Servlet实现简单的用户登录功能实例代码

2023-07-08 19:16:07 65

1、创建html界面





Title



用户名:

密码:

2、创建数据库

CREATETABLEUSER(
			idINTPRIMARYKEYAUTO_INCREMENT,
			usernameVARCHAR(32)UNIQUENOTNULL,
			PASSWORDVARCHAR(32)NOTNULL
		);

3、创建用户实体类

	publicclassUser{
		
		privateintid;
		privateStringusername;
		privateStringpassword;
	publicintgetId(){
		returnid;
		}
		
		publicvoidsetId(intid){
		this.id=id;
		}
		
		publicStringgetUsername(){
		returnusername;
		}
		
		publicvoidsetUsername(Stringusername){
		this.username=username;
		}
		
		publicStringgetPassword(){
		returnpassword;
		}
		
		publicvoidsetPassword(Stringpassword){
		this.password=password;
		}
		
		@Override
		publicStringtoString(){
		return"User{"+
		"id="+id+
		",username='"+username+'\''+
		",password='"+password+'\''+
		'}';
		}
		}

4、创建jdbc工具类

这里使用的是c3p0/druid两种数据库连接池技术分别需要在项目导入相应的jar包

publicclassJDBCUtils{
		
		privatestaticDataSourceds;
		
		static{
		
		try{
		//1.加载配置文件
		Propertiespro=newProperties();
		//使用ClassLoader加载配置文件，获取字节输入流
		InputStreamis=JDBCUtils.class.getClassLoader().getResourceAsStream("druid.properties");
		pro.load(is);
		
		//2.初始化连接池对象
		ds=DruidDataSourceFactory.createDataSource(pro);
		
		}catch(IOExceptione){
		e.printStackTrace();
		}catch(Exceptione){
		e.printStackTrace();
		}
		}
		
		/**
		*获取连接池对象
		*/
		publicstaticDataSourcegetDataSource(){
		returnds;
		}
/**
		*获取连接Connection对象
		*/
		publicstaticConnectiongetConnection()throwsSQLException{
		returnds.getConnection();
		}

system.out.println("=============================================================")
publicclassJDBCButil{
	finalstaticComboPooledDataSourcecomboPooledDataSource=newComboPooledDataSource();
	//获取连接方法
	//返回一个连接对象
	publicstaticConnectiongetCon(){
		//连接使用c3p0进行获取
		//使用c3p0数据库连接池获取连接
		Connectionconnection=null;
		try{
			connection=comboPooledDataSource.getConnection();
		}catch(SQLExceptione){
			System.err.println("获取连接失败");
			returnnull;
		}
		returnconnection;
	}

	//DML方法
	//不支持事务单条sql语句执行
	publicstaticbooleanDML(Stringsql,Object...o){
		//获取连接
		Connectioncon=getCon();
		//创建预编译对象
		try{
			PreparedStatementps=con.prepareStatement(sql);
			for(inti=0;iArrayListDQL(Stringsql,Classc,Object...o){
		ArrayListlist=newArrayList<>();
		try{
			//获取连接
			Connectioncon=getCon();
			//准备预编译对象
			PreparedStatementps=con.prepareStatement(sql);
			//获取元数据准备存储所有列名的数组
			ResultSetMetaDatametaData=ps.getMetaData();
			//创建指定长度用于存储列名的数组
			String[]names=newString[metaData.getColumnCount()];
			//循环为names数组进行赋值
			for(inti=0;i
5、创建提供登录方法的userdao
	publicclassUserDao{
		
		//声明JDBCTemplate对象共用
		privateJdbcTemplatetemplate=newJdbcTemplate(JDBCUtils.getDataSource());
		/**
		*登录方法
		*@paramloginUser只有用户名和密码
		*@returnuser包含用户全部数据,没有查询到，返回null
		*/
		publicUserlogin(UserloginUser){
		try{
		//1.编写sql
		Stringsql="select*fromuserwhereusername=?andpassword=?";
		//2.调用query方法
		Useruser=template.queryForObject(sql,
		newBeanPropertyRowMapper(User.class),
		loginUser.getUsername(),loginUser.getPassword());
		returnuser;
		}catch(DataAccessExceptione){
		e.printStackTrace();
		returnnull;
		}
		}
		}
	

6、编写登录的servlet


@WebServlet("/loginServlet")
		publicclassLoginServletextendsHttpServlet{
		@Override
		protectedvoiddoGet(HttpServletRequestreq,HttpServletResponseresp)throwsServletException,IOException{
		//1.设置编码
		req.setCharacterEncoding("utf-8");
		//2.获取请求参数
		Stringusername=req.getParameter("username");
		Stringpassword=req.getParameter("password");
		//3.封装user对象
		UserloginUser=newUser();
		loginUser.setUsername(username);
		loginUser.setPassword(password);
		
		//4.调用UserDao的login方法
		UserDaodao=newUserDao();
		Useruser=dao.login(loginUser);
		
		//5.判断user
		if(user==null){
		//登录失败
		req.getRequestDispatcher("/failServlet").forward(req,resp);
		}else{
		//登录成功
		//存储数据
		req.setAttribute("user",user);
		//转发
		req.getRequestDispatcher("/successServlet").forward(req,resp);
		}
		
		}
		@Override
		protectedvoiddoPost(HttpServletRequestreq,HttpServletResponseresp)throwsServletException,IOException{
		this.doGet(req,resp);
		}
		}
		

7、编写FailServlet和SuccessServlet类
	publicclassSuccessServletextendsHttpServlet{
		protectedvoiddoPost(HttpServletRequestrequest,HttpServletResponseresponse)throwsServletException,IOException{
		//获取request域中共享的user对象
		Useruser=(User)request.getAttribute("user");
		
		if(user!=null){
		//给页面写一句话
		
		//设置编码
		response.setContentType("text/html;charset=utf-8");
		//输出
		response.getWriter().write("登录成功！"+user.getUsername()+",欢迎您");
		}
		}		
		@WebServlet("/failServlet")
		publicclassFailServletextendsHttpServlet{
		protectedvoiddoPost(HttpServletRequestrequest,HttpServletResponseresponse)throwsServletException,IOException{
		//给页面写一句话
		
		//设置编码
		response.setContentType("text/html;charset=utf-8");
		//输出
		response.getWriter().write("登录失败，用户名或密码错误");
		
		}
		
		protectedvoiddoGet(HttpServletRequestrequest,HttpServletResponseresponse)throwsServletException,IOException{
		this.doPost(request,response);
		}
		}
		
		
		

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Servlet实现简单的用户登录功能实例代码

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