基于Servlet、JSP、JDBC、MySQL的登录模块(含过滤器的使用和配置)

接前文的注册模块，本篇是登录模块。主要包括登录主界面，和登录相关编写的LoginAction、LoginDao和LoginService。以及配置的Filter。下面按逻辑顺序记录详细过程和代码:

一、在前文的index目录点击登录按钮后，通过javascript跳转至LoginAction。

<script type="text/javascript">
function login(){
var th = document.form1;
if(th.username.value==""){
alert("用户名不能为空！！");
th.username.focus();
return ;
}
if(th.pswd.value==""){
alert("密码不能为空！！");
th.pswd.focus();
return ;
}
th.action="<%=path%>/servlet/LoginAction";
th.submit();
}
</script>

LogingAction.java

package com.product.login.action;
import java.io.IOException;
import java.io.PrintWriter;
import java.util.ArrayList;
import java.util.List;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import com.product.login.dao.LoginDao;
import com.product.login.service.LoginService;
public class LoginAction extends HttpServlet {
private LoginService service;
/**
* Constructor of the object.
*/
public LoginAction() {
super();
}
/**
* Destruction of the servlet. <br>
*/
public void destroy() {
super.destroy(); // Just puts "destroy" string in log
// Put your code here
}
/**
* 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 {
this.doPost(request, response);
}
/**
* 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 {
request.setCharacterEncoding("utf-8");
response.setContentType("text/html; charset=utf-8");
String path = request.getContextPath();
PrintWriter out = response.getWriter();
String username = request.getParameter("username");
String pswd = request.getParameter("pswd");
List<Object> params = new ArrayList<Object>();
params.add(username);
params.add(pswd);
boolean flag = service.login(params);
out.println("username = " + username);
out.println("pswd = " + pswd);
if(flag){
request.getSession().setAttribute("username", username);
response.sendRedirect(path + "/main.jsp");
}else{
out.println("登录失败 ");
}
out.flush();
out.close();
}
/**
* Initialization of the servlet. <br>
*
* @throws ServletException if an error occurs
*/
public void init() throws ServletException {
// Put your code here
service = new LoginDao();
}
}

        if(flag){
        request.getSession().setAttribute("username", username);
        response.sendRedirect(path + "/main.jsp");
        }

LoginService.java

package com.product.login.service;
import java.util.List;
public interface LoginService {
public boolean login(List<Object> params);
}

package com.product.login.dao;
import java.util.List;
import java.util.Map;
import com.product.jdbc.dbutil.JdbcUtils;
import com.product.login.service.LoginService;
public class LoginDao implements LoginService {
private JdbcUtils jdbcUtils;
public LoginDao(){
jdbcUtils = new JdbcUtils();
}
@Override
public boolean login(List<Object> params) {
// TODO Auto-generated method stub
boolean flag = false;
String sql = "select * from userinfo where username = ? and pswd = ?";
try{
jdbcUtils.getConnection();
Map<String, Object> map = jdbcUtils.findSimpleResult(sql, params);
flag = (!map.isEmpty()) ? true : false;
}catch(Exception e){
e.printStackTrace();
}finally{
jdbcUtils.releaseConn();
}
return flag;
}
}

main.jsp代码如下:

<%@ page language="java" import="java.util.*" pageEncoding="utf-8"%>
<%
String path = request.getContextPath();
%>
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Frameset//EN" "http://www.w3c.org/TR/1999/REC-html401-19991224/frameset.dtd">
<HTML xmlns="http://www.w3.org/1999/xhtml">
<HEAD>
<TITLE>后台管理系统</TITLE>
<META http-equiv=content-type content="text/html; charset=utf-8">
</HEAD>
<FRAMESET rows=105,* cols="*" bordercolor="04376E">
<FRAME name=ads marginWidth=0 marginHeight=0 src="<%=path%>/top.jsp"
frameBorder=0 noResize scrolling=no longDesc="">
<FRAMESET rows=675 cols=198,* frameborder="yes">
<FRAME name=list marginWidth=0 marginHeight=0 src="<%=path%>/left.jsp"
frameBorder=0 noResize scrolling=yes longDesc="">
<FRAME name=main marginWidth=0 marginHeight=0
src="<%=path%>/postdata.jsp" frameBorder=0 scrolling=yes longDesc="">
</FRAMESET>
<NOFRAMES>
</NOFRAMES>
</FRAMESET>
<body>
</body>
</HTML>

在index.jsp里增加了底部的jsp，使用的是iframe：

<IFRAME name="top" align="default" src="<%=path %>/bottom.jsp"
frameBorder=0 width=100% scrolling=no height=88>
<h1>&nbsp;</h1>
</IFRAME>

正好可以对比其区别，详见链接1 链接2 链接3  iframe使用时常常要和target配合使用，参见  链接1 链接2

top.jsp left.jsp postdata.jsp这三个的代码就不贴了，在源码里。

四：filter的使用

起因是浏览器直接输入http://localhost:8080/xianfengYan/main.jsp 这时还没有登录，没有验证，我们不希望游客访问这个界面，因此需要加个过滤器进行过滤，直接将页面跳转至index.jsp.

新建包package com.product.filter;

MyFilter.java

package com.product.filter;
import java.io.IOException;
import javax.servlet.Filter;
import javax.servlet.FilterChain;
import javax.servlet.FilterConfig;
import javax.servlet.ServletException;
import javax.servlet.ServletRequest;
import javax.servlet.ServletResponse;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
public class MyFilter implements Filter {
@Override
public void destroy() {
// TODO Auto-generated method stub
}
@Override
public void doFilter(ServletRequest request, ServletResponse response,
FilterChain chain) throws IOException, ServletException {
// TODO Auto-generated method stub
//过滤用户的请求，判断是否登录
HttpServletRequest httpServletRequest = (HttpServletRequest)request;
HttpServletResponse httpServletResponse = (HttpServletResponse)response;
httpServletRequest.setCharacterEncoding("utf-8");
httpServletResponse.setCharacterEncoding("utf-8");
String path = httpServletRequest.getContextPath();
String username = (String)httpServletRequest.getSession().getAttribute("username");
if(username == null){
httpServletResponse.sendRedirect(path + "/index.jsp");
}
chain.doFilter(httpServletRequest, httpServletResponse);
}
@Override
public void init(FilterConfig arg0) throws ServletException {
// TODO Auto-generated method stub
}
}

	<filter>
<filter-name>MyFilter</filter-name>
<filter-class>com.product.filter.MyFilter</filter-class>
</filter>
<filter-mapping>
<filter-name>MyFilter</filter-name>
<url-pattern>/main.jsp</url-pattern>
</filter-mapping>

代码下载链接:http://download.csdn.net/detail/yanzi1225627/7448175

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