public static BeanInfo getBeanInfo(Class<?> beanClass)
? ? ? ? throws IntrospectionException
? ? {
? ? ? ? if (!ReflectUtil.isPackageAccessible(beanClass)) {
? ? ? ? ? ? return (new Introspector(beanClass, null, USE_ALL_BEANINFO)).getBeanInfo();
? ? ? ? }
? ? ? ? ThreadGroupContext context = ThreadGroupContext.getContext();
? ? ? ? BeanInfo beanInfo;
? ? ? ? synchronized (declaredMethodCache) {
? ? ? ? ? ? beanInfo = context.getBeanInfo(beanClass);
? ? ? ? }
? ? ? ? if (beanInfo == null) {
? ? ? ? ? ? beanInfo = new Introspector(beanClass, null, USE_ALL_BEANINFO).getBeanInfo();
? ? ? ? ? ? synchronized (declaredMethodCache) {
? ? ? ? ? ? ? ? context.putBeanInfo(beanClass, beanInfo);
? ? ? ? ? ? }
? ? ? ? }
? ? ? ? return beanInfo;
? ? }

final class ThreadGroupContext {
//WeakIdentityMap 判斷key是否重復(fù)只判斷hash是否相等，不調(diào)用equals
? ? private static final WeakIdentityMap<ThreadGroupContext> contexts = new WeakIdentityMap<ThreadGroupContext>() {
? ? ? ? protected ThreadGroupContext create(Object key) {
? ? ? ? ? ? return new ThreadGroupContext();
? ? ? ? }
? ? };

? ? /**
? ? ?* Returns the appropriate {@code ThreadGroupContext} for the caller,
? ? ?* as determined by its {@code ThreadGroup}.
? ? ?*
? ? ?* @return ?the application-dependent context
? ? ?*/
? ? static ThreadGroupContext getContext() {
? ? ? ? return contexts.get(Thread.currentThread().getThreadGroup());
? ? }
。
。
。
}

/**
?* Listener that flushes the JDK's {@link java.beans.Introspector JavaBeans Introspector}
?* cache on web app shutdown. Register this listener in your {@code web.xml} to
?* guarantee proper release of the web application class loader and its loaded classes.
?*
?* <p><b>If the JavaBeans Introspector has been used to analyze application classes,
?* the system-level Introspector cache will hold a hard reference to those classes.
?* Consequently, those classes and the web application class loader will not be
?* garbage-collected on web app shutdown!</b> This listener performs proper cleanup,
?* to allow for garbage collection to take effect.
?*
?* <p>Unfortunately, the only way to clean up the Introspector is to flush
?* the entire cache, as there is no way to specifically determine the
?* application's classes referenced there. This will remove cached
?* introspection results for all other applications in the server too.
?*
?* <p>Note that this listener is <i>not</i> necessary when using Spring's beans
?* infrastructure within the application, as Spring's own introspection results
?* cache will immediately flush an analyzed class from the JavaBeans Introspector
?* cache and only hold a cache within the application's own ClassLoader.
?*
?* <b>Although Spring itself does not create JDK Introspector leaks, note that this
?* listener should nevertheless be used in scenarios where the Spring framework classes
?* themselves reside in a 'common' ClassLoader (such as the system ClassLoader).</b>
?* In such a scenario, this listener will properly clean up Spring's introspection cache.
?*
?* <p>Application classes hardly ever need to use the JavaBeans Introspector
?* directly, so are normally not the cause of Introspector resource leaks.
?* Rather, many libraries and frameworks do not clean up the Introspector:
?* e.g. Struts and Quartz.
?*
?* <p>Note that a single such Introspector leak will cause the entire web
?* app class loader to not get garbage collected! This has the consequence that
?* you will see all the application's static class resources (like singletons)
?* around after web app shutdown, which is not the fault of those classes!
?*
?* <p><b>This listener should be registered as the first one in {@code web.xml},
?* before any application listeners such as Spring's ContextLoaderListener.</b>
?* This allows the listener to take full effect at the right time of the lifecycle.

public class IntrospectorCleanupListener implements ServletContextListener {

? ? @Override
? ? public void contextInitialized(ServletContextEvent event) {
? ? ? ? CachedIntrospectionResults.acceptClassLoader(Thread.currentThread().getContextClassLoader());
? ? }

? ? @Override
? ? public void contextDestroyed(ServletContextEvent event) {
? ? ? ? CachedIntrospectionResults.clearClassLoader(Thread.currentThread().getContextClassLoader());
? ? ? ? Introspector.flushCaches();
? ? }
}

CachedIntrospectionResults.acceptClassLoader(Thread.currentThread().getContextClassLoader())

package com.jasun.test;
 
 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 org.apache.commons.beanutils.BeanUtils;
 
 
 publicclass IntrospectorTest {
 
publi 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
 
           //使用BeanUtils工具包操作JavaBean
        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);
    }
    
/**
     * 設(shè)置屬性
     * 
     * @param clazz 對象名
     * @param propertyName 屬性名
     * @param value 屬性值
*/
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;
            }
        }
    }
    
/**
     * 獲取屬性
     * 
     * @param clazz 對象名
     * @param propertyName 屬性名
     * @return
     * @throws IntrospectionException 
     * @throws InvocationTargetException 
     * @throws IllegalAccessException 
     * @throws IllegalArgumentException 
*/
private static Object getProperty(Object clazz, String propertyName) 
throws IntrospectionException, IllegalArgumentException, IllegalAccessException, InvocationTargetException{
//方法一
 /*PropertyDescriptor pd=new PropertyDescriptor(propertyName, clazz.getClass());
        Method methodGet=pd.getReadMethod();
        return methodGet.invoke(clazz);*/
        
//方法二
         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;
    }
    
}

package com.ljq.test;
 
publicclass 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;
    }
 
publicvoid setUserName(String userName) {
    this.userName = userName;
    }
 
public String getPwd() {
    return pwd;
    }
 
publicvoid setPwd(String pwd) {
    this.pwd = pwd;
    }
 
}

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 {
 
 private String name;
 
 private int age;
 
 /**
  * @return the age
  */
 public int getAge() {
  return age;
 }
 
 /**
  * @param age the age to set
  */
 public void setAge(int age) {
  this.age = age;
 }
 
 /**
  * @return the name
  */
 public String getName() {
  return name;
 }
 
 /**
  * @param name the name to set
  */
 public void setName(String name) {
  this.name = name;
 }
 
}
 
public class IntrospectorTest {
 
 /**
  * @param args
  * @throws IntrospectionException
  */
 public static void main(String[] args) throws IntrospectionException {
  // TODO Auto-generated method stub
  BeanInfo beanInfo = Introspector.getBeanInfo(Person.class);
  
  System.out.println("BeanDescriptor===========================================");
  BeanDescriptor beanDesc = beanInfo.getBeanDescriptor();
  Class cls = beanDesc.getBeanClass();
  System.out.println(cls.getName());
  
  System.out.println("MethodDescriptor===========================================");
  MethodDescriptor[] methodDescs = beanInfo.getMethodDescriptors();
  for (int i = 0; i < methodDescs.length; i++) {
   Method method = methodDescs[i].getMethod();
   System.out.println(method.getName());
  }
  
  System.out.println("PropertyDescriptor===========================================");
  PropertyDescriptor[] propDescs = beanInfo.getPropertyDescriptors();
  for (int i = 0; i < propDescs.length; i++) {
   Method methodR = propDescs[i].getReadMethod();
   if (methodR != null) {
    System.out.println(methodR.getName());
   }
   Method methodW = propDescs[i].getWriteMethod();
   if (methodW != null) {
    System.out.println(methodW.getName());
   }
  }
 }
 
}