Struts ActionFrom 原理 實現

原理

上圖： 

 

 

 

 

簡單實現：

package com.vili.wems.web.webservice.ma.information;
import java.beans.IntrospectionException;
import java.beans.Introspector;
import java.beans.PropertyDescriptor;
import java.lang.reflect.InvocationTargetException;
import java.util.Enumeration;

import javax.servlet.http.HttpServletRequest;

import org.apache.commons.beanutils.BeanUtils;
import org.apache.struts.action.ActionForm;

public class FormUtils {

  public static void fillForm(HttpServletRequest request,String formFullClassName,String formName){
  try {
   //1.利用JAVA的反射機制得到當前傳進來的BEAN對象
   ActionForm form =(ActionForm)Class.forName(formFullClassName).newInstance();
   PropertyDescriptor[] properties = Introspector.getBeanInfo(form.getClass()).getPropertyDescriptors();

   //2.取得頁面中的傳遞元素
   Enumeration formParameters = request.getParameterNames();

   //3.遍歷元素
   while(formParameters.hasMoreElements()){
    String parameterName = (String)formParameters.nextElement();

    for(PropertyDescriptor property:properties){
     String properyName = property.getName();

     //4.比較兩個對象的名稱是否相等,若是相等則填充FORM
     if(parameterName.equals(properyName))
     {
      String propertyValue = request.getParameter(properyName);
      BeanUtils.setProperty(form, properyName, propertyValue);
     }
    }

   }

   //5.保存填充好的對象
   request.getSession().setAttribute(formName, form);
  } catch (InstantiationException e) {
   // TODO Auto-generated catch block
   e.printStackTrace();
  } catch (IllegalAccessException e) {
   // TODO Auto-generated catch block
   e.printStackTrace();
  } catch (ClassNotFoundException e) {
   // TODO Auto-generated catch block
   e.printStackTrace();
  } catch (IntrospectionException e) {
   // TODO Auto-generated catch block
   e.printStackTrace();
  } catch (InvocationTargetException e) {
   // TODO Auto-generated catch block
   e.printStackTrace();
  }

  }

}