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  • SpringMVC demo 小例子,实现简单的登录和注册

    1.创建一个动态的web工程

    2.导入springMvc所需要的jar包(这里可以去网上找,资源有很多)

    前两部就不详细描述了,后面才是正经代码~

    首先有一个web.xml文件,这个属于大配置文件,由于只要写login,里面简单配置一下基本环境就可以

    <servlet>
        <servlet-name>springmvc</servlet-name>
        <servlet-class>
            org.springframework.web.servlet.DispatcherServlet
        </servlet-class>
        <load-on-startup>1</load-on-startup>
      </servlet>
      <servlet-mapping>
         <servlet-name>springmvc</servlet-name>
         <url-pattern>/</url-pattern>
      </servlet-mapping>

    加入的这个叫Dispatcher Servlet,可以根据servlet-name找到对应的小配置文件,也就是配置spring MVC的文件

    在web.xml文件同级目录下新建springmvc-servlet.xml文件,下面是springmvc-servlet.xml文件中的内容

    <?xml version="1.0" encoding="UTF-8"?>
    <beans xmlns="http://www.springframework.org/schema/beans"
        xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
     xmlns:p="http://www.springframework.org/schema/p"
        xmlns:context="http://www.springframework.org/schema/context"
        xmlns:mvc="http://www.springframework.org/schema/mvc"
        xsi:schemaLocation="
        http://www.springframework.org/schema/beans
        http://www.springframework.org/schema/beans/spring-beans-3.0.xsd
        http://www.springframework.org/schema/context
        http://www.springframework.org/schema/context/spring-context-3.0.xsd
        http://www.springframework.org/schema/mvc 
        http://www.springframework.org/schema/mvc/spring-mvc-3.0.xsd">
        <!--默认的注解映射的支持 -->
        <mvc:annotation-driven/>
        <!--启用自动扫描 -->
        <context:component-scan base-package="controller"/>
        <bean class="org.springframework.web.servlet.view.InternalResourceViewResolver">
            <property name="prefix" value="/WEB-INF/jsp/"/>
            <property name="suffix" value=".jsp"/>
        </bean>
    </beans>

    注意说明的是,启动自动扫描,spring会在指定的包下(例如我这里是controller包),自动扫描标注@Controller的类

    prefix指的是返回的值给自动加一个前缀,同理suffix指的就是后缀

     

    看到这里也是够辛苦了,上面是给出的完整目录,下面开始写逻辑代码,先从loginController开始

    @Controller
    public class LoginController {
        @RequestMapping(value="/",method=RequestMethod.GET)
        public String sayHello(){
            //model.addAttribute("msg", "Hello,World!");
            return "login";
        }

    解释上面代码,@Controller,标注这个类是Controller类,spring会自动进行扫描,@Request Mapping中的value指的是url中的地址后缀,设置成/的目的当然是为了方便啊,

    比如启动工程时,url只需要输入什么localhost:8080/项目名,它就会自动跳转到login页面;method指的是来的url是post请求还是get请求

    return的是login字符串,大家还记得上面说的prefix了吧,它就会把你的url自动拼接上,完整路径就是下面这个

    /WEB-INF/jsp/login.jsp

     接下来看login.jsp

    <%@ page language="java" contentType="text/html; charset=UTF-8"
        pageEncoding="UTF-8"%>
    <!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
    <html>
    <head>
    <meta http-equiv="Content-Type" content="text/html; charset=UTF-8">
    <title>login</title>
    </head>
    <body>
        <form action="login" method="post">
            用户名:<input type="text" name="username"/><br/>&nbsp;&nbsp;码:<input type="password" name="password"/>
            <input type="submit" value="登陆"/>
            <a href="regist">注册</a>
        </form>
    </body>
    </html>

    这里的action返回的是login,Controller会自动捕获到这个请求,于是在login Controller中要有一个方法来捕获这个请求

    @RequestMapping(value="login",method=RequestMethod.POST)
        public String login(Model model, // 向前台页面传的值放入model中
                HttpServletRequest request){ // 从前台页面取得的值
            String username = request.getParameter("username");
            String password = request.getParameter("password");
            String user_name = LoginCheck.check(username, password);
            if(user_name != null && user_name != ""){
                model.addAttribute("msg", user_name);
                return "success";
            }else{
                return "login2";
            }
        }

    登陆嘛,当然要有验证,于是就有了LoginCheck,不多说,上代码

    package logic;
    
    import java.sql.Connection;
    import java.sql.PreparedStatement;
    import java.sql.ResultSet;
    
    import dao.Dao;
    
    public class LoginCheck {
        
        public static String check(String username,String password){
            try {
                Connection conn = Dao.getConnection();
                PreparedStatement p = conn.prepareStatement("select * from user_t where user_name=? and password=?");
                p.setString(1, username);
                p.setString(2, password);
                ResultSet rs = p.executeQuery();
                if(rs.next()){
                    String user_name = rs.getString("user_name");
                    Dao.close(rs, p, conn);
                    return user_name;
                }
                Dao.close(rs, p, conn);
            } catch (Exception e) {
                e.printStackTrace();
            }
            return "";
        }
    }

    向数据库查询就要有DAO啦,Dao网上都有,我的就是在网上随便找一个改改就用了~

    package dao;
    
    import java.sql.Connection;
    import java.sql.DriverManager;
    import java.sql.PreparedStatement;
    import java.sql.ResultSet;
    import java.sql.SQLException;
    
    public class Dao {
        // 获取数据库连接
        public static Connection getConnection(){
            
            Connection conn = null;
            String url = "jdbc:mysql://127.0.0.1:3306/test?characterEncoding=utf8&useSSL=false&serverTimezone=Hongkong";
            try
            {
                Class.forName("com.mysql.cj.jdbc.Driver");
                conn = DriverManager.getConnection(url,"root","数据库密码");//大家分享代码的时候也不要暴露自己的数据库密码,这样是非常不安全的
            }
            catch(ClassNotFoundException e)
            {
                e.printStackTrace();
                System.out.println("数据库驱动加载出错");
            }
            catch(SQLException e)
            {
                e.printStackTrace();
                System.out.println("数据库出错");
            }
            return conn;
        }
         //关闭相关通道
        public static void close(ResultSet rs,PreparedStatement p,Connection conn)
        {
            try
            {
                if(!rs.isClosed()){
                    rs.close();
                }
                if(!p.isClosed()){
                    p.close();
                }
                if(!conn.isClosed()){
                    conn.close();
                }
            }
            catch(SQLException e)
            {
                e.printStackTrace();
                System.out.println("数据关闭出错");
            }
        }
        //关闭相关通道
        public static void close(PreparedStatement p,Connection conn)
        {
            try
            {
                if(!p.isClosed()){
                    p.close();
                }
                if(!conn.isClosed()){
                    conn.close();
                }
            }
            catch(SQLException e)
            {
                e.printStackTrace();
                System.out.println("数据关闭出错");
            }
        }
    }

    好了,如果查询的结果匹配上数据库中查询到的值了,那么就可以跳转到success页面了,success.jsp

    <%@ page language="java" contentType="text/html; charset=UTF-8"
        pageEncoding="UTF-8"%>
    <!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
    <html>
    <head>
    <meta http-equiv="Content-Type" content="text/html; charset=UTF-8">
    <title>登陆成功</title>
    </head>
    <body>
        登陆成功!
        欢迎~${msg};
    </body>
    </html>

    login大功告成,接下来的注册页面和这个道理相似,我不多废话了,把代码附上供大家参考

    首先是regist.jsp

    <%@ page language="java" contentType="text/html; charset=UTF-8"
        pageEncoding="UTF-8"%>
    <!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
    <html>
    <head>
    <meta http-equiv="Content-Type" content="text/html; charset=UTF-8">
    <title>注册页面</title>
    </head>
    <body>
        <form action="registSuccess" method="Post">
            用户名:<input type="text" name="username"/>&nbsp;&nbsp;码<input type="text" name="password"/>&nbsp;&nbsp;龄<input type="number" name="age"/>
            <input type="submit" value="提交"/>
        </form>
    </body>
    </html>

    接下来是RegistController

    package controller;
    
    import javax.servlet.http.HttpServletRequest;
    
    import org.springframework.stereotype.Controller;
    import org.springframework.ui.Model;
    import org.springframework.web.bind.annotation.RequestMapping;
    import org.springframework.web.bind.annotation.RequestMethod;
    
    import logic.RegistCheck;
    
    @Controller
    public class RegistController {
        @RequestMapping(value="regist",method=RequestMethod.GET)
        public String regist(){
            return "regist";
        }
        
        @RequestMapping(value="registSuccess",method=RequestMethod.POST)
        public String registSuccess(HttpServletRequest request,Model model){
            String username = request.getParameter("username");
            String password = request.getParameter("password");
            String age = request.getParameter("age");
            
            if(RegistCheck.registCheck(username, password,age)){
                model.addAttribute("username", username);
                return "login";
            }else{
                return "regist2";
            }
        }
    }

    接下来是RegistCheck

    package logic;
    
    import java.sql.Connection;
    import java.sql.PreparedStatement;
    
    import dao.Dao;
    
    public class RegistCheck {
        
        public static boolean registCheck(String username,String password,String age){
            String user_name = LoginCheck.check(username, password);
            if(user_name == null || user_name == ""){
                try {
                    Connection conn = Dao.getConnection();
                    PreparedStatement p = conn.prepareStatement("insert user_t(user_name,password,age) VALUES (?,?,?);");
                    p.setString(1, username);
                    p.setString(2, password);
                    p.setString(3, age);
                    p.executeUpdate();
                    System.out.println("注册成功");
                    Dao.close(p, conn);
                    return true;
                } catch (Exception e) {
                    e.printStackTrace();
                }
            }
            return false;
        }
    }

    还有一个registSuccess.jsp,成功返回的页面,我只是放了个空页面,没内容

    <%@ page language="java" contentType="text/html; charset=UTF-8"
        pageEncoding="UTF-8"%>
    <!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
    <html>
    <head>
    <meta http-equiv="Content-Type" content="text/html; charset=UTF-8">
    <title>注册成功</title>
    </head>
    <body>
        注册成功!
    </body>
    </html>

    好了,现在为止login和注册页面都写好了,新人刚到公司的时候非常容易碰到这样的小练习,哈哈哈说多了,喜欢就点赞哈

    欢迎转载,转载请注明出处~

    Java从学习到放弃,MySQL从删库到跑路,哈哈哈

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  • 原文地址:https://www.cnblogs.com/gode/p/7374371.html
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