Java 如何使用GSON反序列化自定义映射
我正在使用Apache Collection的Java 如何使用GSON反序列化自定义映射,java,serialization,gson,deserialization,apache-commons-collection,Java,Serialization,Gson,Deserialization,Apache Commons Collection,我正在使用Apache Collection的BidiMap,它提供了DualHashBidiMap类。我必须在这个项目中使用这个类 它的序列化没有问题。但我对反序列化有问题 下面是一个示例类: package com.description; import org.apache.commons.collections4.BidiMap; import org.apache.commons.collections4.bidimap.DualHashBidiMap; public class
BidiMap
,它提供了DualHashBidiMap
类。我必须在这个项目中使用这个类
它的序列化没有问题。但我对反序列化有问题
下面是一个示例类:
package com.description;
import org.apache.commons.collections4.BidiMap;
import org.apache.commons.collections4.bidimap.DualHashBidiMap;
public class Sample {
private String id;
private String adress;
BidiMap<Integer, String> items = new DualHashBidiMap<Integer, String>();
public Sample() {
}
public String getId() {
return id;
}
public void setId(String id) {
this.id = id;
}
public String getAdress() {
return adress;
}
public void setAdress(String adress) {
this.adress = adress;
}
public BidiMap<Integer, String> getItems() {
return items;
}
public void setItems(BidiMap<Integer, String> items) {
this.items = items;
}
}
为什么需要使用BidiMap 检查以下各项: 稍后尝试使用Map或LinkedHashMap或手动从Map解析为BidiMap类型,以检查错误是否仍然存在。编写类型适配器也是一种选择 顺便说一下:您的JSON不是
Map
,而是Map
Map{1:“手套”,“90:“靴子”}
我以前尝试过GSON,它可以很好地与Java中的本机类型配合使用。我从未尝试过解析其他库,因为我认为您需要一个TypeAdapter。这并不是那么简单,但可以做到:
public class BidiMapTypeAdapterFactory implements TypeAdapterFactory {
@Override
public <T> TypeAdapter<T> create(Gson gson, TypeToken<T> type) {
if (!BidiMap.class.isAssignableFrom(type.getRawType())) {
return null;
}
final TypeAdapter<T> delegate = gson.getDelegateAdapter(this, type);
return new TypeAdapter<T>() {
@Override
public void write(JsonWriter out, T value) throws IOException {
delegate.write(out, value);
}
@Override
public T read(JsonReader in) throws IOException {
return (T) new DualHashBidiMap<>((Map) delegate.read(in));
}
};
}
}
现在您可以运行您的示例了,它应该可以工作了
result : {"id":"12312xoa01","adress":"Houston, 43.1","items":{"1":"gloves","90":"boots"}}
java.lang.IllegalArgumentException: Can not set org.apache.commons.collections4.BidiMap field com.description.Sample.items to java.util.LinkedHashMap
at sun.reflect.UnsafeFieldAccessorImpl.throwSetIllegalArgumentException(UnsafeFieldAccessorImpl.java:164)
at sun.reflect.UnsafeFieldAccessorImpl.throwSetIllegalArgumentException(UnsafeFieldAccessorImpl.java:168)
at sun.reflect.UnsafeObjectFieldAccessorImpl.set(UnsafeObjectFieldAccessorImpl.java:81)
at java.lang.reflect.Field.set(Field.java:741)
at com.google.gson.internal.bind.ReflectiveTypeAdapterFactory$1.read(ReflectiveTypeAdapterFactory.java:118)
at com.google.gson.internal.bind.ReflectiveTypeAdapterFactory$Adapter.read(ReflectiveTypeAdapterFactory.java:216)
at com.google.gson.Gson.fromJson(Gson.java:879)
at com.google.gson.Gson.fromJson(Gson.java:844)
at com.google.gson.Gson.fromJson(Gson.java:793)
at com.google.gson.Gson.fromJson(Gson.java:765)
at Main.main(Main.java:79)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:57)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
at java.lang.reflect.Method.invoke(Method.java:606)
at com.intellij.rt.execution.application.AppMain.main(AppMain.java:144)
public class BidiMapTypeAdapterFactory implements TypeAdapterFactory {
@Override
public <T> TypeAdapter<T> create(Gson gson, TypeToken<T> type) {
if (!BidiMap.class.isAssignableFrom(type.getRawType())) {
return null;
}
final TypeAdapter<T> delegate = gson.getDelegateAdapter(this, type);
return new TypeAdapter<T>() {
@Override
public void write(JsonWriter out, T value) throws IOException {
delegate.write(out, value);
}
@Override
public T read(JsonReader in) throws IOException {
return (T) new DualHashBidiMap<>((Map) delegate.read(in));
}
};
}
}
GsonBuilder b = new GsonBuilder().registerTypeAdapterFactory(new BidiMapTypeAdapterFactory());
Gson gson = b.create();