表单数据封装

package cn.itcast.servlet;

import java.beans.BeanInfo;
import java.beans.Introspector;
import java.beans.PropertyDescriptor;
import java.io.IOException;
import java.lang.reflect.Method;
import java.util.Map;

import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

import cn.itcast.domain.Person;

/**
* 通过内省实现 jsp:setProperty 相同效果
*
*
*/
public class IntrospectorServlet extends HttpServlet {

   public void doGet(HttpServletRequest request, HttpServletResponse response)
           throws ServletException, IOException {
       // 将请求参数，自动封装 JavaBean对象中
       request.setCharacterEncoding("utf-8");
       // 封装目标对象
       Person person = new Person();
       // 请求参数
       Map<String, String[]> parameterMap = request.getParameterMap();

       try {
           setProperty(person, parameterMap);
       } catch (Exception e) {
           e.printStackTrace();
       }

       System.out.println(person.getName());
       System.out.println(person.getAge());
   }

   // 将请求参数中 map的key 与传入对象属性名称比较，如果一致，将参数的值赋值给对象属性
   private void setProperty(Object obj, Map<String, String[]> parameterMap)
           throws Exception {
       // 内省获得BeanInfo
       BeanInfo beanInfo = Introspector.getBeanInfo(obj.getClass());
       // 获得所有属性描述器
       PropertyDescriptor[] propertyDescriptors = beanInfo
               .getPropertyDescriptors();
       // 遍历所有属性
       for (PropertyDescriptor propertyDescriptor : propertyDescriptors) {
           // 获得属性名称
           String propertyName = propertyDescriptor.getName();
           // 判断属性在map中是否存在对应值
           if (parameterMap.containsKey(propertyName)) {
               // 获得map参数值
               String value = parameterMap.get(propertyName)[0];
               // 获得属性写方法
               Method setter = propertyDescriptor.getWriteMethod();
               // 将value 写到属性中
               setter.invoke(obj, value);
           }
       }
   }

   public void doPost(HttpServletRequest request, HttpServletResponse response)
           throws ServletException, IOException {
       doGet(request, response);
   }

}

package cn.itcast.jsp;

import java.beans.BeanInfo;
import java.beans.Introspector;
import java.beans.PropertyDescriptor;
import java.io.IOException;
import java.lang.reflect.Method;
import java.util.Map;

import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

public class PackageServlet extends HttpServlet {

   public void doGet(HttpServletRequest request, HttpServletResponse response)
           throws ServletException, IOException {
       /* //传统方法封装数据
       //解决向页面输出中文乱码问题,设置浏览器打开页面时采用的编码格式；设置页面response缓冲区乱码问题
       response.setHeader("content-type", "text/html;charset=UTF-8");
       response.setCharacterEncoding("UTF-8");
       //获取请求中的数据
       String name = request.getParameter("usename");
       String password = request.getParameter("password");
       //封装数据
       Use use = new Use();
       use.setUsename(name);
       use.setPassword(password);
       //想页面输出
       response.getWriter().write(use.getUsename()+ use.getPassword());*/
       //传统方法封装数据
       //获取表单数据
       Map<String,String[]> map = request.getParameterMap();
       //创建对象
       Use use = new Use();
       //自己编写封装数据方法
       try {
           populate(map,use);
       } catch (Exception e) {
           // TODO Auto-generated catch block
           e.printStackTrace();
       }
       //完成数据封装，控制台输出显示
       System.out.println(use.getUsename() + use.getPassword());
   }
   /**
   * 完成数据封装
   * @param map
   * @param use
   * @throws Exception
   */
   private void populate(Map<String, String[]> map, Use use) throws Exception {
       //利用内省；通过Introspector的静态方法获取类信息
       BeanInfo info = Introspector.getBeanInfo(use.getClass());
       //获取属性描述 BeanInfo
       PropertyDescriptor[] pdfs = info.getPropertyDescriptors();
       //循环遍历，获取属性名称
       for(PropertyDescriptor pdf: pdfs) {
           //获取属性名称
           String name = pdf.getName();
           //判断，封装数据
           if(map.containsKey(name)) {
               //获取属性的写方法
               Method m = pdf.getWriteMethod();
               //执行
               m.invoke(use, map.get(name)[0]);
           }
       }
   }

   public void doPost(HttpServletRequest request, HttpServletResponse response)
           throws ServletException, IOException {
       doGet(request, response);
   }

}

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