[英]Deserializing a Map<String, Object> field with Gson
我有一個具有這種結構的User對象:
class User {
private String id;
private String name;
private Map<String, Object> properties;
// GETTERS & SETTERS
}
我有一個具有這種結構的JSON字符串:
{
"user": {
"id:"123456789",
"name:"azerty",
"emailHash":"123456789", // not used in User class
"properties": {
"p1":1,
"p2":"test",
"p3":[1, 2, 3, 4],
"p4":{
etc...
}
}
}
}
屬性的鍵是String,屬性的值可以是String,int,Array,boolean,Map等。
我嘗試用Gson反序列化這個JSON字符串:
JsonParser parser = new JsonParser();
JsonElement element = parser.parse(jsonString);
JsonObject object = element.getAsJsonObject();
GsonBuilder builder = new GsonBuilder();
builder.setFieldNamingPolicy(FieldNamingPolicy.LOWER_CASE_WITH_UNDERSCORES);
Gson gson = builder.create();
User user = (User) gson.fromJson(object.get("user"), new TypeToken<User>() {}.getType());
字段'id'和'name'被正確注入,但字段'properties'保持為null。
你知道我做錯了什么嗎? 在此先感謝您的幫助!
對我來說這段代碼:
public class Main {
public static void main(String[] args) throws IOException {
GsonBuilder builder = new GsonBuilder();
builder.setFieldNamingPolicy(FieldNamingPolicy.LOWER_CASE_WITH_UNDERSCORES);
Gson gson = builder.create();
FileInputStream inputStream = new FileInputStream(new File("bobi.json"));
InputStreamReader reader = new InputStreamReader(inputStream);
User user = gson.fromJson(reader, User.class);
System.out.println(user.getName());
System.out.println(user.getId());
for (String property : user.getProperties().keySet()) {
System.out.println("Key: " + property + " value: " + user.getProperties().get(property));
}
reader.close();
}
打印這個:
azerty
123456789
Key: p1 value: 1.0
Key: p2 value: test
Key: p3 value: [1.0, 2.0, 3.0, 4.0]
Key: p4 value: {}
但是,請記住,我已經解析了我解析的文件中的包裝json對象。 該文件是:
{
"id":"123456789",
"name" : "azerty",
"emailHash":"123456789",
"properties": {
"p1":1,
"p2":"test",
"p3":[1, 2, 3, 4],
"p4":{
}
}
}
另外,我添加了關於name
和id
結束雙引號,你在樣本中沒有。
OP請求的User
類。 我為打印原因添加了getter和setter:
import java.util.Map;
class User {
private String id;
private String name;
private Map<String, Object> properties;
public String getId() {
return id;
}
public void setId(String id) {
this.id = id;
}
public String getName() {
return name;
}
public void setName(String name) {
this.name = name;
}
public Map<String, Object> getProperties() {
return properties;
}
public void setProperties(Map<String, Object> properties) {
this.properties = properties;
}
}
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