杰克逊解析器到Java对象

问题描述

我正在使用Jackson解析对象.有时我需要对象列表.

I am using Jackson to parse object. sometime I need list of objects.

当我这样使用时

 List<MyObject> mapper.readValue(file , new TypeReference<MyObject>() {})

但是当我这样使用它时，它就不起作用了

but when I am using it like this its not working

public class JsonMocksRepository<T>{

    public  T getObject() throws Exception{

        return mapper.readValue(file ,new TypeReference<T>());
    }
}

我需要做什么?基本上，我想使用泛型来获取正确的类

What I need to do ?Basically I want to use generics to get the right class

推荐答案

这是因为类型擦除.在运行时没有可用的T表示的实际类型的信息，因此您的TypeReference实际上就是TypeReference<Object>.

This is because of type erasure. There is no information about the actual type represented by T available at runtime, so your TypeReference will be effectively be simply TypeReference<Object>.

如果要使用JsonMocksRepository的通用实例，则需要在构造时注入TypeReference:

If you want a generic instance of JsonMocksRepository, you will need to inject the TypeReference at construction time:

public class JsonMocksRepository<T>{
  private final TypeReference<T> typeRef;

  public JsonMocksRepository(TypeReference<T> typeRef) {
    this.typeRef = typeRef;
  }

  public T getObject() throws Exception{
    return mapper.readValue(file, typeRef);
  }
}

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