学步园

反射就是把java类中各种成分映射成相应的java类

Constructor：

Method：

Field：

Constructor con=Pet.class.getConstructor(Integer.class,String.class);
Pet p=(Pet)con.newInstance(new Integer(456),new String("hello word!"));
System.out.println(p.getName()+p.getId());
Field field=p.getClass().getDeclaredField("id");//获得定义了的字段  ||  getField("id")公有

field.setAccessible(true);//当获得私有字段时需设置
System.out.println(field.get(p));

1、java的反射用法：

①找到类：Class cl = Class.forName("java.util.Date");
②创建对象(要求这个类中含有空参数的构造方法)：Object obj = cl.newInstence();
③根据名称和参数找方法：Method method1 = cl.getMethod("getTime");//如果没有参数不用写第二个参数如果有参数的如：Method method2 = cl.getMethod("setTime",long.class);   

④在某个对象上面执行方法，Object result = method1.invoke(obj);//如果有参数的Object result = method2.invoke(obj,21317362721);

执行的方如果有返回值，将返回值返回，否则返回null 

⑤如果invoke方法的第一个参数为NULL,说明该Method对象对应的是一个静态的方法

public static void test(Object o,String str) throws Exception{
	o=Class.forName("org.han.entity.Pet").newInstance();
	Method method = o.getClass().getMethod(str, new Class[] {String.class});
	method.invoke(o, new Object[]{"hello word!"}); //JDK1.4   ||   JDK1.5 
invoke(o,Object...args)


}

2、封装javaBeen

public static void beenObject(Object object, String[] fields,
			Object[] params) throws Exception {
	Class<?> cl = object.getClass();
	for (int i = 0; i < fields.length; i++) {
		StringBuffer buffer = new StringBuffer();
		Field field = cl.getDeclaredField(fields[i]);
		Class<?> paramType = field.getType();
		buffer.append("set");
		buffer.append(fields[i].substring(0, 1).toUpperCase());
		buffer.append(fields[i].substring(1));
		Method method = cl.getDeclaredMethod(buffer.toString(), paramType);
		method.invoke(object, params[i]);
	}
}

或

	public Object mysetter1(String s,Map<String,Object> k_v) throws Exception{
		Class o = Class.forName(s);
		Object obj = o.newInstance();
		Iterator<String> it = k_v.keySet().iterator();
		Pattern pattern = Pattern.compile("^\\w");
		while(it.hasNext()){
			String pro = it.next();
			Matcher matcher = pattern.matcher(pro);
			String m_name = "set";
			if(matcher.find()){
				m_name += matcher.replaceFirst(matcher.group(0).toUpperCase());
			}
			o.getMethod(m_name, k_v.get(pro).getClass()).invoke(obj, k_v.get(pro));
		}
		return obj;
	}