• 项目的结构目录如下
  
• 配置pom.xml:

<?xml version="1.0" encoding="UTF-8"?>
<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
    xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
    <modelVersion>4.0.0</modelVersion>

    <groupId>com.loren</groupId>
    <artifactId>LAR</artifactId>
    <version>0.0.1-SNAPSHOT</version>
    <packaging>war</packaging>

    <name>LAR</name>
    <description>Demo project for Spring Boot</description>

    <parent>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-parent</artifactId>
        <version>1.5.8.RELEASE</version>
        <relativePath/> <!-- lookup parent from repository -->
    </parent>

    <properties>
        <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
        <project.reporting.outputEncoding>UTF-8</project.reporting.outputEncoding>
        <java.version>1.8</java.version>
    </properties>

    <dependencies>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-web</artifactId>
        </dependency>

        <dependency>
            <groupId>mysql</groupId>
            <artifactId>mysql-connector-java</artifactId>
            <scope>runtime</scope>
        </dependency>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-tomcat</artifactId>
            <scope>provided</scope>
        </dependency>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-test</artifactId>
            <scope>test</scope>
        </dependency>
        <dependency>  
           <groupId>org.springframework.boot</groupId>  
           <artifactId>spring-boot-starter-data-jpa</artifactId>  
        </dependency>  
        <dependency>  
            <groupId>org.springframework.boot</groupId>  
            <artifactId>spring-boot-starter-thymeleaf</artifactId>  
        </dependency>  

        <dependency>  
            <groupId>com.alibaba</groupId>  
            <artifactId>fastjson</artifactId>  
            <version>1.2.16</version>  
        </dependency>

        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-freemarker</artifactId>
        </dependency>
    </dependencies>

    <build>
        <plugins>
            <plugin>
                <groupId>org.springframework.boot</groupId>
                <artifactId>spring-boot-maven-plugin</artifactId>
            </plugin>
        </plugins>
    </build>


</project>

• 编写application.yml，使项目连接到MySql数据库

server: 
    port: 8080
    context-path: /

spring: 
    datasource:
      driver-class-name: com.mysql.jdbc.Driver
      url: jdbc:mysql://localhost:3306/db_user
      username: root
      password: 123456
    jpa:
      hibernate:
        ddl-auto: update
      show-sql: true  

• 创建实体对象Use

package com.loren.demo.entity;

import javax.persistence.Entity;
import javax.persistence.GeneratedValue;
import javax.persistence.Id;

@Entity
public class User{
    
    @Id
    @GeneratedValue
    private Long id;
    private String username;
    private String password;
    private String tel;
    private String realname;


    public UserEntity() {}
    public UserEntity(String username,String password) {
        this.username=username;
        this.password=password;
    }
    public Long getId() {
        return id;
    }
    public void setId(Long id) {
        this.id = id;
    }
    public String getUsername() {
        return username;
    }
    public void setUsername(String username) {
        this.username = username;
    }
    public String getPassword() {
        return password;
    }
    public void setPassword(String password) {
        this.password = password;
    }
    public String getTel() {
        return tel;
    }
    public void setTel(String tel) {
        this.tel = tel;
    }
    public String getRealname() {
        return realname;
    }
    public void setRealname(String realname) {
        this.realname = realname;
    }

}

• 创建UserDao

package com.loren.demo.dao;

import org.springframework.data.jpa.repository.JpaRepository;
import org.springframework.data.jpa.repository.Query;
import org.springframework.data.repository.CrudRepository;
import org.springframework.stereotype.Repository;

import com.loren.demo.entity.User;

@Repository
public interface UserDao extends JpaRepository<User, Long>{
    @Query("select s from User s where s.username=?1 and s.password=?2")
    public UserEntity findBynameAndPassword(String username,String password);
    @Query("select s from User s where s.username=?")
    public UserEntity findByName(String username);

}

• 创建UserController

package com.loren.demo.controller;

import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpSession;

import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Controller;
import org.springframework.web.bind.annotation.RequestMapping;

import com.loren.demo.dao.UserDao;
import com.loren.demo.entity.UserEntity;

@Controller
@RequestMapping("/user/*")
public class IndexController {
    
    @Autowired
    private UserDao userdao;

    private User user=new User();

    @RequestMapping("/index")
    public String index(HttpSession httpSession) {
        httpSession.getAttribute("userLogin");
        return "index";
    }


    @RequestMapping("/register")
    public String register() {
        return "register";
    }

    @RequestMapping("/login")
    public String login() {
        String str="";
        String username=user.getUsername();
        if(username!=null) {
        str="index";
        }else {
            str="login";
        }
        return str;
    }


    @RequestMapping("/uregister")
    public String register(HttpServletRequest request) {
        String username=request.getParameter("username");
        String password=request.getParameter("password");
        String password2=request.getParameter("password2");
        String realname=request.getParameter("realname");
        String str="";
        if(password.equals(password2)) {
            user=userdao.findByName(username);
            if(user==null) {
            User user=new User();
            user.setUsername(username);
            user.setPassword(password);
            user.setRealname(realname);
            userdao.save(user);
            str="login";
            }else {
                str="register";
            }
        }else {
            str="register";
        }
            return str;
    }


    @RequestMapping("/ulogin")
    public String login(HttpServletRequest request,HttpSession session) {
        String username=request.getParameter("username");
        String password=request.getParameter("password");
        user=userdao.findBynameAndPassword(username, password);
        String str="";
        if(user!=null) {
            session.setAttribute("userLogin", user);
            str="index";
        }else {
            str="login";
        }
        return str;
    }
}

• 创建login.ftl

<!DOCTYPE html>
<html>
<head>
<meta charset="UTF-8" />
<title>登陆</title>
</head>
<body>
    <form action="/user/ulogin" method="post">
        <input type="text" name="username" /></br>
        <input type="password" name="password" /></br>
        <input type="submit" value="登陆" /></br>
        <a href="register.html" target="_blank">注册</a>
    </form>
</body>
</html>

• 创建register.ftl

<!DOCTYPE html>
<html>
<head>
<meta charset="UTF-8" />
<title>注册</title>
</head>
<body>
    <form action="/user/uregister" method="post">
        用户名:<input type="text" name="username" /></br>
        密码:<input type="password" name="password" /></br>
        确认密码:<input type="password" name="password2" /></br>
        真实姓名:<input type="text" name="realname" /></br>
        <input type="submit" value="注册">
    </form>
</body>
</html>

• 创建index.ftl

    <!DOCTYPE html>
<html>
<head>
<meta charset="UTF-8" />
<title>登陆成功</title>
</head>
<body>
欢迎您${userLogin.realname }
</body>
</html>