Introspector的使用

最新推荐文章于 2022-09-21 16:00:31 发布

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本文介绍了一种通过Java反射机制操作JavaBean属性的方法，利用Introspector获取Bean的属性描述符，进而实现对指定属性的读取和修改。该方法适用于需要动态处理对象属性的场景。

根据属性名和类Class得到数据

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;

/**
 * Introspector的使用
 * @author 流浪鱼
 *
 */
public class IntrospectorDemo {

	/**
	 * @param args
	 */
	public static void main(String[] args) throws IllegalArgumentException,  IntrospectionException, IllegalAccessException, InvocationTargetException, NoSuchMethodException { 
		 UserInfo userInfo=new UserInfo("zhangsan", "123456"); 
		 String propertyName="userName"; 
		 Object retVal=getProperty(userInfo, propertyName);
		 System.out.println("retVal="+retVal);//retVal=zhangsan 
		 Object value="abc"; 
		 setProperty(userInfo, propertyName, value);
		 retVal=getProperty(userInfo, propertyName);
		 System.out.println("retVal="+retVal); //retVal=abc 27
		/*使用BeanUtils工具包操作JavaBean org.apache.commons.beanutils.BeanUtils
		String userName=BeanUtils.getProperty(userInfo, propertyName); 
		System.out.println("userName="+userName);
		BeanUtils.setProperty(userInfo, propertyName, "linjiqin"); 
		userName=BeanUtils.getProperty(userInfo, propertyName);
		System.out.println("userName="+userName); 
		*/
	}
	
	/**
	 * 
	 * @param clazz
	 * @param propertyName
	 * @return
	 * @throws IntrospectionException 
	 * @throws InvocationTargetException 
	 * @throws IllegalAccessException 
	 * @throws IllegalArgumentException 
	 */
	private static Object getProperty(Object clazz, String propertyName) throws IntrospectionException, IllegalArgumentException, IllegalAccessException, InvocationTargetException{
		/*方法1
		PropertyDescriptor pd=new PropertyDescriptor(propertyName, clazz.getClass());
		Method methodGet=pd.getReadMethod();
		return methodGet.invoke(clazz);
		*/
		 Object retVal=null;
		 BeanInfo beanInfo=Introspector.getBeanInfo(clazz.getClass());
		 PropertyDescriptor[] pds=beanInfo.getPropertyDescriptors();
		 for(PropertyDescriptor pd:pds){
			 if(propertyName.equals(pd.getName())){
				 Method methodGet=pd.getReadMethod();
				 retVal=methodGet.invoke(clazz);
				 break;
			}
		}
		return retVal;
		
	}
	
	/**
	 		* 设置属性
	      * 
	      * @param clazz 对象名
	      * @param propertyName 属性名
	      * @param value 属性值
	      */
	     private static void setProperty(Object clazz, String propertyName, Object value) 
	            throws IntrospectionException,IllegalAccessException, InvocationTargetException{
	         //方法一
	         /*PropertyDescriptor pd=new PropertyDescriptor(propertyName, clazz.getClass());
	         Method methodSet=pd.getWriteMethod();
	         methodSet.invoke(clazz, value);*/
	         
	         //方法二
	          BeanInfo beanInfo=Introspector.getBeanInfo(clazz.getClass());
	         PropertyDescriptor[] pds=beanInfo.getPropertyDescriptors();
	         for(PropertyDescriptor pd:pds){
	             if(propertyName.equals(pd.getName())){
	                 Method methodSet=pd.getWriteMethod();
	                 methodSet.invoke(clazz, value);
	                 break;
	             }
	         }
	     }
	

}

/**
 * IntrospectorDemo测试需要的JavaBean
 * @author 流浪鱼
 *
 */
public class UserInfo {
	private String userName;
	private String pwd;
	
	
	public UserInfo(String userName, String pwd) {
		super();
		this.userName = userName;
		this.pwd = pwd;
	}
	public String getUserName() {
		return userName;
	}
	public void setUserName(String userName) {
		this.userName = userName;
	}
	public String getPwd() {
		return pwd;
	}
	public void setPwd(String pwd) {
		this.pwd = pwd;
	}
	
}