英文:
Abstract class with Gson serialization/deserialization
问题
我期望从一个 JSON 中获取一个 `LinkedList<Request>`。
这些 POJO 类看起来像这样：
@Data
@Builder
public class Request {
private String id;
private List<Parameter> parameters;
}
@Data
@SuperBuilder
public abstract class Parameter implements Serializable {
private String key;
public abstract Object getValue();
}
@Data
@SuperBuilder
@EqualsAndHashCode(callSuper = true)
public class StringParameter extends Parameter implements Serializable {
private String value;
}
@Data
@SuperBuilder
@EqualsAndHashCode(callSuper = true)
public class PasswordParameter extends Parameter implements Serializable {
private String value;
}
序列化工作正常，它生成了 JSON，但在反序列化时出现了问题（也许是抽象类和/或我期望的 `LinkedList`，以及 lombok 的注解）？
我尝试编写了一个 Gson 反序列化器（在网上找到的标准方式），但它没有完成工作。
英文:
I am expecting to get from a json a LinkedList<Request>.
The pojos look like this:
@Data
@Builder
public class Request {
private String id;
private List<Parameter> parameters;
}
@Data
@SuperBuilder
public abstract class Parameter implements Serializable {
private String key;
public abstract Object getValue();
}
@Data
@SuperBuilder
@EqualsAndHashCode(callSuper = true)
public class StringParameter extends Parameter implements Serializable {
private String value;
}
@Data
@SuperBuilder
@EqualsAndHashCode(callSuper = true)
public class PasswordParameter extends Parameter implements Serializable {
private String value;
}
The serialization works fine, it generates the json, but it crashes at deserialization (maybe it's the abstract class or/and that I am expecting a LinkedList and/or the lombok annotations)?
I tryed writting a gson deserializer (quite a standard one found googling), but it doesn't do the job.
答案1
得分: 0
由于 @fluffy 的建议，我成功地跳过了编写自定义的反序列化器，并且利用了 gson-extras 库中的 RuntimeTypeAdapterFactory：
public static void writeObjectToFile(Object object, String filePath) {
RuntimeTypeAdapterFactory<Parameter> parameterAdapterFactory = RuntimeTypeAdapterFactory.of(Parameter.class, "type");
parameterAdapterFactory.registerSubtype(StringParameter.class, "StringParameter");
parameterAdapterFactory.registerSubtype(PasswordParameter.class, "PasswordParameter");
Gson gson = new GsonBuilder().setPrettyPrinting().registerTypeAdapterFactory(parameterAdapterFactory).create();
try {
FileWriter fileWriter = new FileWriter(filePath);
gson.toJson(object, fileWriter);
fileWriter.flush();
fileWriter.close();
} catch (IOException e) {
System.out.println(e.getMessage());
}
}
public static LinkedList<Request> readObjectFromFile(String filePath) {
RuntimeTypeAdapterFactory<Parameter> parameterAdapterFactory = RuntimeTypeAdapterFactory.of(Parameter.class, "type");
parameterAdapterFactory.registerSubtype(StringParameter.class, "StringParameter");
parameterAdapterFactory.registerSubtype(PasswordParameter.class, "PasswordParameter");
Gson gson = new GsonBuilder().setPrettyPrinting().registerTypeAdapterFactory(parameterAdapterFactory).create();
try {
BufferedReader jsonBuffer = new BufferedReader(new FileReader(filePath));
return gson.fromJson(jsonBuffer, new TypeToken<LinkedList<Request>>(){}.getType());
} catch (FileNotFoundException e) {
System.out.println(e.getMessage());
}
return null;
}
我还保留了 lombok 的注解，并且没有为我的 POJO 类编写构造函数和 getter/setter 方法。
英文:
Thanks to @fluffy's suggestion, I managed to skip writing a custom deserialiser and making use of RuntimeTypeAdapterFactory from gson-extras library:
public static void writeObjectToFile(Object object, String filePath) {
RuntimeTypeAdapterFactory<Parameter> parameterAdapterFactory = RuntimeTypeAdapterFactory.of(Parameter.class, "type");
parameterAdapterFactory.registerSubtype(StringParameter.class, "StringParameter");
parameterAdapterFactory.registerSubtype(PasswordParameter.class, "PasswordParameter");
Gson gson = new GsonBuilder().setPrettyPrinting().registerTypeAdapterFactory(parameterAdapterFactory).create();
try {
FileWriter fileWriter = new FileWriter(filePath);
gson.toJson(object, fileWriter);
fileWriter.flush();
fileWriter.close();
} catch (IOException e) {
System.out.println(e.getMessage());
}
}
public static LinkedList<Request> readObjectFromFile(String filePath) {
RuntimeTypeAdapterFactory<Parameter> parameterAdapterFactory = RuntimeTypeAdapterFactory.of(Parameter.class, "type");
parameterAdapterFactory.registerSubtype(StringParameter.class, "StringParameter");
parameterAdapterFactory.registerSubtype(PasswordParameter.class, "PasswordParameter");
Gson gson = new GsonBuilder().setPrettyPrinting().registerTypeAdapterFactory(parameterAdapterFactory).create();
try {
BufferedReader jsonBuffer = new BufferedReader(new FileReader(filePath));
return gson.fromJson(jsonBuffer, new TypeToken<LinkedList<Request>>(){}.getType());
} catch (FileNotFoundException e) {
System.out.println(e.getMessage());
}
return null;
}
I also kept only the lombok annotations and did not write constructors and getters/setters for my POJOs
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