由于是菜鸟 呵呵 一直对java的框架struts struts2 spring hibernate 等 从配置文件中取得类信息 就可以创建和操纵类对象 不明所以
一直耿耿于怀 今日 忍无可忍 决定探索
首先： 通过一个类的父接口的Class对象获得方法对象 method , method.invoke(子类对象，args); 能否调用子类对象的方法 答案是：能
如 import java.lang.reflect.*;
public class Reflect1 {
public static void main(String[] args) {
try {
Class clazz = Animal.class;
Method method = clazz.getMethod("cry",new Class[]{});//此处也可以 clazz.getMethod("cry");
Cat cat = new Cat();
method.invoke(cat,new Object[]{});//此处也可以.invoke(cat);
}catch(Exception ex) {ex.printStackTrace();}
}
}
interface Animal {
void cry() ;
}
class Cat implements Animal{
public void cry() {
System.out.println("miao");
}
}
这样的话 框架就明晰了
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下面我特地的实现了一个不事先知道目标类的代理类 感觉以前的一位好朋友说的一句话特别有道理 当时没有理解 现在有些理解了
“你的对象都被人拿走了 不还人为刀俎 我为鱼肉 了” 一句话 是反射的全部 呵呵
import java.lang.reflect.*;
public class ReflectTest {
public static void main(String[] args) {
try {
Person person2 = new Person();
InvocationHandler handler = new Handler(person2) {
public Object invoke(Object proxy,Method method,Object[] args){
Object obj = null;
System.out.println("start");
try {
System.out.println("!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!");
obj = method.invoke(proxy,args);
}catch(Exception ex){System.out.println("error");}
System.out.println("end");
return obj;
}
};
Animal proxy = new PersonProxy(handler);
proxy.setId(5);
System.out.println(proxy.getId());
}catch(Exception ex) {
ex.printStackTrace();
}
}
}
interface Animal {
void setId(int id);
int getId();
}
class Person implements Animal{
private int id;
public void setId(int id) {
this.id = id;
}
public int getId() {
return this.id;
}
}
abstract class Handler implements InvocationHandler {
public Person person;
Handler(Person p) {
this.person = p;
}
public abstract Object invoke(Object proxy,Method method,Object[] args);
}
final class PersonProxy extends Proxy implements Animal {
private InvocationHandler handler;
Method invokemethod = null;
Object target = null;
public PersonProxy(InvocationHandler invokehandler) {
super(invokehandler);
this.handler = invokehandler;
try{
invokemethod = this.handler.getClass().getMethod("invoke",new Class[]
{Object.class,Method.class,Object[].class});
}catch(Exception ex){}
System.out.println(this.handler.getClass());
Field[] fields = this.handler.getClass().getFields();
System.out.println("----------------------------------------");
System.out.println(fields.length);
for(Field f : fields) {
System.out.println(f.getName());
System.out.println(f.getDeclaringClass());
System.out.println(f.getType());
if(f.getType().getInterfaces()[0] == this.getClass().getInterfaces()[0]){
try{
target = f.get(this.handler);
System.out.println("target:"+target);
}catch(Exception ex){}
break;
}else {continue;}
}
}
public void setId(int id) {
Method method = null;
try {
method = this.getClass().getInterfaces()[0].getMethod("setId",int.class);
}catch(Exception ex) {}
try {
// handler.invoke(this,method,id);
invokemethod.invoke(handler,new Object[]{target,method,new Object[]{new Integer(id)}});
}catch(Exception ex){}
}
public int getId() {
Method method = null;
System.out.println("getId1");
try{
method = this.getClass().getInterfaces()[0].getMethod("getId",new Class[]{});
System.out.println("getId:"+method);
}catch(Exception ex){}
Object obj = null;
try{
// obj = handler.invoke(this,method,new Object[]{});
System.out.println("target:"+target);
obj = invokemethod.invoke(handler,new Object[]{target,method,new Object[]{}});
}catch(Exception ex){}
return ((Integer)obj);
}
}