Guava的TypeToken可以获取通用字段的特定类型吗?

问题描述

我为名为ASN.1的文件格式编写了一个解析器，该解析器使用Guice的 TypeLiteral.getFieldType(Field)将通用字段转换为特定的Java类型，因此我可以构造正确的类型(类似于Jackson或GSON数据绑定).但是，由于我已经依赖Guava了，并且它似乎有了新的TypeLiteral替代品，因此我想改用 TypeToken .根据 Guave TypeToken文档:

I wrote a parser for a file format called ASN.1 that uses Guice’s TypeLiteral.getFieldType(Field) to convert generic fields into specific Java types so I can construct the correct type (similar to Jackson or GSON databinding). But since I already depend on Guava and it seems to have a new TypeLiteral replacement, I’d like to use TypeToken instead. According to the Guave TypeToken documentation:

可以使用 TypeToken 获得字段的简化类型吗?换句话说，我该如何在Guava中执行以下操作?

Can you get the reified type of a field using TypeToken? In other words, how can I do the following in Guava?

import org.junit.Test;
import com.google.inject.TypeLiteral;
public class FieldTypeTest {
    public static class A<T> {
        T a;
    }
    public static class B {
        A<String> b;
    }

    @Test
    public void testTypeToken() throws SecurityException, NoSuchFieldException {
        TypeLiteral<?> reifiedA = TypeLiteral.get(B.class).getFieldType(B.class.getDeclaredField("b"));
        assertEquals(String.class, reifiedA.getFieldType(reifiedA.getRawType().getDeclaredField("a")).getRawType());
    }
}

推荐答案

从我的角度出发，未经验证

From my head, not verified

Type t = B.class.getDeclaredField("b").getGenericType();
Class<?> p = TypeToken.of(t).resolve(
        /* T */  A.getTypeParameters()[0]).getRawType();
// p should be String.class

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