反射获取泛型

package test;

import java.lang.reflect.ParameterizedType;

import java.lang.reflect.Type;

import org.junit.Test;

import junit.framework.TestCase;

class TClass<T> {

}

class GoodClass<T> extends TClass<String> {

public ParameterizedType getClassT() {

return (ParameterizedType) getClass().getGenericSuperclass();

}

}

class BadClass<T> extends TClass<T> {

public ParameterizedType getClassT() {

return (ParameterizedType) getClass().getGenericSuperclass();

}

}

public class GenericsTest extends TestCase {

private void print(Type[] targs) {

System.out.print("actual type arguments are:");

for (int j = 0; j < targs.length; j++) {

System.out.print(" instance of " + targs[j].getClass().getName() + ":");

System.out.println(" (" + targs[j] + ")");

}

}

@Test

public void testGoodClass() throws Exception {

ParameterizedType type = new GoodClass<String>().getClassT();

Type[] types = type.getActualTypeArguments();

print(types);

assertEquals(TClass.class, type.getRawType());

assertEquals(String.class, types[0]);

}

@Test

public void testBadClass() throws Exception {

ParameterizedType type = new BadClass<String>().getClassT();

Type[] types = type.getActualTypeArguments();

print(types);

assertEquals(TClass.class, type.getRawType());

assertEquals(String.class, types[0]);

}

}