Question

当类扩展GenericJson以映射未知属性时，属性不会映射到子类中的正确属性。 json中的属性将转换为LinkedHashMap，而不是映射到实际属性。

import com.google.api.client.json.GenericJson;
import com.google.api.client.util.Key;

public final class Employee extends GenericJson{

    @Key
    private String name;

    @Key
    private String empId;

    @Key
    private Address address;
}

地址类：

import com.google.api.client.json.GenericJson;
import com.google.api.client.util.Key;

public class Address extends GenericJson{

    @Key
    private String state;
}

示例json：

{
  "name": "Bob",
  "empId": "345",
  "address" : {"state" : "xyz"},
  "unknownFiled" : "some value"
}

JSON到对象转换：

  Employee employee = gson.fromJson(fileData, Employee.class);

@Key注释应确保属性映射到类中的变量，但在扩展GenericJson时，json字符串将转换为LinkedHashMap列表。引发的异常如下

Exception in thread "main" java.lang.IllegalArgumentException: Can not set com.test.Address field com.test.Employee.address to com.google.gson.internal.LinkedTreeMap
 at sun.reflect.UnsafeFieldAccessorImpl.throwSetIllegalArgumentException(UnsafeFieldAccessorImpl.java:167)
 at sun.reflect.UnsafeFieldAccessorImpl.throwSetIllegalArgumentException(UnsafeFieldAccessorImpl.java:171)
 at sun.reflect.UnsafeObjectFieldAccessorImpl.set(UnsafeObjectFieldAccessorImpl.java:81)
 at java.lang.reflect.Field.set(Field.java:764)
 at com.google.api.client.util.FieldInfo.setFieldValue(FieldInfo.java:245)
 at com.google.api.client.util.FieldInfo.setValue(FieldInfo.java:206)
 at com.google.api.client.util.GenericData.put(GenericData.java:103)
 at com.google.api.client.util.GenericData.put(GenericData.java:47)
 at com.google.gson.internal.bind.MapTypeAdapterFactory$Adapter.read(MapTypeAdapterFactory.java:188)
 at com.google.gson.internal.bind.MapTypeAdapterFactory$Adapter.read(MapTypeAdapterFactory.java:145)
 at com.google.gson.Gson.fromJson(Gson.java:803)
 at com.google.gson.Gson.fromJson(Gson.java:768)
 at com.google.gson.Gson.fromJson(Gson.java:717)
 at com.google.gson.Gson.fromJson(Gson.java:689)
 at com.test.EmployeeJSONDeserlizer.main(EmployeeJSONDeserlizer.java:20)
 at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
 at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
 at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
 at java.lang.reflect.Method.invoke(Method.java:497)
 at com.intellij.rt.execution.application.AppMain.main(AppMain.java:144)

扩展GenericJson的类无法映射到JSON

0 个答案: