运用JSP和servlet技术借助sina邮件服务发送邮件问题

我把主要代码贴一下，大家有会的帮帮忙，在这里先谢大家了啊!
1.“sendMailServlet”:
package com.handson.dmeo;

import java.io.File;
import java.io.IOException;
import java.util.HashMap;
import java.util.Iterator;
import java.util.List;
import java.util.Map;

import javax.servlet.ServletConfig;
import javax.servlet.ServletContext;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import org.apache.commons.fileupload.FileItem;
import org.apache.commons.fileupload.disk.DiskFileItemFactory;
import org.apache.commons.fileupload.servlet.ServletFileUpload;
import org.apache.commons.mail.EmailAttachment;
import org.apache.commons.mail.EmailException;
import org.apache.commons.mail.MultiPartEmail;

public class sendMailServlet extends HttpServlet {

private static final long serialVersionUID = 1490670461677124926L;
private String savePath;
private ServletContext sc;
private Map <String, String> parameters = new HashMap <String, String>();

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

public void