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1，布局如下2,所用数据库:mysql版.Droptableifexists`user`;CREATETABLE`user`(`id`int(10)unsignedNOTNULLauto_increment,`username`varchar(50)NOTNULLdefault'',`password`varchar(10)defaultNULL,`email`varchar(50)defaultNULL,PRIMARYKEY(`id`),UNIQUEKEY`ID`(`id`),KEY`ID_2`(`id`))ENGINE=InnoDBDEFAULTCHARSET=utf8AUTO_INCREMENT=78;Insertintouservalues(10,shi,123,456);3.DBAccess.javapackagecom.demo.javabean;importjava.sql.DriverManager;importjava.sql.SQLException;importcom.mysql.jdbc.Connection;importcom.mysql.jdbc.ResultSet;importcom.mysql.jdbc.Statement;publicclassDBAccess{privateStringdrv=com.mysql.jdbc.Driver;privateStringurl=jdbc:mysql://localhost:3306/demo;privateStringusr=root;privateStringpwd=;privateConnectionconn=null;privateStatementstm=null;privateResultSetrs=null;publicStringgetDrv(){returndrv;}publicvoidsetDrv(Stringdrv){this.drv=drv;}publicStringgetUrl(){returnurl;}publicvoidsetUrl(Stringurl){this.url=url;}publicStringgetUsr(){returnusr;}publicvoidsetUsr(Stringusr){this.usr=usr;}publicStringgetPwd(){returnpwd;}publicvoidsetPwd(Stringpwd){this.pwd=pwd;}publicConnectiongetConn(){returnconn;}publicvoidsetConn(Connectionconn){this.conn=conn;}publicjava.sql.StatementgetStm(){returnstm;}publicvoidsetStm(Statementstm){this.stm=stm;}publicjava.sql.ResultSetgetRs(){returnrs;}publicvoidsetRs(ResultSetrs){this.rs=rs;}//创建数据库连接函数publicbooleancreateConn(){booleanb=false;try{Class.forName(drv).newInstance();conn=(Connection)DriverManager.getConnection(url,usr,pwd);b=true;}catch(SQLExceptione){}catch(ClassNotFoundExceptione){}catch(InstantiationExceptione){}catch(IllegalAccessExceptione){}returnb;}//更新sql函数publicbooleanupdate(Stringsql){booleanb=false;try{stm=(Statement)conn.createStatement();stm.execute(sql);b=true;}catch(Exceptione){}returnb;}//查询sql函数publicvoidquery(Stringsql){try{stm=(Statement)conn.createStatement();rs=(ResultSet)stm.executeQuery(sql);}catch(Exceptione){}}publicbooleannext(){booleanb=false;try{if(rs.next())b=true;}catch(Exceptione){}returnb;}publicStringgetValue(Stringfield){Stringvalue=null;try{if(rs!=null)value=rs.getString(field);}catch(Exceptione){}returnvalue;}publicvoidcloseRs(){try{if(rs!=null)rs.close();}catch(SQLExceptione){}}publicvoidcloseStm(){try{if(rs!=null)stm.close();}catch(SQLExceptione){}}publicvoidcloseConn(){try{if(rs!=null)conn.close();}catch(SQLExceptione){}}}4.UserBean.javapackagecom.demo.javabean;publicclassUserBean{//登录验证函数publicbooleanvalid(Stringusername,Stringpassword){booleanisValid=false;DBAccessdb=newDBAccess();if(db.createConn()){Stringsql=select*fromuserwhereusername='+username+'andpassword='+password+';db.query(sql);if(db.next()){isValid=true;}db.closeRs();db.closeStm();db.closeConn();}returnisValid;}//检查用户名是否存在publicbooleanisExist(Stringusername){booleanisExist=false;DBAccessdb=newDBAccess();if(db.createConn()){Stringsql=select*fromuserwhereusername='+username+';db.query(sql);if(db.next()){isExist=true;}db.closeRs();db.closeStm();db.closeConn();}returnisExist;}publicvoidadd(Stringusername,Stringpassword,Stringemail){DBAccessdb=newDBAccess();if(db.createConn()){Stringsql=insertintouser(username,password,email)values('+username+','+password+','+email+');db.update(sql);db.closeStm();db.closeConn();}}}5.login_action.jsp%@pagelanguage=javaimport=java.util.*pageEncoding=ISO-8859-1%%@pageimport=com.demo.javabean.UserBean%%Stringpath=request.getContextPath();StringbasePath=request.getScheme()+://+request.getServerName()+:+request.getServerPort()+path+/;%htmlheadbasehref=%=basePath%titleMyJSP'login_action.jsp'startingpage/title/headbody%Stringusername=request.getParameter(username);Stringpassword=request.getParameter(password);if(username==null||password==null){response.sendRedirect(login.jsp);}%%//验证登录booleanisValid=false;UserBeanuserBean=newUserBean();isValid=userBean.valid(username,password);if(isValid){session.setAttribute(username,username);response.sendRedirect(welcome.jsp);}else{response.sendRedirect(login.jsp);}%/body/html6.Login.jsp%@pagelanguage=javaimport=java.util.*pageEncoding=utf-8%%Stringpath=request.getContextPath();StringbasePath=request.getScheme()+://+request.getServerName()+:+request.getServerPort()+path+/;%!DOCTYPEHTMLPUBLIC-//W3C//DTDHTML4.01Transitional//ENhtmlheadbasehref=%=basePath%titleMyJSP'index.jsp'startingpage/title/headbodyThisismyJSPpage.brformname=form1action=login_action.jspmethod=posttablewidth=200border=1trtdcolspan=2登录窗口/td/trtrtd用户名/tdtdinputtype=textname=usernamesize=10/td/trtrtd密码/tdtdinputtype=passwordname=passwordsize=10/td/trtrtdcolspan=2inputtype=submitname=submitvalue=登录ahref=register.jsp注册新用户/a/td/tr/table/form/body/html7.Logout.jsp%@pagelanguage=javaimport=java.util.*pageEncoding=ISO-8859-1%%Stringpath=request.getContextPath();StringbasePath=request.getScheme()+://+request.getServerName()+:+request.getServerPort()+path+/;%!DOCTYPEHTMLPUBLIC-//W3C//DTDHTML4.01Transitional//ENhtmlheadbasehref=%=basePath%titleMyJ