import java.beans.BeanInfo;
import java.beans.IntrospectionException;
import java.beans.Introspector;
import java.beans.PropertyDescriptor;
import java.io.IOException;
import java.io.InputStream;
import java.lang.reflect.InvocationTargetException;
import java.lang.reflect.Method;
import java.util.Properties;public class Demo {public static void main(String[] args) {try {Config bean = ((Config) BeanFactory.getBean("bean.name"));System.out.println(bean);} catch (ClassNotFoundException e) {e.printStackTrace();} catch (IllegalAccessException e) {e.printStackTrace();} catch (InstantiationException e) {e.printStackTrace();}}
}
class Config{private String username;private String password;private String url;public String getUsername() {return username;}public void setUsername(String username) {this.username = username;}public String getPassword() {return password;}public void setPassword(String password) {this.password = password;}public String getUrl() {return url;}public void setUrl(String url) {this.url = url;}@Overridepublic String toString() {return "Config{" +"username='" + username + '\'' +", password='" + password + '\'' +", url='" + url + '\'' +'}';}
}
class BeanFactory{private static Properties p = new Properties();//使用静态代码块读取配置文件static {InputStream inStream = Thread.currentThread().getContextClassLoader().getResourceAsStream("com\\first\\conf.properties");try {p.load(inStream);} catch (IOException e) {e.printStackTrace();}}public static Object getBean(String name) throws ClassNotFoundException, IllegalAccessException, InstantiationException {String beanName = p.getProperty(name);//获取类信息Class<?> aClass = Class.forName(beanName);//实例化一个bean对象Object bean = aClass.newInstance();try {//通过类信息，获取javaBean的描述信息，所以 内省 基于 反射 进行 BeanInfo beanInfo = Introspector.getBeanInfo(aClass);//通过描述信息，获取该类的所有属性描述器,该类必须将属性字段设置get和set方法;（才能获取）PropertyDescriptor[] propertyDescriptors = beanInfo.getPropertyDescriptors();for (int i = 0; i < propertyDescriptors.length; i++) {String propertyName = propertyDescriptors[i].getName();Method writeMethod = propertyDescriptors[i].getWriteMethod();if ("username".equals(propertyName)){//相当于调用了属性的set方法writeMethod.invoke(bean,p.getProperty("user.name"));}else if("password".equals(propertyName)){writeMethod.invoke(bean,p.getProperty("user.password"));}else if("url".equals(propertyName)){writeMethod.invoke(bean,p.getProperty("url"));}}} catch (IntrospectionException e) {e.printStackTrace();} catch (InvocationTargetException e) {e.printStackTrace();}return bean;}
}

bean.name=com.first.Config
user.name=admin
user.password=admin
url=http://www.baidu.com