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数据库设计+编码+运行调试数据库准备：二话不说，上图文件组织如下：首先写出三个JSP页面文件login.jsp%@pagelanguage=javacontentType=text/html;charset=gb2312pageEncoding=gb2312%!DOCTYPEhtmlPUBLIC-//W3C//DTDHTML4.01Transitional//EN=Content-Typecontent=text/html;charset=gb2312title登陆页面/title/headbodycenter登陆界面/centercenterformaction=loginmethod=post用户名inputtype=textname=username/brbr 密码 inputtype=textname=passwordbrinputtype=submitvalue=提交/form/center/body/htmlback.jsp%@pagelanguage=javacontentType=text/html;charset=gb2312pageEncoding=gb2312%!DOCTYPEhtmlPUBLIC-//W3C//DTDHTML4.01Transitional//EN=Content-Typecontent=text/html;charset=gb2312title登陆失败/title/headbody用户密码错误，单击ahref=login.jsp这里/a返回/body/htmlwelcome.jsp%@pageimport=java.util.*contentType=text/html;charset=gb2312pageEncoding=gb2312%!DOCTYPEhtmlPUBLIC-//W3C//DTDHTML4.01Transitional//EN=Content-Typecontent=text/html;charset=gb2312title登陆成功/title/headbody欢迎你！登陆成功！br%Datetoday=newDate();intd=today.getDay();inth=today.getHours();Strings=;if(h0&&h12)s=上午好;elseif(h=12)s=下午好;Stringday[]={日,一,二,三,四,五,六};out.println(s+，今天是星期+day[d]);%/body/html接着，写一个数据库处理类以及一个servlet类DBUtil.javapackagejavabean;importjava.sql.*;publicclassDBUtil{booleanbInited=false;//加载驱动publicvoidinitJDBC()throwsClassNotFoundException{//加载MYSQLJDBC驱动程序Class.forName(com.mysql.jdbc.Driver);bInited=true;System.out.println(SuccessloadingMysqlDriver!);}publicConnectiongetConnection()throwsClassNotFoundException,SQLException{if(!bInited){initJDBC();}//连接URL为jdbc:mysql//服务器地址/数据库名//后面的2个参数分别是登陆用户名和密码Connectionconn=DriverManager.getConnection(jdbc:mysql://localhost:3306/user,root,123);returnconn;}publicbooleanloginSuccess(StringuserName,Stringpassword){booleanreturnValue=false;Stringsql=SELECT*FROMuser;Connectionconn=null;Statementstmt=null;ResultSetrs=null;try{conn=getConnection();stmt=conn.createStatement();rs=stmt.executeQuery(sql);while(rs.next()){StringuserNameInDB=rs.getString(name);StringpasswordInDB=rs.getString(pwd);if(userNameInDB.equals(userName)&&passwordInDB.equals(password)){returnValue=true;break;}}}catch(ClassNotFoundExceptione){e.printStackTrace();}catch(SQLExceptione){e.printStackTrace();}returnreturnValue;}}LoginServlet.javapackageservlet;importjava.io.IOException;importjavax.servlet.ServletConfig;importjavax.servlet.ServletException;importjavax.servlet.ServletRequest;importjavax.servlet.ServletResponse;importjavax.servlet.http.HttpServletRequest;importjavax.servlet.http.HttpServletResponse;importjavabean.DBUtil;publicclassLoginServletimplementsjavax.servlet.Servlet{publicvoiddestroy(){}publicServletConfiggetServletConfig(){returnnull;}publicStringgetServletInfo(){returnnull;}publicvoidinit(ServletConfigarg0)throwsServletException{}publicvoiddoPost(HttpServletRequestrequest,HttpServletResponseresponse)throwsServletException,IOException{StringuserName=request.getParameter(username);//取得用户名Stringpassword=request.getParameter(password);//取得密码DBUtildb=newDBUtil();//构建数据库对象booleancanLogin=db.loginSuccess(userName,password);if(canLogin){//根据登陆情况，跳转页面response.sendRedirect(welcome.jsp);}else{response.sendRedirect(back.jsp);}}publicvoidservice(ServletRequestrequest,ServletResponseresponse)throwsServletException,IOException{HttpServletRequestrq=(HttpServletRequest)request;HttpServletResponsers=(HttpServletResponse)response;doPost(rq,rs);}}最后，web配置文件如下：?xmlversion=1.0encoding=UTF-8?web-appversion=2.4xmlns=:xsi=:schemaLocation=://java.sun.com/xml/ns/j2ee/web-app_2_4.xsdservletservlet-nameLoginServlet/servlet-nameservlet-classservlet.LoginServlet/servlet-class/servletservlet-mappingservlet-nameLoginServlet/servlet-nameurl-pattern/login/url-pattern/servlet-mappingwelcome-file-listwelcome-filelogin.jsp/welcome-file/welcome-file-list/web-app实验注意要点程序运行结果如下：