mybatis框架——实战练习——第一个spring boot + mybatis项目

CREATE TABLE `users` (
  `id` int NOT NULL,
  `name` varchar(255) DEFAULT NULL,
  `age` int DEFAULT NULL,
  PRIMARY KEY (`id`)
) ENGINE=InnoDB DEFAULT CHARSET=utf8mb3;

　　

mysql8安装——mysql-8.0.29——用户名：root--密码：123456--数据库名：mysql8

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工程pom如下：

注意：spring boot 以及mybatis的依赖。有固定的依赖模块。

之前引入了mybatis，运行不起来。

<dependency>
  <groupId>org.mybatis.spring.boot</groupId>
  <artifactId>mybatis-spring-boot-starter</artifactId>
  <version>2.1.1</version>
</dependency>

<?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>org.example</groupId>
  <artifactId>anxinfu</artifactId>
  <version>1.0-SNAPSHOT</version>
  <packaging>war</packaging>

  <name>anxinfu Maven Webapp</name>
  <!-- FIXME change it to the project's website -->
  <url>http://www.example.com</url>

  <properties>
    <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
    <maven.compiler.source>1.7</maven.compiler.source>
    <maven.compiler.target>1.7</maven.compiler.target>
  </properties>

  <parent>
    <groupId>org.springframework.boot</groupId>
    <artifactId>spring-boot-starter-parent</artifactId>
    <version>2.4.5</version>
    <relativePath/> <!-- lookup parent from repository -->
  </parent>


  <dependencies>
    <dependency>
      <groupId>org.springframework.boot</groupId>
      <artifactId>spring-boot-starter-jdbc</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>2.1.1</version>
    </dependency>

    <dependency>
      <groupId>mysql</groupId>
      <artifactId>mysql-connector-java</artifactId>
      <scope>runtime</scope>
    </dependency>
  </dependencies>

  <build>
    <finalName>anxinfu</finalName>
    <pluginManagement><!-- lock down plugins versions to avoid using Maven defaults (may be moved to parent pom) -->
      <plugins>
        <plugin>
          <artifactId>maven-clean-plugin</artifactId>
          <version>3.1.0</version>
        </plugin>
        <!-- see http://maven.apache.org/ref/current/maven-core/default-bindings.html#Plugin_bindings_for_war_packaging -->
        <plugin>
          <artifactId>maven-resources-plugin</artifactId>
          <version>3.0.2</version>
        </plugin>
        <plugin>
          <artifactId>maven-compiler-plugin</artifactId>
          <version>3.8.0</version>
        </plugin>
        <plugin>
          <artifactId>maven-surefire-plugin</artifactId>
          <version>2.22.1</version>
        </plugin>
        <plugin>
          <artifactId>maven-war-plugin</artifactId>
          <version>3.2.2</version>
        </plugin>
        <plugin>
          <artifactId>maven-install-plugin</artifactId>
          <version>2.5.2</version>
        </plugin>
        <plugin>
          <artifactId>maven-deploy-plugin</artifactId>
          <version>2.8.2</version>
        </plugin>
      </plugins>
    </pluginManagement>
  </build>
</project>

　　

application.yml

spring:
  datasource:
    username: root
    password: 123456
    url: jdbc:mysql://localhost:3306/mysql8
    driver-class-name: com.mysql.cj.jdbc.Driver

mybatis:
  config-location: classpath:mybatis/mybatis-config.xml
  mapper-locations: classpath:mybatis/mapper/*.xml

　　

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.test.mapper.UserMapper">
    <select id="findAll" resultType="com.test.entity.MyUser">
        select * from users
    </select>
</mapper>

　　

POJO类：

MyUser

package com.test.entity;

public class MyUser {

        private int id;
        private String name;
        private int age;

        public int getId() {
        return id;
    }

        public void setId(int id) {
        this.id = id;
    }

        public String getName() {
        return name;
    }

        public void setName(String name) {
        this.name = name;
    }

        public int getAge() {
        return age;
    }

        public void setAge(int age) {
        this.age = age;

    }
}

　　

映射：

mapper：

UserMapper 

package com.test.mapper;


import com.test.entity.MyUser;
import org.apache.ibatis.annotations.Mapper;

import java.util.List;

@Mapper
public interface UserMapper {
    public List<MyUser> findAll();
}

　　

服务层，先接口

UserService

package com.test.serviice;


import com.test.entity.MyUser;

import java.util.List;

public interface UserService
{
    List<MyUser> findAll();
}

　　

实现服务接口：

PS： 需要注入

package com.test.serviice.impl;


import com.test.entity.MyUser;
import com.test.mapper.UserMapper;
import com.test.serviice.UserService;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Service;

import java.util.List;

@Service
public class UserServiceImpl implements UserService {
    @Autowired
    UserMapper userMapper;
    @Override
    public List<MyUser> findAll() {
        return userMapper.findAll();
    }

}

　　

控制层：

StartMainController

此处，注入 服务层 接口

package com.test.controller;

import com.test.entity.MyUser;
import com.test.serviice.UserService;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.RestController;

import java.util.List;

@RestController
public class StartMainController
{
    @Autowired
    private UserService userService;

    @GetMapping(value = "/1")
    public List<MyUser> home1()
    {
        // 查询所有网站
        List<MyUser> users = userService.findAll();
        for (MyUser user : users)
        {
            System.out.println(user.getId()+"  "+user.getName()+"  "+user.getName());
        }
        return users;
    }
}

　　

=========================================================================

package com.test;

import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;

@SpringBootApplication
public class SpringBootStart
{
    public static void main(String[] args)
    {
        SpringApplication.run(SpringBootStart.class, args);
    }

}

　　

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http://localhost:8080/1