:00:00",
"GENDER":"Male",
"STAFF_ROLE":"Conductor",
"PHOTO":null
},
{
}
]
您可以使用JSON構造函數將此數組序列化為JSONObjects
數組。 嘗試在Java中尋找JSONObject
和JSONArray
類。 構造函數基本上采用字符串化的JSON(您已經擁有)。
您可以使用Jackson將JSON轉換為對象,包括依賴項:
<dependency>
<groupId>com.fasterxml.jackson.core</groupId>
<artifactId>jackson-databind</artifactId>
<version>2.6.3</version>
</dependency>
然后創建一個POJO類以存儲JSON.pojo類應反映json字符串結構,並應具有適當的字段以映射值(此處示例代碼Staff.class是pojo類)。然后,使用ObjectMapper類可以如下將JSON字符串轉換為java對象:
StringBuffer response;
try (BufferedReader in = new BufferedReader(
new InputStreamReader(con.getInputStream()))) {
String inputLine;
response = new StringBuffer();
while ((inputLine = in.readLine()) != null) {
response.append(inputLine);
}
}
System.out.print(response.toString());
ObjectMapper mapper = new ObjectMapper();
//JSON from file to Object
Staff obj = mapper.readValue(new File("c:\\file.json"), Staff.class);
//JSON from String to Object
Staff obj = mapper.readValue(response.toString(), Staff.class);
讀取JSON字符串並將其轉換為對象的另一種簡單方法是:
JSON字符串:
{
"lastName":"Smith",
"address":{
"streetAddress":"21 2nd Street",
"city":"New York",
"state":"NY",
"postalCode":10021
},
"age":25,
"phoneNumbers":[
{
"type":"home", "number":"212 555-1234"
},
{
"type":"fax", "number":"212 555-1234"
}
],
"firstName":"John"
}
public class JSONReadExample
{
public static void main(String[] args) throws Exception
{
// parsing file "JSONExample.json"
Object obj = new JSONParser().parse(new FileReader("JSONExample.json"));
// typecasting obj to JSONObject
JSONObject jo = (JSONObject) obj;
// getting firstName and lastName
String firstName = (String) jo.get("firstName");
String lastName = (String) jo.get("lastName");
System.out.println(firstName);
System.out.println(lastName);
// getting age
long age = (long) jo.get("age");
System.out.println(age);
// getting address
Map address = ((Map)jo.get("address"));
// iterating address Map
Iterator<Map.Entry> itr1 = address.entrySet().iterator();
while (itr1.hasNext()) {
Map.Entry pair = itr1.next();
System.out.println(pair.getKey() + " : " + pair.getValue());
}
// getting phoneNumbers
JSONArray ja = (JSONArray) jo.get("phoneNumbers");
// iterating phoneNumbers
Iterator itr2 = ja.iterator();
while (itr2.hasNext())
{
itr1 = ((Map) itr2.next()).entrySet().iterator();
while (itr1.hasNext()) {
Map.Entry pair = itr1.next();
System.out.println(pair.getKey() + " : " + pair.getValue());
}
}
}
}
以供參考:
https://www.geeksforgeeks.org/parse-json-java/
https://www.mkyong.com/java/jackson-2-convert-java-object-to-from-json/
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