对JavaBean内省的操作

最新推荐文章于 2021-02-16 19:11:09 发布

原创最新推荐文章于 2021-02-16 19:11:09 发布 · 105 阅读

0 ·

CC 4.0 BY-SA版权

文章标签：

#ASP #Java #Bean #Web

JavaSE 专栏收录该内容

4 篇文章

订阅专栏

本文介绍了一种使用Java反射技术动态设置和获取对象属性的方法。通过`PropertyDescriptor`、`Introspector`等类，实现对指定对象的属性进行读写操作。文章提供了具体的代码实例，演示了两种不同的方式来调用对象的getter方法获取属性值。

摘要生成于 C知道，由 DeepSeek-R1 满血版支持，前往体验 >

在这里主要用到了反射技术。用到类如下：

IntroSpector
BeanInfo
PropertyDescriptor
Method

package com.sunrex.demo02;

import java.beans.BeanInfo;
import java.beans.IntrospectionException;
import java.beans.Introspector;
import java.beans.PropertyDescriptor;
import java.lang.reflect.InvocationTargetException;
import java.lang.reflect.Method;

import com.sunrex.demo02.bean.ReflectBean;

public class PropertyDescriptorTest {

	public static void main(String[] args) throws IntrospectionException, ClassNotFoundException, IllegalArgumentException, IllegalAccessException, InvocationTargetException {
		ReflectBean rb = new ReflectBean();
		String usernameProperty = "username";
		String iTextProperty = "iText";
		String AspProperty = "Asp";
		String CPUProperty = "CPU";
		
		//username
		setPropertyValue(rb, usernameProperty, "jianghailiang");
		System.out.println("方法一：" + getPropertyValue(rb, usernameProperty));
		//iText
		setPropertyValue(rb, iTextProperty, "itext pdf");
		System.out.println("方法二：" + getPropertyValue2(rb, iTextProperty));
		//Asp
		setPropertyValue(rb, AspProperty, "web Asp");
		System.out.println("方法二：" + getPropertyValue2(rb, AspProperty));
		//username
		setPropertyValue(rb, CPUProperty, "Computer CPU");
		System.out.println("方法一：" + getPropertyValue(rb, CPUProperty));
		
		
	}
	/**
	 * 为obj对象的属性设置值
	 * @param obj
	 * @param propertyName
	 * @param propertyNameValue
	 */
	public static void setPropertyValue(Object obj, String propertyName, String propertyNameValue){
		try {
			PropertyDescriptor pd = new PropertyDescriptor(propertyName, obj.getClass());
			Method methodSetter = pd.getWriteMethod();
			methodSetter.invoke(obj, propertyNameValue);
		} catch (IntrospectionException e) {
			e.printStackTrace();
		} catch (IllegalArgumentException e) {
			e.printStackTrace();
		} catch (IllegalAccessException e) {
			// TODO Auto-generated catch block
			e.printStackTrace();
		} catch (InvocationTargetException e) {
			// TODO Auto-generated catch block
			e.printStackTrace();
		}
	}

	
	/**
	 * 方法一：调用obj对象的getter
	 */
	public static Object getPropertyValue(Object obj, String propertyName) {
		Object objValue = null;
		try {
			BeanInfo beanInfo = Introspector.getBeanInfo(obj.getClass());
			PropertyDescriptor[] props = beanInfo.getPropertyDescriptors();
			for(PropertyDescriptor pd : props) {
				//如果遍历到得属性名与参数传进来的属性名，相等则返回属性的值
				if(pd.getName().equals(propertyName)) {
					Method methodGetter = pd.getReadMethod();//获取到getter方法
					objValue = methodGetter.invoke(obj);//调用对象obj的getter方法
					break;
				}
			}
		} catch (IntrospectionException e) {
			e.printStackTrace();
		} catch (IllegalArgumentException e) {
			e.printStackTrace();
		} catch (IllegalAccessException e) {
			e.printStackTrace();
		} catch (InvocationTargetException e) {
			e.printStackTrace();
		}
		return objValue;
	}
	
	/**
	 * 方法二：调用obj对象的getter
	 * @param obj
	 * @param propertyName
	 * @return
	 */
	public static Object getPropertyValue2(Object obj, String propertyName) {
		Object objValue = null;
		try {
			PropertyDescriptor pd = 
				new PropertyDescriptor(propertyName, obj.getClass());
			Method methodGetter = pd.getReadMethod();
			objValue = methodGetter.invoke(obj);
		} catch (IntrospectionException e) {
			e.printStackTrace();
		} catch (IllegalArgumentException e) {
			e.printStackTrace();
		} catch (IllegalAccessException e) {
			e.printStackTrace();
		} catch (InvocationTargetException e) {
			e.printStackTrace();
		}
		
		return objValue;
	}
}