SpringBoot与MyBatis整合，底层数据库为mysql的使用示例

Love The Way You Lie 2022-04-22 13:06 145阅读 0赞

** 项目下载链接：https://github.com/DFX339/bootdemo.git**

** **

**新建maven项目，web项目，项目名为 bootdemo**

项目结构目录如下:还有个pom.xml文件没有在截图里面

项目需要编写的文件主要有：

项目启动类：  Application.java   ServletInitializer.java

前端控制器类：UserController.java

业务层的接口与实现类：UserIservice.java  UserService.java

Mybatis的接口： UserMapper.java

接口对应的mapper文件：UserMapper.xml

实体类：User.java

maven项目的配置文件： pom.xml

![format_png][]

**（1）编写实体类 User.java**

![复制代码][aHR0cHM6Ly9jb21tb24uY25ibG9ncy5jb20vaW1hZ2VzL2NvcHljb2RlLmdpZg]

package smm.springboot_ftl.bean;
    
    /**
     * User实体类
     * @author Administrator
     *
     */
    public class User {
        
        private int id;
        private String username;
        private String password;
        private int age;
        
        public User(){}
    
        public int getId() {
            return id;
        }
    
        public void setId(int 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 int getAge() {
            return age;
        }
    
        public void setAge(int age) {
            this.age = age;
        }
        
    }

![复制代码][aHR0cHM6Ly9jb21tb24uY25ibG9ncy5jb20vaW1hZ2VzL2NvcHljb2RlLmdpZg]

**（2）登录mysql数据库，新建数据库 springboot\_mybatis（数据库名）**

新建表 user（表名），表的字段如图所示

![format_png 1][]

**（3）编写持久层接口：  UserMapper.java  (定义操作数据库的方法)  这里切记要用@Mapper注解标识**

![复制代码][aHR0cHM6Ly9jb21tb24uY25ibG9ncy5jb20vaW1hZ2VzL2NvcHljb2RlLmdpZg]

package smm.springboot_ftl.mapper;
    
    import org.apache.ibatis.annotations.Mapper;
    
    import smm.springboot_ftl.bean.User;
    
    @Mapper
    public interface UserMapper {
    
        public void insert(User user);
    
        public void update(User user);
        
        public void delete(int id);
        
        public User find(int id);
    }

![复制代码][aHR0cHM6Ly9jb21tb24uY25ibG9ncy5jb20vaW1hZ2VzL2NvcHljb2RlLmdpZg]

**（4）编写持久层接口对应的mapper.xml文件： UserMapper.xml  （编写增删改查对应的sql语句）**

** 存储位置： src/main/resources/mapper**

![复制代码][aHR0cHM6Ly9jb21tb24uY25ibG9ncy5jb20vaW1hZ2VzL2NvcHljb2RlLmdpZg]

<?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="smm.springboot_ftl.mapper.UserMapper">  
    
        
        <insert id = "insert" parameterType="smm.springboot_ftl.bean.User">
            INSERT INTO USER(ID,USERNAME,PASSWORD,AGE) VALUES(#{id},#{username},#{password},#{age});
        </insert>
        
        
        <update id="update" parameterType="smm.springboot_ftl.bean.User">
            UPDATE USER SET USERNAME=#{username} , PASSWORD=#{password} , AGE = #{age} WHERE ID=#{id}
        </update>
        
        
        <select id="find" parameterType="int" resultType="smm.springboot_ftl.bean.User">
            SELECT ID,USERNAME,PASSWORD,AGE FROM USER WHERE ID=#{0}
        </select>
        
        
        <delete id="delete" parameterType="int">
            DELETE FROM USER WHERE ID=#{0}
        </delete>
    </mapper>

![复制代码][aHR0cHM6Ly9jb21tb24uY25ibG9ncy5jb20vaW1hZ2VzL2NvcHljb2RlLmdpZg]

**（5）编写业务层接口： UserIService.java**

![复制代码][aHR0cHM6Ly9jb21tb24uY25ibG9ncy5jb20vaW1hZ2VzL2NvcHljb2RlLmdpZg]

package smm.springboot_ftl.service;
    
    import org.springframework.stereotype.Component;
    
    import smm.springboot_ftl.bean.User;
    
    
    public interface UserIService {
        
        public void insert(User user);

public void update(User user) ；
    
        public User find(int id)；
      
        public void delete(int id)；

}

![复制代码][aHR0cHM6Ly9jb21tb24uY25ibG9ncy5jb20vaW1hZ2VzL2NvcHljb2RlLmdpZg]

**（6）编写业务层接口的实现类：UserService.java （切记要使用@Service("userService")类标识类，表示这是service）**

@ComponentScan({"ssm.springboot_ftl.mapper"})：是为了找到对应的UserMapper对象

![复制代码][aHR0cHM6Ly9jb21tb24uY25ibG9ncy5jb20vaW1hZ2VzL2NvcHljb2RlLmdpZg]

package smm.springboot_ftl.service;
    
    import javax.annotation.Resource;
    
    import org.springframework.context.annotation.ComponentScan;
    import org.springframework.stereotype.Component;
    import org.springframework.stereotype.Service;
    
    import smm.springboot_ftl.bean.User;
    import smm.springboot_ftl.mapper.UserMapper;
    
    
    @ComponentScan({"ssm.springboot_ftl.mapper"})
    @Service("userService")
    public class UserService implements UserIService{
    
        @Resource
        private UserMapper userMapper;
        
        @Override
        public void insert(User user) {
            userMapper.insert(user);
        }
    
        public void update(User user) {
            userMapper.update(user);
        }
    
        public User find(int id) {
            return userMapper.find(id);
        }
        
        public void delete(int id){
            userMapper.delete(id);
        }
    }

![复制代码][aHR0cHM6Ly9jb21tb24uY25ibG9ncy5jb20vaW1hZ2VzL2NvcHljb2RlLmdpZg]

**（7）编写前端控制器类： UserController.java**

切记需要使用 @RestController 标识这个类，SpringBoot中新加的注解。

@RestController注解，相当于@Controller+@ResponseBody两个注解的结合，返回json数据不需要在方法前面加@ResponseBody注解了，但使用@RestController这个注解，就不能返回jsp,html页面，视图解析器无法解析jsp,html页面

如果需要返回数据到jsp或者html页面，则使用@Controller注解。这里推荐使用@Controller注解，因为需要直接返回数据的时候可以增加@ResponseBody注解

@ComponentScan(\{"smm.springboot\_ftl.service"\}) ：标识业务层的类，用来找到业务层对象，smm.springboot\_ftl.service是业务类的路径

@MapperScan("smm.springboot\_ftl.mapper") ：标识持久层mapper接口，用来找到mapper对象， smm.springboot\_ftl.mapper是接口的路径

这三个注解都不能少！！！ 少了SpringBoot就无法正常启动了！！

![复制代码][aHR0cHM6Ly9jb21tb24uY25ibG9ncy5jb20vaW1hZ2VzL2NvcHljb2RlLmdpZg]

package smm.springboot_ftl.action;
    
    import java.util.Map;
    
    import javax.annotation.Resource;
    
    import org.mybatis.spring.annotation.MapperScan;
    import org.springframework.boot.SpringApplication;
    import org.springframework.boot.autoconfigure.EnableAutoConfiguration;
    import org.springframework.boot.autoconfigure.SpringBootApplication;
    import org.springframework.context.annotation.ComponentScan;
    import org.springframework.stereotype.Controller;
    import org.springframework.web.bind.annotation.RequestMapping;
    import org.springframework.web.bind.annotation.RequestMethod;
    import org.springframework.web.bind.annotation.RestController;
    import org.springframework.web.servlet.ModelAndView;
    
    import smm.springboot_ftl.bean.User;
    import smm.springboot_ftl.service.UserService;
    /**
     * 在定义一个Rest接口时，我们通常会使用GET，POST，PUT，DELETE几种方式来完成我们所需要进行CRUD的一些操作，
     * 我们在这里罗列和教大家在实际开发中的使用，一些基本概念我们就不再赘述，例如使用POST的优缺点，可使用参数的大小限制等地：
    
        GET：一般用于查询数据，不办函数据的更新以及插入操作。由于明文传输的关系，我们一般用来获取一些无关用户的信息。
    
        POST：一般用于数据的插入操作，也是使用最多的传输方式，但是在H5调用时会有跨域的问题，一般使用JSONP来解决。
    
        PUT：我们使用PUT方式来对数据进行更新操作。
    
        DELETE：用于数据删除，注意在数据库内是逻辑删除（改变数据状态，用户不再查询得到，但还保留在数据库内）还是物理删除（真删了）。
    
     * @author Administrator
     *
     */
    @RestController
    @ComponentScan({"smm.springboot_ftl.service"})
    @MapperScan("smm.springboot_ftl.mapper")
    public class UserController {
        
        @Resource
        private UserService userService;
        
         @RequestMapping("/say")  
         public String say(){  
             return "springboot-a"+userService;
         }  
        
        @RequestMapping("/find")
        public String find(){
            User user =  userService.find(18);
            ModelAndView mav = new ModelAndView();
            mav.addObject("user","sadf");
            return "HelloWord"+"fasdf--"+user.getUsername()+"--"+user.getPassword();
        }
        
        
        @RequestMapping("/ajax")
        public String find1(){
            return "[''message':'123dfx']";
        }
        
    //    public static void main(String[] args){
    //        SpringApplication.run(UserController.class,args);
    //    }
    }

![复制代码][aHR0cHM6Ly9jb21tb24uY25ibG9ncy5jb20vaW1hZ2VzL2NvcHljb2RlLmdpZg]

**（8）ServletInitializer.java  这个类的主要内容如下：**

![复制代码][aHR0cHM6Ly9jb21tb24uY25ibG9ncy5jb20vaW1hZ2VzL2NvcHljb2RlLmdpZg]

package smm.springboot_ftl;
    
    import org.springframework.boot.builder.SpringApplicationBuilder;
    import org.springframework.boot.web.support.SpringBootServletInitializer;
    
    public class ServletInitializer extends SpringBootServletInitializer {
    
        @Override
        protected SpringApplicationBuilder configure(SpringApplicationBuilder application) {
            return application.sources(Application.class);
        }
    
    }

![复制代码][aHR0cHM6Ly9jb21tb24uY25ibG9ncy5jb20vaW1hZ2VzL2NvcHljb2RlLmdpZg]

**（9）SpringBoot的配置文件： application.properties 文件内容如下：**

** 存储位置： src/main/resources**

**server.context-path ： 配置访问该项目的项目路径，不配置时默认为 /  ,配置后必须加上项目名才能访问项目**

![复制代码][aHR0cHM6Ly9jb21tb24uY25ibG9ncy5jb20vaW1hZ2VzL2NvcHljb2RlLmdpZg]

server.context-path=/HelloWorld
    
    spring.datasource.driver-class-name =com.mysql.jdbc.Driver
    spring.datasource.url =jdbc:mysql://localhost:3306/springboot_mybatis
    spring.datasource.username =root
    spring.datasource.password =root
          
    mybatis.typeAliasesPackage=smm.springboot_ftl.bean  
    mybatis.mapperLocations=classpath:/mapper/UserMapper.xml 
    
    ## Freemarker \u914D\u7F6E  
    ## \u6587\u4EF6\u914D\u7F6E\u8DEF\u5F84
    spring.freemarker.template-loader-path=classpath:/templates/
    spring.freemarker.cache=false
    spring.freemarker.charset=UTF-8
    spring.freemarker.check-template-location=true
    spring.freemarker.content-type=text/html
    spring.freemarker.expose-request-attributes=true
    spring.freemarker.expose-session-attributes=true
    spring.freemarker.request-context-attribute=request
    spring.freemarker.suffix=.ftl

![复制代码][aHR0cHM6Ly9jb21tb24uY25ibG9ncy5jb20vaW1hZ2VzL2NvcHljb2RlLmdpZg]

**（10）配置maven项目的配置文件，pom.xml**

![复制代码][aHR0cHM6Ly9jb21tb24uY25ibG9ncy5jb20vaW1hZ2VzL2NvcHljb2RlLmdpZg]

<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/maven-v4_0_0.xsd">
        <modelVersion>4.0.0</modelVersion>
        <groupId>smm</groupId>
        <artifactId>bootdemo</artifactId>
        <packaging>war</packaging>
        <version>0.0.1-SNAPSHOT</version>
        <name>bootdemo Maven Webapp</name>
        <url>http://maven.apache.org</url>
        
        <parent>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-parent</artifactId>
            <version>1.5.6.RELEASE</version>
            <relativePath/> 
        </parent>
        
        <build>
            <finalName>bootdemo</finalName>
            <plugins>
                <plugin>
                    <inherited>true</inherited>
                    <groupId>org.apache.maven.plugins</groupId>
                    <artifactId>maven-compiler-plugin</artifactId>
                    <version>3.5.1</version>
                    <configuration>
                        <source>${compiler.source}</source>
                        <target>${compiler.target}</target>
                        <encoding>${project.build.sourceEncoding}</encoding>
                        <compilerArguments>
                            <extdirs>${project.basedir}/src/main/webapp/WEB-INF/lib</extdirs>
                        </compilerArguments>
                    </configuration>
                </plugin>
                
                <plugin>
                    <groupId>org.springframework.boot</groupId>
                    <artifactId>spring-boot-maven-plugin</artifactId>
                </plugin>
            </plugins>
        </build>
        <properties>
            <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
            <compiler.source>1.7</compiler.source>
            <compiler.target>1.7</compiler.target>
    
            
            <servlet.version>3.1.0</servlet.version>
            <jsp.version>2.3.1</jsp.version>
            <jstl.version>1.2</jstl.version>
            <junit.version>4.12</junit.version>
        </properties>
        <dependencies>
            
            <dependency>
                <groupId>junit</groupId>
                <artifactId>junit</artifactId>
                <version>${junit.version}</version>
                <scope>test</scope>
            </dependency>
            <dependency>
                <groupId>javax.servlet</groupId>
                <artifactId>javax.servlet-api</artifactId>
                <version>${servlet.version}</version>
                <scope>provided</scope>
            </dependency>
            <dependency>
                <groupId>javax.servlet.jsp</groupId>
                <artifactId>javax.servlet.jsp-api</artifactId>
                <version>${jsp.version}</version>
                <scope>provided</scope>
            </dependency>
            <dependency>
                <groupId>javax.servlet</groupId>
                <artifactId>jstl</artifactId>
                <version>${jstl.version}</version>
            </dependency>
            
            <dependency>
                <groupId>org.objenesis</groupId>
                <artifactId>objenesis</artifactId>
                <version>1.2</version>
            </dependency>
            
            <dependency>
                <groupId>org.mybatis.spring.boot</groupId>
                <artifactId>mybatis-spring-boot-starter</artifactId>
                <version>1.2.0</version>
            </dependency>
            
            <dependency>
                <groupId>org.springframework.boot</groupId>
                <artifactId>spring-boot-starter-web</artifactId>
            </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-configuration-processor</artifactId>
                <optional>true</optional>
            </dependency>
            
            <dependency>
                <groupId>mysql</groupId>
                <artifactId>mysql-connector-java</artifactId>
                <version>5.1.6</version>
                <scope>runtime</scope>
            </dependency> 
           
           <dependency>  
                <groupId>org.springframework.boot</groupId>  
                <artifactId>spring-boot-starter-freemarker</artifactId>  
            </dependency> 
    
        </dependencies>
        
    </project>

![复制代码][aHR0cHM6Ly9jb21tb24uY25ibG9ncy5jb20vaW1hZ2VzL2NvcHljb2RlLmdpZg]

** （11）启动项目，访问项目。**

进入 Application.java

右击 --》  Run   As  --》  Java Application

启动成功后，在浏览器通过URL访问：  http://当前ip：8080/**server.context-path指定的值 **/RequestMapping对应的值

例如： http://127.0.0.1:8080/HelloWorld/find

访问结果如图所示：**（注意，这里自己要往数据库中插入一条数据，id为UserController类中find方法对应的id）**

**![format_png 2][]**

[format_png]: /images/20220422/6f9f9fb521844fefb05edefe8e4ccd60.png
[aHR0cHM6Ly9jb21tb24uY25ibG9ncy5jb20vaW1hZ2VzL2NvcHljb2RlLmdpZg]: /images/20220422/2c627bdf1ebc4f77a85f2fb3c084cb28.png
[format_png 1]: /images/20220422/3f76841c590c4b39b7f68a06a91266e8.png
[format_png 2]: /images/20220422/160907381f6347d8afaf690accd2c58a.png