sayhello.java

整个系统采用MVC开发模式

package lp;

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

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 bean.User;
import bean.UserDAO;;


public class SayHello extends HttpServlet {
	public void doPost(HttpServletRequest request, HttpServletResponse response)
			throws ServletException, IOException {
		//设置生成文件的类型和编码格式
		response.setContentType("text/xml; charset=UTF-8");
		response.setHeader("Cache-Control", "no-cache");
		PrintWriter out = response.getWriter();
		String output = "";
		
		//从数据库中取出用户信息进行比较
		String logout = request.getParameter("logout");
		String name = request.getParameter("name");
		String pswd = request.getParameter("pswd");
		System.out.println("从客户端传过来的参数为: logout = " +  logout + ";name = "+ name + "; pswd = " +pswd); 
		System.out.println("~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~");
		if(logout != null)
		{
			output ="<response>logout</response>";
			HttpSession session = request.getSession();
			session.setAttribute("username", null);
		}
		
		else if(name == "" || pswd == "")
		{
			output ="<response>failing</response>";
		}
		else
		{
			UserDAO userDAO = new UserDAO();
			String sql = "select * from user where username = '" + name + "'";
			
			System.out.println("执行SQL语句为: "+ sql);
			
			try {
				ArrayList<User> result = userDAO.userSelect(sql);
				
				System.out.println("执行SQL语句结果为: "+ result.toString()); 
				
				if(result != null)
				{
					String realpswd = result.get(0).getPassword();
					System.out.println("查到的密码为: "+ realpswd); 
					
					//处理接收到的参数，生成响应的XML文档
						if( !realpswd.equals(pswd))
						{
							 output ="<response>failing</response>";
						}
						else 
						{
							output ="<response>"+request.getParameter("name")+"</response>";
							HttpSession session = request.getSession(true);
							session.setAttribute("username", name);
						}	
				}
			} catch (Exception e) {
				// TODO Auto-generated catch block
				e.printStackTrace();
			}
		}
		out.println(output);
		System.out.println("servlet的处理结果为: "+ output); 
		out.close();
	}
	public void doGet(HttpServletRequest request, HttpServletResponse response)
			throws ServletException, IOException {
		doPost(request, response);
	}
}