querymailservlet.java

运用JSP/servlet/JavaBean 技术

package com.lovo.controller;

import java.io.IOException;
import java.io.PrintWriter;
import java.util.List;

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

import com.lovo.po.Mail;
import com.lovo.po.MailVo;
import com.lovo.service.IMailBo;
import com.lovo.service.IMailBoImpl;

public class QueryMailServlet extends HttpServlet
{
	/** mailBo接口，用于业务方法调用 */
	private IMailBo mailBo = new IMailBoImpl();

	/**
	 * The doGet method of the servlet. <br>
	 *
	 * This method is called when a form has its tag value method equals to get.
	 * 
	 * @param request the request send by the client to the server
	 * @param response the response send by the server to the client
	 * @throws ServletException if an error occurred
	 * @throws IOException if an error occurred
	 */
	public void doGet(HttpServletRequest request, HttpServletResponse response)
			throws ServletException, IOException
	{
		/** 设置响应文件类型及字符集编码 */
		response.setContentType("text/xml; charset=utf-8");
		/** 设置响应头，让浏览器不缓存信息 */
		response.setHeader("Cache-control", "no-cache");
		/** 获取请求查询的用户的userId */
		int userId = Integer.parseInt(request.getParameter("userId"));
		/** 获取请求查询的邮件的类型 */
		int mailStatus = Integer.parseInt(request.getParameter("mailStatus"));
		/** 查询信件 */
		List<MailVo> mailList = mailBo.queryMail(userId, mailStatus);
		/** 将查到的信件添加到session以便后面操作 */
		HttpSession session = request.getSession();
		switch(mailStatus)
		{
		case Mail.DRAFT_MAIL: session.setAttribute("draftMailList", mailList);
		break;
		case Mail.SENDED_MAIL: session.setAttribute("sendedMailList", mailList);
		break;
		case Mail.DELETED_MAIL: session.setAttribute("deletedMailList", mailList);
		break;
		}
		boolean needCreateXML  = true;//标志是否需要构建xml
		int mailLength = mailList == null ? 0 : mailList.size();//信件数量
//		System.out.println("请求查询的帐号id=" + userId);
//		System.out.println("请求查询的邮件status=" + mailStatus);
//		System.out.println("查询得到的邮件数量=" + mailLength);
		/**
		 * 判断是否需要构建xml，如果没有信件则无需构建xml
		 */
		if(mailLength == 0)
		{
			needCreateXML = false;
		}
		/** 无信息返回 */
		if(needCreateXML == false)
		{
			return;
		}
//		System.out.println("needCreateXML=" + needCreateXML);
		/** 获得输出流 */
		PrintWriter writer = response.getWriter();
		/** 构建xml */
		writer.println("<?xml version='1.0' encoding='UTF-8'?>");
		writer.println("<mail>");
		String who = "";//存收件人，或发件人帐号
		String mailTitle = "";//存邮件主题
		int mailId = 0;//存邮件Id
		MailVo mailVo = null;//存当前邮件
		/**
		 * 遍历mailList获得要返回页面的信息并构建xml
		 */
		for(int i = 0; i < mailLength; i++)
		{
			/** 获得当前邮件 */
			mailVo = mailList.get(i);
			/**
			 * 如果要查询的是已删除信件，那么获得它的发件人帐号，否则获得收件人帐号
			 */
			if(mailStatus == Mail.DELETED_MAIL)
			{
				/** 要查的是已删除信件，获得发件人帐号 */
				who = mailVo.getWhoSendedName();
			}
			else
			{
				/** 要查的是草稿信件或已发送信件，获得收件人帐号 */
				who = mailVo.getWhoReceiveName();
			}
			/** 获得信件主题 */
			mailTitle = mailVo.getMailTitle();
			/** 获取信件主键mailId */
			mailId = mailVo.getMailId();
			/** 把获得的信息构建成xml */
			writer.println("<letter>");
			writer.println("<who>" + who + "</who>");
			writer.println("<mailtitle>" + mailTitle + "</mailtitle>");
			writer.println("<mailid>" + mailId + "</mailid>");
			writer.println("</letter>");
		}
		writer.println("</mail>");
		writer.close();
	}

	/**
	 * The doPost method of the servlet. <br>
	 *
	 * This method is called when a form has its tag value method equals to post.
	 * 
	 * @param request the request send by the client to the server
	 * @param response the response send by the server to the client
	 * @throws ServletException if an error occurred
	 * @throws IOException if an error occurred
	 */
	public void doPost(HttpServletRequest request, HttpServletResponse response)
			throws ServletException, IOException
	{
		doGet(request, response);
	}

}