使用抽象类扩展

package common;

import java.util.List;
import java.util.function.Consumer;

public abstract class BaseMap<T> {
// ? extends T 表示下界
// ? super T 表示上界
private List<? extends T> list;

public BaseMap(List<? extends T> list) {
super();
this.list = list;
}

public abstract <A extends T> Object procecss(A obj);

/***
* 注意: forEach(Consumer<? super T> action)
*/
public void printAll() {

this.list.forEach(new Consumer<T>() {
@Override
public void accept(T t) {
System.out.println(BaseMap.this.procecss(t));
}
});
}
}

package common;

import java.util.List;

public class UpperMap<T> extends BaseMap<T> {

public UpperMap(List<? extends T> list) {
super(list);
// TODO Auto-generated constructor stub
}

@Override
public <A extends T> Object procecss(A obj) {
// TODO Auto-generated method stub
return obj.toString().toUpperCase();
}

}

package common;

import java.util.ArrayList;
import java.util.List;

public class Demo {
/***
* 使用装饰模式开发
*
* @param args
*/
public static void main(String[] args) {
List<String> list = new ArrayList<String>();
list.add("scala");
list.add("java");
list.add("php");

BaseMap<String> up = new UpperMap<String>(list);
up.printAll();

}

}