JSP+Servlet+JavaBean实现登录网页实例详解
本文实例讲述了JSP+Servlet+JavaBean实现登录网页的方法。分享给大家供大家参考。具体如下：
这里涉及到四个文件:
1.登录页面:login.html
2.登录成功欢迎页面:login_success.jsp
3.登录失败页面:login_failure.jsp
4.Servlet处理文件:LoginServlet.java
其实还涉及到一个文件:web.xml,这个后面再说:
下面分别介绍这几个文件:
1.登录页面:login.html
<!--该Login页面是一个简单的登录界面-->
<!--
该JSP程序是用来测试与MySQL数据库的连接，
需要一个数据库：LearnJSP，和其中一个表：userinfo
表中有两个字段分别为：UserNamevarchar(20)notnull,UserPwdvarchar(20)notnull
-->
<html>
<head>
<title>登录</title>
<metahttp-equiv="content-type"content="text/html;charset=UTF-8">
<metahttp-equiv="Content-Language"content="ch-cn">
</head>
<body>
<!--Form用来提取用户填入并提交的信息-->
<formmethod="post"name="frmLogin"action="LoginServlet">
<h1align="center">用户登录</h1><br>
<divalign="center">用户名：
<inputtype="text"name="txtUserName"value="Yourname"
size="20"maxlength="20"
onfocus="if(this.value=='Yourname')this.value='';"><br>密码：
<inputtype="password"name="txtPassword"value="Yourpassword"
size="20"maxlength="20"
onfocus="if(this.value=='Yourpassword')this.value='';"><br>
<inputtype="submit"name="Submit"value="提交"onClick="validateLogin();">
<inputtype="reset"name="Reset"value="重置"><br>
</div>
</form>
<!--javaScript函数validateLogin(),用来验证用户名和密码是否为空-->
<scriptlanguage="javaScript">
functionvalidateLogin()
{
varsUserName=document.frmLogin.txtUserName.value;
varsPassword=document.frmLogin.txtPassword.value;
if(sUserName=="")
{
alert("请输入用户名！");
returnfalse;
}
if(sPassword=="")
{
alert("请输入密码！");
returnfalse;
}
}
</script>
</body>
</html>
2.登录成功欢迎页面:login_success.jsp
<%@pagelanguage="java"contentType="text/html;charset=UTF-8"
pageEncoding="UTF-8"%>
<!DOCTYPEHTMLPUBLIC"-//W3C//DTDHTML4.01Transitional//EN">
<html>
<head>
<title>MyJSP'login_failure.jsp'startingpage</title>
<metahttp-equiv="content-type"content="text/html;charset=UTF-8">
<metahttp-equiv="pragma"content="no-cache">
<metahttp-equiv="cache-control"content="no-cache">
<metahttp-equiv="expires"content="0">
<metahttp-equiv="keywords"content="keyword1,keyword2,keyword3">
<metahttp-equiv="description"content="Thisismypage">
<!--
<linkrel="stylesheet"type="text/css"href="styles.css">
-->
</head>
<body>
<%
StringuserName=(String)session.getAttribute("UserName");
%>
<divalign=center>
<%=userName%>
欢迎您，登录成功！
</div>
</body>
</html>
3.登录失败页面:login_failure.jsp
<%@pagelanguage="java"contentType="text/html;charset=UTF-8"
pageEncoding="UTF-8"%>
<!DOCTYPEHTMLPUBLIC"-//W3C//DTDHTML4.01Transitional//EN">
<html>
<head>
<title>MyJSP'login_failure.jsp'startingpage</title>
<metahttp-equiv="content-type"content="text/html;charset=UTF-8">
<metahttp-equiv="pragma"content="no-cache">
<metahttp-equiv="cache-control"content="no-cache">
<metahttp-equiv="expires"content="0">
<metahttp-equiv="keywords"content="keyword1,keyword2,keyword3">
<metahttp-equiv="description"content="Thisismypage">
<!--
<linkrel="stylesheet"type="text/css"href="styles.css">
-->
</head>
<body>
<%
StringuserName=(String)session.getAttribute("UserName");
%>
<divalign=center>
<%=userName%>
对不起，登录失败！
</div>
</body>
</html>
4.Servlet处理文件:LoginServlet.java
/**
*该JSP程序是用来测试与MySQL数据库的连接，
*需要一个数据库：LearnJSP，和其中一个表：userinfo
*表中有两个字段分别为：UserNamevarchar(20)notnull,UserPwdvarchar(20)notnull
*/
packagezieckey.login.servlet;
importjava.sql.Statement;
importjava.io.IOException;
importjava.sql.DriverManager;
importjava.sql.ResultSet;
importjava.sql.SQLException;
importjavax.servlet.Servlet;
importjavax.servlet.ServletException;
importjavax.servlet.http.HttpServlet;
importjavax.servlet.http.HttpServletRequest;
importjavax.servlet.http.HttpServletResponse;
publicclassLoginServletextendsHttpServletimplementsServlet
{
publicLoginServlet()
{
//TODOAuto-generatedconstructorstub
}
/*
*(non-Javadoc)
*
*@seejavax.servlet.http.HttpServlet#doGet(javax.servlet.http.HttpServletRequest,
*javax.servlet.http.HttpServletResponse)
*/
@Override
protectedvoiddoGet(HttpServletRequestarg0,HttpServletResponsearg1)
throwsServletException,IOException
{
}
/*
*(non-Javadoc)
*
*@seejavax.servlet.http.HttpServlet#doPost(javax.servlet.http.HttpServletRequest,
*javax.servlet.http.HttpServletResponse)
*/
@Override
protectedvoiddoPost(HttpServletRequestrequest,HttpServletResponseresponse)
throwsServletException,IOException
{
response.setContentType("text/html");
Stringresult="";
//获取用户名
StringsUserName=request.getParameter("txtUserName");
if(sUserName==""||sUserName==null||sUserName.length()>20)
{
try
{
result="请输入用户名（不超过20字符）！";
request.setAttribute("ErrorUserName",result);
response.sendRedirect("login.html");
}catch(Exceptione)
{
}
}
//获取密码
StringsPasswd=request.getParameter("txtPassword");
if(sPasswd==""||sPasswd==null||sPasswd.length()>20)
{
try
{
result="请输入密码（不超过20字符）！";
request.setAttribute("ErrorPassword",result);
response.sendRedirect("login.html");
}catch(Exceptione)
{
}
}
//登记JDBC驱动程序
try
{
Class.forName("org.gjt.mm.mysql.Driver").newInstance();
}catch(InstantiationExceptione)
{
//TODOAuto-generatedcatchblock
e.printStackTrace();
System.out.println("InstantiationException");
}catch(IllegalAccessExceptione)
{
//TODOAuto-generatedcatchblock
e.printStackTrace();
System.out.println("IllegalAccessException");
}catch(ClassNotFoundExceptione)
{
//TODOAuto-generatedcatchblock
e.printStackTrace();
System.out.println("ClassNotFoundException");
}
//连接参数与Access不同
Stringurl="jdbc:mysql://localhost/LearnJSP";
//建立连接
java.sql.Connectionconnection=null;
Statementstmt=null;
ResultSetrs=null;
try
{
connection=DriverManager.getConnection(url,"root","011124");
stmt=connection.createStatement();
//SQL语句
Stringsql="select*fromuserinfowhereusername='"+sUserName
+"'anduserpwd='"+sPasswd+"'";
rs=stmt.executeQuery(sql);//返回查询结果
}catch(SQLExceptione)
{
//TODOAuto-generatedcatchblock
e.printStackTrace();
}
try
{
if(rs.next())//如果记录集非空，表明有匹配的用户名和密码，登陆成功
{
//登录成功后将sUserName设置为session变量的UserName
//这样在后面就可以通过session.getAttribute("UserName")来获取用户名，
//同时这样还可以作为用户登录与否的判断依据
request.getSession().setAttribute("UserName",sUserName);
response.sendRedirect("login_success.jsp");
}else
{
//否则登录失败
//response.sendRedirect("MyJsp.jsp");
response.sendRedirect("login_failure.jsp");
}
}catch(SQLExceptione)
{
//TODOAuto-generatedcatchblock
e.printStackTrace();
}
try
{
if(null!=rs)
{
rs.close();
}
if(null!=stmt)
{
stmt.close();
}
if(null!=connection)
{
connection.close();
}
}catch(SQLExceptione)
{
//TODOAuto-generatedcatchblock
e.printStackTrace();
}
}
/**
*
*/
privatestaticfinallongserialVersionUID=1L;
}
为了让这个网站正常运行还要到web.xml中注册一下,
现该文件内容修改如下:
<?xmlversion="1.0"encoding="UTF-8"?> <web-appxmlns="http://java.sun.com/xml/ns/j2ee"xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"version="2.4"xsi:schemaLocation="http://java.sun.com/xml/ns/j2eehttp://java.sun.com/xml/ns/j2ee/web-app_2_4.xsd"> <servlet> <display-name>LoginServlet</display-name> <servlet-name>LoginServlet</servlet-name> <servlet-class>zieckey.login.servlet.LoginServlet</servlet-class> </servlet> <servlet-mapping> <servlet-name>LoginServlet</servlet-name> <url-pattern>/LoginServlet</url-pattern> </servlet-mapping> </web-app>
好了,这几个文件就可以构成我们的这个登录界面了.
注意事项:
1.文件目录形式
login.html,login_success.html,login_failure.html这三个文件放在同一目录,
LoginServlet.java该文件的字节码文件LoginServlet.class放在WEB-INF/classes目录下(注意jar包顺序)
现在整个工程的目录形式是:
M:/Tomcat5.5/webapps/JSP_Servlet_JavaBean_Login的目录
007-01-18 15:16 <DIR> META-INF
007-01-18 15:16 <DIR> WEB-INF
007-01-18 16:17 1,801login.html
007-01-18 15:48 858login_failure.jsp
007-01-18 15:40 234login_success.html
007-01-18 15:46 781MyJsp.jsp
007-01-18 16:12 859login_success.jsp
M:/Tomcat5.5/webapps/JSP_Servlet_JavaBean_Login/WEB-INF的目录
007-01-18 15:16 <DIR> classes
007-01-18 15:16 <DIR> lib
007-01-18 16:21 606web.xml
M:/Tomcat5.5/webapps/JSP_Servlet_JavaBean_Login/WEB-INF/classes/zieckey/login/servlet的目录
2007-01-18 16:18 3,900LoginServlet.class
2.其他注意事项
数据库MySQL服务器程序要先启动起来.
希望本文所述对大家的JSP程序设计有所帮助。