1.1. 用反射访问参数化类型
使用反射机制可以获取到一部分参数化类型有关的信息。
public class GenericParameterTest5 {
static class Base{}
static class Generic<T extends Base>{
public T work( List<T> list){
return list.get(0);
}
public T work( T obj){
return obj;
}
}
public static void main(String[] args) {
try {
//public T work( List<T> list){
Method method1 = Generic.class.getMethod("work", List.class);
System.out.println(method1.getParameters()[0].getType());
Type t1 = method1.getGenericParameterTypes()[0];
ParameterizedType pt = (ParameterizedType)t1;
System.out.println("rawtype:" +pt.getRawType()
+ "actualtype:" + pt.getActualTypeArguments()[0].getTypeName());
System.out.println("-------------");
//public T work( T obj){
Method method2 = Generic.class.getMethod("work", Base.class);
System.out.println(method2.getParameters()[0].getType());
Type t2 = method2.getGenericParameterTypes()[0];
TypeVariable<?> tv = (TypeVariable)t2;
System.out.println(tv.getTypeName());
GenericDeclaration gd = tv.getGenericDeclaration();
System.out.println(gd.getTypeParameters()[0]);
} catch (NoSuchMethodException | SecurityException e) {
e.printStackTrace();
}
}
}
运行结果如下：
interface java.util.List
rawtype:interface java.util.Listactualtype:T
-------------
class com.test.javatechnology.genericparameter.GenericParameterTest5$Base
T
T