获取Java类的类型类使用反射

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英文:

Obtaining type class from java class using reflections

问题

I currently have a setup like this:

public abstract class Configurable<T> {
    //...
}
public class ConfigurableBoolean extends Configurable<Boolean> {
    //...
}

I'm looking to obtain a Boolean class from ConfigurableBoolean but Integer on a ConfigurableInt (similar setup)

英文:

I currently have a setup like this:

public abstract class Configurable&lt;T&gt; {
    //...
}
public class ConfigurableBoolean extends Configurable&lt;Boolean&gt; {
    //...
}

I'm looking to obtain a Boolean class from ConfigurableBoolean but Integer on a ConfigurableInt (similar setup)

答案1

得分: 2

Here is the translated content:

如果它只是"一步"(你要检查的类型的直接父类是Configurable<C>,其中C是一个非参数化类),那么它就是

@SuppressWarnings("unchecked")
<T> Class<? extends T> getConfigType(Class<? extends Configurable<? extends T>> clazz) {
    String err = "configuration type of " + clazz + " is too hard to find";
    if (!(clazz.getGenericSuperclass() instanceof ParameterizedType)) throw new UnsupportedOperationException(err);
    var configurable = (ParameterizedType) clazz.getGenericSuperclass();
    if (configurable.getRawType() != Configurable.class) throw new UnsupportedOperationException(err);
    var args = configurable.getActualTypeArguments();
    if (args.length != 1 || !(args[0] instanceof Class)) throw new UnsupportedOperationException(err);
    return (Class<? extends T>) args[0];
}

你可以修改这个来搜索"更深":递归查找父类,直到找到Configurable,甚至可以跟踪类型参数的赋值,以处理类似于

class ConfigurableList<T> extends Configurable<List<T>> { }
class ConfigurableListBoolean extends ConfigurableList<Boolean> { }

但除此之外,这似乎能够处理你的情况。

英文:

If it's just "one step" (the direct superclass of the type you're inspecting is Configurable&lt;C&gt; where C is a non-parametrized class), then it's

@SuppressWarnings(&quot;unchecked&quot;) &lt;T&gt; Class&lt;? extends T&gt; getConfigType(Class&lt;? extends Configurable&lt;? extends T&gt;&gt; clazz) {
    String err = &quot;configuration type of &quot; + clazz + &quot; is too hard to find&quot;;
    if(!(clazz.getGenericSuperclass() instanceof ParameterizedType)) throw new UnsupportedOperationException(err);
    var configurable = (ParameterizedType)clazz.getGenericSuperclass();
    if(configurable.getRawType() != Configurable.class) throw new UnsupportedOperationException(err);
    var args = configurable.getActualTypeArguments();
    if(args.length != 1 || !(args[0] instanceof Class)) throw new UnsupportedOperationException(err);
    return (Class&lt;? extends T&gt;)args[0];
}

You could modify this to search "harder": recursing up the superclasses until it finds Configurable, and maybe even tracking the assignments of type parameters so it can handle things like

class ConfigurableList&lt;T&gt; extends Configurable&lt;List&lt;T&gt;&gt; { }
class ConfigurableListBoolean extends ConfigurableList&lt;Boolean&gt; { }

but otherwise this seems to handle your case.

huangapple
  • 本文由 发表于 2020年7月29日 07:30:58
  • 转载请务必保留本文链接:https://go.coder-hub.com/63144245.html
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