利用IDEA搭建SpringBoot项目，整合mybatis，实现简单的登录功能。

分手后的思念是犯贱 2021-07-26 18:56 368阅读 0赞

Spring Boot 主要目标是：

*  为所有 Spring 的开发者提供一个非常快速的、广泛接受的入门体验
 *  开箱即用（启动器starter-其实就是SpringBoot提供的一个jar包），但通过自己设置参数（.properties），即可快速摆脱这种方式。
 *  提供了一些大型项目中常见的非功能性特性，如内嵌服务器、安全、指标，健康检测、外部化配置等
 *  绝对没有代码生成，也无需 XML 配置。

更多细节，大家可以到[官网][Link 1]查看。

**创建maven项目时，groupid和artifactid怎么写比较合适呢？**

这两个属性，就可以理解成地球上的经纬度，maven仓库，就是相应的地球。当我们要去某一个点找寻龙珠的时候，必要通过龙珠搜索器才能找得到。龙珠搜索器就是通过“经纬度”才能定位到龙珠的地点！

**groupid呢，分为三段**

第一段：域。常见的有：cn(china)，org(非营利组织)，com(商业组织)

第二段：组织。如果你是美团的，就是meituan。如果是个人的小项目，比如说，就是Only。

第三段：子项目。你创建这个项目，肯定是有名字的对伐。这里，就写你项目的名字。

**artifactid呢，我觉得一段两段都可以**

一段怎么讲？就是子项目名就ok

两端怎么说？子项目还能继续细分，比如测试项目，那就是xxx-test。再比如说练习项目，那就是xxx-train。

--------------------

### 一，搭建项目： ###

**1、**打开IDEA，点击File→New→Project...

![watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3FxXzIwNzU3NDg5_size_16_color_FFFFFF_t_70][]

**2、**点击project...后，选择java jdk版本，然后点击next

而Spring initializr 是Spring 官方提供的一个用来初始化一个Spring boot 项目的工具。在idea中，当我们选择project...后， 在左侧就能看到Spring initializr， 点击Next 就可以选择组件。

![watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3FxXzIwNzU3NDg5_size_16_color_FFFFFF_t_70 1][]

**3、**接下来修改 **groupid **和 **artifactid **。然后点击NEXT进行下一步

![watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3FxXzIwNzU3NDg5_size_16_color_FFFFFF_t_70 2][]

**5、**在当前页面中我们一次选择左侧的Web、Template Engines、SQL。然后在中间部分选择我们需要的选项，最终选择结果如最右侧所示。然后点击NEXT，进行下一步。

![watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3FxXzIwNzU3NDg5_size_16_color_FFFFFF_t_70 3][]

![watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3FxXzIwNzU3NDg5_size_16_color_FFFFFF_t_70 4][]

![watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3FxXzIwNzU3NDg5_size_16_color_FFFFFF_t_70 5][]

**6、**进人创建项目的最后一个页面，在这里我们可以修改项目保存的位置。确认自己输入的内容，点击Fiish即可完成项目的创建

![watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3FxXzIwNzU3NDg5_size_16_color_FFFFFF_t_70 6][]

**6、点击finish，完成项目初始化。**

### 二、启动项目、添加配置文件等 ###

1、打开新项目后，我们可以观察一下左侧的项目结构。

生成的项目中，resources文件夹下，static文件夹下存放静态文件，比如css、js、html和图片等 。

templates下存放html文件，controller默认访问该文件夹下的html文件。

这个在application.properties配置文件中是可以修改的。

![watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3FxXzIwNzU3NDg5_size_16_color_FFFFFF_t_70 7][]

下面为项目生成的**pom.xml**文件：

<?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 https://maven.apache.org/xsd/maven-4.0.0.xsd">
    	<modelVersion>4.0.0</modelVersion>
    	<parent>
    		<groupId>org.springframework.boot</groupId>
    		<artifactId>spring-boot-starter-parent</artifactId>
    		<version>2.1.9.RELEASE</version>
    		<relativePath/> 
    	</parent>
    	<groupId>com.only-demo</groupId>
    	<artifactId>springboot-demo</artifactId>
    	<version>0.0.1-SNAPSHOT</version>
    	<name>springboot-demo</name>
    	<description>Demo project for Spring Boot</description>
    
    	<properties>
    		<java.version>1.8</java.version>
    	</properties>
    
    	<dependencies>
    		<dependency>
    			<groupId>org.springframework.boot</groupId>
    			<artifactId>spring-boot-starter-data-jdbc</artifactId>
    		</dependency>
    		<dependency>
    			<groupId>org.springframework.boot</groupId>
    			<artifactId>spring-boot-starter-thymeleaf</artifactId>
    		</dependency>
    		<dependency>
    			<groupId>org.springframework.boot</groupId>
    			<artifactId>spring-boot-starter-web</artifactId>
    		</dependency>
    		<dependency>
    			<groupId>org.mybatis.spring.boot</groupId>
    			<artifactId>mybatis-spring-boot-starter</artifactId>
    			<version>2.1.0</version>
    		</dependency>
    
    		<dependency>
    			<groupId>mysql</groupId>
    			<artifactId>mysql-connector-java</artifactId>
    			<scope>runtime</scope>
    		</dependency>
    		<dependency>
    			<groupId>org.springframework.boot</groupId>
    			<artifactId>spring-boot-starter-test</artifactId>
    			<scope>test</scope>
    		</dependency>
    	</dependencies>
    
    	<build>
    		<plugins>
    			<plugin>
    				<groupId>org.springframework.boot</groupId>
    				<artifactId>spring-boot-maven-plugin</artifactId>
    			</plugin>
    		</plugins>
    	</build>
    
    </project>

**2、**了解项目的文件结构后，我们尝试着启动项目。我们发现项目启动过程中出现错误，错误信息如图。

![watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3FxXzIwNzU3NDg5_size_16_color_FFFFFF_t_70 8][]

这是因为我们创建Spring Boot项目初始化时，在选择组件时添加了mysql、mybatis，但现在还没有配置数据库，导致项目启动报错。

我们需要在项目的application.properties文件中配置数据信息。如图所示，是我自己配置的数据库，具体情况根据自己数据库的设置配置。

![20191009122209532.png][]

spring.datasource.driver-class-name = com.mysql.jdbc.Driver
    spring.datasource.url = jdbc:mysql://127.0.0.1:3306/ssm
    spring.datasource.username = root
    spring.datasource.password = nideshengri

数据库采用MySQL数据库，下面是数据库的设计，只有几个简单的字段

![watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3FxXzIwNzU3NDg5_size_16_color_FFFFFF_t_70 9][]

这里也可以不使用**application.properties**文件，采用更加简洁的**application.yml**文件。将resource文件夹下原有的**application.properties**文件删除，创建**application.yml**配置文件（备注：其实SpringBoot底层会把application.yml文件解析为application.properties）， 文件的内容如下(此处只配置最基本的)：

接下来再次尝试重新启动项目。发现项目可以正常启动了。可以打开浏览器访问[http://localhost:8080/][http_localhost_8080]，访问结果如图所示。证明项目正常启动了。

![watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3FxXzIwNzU3NDg5_size_16_color_FFFFFF_t_70 10][]

### 三、项目整合mybatis ###

**1、**在**application.yml**文件中添加mybatis。

server:
      port: 8080
    spring:
        datasource:
            name: ssm
            url: jdbc:mysql://127.0.0.1:3306/ssm?serverTimezone=UTC
            username: root
            password: nideshengri
            driver-class-name: com.mysql.jdbc.Driver
    
    
    mybatis:
      mapper-locations: classpath:mapper/*.xml  #注意：一定要对应mapper映射xml文件的所在路径
      type-aliases-package: com.onlydemo.springbootdemo.entity  # 注意：对应实体类的路径
      configuration:
          log-impl: org.apache.ibatis.logging.stdout.StdOutImpl #日志打印sql语句

**2、**在**pom.xml**中添加 **mybatis generator **自动生成代码插件。

<build>
    		<plugins>
    			<plugin>
    				<groupId>org.springframework.boot</groupId>
    				<artifactId>spring-boot-maven-plugin</artifactId>
    			</plugin>
    			
    			<plugin>
    				<groupId>org.mybatis.generator</groupId>
    				<artifactId>mybatis-generator-maven-plugin</artifactId>
    				<version>1.3.1</version>
    				<configuration>
    					<configurationFile>${basedir}/src/main/resources/generator/generatorConfig.xml</configurationFile>
    					<overwrite>true</overwrite>
    					<verbose>true</verbose>
    				</configuration>
    			</plugin>
    		</plugins>
    	</build>

**3、**在**resource**文件夹下创建**generator**文件夹，并在文件夹中创建**generatorConfig.xml**文件。文件内容如下所示：

<?xml version="1.0" encoding="UTF-8"?>
    <!DOCTYPE generatorConfiguration
            PUBLIC "-//mybatis.org//DTD MyBatis Generator Configuration 1.0//EN"
            "http://mybatis.org/dtd/mybatis-generator-config_1_0.dtd">
    <generatorConfiguration>
        
        <classPathEntry  location="D:\Develop\MySQL\mysql-connector-java-5.1.36.jar"/>
        <context id="DB2Tables"  targetRuntime="MyBatis3">
            <commentGenerator>
                <property name="suppressDate" value="true"/>
                
                <property name="suppressAllComments" value="false"/>
            </commentGenerator>
            
            <jdbcConnection driverClass="com.mysql.jdbc.Driver" connectionURL="jdbc:mysql://127.0.0.1/ssm" userId="root" password="nideshengri">
            </jdbcConnection>
            <javaTypeResolver>
                <property name="forceBigDecimals" value="false"/>
            </javaTypeResolver>
            
            <javaModelGenerator targetPackage="com.onlydemo.springbootdemo.entity" targetProject="src/main/java">
                <property name="enableSubPackages" value="true"/>
                <property name="trimStrings" value="true"/>
            </javaModelGenerator>
            
            <sqlMapGenerator targetPackage="resources.mapper" targetProject="src/main">
                <property name="enableSubPackages" value="true"/>
            </sqlMapGenerator>
            
            <javaClientGenerator type="XMLMAPPER" targetPackage="com.onlydemo.springbootdemo.mapper" targetProject="src/main/java">
                <property name="enableSubPackages" value="true"/>
            </javaClientGenerator>
            
            <table tableName="user" domainObjectName="user" enableCountByExample="false" enableUpdateByExample="false" enableDeleteByExample="false" enableSelectByExample="false" selectByExampleQueryId="false"></table>
        </context>
    </generatorConfiguration>

**4、**所有文件创建完成后，还需要进行简单的配置。Run→Edit Configurations...，然后选择maven，配置Command line

![watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3FxXzIwNzU3NDg5_size_16_color_FFFFFF_t_70 11][]

![watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3FxXzIwNzU3NDg5_size_16_color_FFFFFF_t_70 12][]

![watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3FxXzIwNzU3NDg5_size_16_color_FFFFFF_t_70 13][]

**5、**所用文件创建完成，并配置好相关设置，重新启动项目，启动后运行generator。通过控制台可以看见代码是否生成成功，或失败的原因。如果代码生成成功，可以在项目文件夹中看见生成的项目

![2019100913070618.png][]

这个过程共生成三个文件，一个实体类，dao，还有sql语句。

**5.1、生成的实体类entity：**

package com.onlydemo.springbootdemo.entity;
    
    public class user {
        /**
         * This field was generated by MyBatis Generator.
         * This field corresponds to the database column user.id
         *
         * @mbggenerated
         */
        private Integer id;
    
        /**
         * This field was generated by MyBatis Generator.
         * This field corresponds to the database column user.username
         *
         * @mbggenerated
         */
        private String username;
    
        /**
         * This field was generated by MyBatis Generator.
         * This field corresponds to the database column user.password
         *
         * @mbggenerated
         */
        private String password;
    
        /**
         * This field was generated by MyBatis Generator.
         * This field corresponds to the database column user.sex
         *
         * @mbggenerated
         */
        private String sex;
    
        /**
         * This field was generated by MyBatis Generator.
         * This field corresponds to the database column user.age
         *
         * @mbggenerated
         */
        private Integer age;
    
        /**
         * This method was generated by MyBatis Generator.
         * This method returns the value of the database column user.id
         *
         * @return the value of user.id
         *
         * @mbggenerated
         */
        public Integer getId() {
            return id;
        }
    
        /**
         * This method was generated by MyBatis Generator.
         * This method sets the value of the database column user.id
         *
         * @param id the value for user.id
         *
         * @mbggenerated
         */
        public void setId(Integer id) {
            this.id = id;
        }
    
        /**
         * This method was generated by MyBatis Generator.
         * This method returns the value of the database column user.username
         *
         * @return the value of user.username
         *
         * @mbggenerated
         */
        public String getUsername() {
            return username;
        }
    
        /**
         * This method was generated by MyBatis Generator.
         * This method sets the value of the database column user.username
         *
         * @param username the value for user.username
         *
         * @mbggenerated
         */
        public void setUsername(String username) {
            this.username = username == null ? null : username.trim();
        }
    
        /**
         * This method was generated by MyBatis Generator.
         * This method returns the value of the database column user.password
         *
         * @return the value of user.password
         *
         * @mbggenerated
         */
        public String getPassword() {
            return password;
        }
    
        /**
         * This method was generated by MyBatis Generator.
         * This method sets the value of the database column user.password
         *
         * @param password the value for user.password
         *
         * @mbggenerated
         */
        public void setPassword(String password) {
            this.password = password == null ? null : password.trim();
        }
    
        /**
         * This method was generated by MyBatis Generator.
         * This method returns the value of the database column user.sex
         *
         * @return the value of user.sex
         *
         * @mbggenerated
         */
        public String getSex() {
            return sex;
        }
    
        /**
         * This method was generated by MyBatis Generator.
         * This method sets the value of the database column user.sex
         *
         * @param sex the value for user.sex
         *
         * @mbggenerated
         */
        public void setSex(String sex) {
            this.sex = sex == null ? null : sex.trim();
        }
    
        /**
         * This method was generated by MyBatis Generator.
         * This method returns the value of the database column user.age
         *
         * @return the value of user.age
         *
         * @mbggenerated
         */
        public Integer getAge() {
            return age;
        }
    
        /**
         * This method was generated by MyBatis Generator.
         * This method sets the value of the database column user.age
         *
         * @param age the value for user.age
         *
         * @mbggenerated
         */
        public void setAge(Integer age) {
            this.age = age;
        }
    }

**5.2、生成的Dao：**

package com.onlydemo.springbootdemo.mapper;
    
    import com.onlydemo.springbootdemo.entity.user;
    
    public interface userMapper {
        /**
         * This method was generated by MyBatis Generator.
         * This method corresponds to the database table user
         *
         * @mbggenerated
         */
        int deleteByPrimaryKey(Integer id);
    
        /**
         * This method was generated by MyBatis Generator.
         * This method corresponds to the database table user
         *
         * @mbggenerated
         */
        int insert(user record);
    
        /**
         * This method was generated by MyBatis Generator.
         * This method corresponds to the database table user
         *
         * @mbggenerated
         */
        int insertSelective(user record);
    
        /**
         * This method was generated by MyBatis Generator.
         * This method corresponds to the database table user
         *
         * @mbggenerated
         */
        user selectByPrimaryKey(Integer id);
    
        /**
         * This method was generated by MyBatis Generator.
         * This method corresponds to the database table user
         *
         * @mbggenerated
         */
        int updateByPrimaryKeySelective(user record);
    
        /**
         * This method was generated by MyBatis Generator.
         * This method corresponds to the database table user
         *
         * @mbggenerated
         */
        int updateByPrimaryKey(user record);
    }

**5.3、生成的SQL语句（其中一些没有用的注释被我删掉了）：**

<?xml version="1.0" encoding="UTF-8" ?>
    <!DOCTYPE mapper PUBLIC "-//mybatis.org//DTD Mapper 3.0//EN" "http://mybatis.org/dtd/mybatis-3-mapper.dtd" >
    <mapper namespace="com.onlydemo.springbootdemo.mapper.userMapper" >
      <resultMap id="BaseResultMap" type="com.onlydemo.springbootdemo.entity.user" >
        
        <id column="id" property="id" jdbcType="INTEGER" />
        <result column="username" property="username" jdbcType="VARCHAR" />
        <result column="password" property="password" jdbcType="VARCHAR" />
        <result column="sex" property="sex" jdbcType="VARCHAR" />
        <result column="age" property="age" jdbcType="INTEGER" />
      </resultMap>
      <sql id="Base_Column_List" >
        
        id, username, password, sex, age
      </sql>
      <select id="selectByPrimaryKey" resultMap="BaseResultMap" parameterType="java.lang.Integer" >
        
        select 
        <include refid="Base_Column_List" />
        from user
        where id = #{id,jdbcType=INTEGER}
      </select>
      <delete id="deleteByPrimaryKey" parameterType="java.lang.Integer" >
        
        delete from user
        where id = #{id,jdbcType=INTEGER}
      </delete>
      <insert id="insert" parameterType="com.onlydemo.springbootdemo.entity.user" >
        
        insert into user (id, username, password, 
          sex, age)
        values (#{id,jdbcType=INTEGER}, #{username,jdbcType=VARCHAR}, #{password,jdbcType=VARCHAR}, 
          #{sex,jdbcType=VARCHAR}, #{age,jdbcType=INTEGER})
      </insert>
      <insert id="insertSelective" parameterType="com.onlydemo.springbootdemo.entity.user" >
        
        insert into user
        <trim prefix="(" suffix=")" suffixOverrides="," >
          <if test="id != null" >
            id,
          </if>
          <if test="username != null" >
            username,
          </if>
          <if test="password != null" >
            password,
          </if>
          <if test="sex != null" >
            sex,
          </if>
          <if test="age != null" >
            age,
          </if>
        </trim>
        <trim prefix="values (" suffix=")" suffixOverrides="," >
          <if test="id != null" >
            #{id,jdbcType=INTEGER},
          </if>
          <if test="username != null" >
            #{username,jdbcType=VARCHAR},
          </if>
          <if test="password != null" >
            #{password,jdbcType=VARCHAR},
          </if>
          <if test="sex != null" >
            #{sex,jdbcType=VARCHAR},
          </if>
          <if test="age != null" >
            #{age,jdbcType=INTEGER},
          </if>
        </trim>
      </insert>
      <update id="updateByPrimaryKeySelective" parameterType="com.onlydemo.springbootdemo.entity.user" >
        
        update user
        <set >
          <if test="username != null" >
            username = #{username,jdbcType=VARCHAR},
          </if>
          <if test="password != null" >
            password = #{password,jdbcType=VARCHAR},
          </if>
          <if test="sex != null" >
            sex = #{sex,jdbcType=VARCHAR},
          </if>
          <if test="age != null" >
            age = #{age,jdbcType=INTEGER},
          </if>
        </set>
        where id = #{id,jdbcType=INTEGER}
      </update>
      <update id="updateByPrimaryKey" parameterType="com.onlydemo.springbootdemo.entity.user" >
        
        update user
        set username = #{username,jdbcType=VARCHAR},
          password = #{password,jdbcType=VARCHAR},
          sex = #{sex,jdbcType=VARCHAR},
          age = #{age,jdbcType=INTEGER}
        where id = #{id,jdbcType=INTEGER}
      </update>
    </mapper>

### 四、测试访问 ###

做好以上的准备以后，可以简单的写一个小页面，试着访问一下。

同时这个时候可以自己了解一下**@Controller**与**@RestController**的区别，以及**@ResponseBody**的用法。

**1、**比如templates下面写一个简单的HTML页面，**HelloWord.html**。

<!DOCTYPE html>
    <html lang="en">
    <head>
        <meta charset="UTF-8">
        <title>HelloWord</title>
    </head>
    <body>
    <h1>hello springboot!!!</h1>
    </body>
    </html>

**2、**访问页面的controller。**HelloController.java**

package com.onlydemo.springbootdemo.controller;
    
    import org.springframework.stereotype.Controller;
    import org.springframework.web.bind.annotation.RequestMapping;
    
    /**
     * @ClassName helloController
     * @Author liming
     * @Description //TODO
     * @Date 2019/10/9 13:13
     **/
    @Controller
    @RequestMapping(value = {"/hello"})
    public class HelloController {
        @RequestMapping(value = {"/springboot"})
        public String hello(){
            return "HelloWord";
        }
    }

**3、重新启动项目，访问[http://localhost:8080/hello/springboot][http_localhost_8080_hello_springboot]，访问的结果如下所示。**

![watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3FxXzIwNzU3NDg5_size_16_color_FFFFFF_t_70 14][]

### **五、编写用户登录过程代码** ###

**1、**编写简单的登录页面与注册页面

（1）登录页面  **userLogin.html**

<!DOCTYPE html>
    <html lang="en">
    <head>
        <meta charset="UTF-8">
        <title>用户登录</title>
    </head>
    <body>
    请输入用户名与密码登录
    <form action="/userLogin" method="post">
        用户名：<input type="text" name="username" /><br>
        密   码：<input type="password" name="password" /><br>
        <input type="submit" value="登录" />
        <a href="/registerpage" target="_blank">注册</a>
    </form>
    </body>
    </html>

页面效果：

![2019100913293731.png][]

（3）登录成功页面  **loginSuccess.html**

<!DOCTYPE html>
    <html lang="en">
    <head>
        <meta charset="UTF-8">
        <title>登录成功</title>
    </head>
    <body>
    <h1>用户名与密码正确，登录成功！！！</h1>
     
    </body>
    </html>

页面效果：

![20191009140057684.png][]

（4）登录失败页面  **loginError.html**

<!DOCTYPE html>
    <html lang="en">
    <head>
        <meta charset="UTF-8">
        <title>登录失败</title>
    </head>
    <body>
    <h1>用户名或密码错误，登录失败！！！</h1>
    </body>
    </html>

页面效果：

![20191009141603539.png][]

**2、**对于写代码的顺序，我是从xml（sql语句）开始写，然后Dao，Service，最后写Controller。下面为我的部分代码。（开始生成的代码没有用到的部分被我删除掉了）

（1）xml（sql语句） **userMapper.xml**

<?xml version="1.0" encoding="UTF-8" ?>
    <!DOCTYPE mapper PUBLIC "-//mybatis.org//DTD Mapper 3.0//EN" "http://mybatis.org/dtd/mybatis-3-mapper.dtd" >
    <mapper namespace="com.onlydemo.springbootdemo.mapper.userMapper" >
      
      <select id="userlogin" parameterType="user" resultType="User">
        SELECT id,username,password,age FROM user WHERE username = #{username} AND password = #{password}
      </select>
    
      
      <insert id="adduser" parameterType="user" useGeneratedKeys="true" keyProperty="id">
        INSERT INTO user (username,password,age) VALUES (#{username},#{password},#{age})
      </insert>
    
      
      <insert id="adduser1" parameterType="user">
        INSERT INTO user (id,username,password,age) VALUES (UUID(),#{username},#{password},#{age})
      </insert>
    </mapper>

（2）Dao层 **userMapper.java**

package com.onlydemo.springbootdemo.mapper;
    
    import com.onlydemo.springbootdemo.entity.User;
    import org.apache.ibatis.annotations.Mapper;
    import org.apache.ibatis.annotations.Param;
    import org.springframework.stereotype.Component;
    
    @Mapper
    @Component
    public interface userMapper {
        //用户登录
        User userlogin(@Param("username") String username, @Param("password") String password);
    
        //注册新用户(方式1)
        int adduser(@Param("username") String username, @Param("password") String password, @Param("age") int age);
    
        //注册新用户（方式2）
        int adduser1(@Param("username") String username, @Param("password") String password, @Param("age") int age);
    
    }

（3）Servicr层  **UserLoginService.java**

package com.onlydemo.springbootdemo.service;
    
    import com.onlydemo.springbootdemo.entity.User;
    import com.onlydemo.springbootdemo.mapper.userMapper;
    import org.springframework.beans.factory.annotation.Autowired;
    import org.springframework.stereotype.Service;
    
    /**
     * @ClassName UserLoginService
     * @Author liming
     * @Description //TODO
     * @Date 2019/10/9 14:43
     **/
    @Service
    public class UserLoginService {
        /**
         * 注入dao
         */
        @Autowired
        private userMapper usermapper;
    
        //用户登录
        public User userLogin(String username, String password){
            User user = usermapper.userlogin(username,password);
            return user;
        }
    
        //注册新用户
        public int adduser(String username,String password,int age){
            return usermapper.adduser(username,password,age);
            //return usermapper.adduser1(username,password,age);     //对应sql语句中的第二种注册方式
        }
    }

（4）Controller层  **UserLoginController.java**

package com.onlydemo.springbootdemo.controller;
    
    import com.onlydemo.springbootdemo.entity.User;
    import com.onlydemo.springbootdemo.service.UserLoginService;
    import org.springframework.beans.factory.annotation.Autowired;
    import org.springframework.stereotype.Controller;
    import org.springframework.web.bind.annotation.RequestMapping;
    import org.springframework.web.bind.annotation.RequestParam;
    import org.springframework.web.bind.annotation.ResponseBody;
    
    import javax.servlet.http.HttpServletRequest;
    
    /**
     * @ClassName UserLoginController
     * @Author liming
     * @Description //TODO
     * @Date 2019/10/9 14:45
     **/
    @Controller
    public class UserLoginController {
    
        /**
         * 注入service
         */
        @Autowired
        private UserLoginService userLoginService;
    
        /**
         * 跳转到用户登录页面
         * @return 登录页面
         */
        @RequestMapping(value = {"/loginHtml"})
        public String loginHtml(){
            return "userLogin";
        }
    
        /**
         * 跳转到用户注册页面
         * @return 注册页面
         */
        @RequestMapping(value = {"/registerpage"})
        public String registerpage(){
            return "register";
        }
    
        /**
         * 获取用户名与密码，用户登录
         * @return 登录成功页面
         */
        @RequestMapping(value = {"/userLogin"})
        public String userLogin(@RequestParam("username") String username, @RequestParam("password") String password, HttpServletRequest request){
    
            User user = userLoginService.userLogin(username,password);
    
            if(user != null){                                                  //登录成功
                request.getSession().setAttribute("session_user",user);     //将用户信息放入session
                return "loginSuccess";
            }
            return "loginError";
        }
    
        /**
         * 注册新用户
         * @return 注册结果
         */
        @ResponseBody
        @RequestMapping(value = {"/uregister"})
        public String addUser(@RequestParam("username") String username,
                              @RequestParam("password") String password,
                              @RequestParam("password2") String password2,
                              @RequestParam("age") int age){
    
            if(!password.equals(password2)){
    
                return "两次密码不相同，注册失败！！";
            }else {
                int res = userLoginService.adduser(username,password,age);
                if(res == 0){
                    return "注册失败！";
                }else {
                    return "注册成功！";
                }
            }
    
        }
    }

[Link 1]: http://projects.spring.io/spring-boot/
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[20191009122209532.png]: /images/20210726/e8a889b26e144333836165041891cc92.png
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[http_localhost_8080]: http://localhost:8080/
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[2019100913070618.png]: /images/20210726/17ae2106abc3422291378aa1f9a2ab0e.png
[http_localhost_8080_hello_springboot]: http://localhost:8080/hello/springboot
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[2019100913293731.png]: /images/20210726/63cc037a9b154303ba58ce97c5d648cc.png
[20191009140057684.png]: /images/20210726/faf9a6f8c15a411782b684e974827db4.png
[20191009141603539.png]: /images/20210726/e840e15dbcf84e09a6c2b6de75b8953f.png