这是使用Proxy类的纯 Java 实现:
import java.lang.reflect.*;
import java.util.*;
public class Demo
{
public static void main(String[] args)
{
Map<String, String> map = new HashMap<String, String>();
map.put("onStart", "abc");
map.put("onEnd", "def");
Library library = new LibraryProxy(map, new LibraryImpl()).proxy();
library.onStart();
library.onEnd();
library.onRun();
}
}
interface Library
{
void onStart();
void onEnd();
void onRun();
}
class LibraryImpl
{
public void abc() { System.out.println("Start"); }
public void def() { System.out.println("End"); }
}
class LibraryProxy implements InvocationHandler
{
Map<String, String> map;
Object impl;
public LibraryProxy(Map<String, String> map, Object impl)
{
this.map = map;
this.impl = impl;
}
public Library proxy()
{
return (Library) Proxy.newProxyInstance(Library.class.getClassLoader(),
new Class[] { Library.class }, this);
}
@Override
public Object invoke(Object proxy, Method m, Object[] args) throws Throwable
{
Object res = null;
String name = map.get(m.getName());
if (name == null) {
System.out.println("[" + m.getName() + " is not defined]");
} else {
m = impl.getClass().getMethod(name, m.getParameterTypes());
res = m.invoke(impl, args);
}
System.out.println("super duper");
return res;
}
}
输出:
Start
super duper
End
super duper
[onRun is not defined]
super duper