Introspector与反射
来源:互联网 发布:java 2d游戏编程 编辑:程序博客网 时间:2024/06/16 21:00
一》:Introspector类介绍
Introspector与反射类似,主要是对Java Bean属性、方法等的一种处理方法.
1. Class Diagram
2. 实例
package com.siyuan.jdktest;
import java.beans.BeanDescriptor;
import java.beans.BeanInfo;
import java.beans.IntrospectionException;
import java.beans.Introspector;
import java.beans.MethodDescriptor;
import java.beans.PropertyDescriptor;
import java.lang.reflect.Method;
class Person {
}
public class IntrospectorTest {
}
3. 运行结果
BeanDescriptor===========================================
com.siyuan.jdktest.Person
MethodDescriptor===========================================
hashCode
setAge
equals
wait
wait
notify
getClass
toString
getAge
notifyAll
setName
wait
getName
PropertyDescriptor===========================================
getAge
setAge
getClass
getName
setName
二》:JAVA反射机制
JAVA反射机制是在运行状态中,对于任意一个类,都能够知道这个类的所有属性和方法;对于任意一个对象,都能够调用它的任意一个方法;这种动态获取的信息以及动态调用对象的方法的功能称为java语言的反射机制。
Java反射机制主要提供了以下功能:
1.
- public
throwsObject getProperty(Object owner, String fieldName) Exception { -
Class ownerClass = owner.getClass(); -
-
Field field = ownerClass.getField(fieldName); -
-
Object property = field.get(owner); -
-
returnproperty; - }
public Object getProperty(Object owner, String fieldName) throws Exception (
Class ownerClass = owner.getClass();
Field field = ownerClass.getField(fieldName);
Object property = field.get(owner);
return property;
}
Class
Field
Object
2.
- public
Object getStaticProperty(String className, String fieldName) -
throwsException { -
Class ownerClass = Class.forName(className); -
-
Field field = ownerClass.getField(fieldName); -
-
Object property = field.get(ownerClass); -
-
returnproperty; - }
public Object getStaticProperty(String className, String fieldName) throws Exception { Class ownerClass = Class.forName(className); Field field = ownerClass.getField(fieldName); Object property = field.get(ownerClass); return property; }
Class
Field
Object
3.
- public
throwsObject invokeMethod(Object owner, String methodName, Object[] args) Exception { -
-
Class ownerClass = owner.getClass(); -
-
newClass[] argsClass = Class[args.length]; -
-
for int( 0,i = j = args.length; i < j; i++) { -
argsClass[i] = args[i].getClass(); -
} -
-
Method method = ownerClass.getMethod(methodName,argsClass); -
-
returnmethod.invoke(owner, args); - }
public Object invokeMethod(Object owner, String methodName, Object[] args) throws Exception { Class ownerClass = owner.getClass(); Class[] argsClass = new Class[args.length]; for (int i = 0, j = args.length; i < j; i++) { argsClass[i] = args[i].getClass(); } Method method = ownerClass.getMethod(methodName,argsClass); return method.invoke(owner, args); }
Class
5~9行:配置参数的Class数组,作为寻找Method的条件。
Method
method.invoke(owner,
4.
- public
Object invokeStaticMethod(String className, String methodName, -
throwsObject[] args) Exception { -
Class ownerClass = Class.forName(className); -
-
newClass[] argsClass = Class[args.length]; -
-
for int( 0,i = j = args.length; i < j; i++) { -
argsClass[i] = args[i].getClass(); -
} -
-
Method method = ownerClass.getMethod(methodName,argsClass); -
-
return null,method.invoke( args); -
}
public Object invokeStaticMethod(String className, String methodName, Object[] args) throws Exception { Class ownerClass = Class.forName(className); Class[] argsClass = new Class[args.length]; for (int i = 0, j = args.length; i < j; i++) { argsClass[i] = args[i].getClass(); } Method method = ownerClass.getMethod(methodName,argsClass); return method.invoke(null, args); }
基本的原理和实例3相同,不同点是最后一行,invoke的一个参数是null,因为这是静态方法,不需要借助实例运行。
5.
- public
throwsObject newInstance(String className, Object[] args) Exception { -
Class newoneClass = Class.forName(className); -
-
newClass[] argsClass = Class[args.length]; -
-
for int( 0,i = j = args.length; i < j; i++) { -
argsClass[i] = args[i].getClass(); -
} -
-
Constructor cons = newoneClass.getConstructor(argsClass); -
-
returncons.newInstance(args); -
- }
public Object newInstance(String className, Object[] args) throws Exception { Class newoneClass = Class.forName(className); Class[] argsClass = new Class[args.length]; for (int i = 0, j = args.length; i < j; i++) { argsClass[i] = args[i].getClass(); } Constructor cons = newoneClass.getConstructor(argsClass); return cons.newInstance(args); }
这里说的方法是执行带参数的构造函数来新建实例的方法。如果不需要参数,可以直接使用newoneClass.newInstance()来实现。
Class
第5~第9行:得到参数的Class数组。
Constructor
cons.newInstance(args):新建实例。
6.
- public
booleanisInstance(Object obj, Class cls) { -
returncls.isInstance(obj); - }
public boolean isInstance(Object obj, Class cls) { return cls.isInstance(obj); }
7.
- public
intObject getByArray(Object array, index) { -
returnArray.get(array,index); - }
public Object getByArray(Object array, int index) { return Array.get(array,index); }
- Introspector与反射
- Introspector与反射
- java反射与内省(Introspector)
- Java反射与内省(Introspector)
- Java反射与内省(Introspector)
- Java反射与内省(Introspector)
- Java反射与内省(Introspector)
- Java反射与内省(Introspector)
- Java反射与内省(Introspector)
- Java反射与内省(Introspector)
- Java反射(Reflection)与内省(Introspector)
- Java 内省(Introspector)与反射(Reflect)
- 【转】JAVA的内省(introspector)与反射(reflection)
- JAVA的内省(introspector)与反射(reflection)
- JAVA的内省(introspector)与反射(reflection)
- JAVA 的内省(introspector)与反射(reflection)
- JAVA 的内省(introspector)与反射(reflection)
- JAVA的反射(reflection)与 内省(introspector)
- javascript--正则表达式
- 剑指offer:(4)树:重建二叉树
- 微信服务号报警
- MessageFormat用法一
- PHP自动发送邮件
- Introspector与反射
- AJAX --- 一种创建交互式网页应用的网页开发技术
- 新的港湾
- JSON --- 一种轻量级的数据交换格式
- 动态类型语言&静态类型语言
- forward与redirect区别
- npm --- Node.js包管理器
- hashcode与equals
- java泛型的用法和方法