protostuff反序列化空集合为null。
问题描述
有一个class A,含一个集合字段。创建对象时,如果集合字段赋值empty(不是null),那么反序列化后该字段变为null。
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| public class A {
List<Object> lo;
String name;
}
A a = new A();
a.setLo(new ArrarList<>());
a.setName("a");
var b = serialize(a);
var c = deserialize(b);
// c.lo is null
|
原因分析
这是因为protostuff默认不序列collection本身,只序列化collection里面的元素。
解决1:
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| private List<String> foo = new ArrayList<String>();
|
解决2:
You can use this scheme,an empty List after deserialization
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IdStrategy strategy = new DefaultIdStrategy(IdStrategy.DEFAULT_FLAGS
| IdStrategy.COLLECTION_SCHEMA_ON_REPEATED_FIELDS ,null,0);
schema = RuntimeSchema.createFrom(originClazz, strategy);
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解决3:
If you are to purely use this to replace java serialization (no compatibility with protobuf), set the following system properties:
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| -Dprotostuff.runtime.always_use_sun_reflection_factory=true
-Dprotostuff.runtime.preserve_null_elements=true
-Dprotostuff.runtime.morph_collection_interfaces=true
-Dprotostuff.runtime.morph_map_interfaces=true
-Dprotostuff.runtime.morph_non_final_pojos=true
|
Reference
- Can not correctly deserialize empty List · Issue #219 · protostuff/protostuff (github.com)
- protostuff/RuntimeEnv.java at master · protostuff/protostuff (github.com)
- Empty ArrayList data member being deserialized back as null (google.com)