如何使用Gson序列化java.nio.file.Path? [英] How to serialize java.nio.file.Path with Gson?
问题描述
当试图序列化包含 java的
Object
时,得到 java.lang.StackOverflowError
.nio.file.Path
即使我写道:
public class PathConverter实现JsonDeserializer< Path>,JsonSerializer< Path> {
@Override
public Path deserialize(JsonElement jsonElement,Type type,JsonDeserializationContext jsonDeserializationContext)throws JsonParseException {
return Paths.get(jsonElement.getAsString());
$ b @Override
public JsonElement serialize(Path path,Type type,JsonSerializationContext jsonSerializationContext){
return new JsonPrimitive(path.toString());
}
}
并应用它:
字符串json = new GsonBuilder()
.registerTypeAdapter(Path.class,new PathConverter())
.create()
.toJson(constructorSetup,new TypeToken< ConstructorSetup>(){} .getType());
我仍然无法序列化这个类:
public class ConstructorSetup {
private Path appIconMimmapDirPathOnPc;
$ / code $ / pre
$ b $ Stacktrace :(完整版 pastebin )
线程main java.lang.StackOverflowError
,位于com.google.gson.internal。$ Gson $ Types.resolve($ Gson $ Types.java:380)
,位于com.google.gson.internal。$ Gson $ Types.resolve($ Gson $ Types.java:375)
在com.google.gson.internal。$ Gson $ Types.resolve($ Gson $ Types.java:380)
...
在com.google.gson.internal。$ Gson $ Types.resolve($ Gson $ Types.java:380)
在com.google.gson.internal。$ Gson $ Types.resolve($ Gson $ Types.java:355)
at com.google.gson.internal.bind.ReflectiveTypeAdapterFactory.getBoundFields(ReflectiveTypeAdapterFactory.java:117)
at com.google.gson.internal.bind.ReflectiveTypeAdapterFactory.create (ReflectiveTypeAdapterFactory.java:72)
在com.google.gson.Gson.getAdapter(Gson.java:356)
在com.google.gson.internal.bind.ReflectiveTypeAdapterFact ory $ 1.< init>(ReflectiveTypeAdapterFactory.java:82)
at com.google.gson.internal.bind.ReflectiveTypeAdapterFactory.createBoundField(ReflectiveTypeAdapterFactory.java:81)
at com.google.gson。 internal.bind.ReflectiveTypeAdapterFactory.getBoundFields(ReflectiveTypeAdapterFactory.java:118)
,com.google.gson.internal.bind.ReflectiveTypeAdapterFactory.create(ReflectiveTypeAdapterFactory.java:72)
,位于com.google.gson。 Gson.getAdapter(Gson.java:356)
...
在com.google.gson.internal.bind.ReflectiveTypeAdapterFactory $ 1.< init>(ReflectiveTypeAdapterFactory.java:82)
com.google.gson.internal.bind.ReflectiveTypeAdapterFactory.createBoundField(ReflectiveTypeAdapterFactory.java:81)
at com.google.gson.internal.bind.ReflectiveTypeAdapterFactory.getBoundFields(ReflectiveTypeAdapterFactory.java:118)
在com.google.gson.internal.bind.ReflectiveTypeAdapterFactory.create(ReflectiveTypeAdapterFactory.java:72)
at com.google.gson.Gson.getAdapter(Gson.java:356)
任何解决方案?
解决方案 您的问题在于 Path 是接口
。让我们假设你使用了 Paths.get(/)
,它将在我的Windows PC上创建类似于 WindowsPath
的实例。现在,你必须告诉GSON如何反序列化这种类型:
ConstructorSetup setup = new ConstructorSetup();
setup.setAppIconMimmapDirPathOnPc(Paths.get(/));
//这里我们得到了我们Path对象的实际类类型
Class classT = setup.getAppIconMimmapDirPathOnPc()。getClass();
gson gson = new GsonBuilder()。registerTypeAdapter(classT,new MyPathConverter())
您可以使用的另一种方法是 registerTypeHierarchyAdapter
:
.registerTypeHierarchyAdapter(Path.class,new MyPathConverter())
typeHierarchyAdapter的目的是覆盖当你想要一个类型的所有子类型相同的表示,这正是你的情况与路径
。
I get java.lang.StackOverflowError
when trying to serialize Object
that contains java.nio.file.Path
Even when i wrote:
public class PathConverter implements JsonDeserializer<Path>, JsonSerializer<Path> {
@Override
public Path deserialize(JsonElement jsonElement, Type type, JsonDeserializationContext jsonDeserializationContext) throws JsonParseException {
return Paths.get(jsonElement.getAsString());
}
@Override
public JsonElement serialize(Path path, Type type, JsonSerializationContext jsonSerializationContext) {
return new JsonPrimitive(path.toString());
}
}
and apply it:
String json = new GsonBuilder()
.registerTypeAdapter(Path.class, new PathConverter())
.create()
.toJson(constructorSetup, new TypeToken<ConstructorSetup>() {}.getType());
I still can't serialize this class:
public class ConstructorSetup {
private Path appIconMimmapDirPathOnPc;
}
Stacktrace: (full on pastebin)
Exception in thread "main" java.lang.StackOverflowError
at com.google.gson.internal.$Gson$Types.resolve($Gson$Types.java:380)
at com.google.gson.internal.$Gson$Types.resolve($Gson$Types.java:375)
at com.google.gson.internal.$Gson$Types.resolve($Gson$Types.java:380)
...
at com.google.gson.internal.$Gson$Types.resolve($Gson$Types.java:380)
at com.google.gson.internal.$Gson$Types.resolve($Gson$Types.java:355)
at com.google.gson.internal.bind.ReflectiveTypeAdapterFactory.getBoundFields(ReflectiveTypeAdapterFactory.java:117)
at com.google.gson.internal.bind.ReflectiveTypeAdapterFactory.create(ReflectiveTypeAdapterFactory.java:72)
at com.google.gson.Gson.getAdapter(Gson.java:356)
at com.google.gson.internal.bind.ReflectiveTypeAdapterFactory$1.<init>(ReflectiveTypeAdapterFactory.java:82)
at com.google.gson.internal.bind.ReflectiveTypeAdapterFactory.createBoundField(ReflectiveTypeAdapterFactory.java:81)
at com.google.gson.internal.bind.ReflectiveTypeAdapterFactory.getBoundFields(ReflectiveTypeAdapterFactory.java:118)
at com.google.gson.internal.bind.ReflectiveTypeAdapterFactory.create(ReflectiveTypeAdapterFactory.java:72)
at com.google.gson.Gson.getAdapter(Gson.java:356)
...
at com.google.gson.internal.bind.ReflectiveTypeAdapterFactory$1.<init>(ReflectiveTypeAdapterFactory.java:82)
at com.google.gson.internal.bind.ReflectiveTypeAdapterFactory.createBoundField(ReflectiveTypeAdapterFactory.java:81)
at com.google.gson.internal.bind.ReflectiveTypeAdapterFactory.getBoundFields(ReflectiveTypeAdapterFactory.java:118)
at com.google.gson.internal.bind.ReflectiveTypeAdapterFactory.create(ReflectiveTypeAdapterFactory.java:72)
at com.google.gson.Gson.getAdapter(Gson.java:356)
Any solution?
解决方案 Your problem is that Path
is an interface
. Let's suppose you used Paths.get("/")
which will create instance of something like WindowsPath
on my Windows PC. Now, you have to tell GSON how to deserialize this type:
ConstructorSetup setup = new ConstructorSetup();
setup.setAppIconMimmapDirPathOnPc(Paths.get("/"));
// here we get actual class type of our Path object
Class classT = setup.getAppIconMimmapDirPathOnPc().getClass();
Gson gson = new GsonBuilder().registerTypeAdapter(classT, new MyPathConverter())
Another approach you can go with is to registerTypeHierarchyAdapter
:
.registerTypeHierarchyAdapter(Path.class, new MyPathConverter())
The purpose of typeHierarchyAdapter is to cover the case when you want the same representation for all subtypes of a type, which is exactly your case with Path
.
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