我想使用 google-gson 将 json 数据解析为 java 对象.
这是我要解析的数据示例:
{"isBean":{"userName":"test","password":"password112"}}
IsBean.java
public interface IsBean extends Serializable,IsSerializable{
long getId();
}
用户.java
public class User implements IsBean,IsSerializable,Serializable {
String userName;
String password;
public String getUserName() {
return userName;
}
public void setUserName(String userName) {
this.userName = userName;
}
public String getPassword() {
return password;
}
public void setPassword(String password) {
this.password = password;
}
@Override
public long getId() {
return 0;
}
}
RequestObj.java
public class RequestObj implements IsBean, Serializable,IsSerializable{
IsBean isBean;
@Override
public long getId() {
return 0;
}
public IsBean getIsBean() {
return isBean;
}
public void setIsBean(IsBean isBean) {
this.isBean = isBean;
}
}
测试.java
public class Test {
public static void main(String[] args) {
Gson gson = new Gson();
User user=new User();
user.setPassword("password112");
user.setUserName("test");
RequestObj requestObj=new RequestObj();
requestObj.setIsBean(user);
String jsonStr=gson.toJson(requestObj);
System.out.println("jsonStr--->"+jsonStr);
try{
RequestObj request=gson.fromJson(jsonStr, RequestObj.class);
}catch (Exception e) {
e.printStackTrace();
}
}
}
错误:
java.lang.RuntimeException: Unable to invoke no-args constructor for interface com.test.gson.shared.IsBean. Register an InstanceCreator with Gson for this type may fix this problem.
at com.google.gson.internal.ConstructorConstructor$8.construct(ConstructorConstructor.java:167)
at com.google.gson.internal.bind.ReflectiveTypeAdapterFactory$Adapter.read(ReflectiveTypeAdapterFactory.java:162)
at com.google.gson.internal.bind.ReflectiveTypeAdapterFactory$1.read(ReflectiveTypeAdapterFactory.java:93)
at com.google.gson.internal.bind.ReflectiveTypeAdapterFactory$Adapter.read(ReflectiveTypeAdapterFactory.java:172)
at com.google.gson.Gson.fromJson(Gson.java:795)
at com.google.gson.Gson.fromJson(Gson.java:761)
at com.google.gson.Gson.fromJson(Gson.java:710)
at com.google.gson.Gson.fromJson(Gson.java:682)
at com.test.gson.server.Test.main(Test.java:18)
Caused by: java.lang.reflect.InvocationTargetException
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:39)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)
at java.lang.reflect.Method.invoke(Method.java:597)
at com.google.gson.internal.UnsafeAllocator$1.newInstance(UnsafeAllocator.java:48)
at com.google.gson.internal.ConstructorConstructor$8.construct(ConstructorConstructor.java:164)
... 8 more
Caused by: java.lang.InstantiationException: com.test.gson.shared.IsBean
at sun.misc.Unsafe.allocateInstance(Native Method)
... 14 more
最佳答案
在没有看到 CommunicationObject
的代码的情况下,我不能肯定地说但是我有把握地猜测该类有一个类型为 IsBean
的字段,您可以在其中使用它用来保存 User
。如果是这样,问题是 GSON 扫描类 CommunicationObject
的对象 obj
的字段,并根据字段定义,字段的值(类型为 IsBean
) 必须创建,但由于类型是接口(interface),它不能为该字段创建实例对象。
换句话说,由于JSON字段没有指定对象类型,GSON必须依赖字段定义的类型来为字段值创建实例,如果类型是接口(interface)则无法做到。
因此,如果对您有意义,请考虑更改该字段的类型。或者考虑创建 InstanceCreator
IsBean
(怀疑它在逻辑上是可能的)。
另请参阅:Deserializing an abstract class in Gson
希望这对您有所帮助。
关于java - 使用gson将json解析为java对象的问题,我们在Stack Overflow上找到一个类似的问题: https://stackoverflow.com/questions/13873887/