SpringBoot整合Mybatis完整詳細(xì)版

轉(zhuǎn)載自：https://blog.csdn.net/iku5200/article/details/82856621

IDE：idea、DB：mysql

  • 新建一個(gè)Spring Initializr項(xiàng)目
  • 創(chuàng)建項(xiàng)目的文件結(jié)構(gòu)以及jdk的版本

  • 選擇項(xiàng)目所需要的依賴

  • 修改項(xiàng)目名，finish完成

  • 來看下建好后的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.example</groupId>
    <artifactId>demo</artifactId>
    <version>0.0.1-SNAPSHOT</version>
    <packaging>jar</packaging>
 
    <name>demo</name>
    <description>Demo project for Spring Boot</description>
 
    <parent>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-parent</artifactId>
        <version>2.0.5.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-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>1.3.2</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>
  • 修改配置文件
    本文不使用application.properties文件 而使用更加簡(jiǎn)潔的application.yml文件。將resource文件夾下原有的application.properties文件刪除，創(chuàng)建application.yml配置文件（備注：其實(shí)SpringBoot底層會(huì)把a(bǔ)pplication.yml文件解析為application.properties），本文創(chuàng)建了兩個(gè)yml文件（application.yml和application-dev.yml），分別來看一下內(nèi)容

application.yml

spring:
  profiles:
    active: dev

application-dev.yml

server:
  port: 8080
 
spring:
  datasource:
    username: root
    password: ok123
    url: jdbc:mysql://localhost:3306/springboot?useUnicode=true&characterEncoding=utf-8&useSSL=true&serverTimezone=UTC
    driver-class-name: com.mysql.jdbc.Driver
 
mybatis:
  mapper-locations: classpath:mapper/*Mapper.xml
  type-aliases-package: com.example.entity
 
#showSql
logging:
  level:
    com:
      example:
        mapper : debug

兩個(gè)文件的意思是：

在項(xiàng)目中配置多套環(huán)境的配置方法。
因?yàn)楝F(xiàn)在一個(gè)項(xiàng)目有好多環(huán)境，開發(fā)環(huán)境，測(cè)試環(huán)境，準(zhǔn)生產(chǎn)環(huán)境，生產(chǎn)環(huán)境，每個(gè)環(huán)境的參數(shù)不同，所以我們就可以把每個(gè)環(huán)境的參數(shù)配置到y(tǒng)ml文件中，這樣在想用哪個(gè)環(huán)境的時(shí)候只需要在主配置文件中將用的配置文件寫上就行如application.yml

筆記：在Spring Boot中多環(huán)境配置文件名需要滿足application-{profile}.yml的格式，其中{profile}對(duì)應(yīng)你的環(huán)境標(biāo)識(shí)，比如：
application-dev.yml：開發(fā)環(huán)境
application-test.yml：測(cè)試環(huán)境
application-prod.yml：生產(chǎn)環(huán)境
至于哪個(gè)具體的配置文件會(huì)被加載，需要在application.yml文件中通過spring.profiles.active屬性來設(shè)置，其值對(duì)應(yīng){profile}值。

還有配置文件中最好不要有中文注釋，會(huì)報(bào)錯(cuò)。

接下來把啟動(dòng)文件移到com.example下，而且springboot的啟動(dòng)類不能放在java目錄下?。?！必須要個(gè)包將它包進(jìn)去

否則會(huì)報(bào)錯(cuò)誤：

Your ApplicationContext is unlikely to start due to a @ComponentScan of the default package.

這個(gè)原因值得注意就是因?yàn)橛袝r(shí)候很難在IDEA中的項(xiàng)目目錄認(rèn)出來這個(gè)錯(cuò)誤并且還容易掃描不到一些類


正確寫法，啟動(dòng)類沒有直接放在java目錄下

錯(cuò)誤寫法，啟動(dòng)類直接放在java目錄下
  • 然后開始創(chuàng)建實(shí)體類實(shí)現(xiàn)業(yè)務(wù)流程
    創(chuàng)建包c(diǎn)ontroller、entity、mapper、service。resources下創(chuàng)建mapper文件夾，用于寫sql語句，也可以用注解的方式直接寫在mapper文件里。下面直接貼代碼

數(shù)據(jù)庫(kù)表結(jié)構(gòu)

CREATE TABLE `t_user` (
  'id' int(32) NOT NULL AUTO_INCREMENT,
  'userName' varchar(32) NOT NULL,
  'passWord' varchar(50) NOT NULL,
  'realName' varchar(32) DEFAULT NULL,
  PRIMARY KEY ('id')
) ENGINE=InnoDB AUTO_INCREMENT=3 DEFAULT CHARSET=utf8;
用戶表

entity.java

package com.example.entity;
 
public class User {
    private Integer id;
    private String userName;
    private String passWord;
    private String realName;
 
    public Integer getId() {
        return id;
    }
 
    public void setId(Integer 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 getRealName() {
        return realName;
    }
 
    public void setRealName(String realName) {
        this.realName = realName;
    }
 
    @Override
    public String toString() {
        return "User{" +
                "id=" + id +
                ", userName='" + userName + '\'' +
                ", passWord='" + passWord + '\'' +
                ", realName='" + realName + '\'' +
                '}';
    }
}

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.example.mapper.UserMapper">
    <select id="selectUserById" parameterType="int" resultType="User">
        SELECT * FROM t_user WHERE id = #{id}
    </select>
</mapper>

UserMapper.java

package com.example.mapper;

import com.example.entity.User;
import org.springframework.stereotype.Repository;

@Repository
public interface UserMapper {

    public User selectUserById(int id);
}

UserService.java

package com.example.service;

import com.example.entity.User;

public interface UserService {

    public User selectUserById(int id);
}

UserServiceImpl.java

package com.example.service.Impl;

import com.example.entity.User;
import com.example.mapper.UserMapper;
import com.example.service.UserService;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Service;


@Service
public class UserServiceImpl implements UserService {

    @Autowired
    private UserMapper userMapper;

    @Override
    public User selectUserById(int id) {
        return userMapper.selectUserById(id);
    }
}

UserController.java

package com.example.controller;

import com.example.service.UserService;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.web.bind.annotation.PathVariable;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RestController;

@RestController
public class UserController {

    @Autowired
    private UserService userService;

    @RequestMapping("/getUser/{id}")
    public String getUser(@PathVariable("id") int id){
        return userService.selectUserById(id).toString();
    }
}

  • 完成以上，下面在啟動(dòng)類里加上注解用于給出需要掃描的mapper文件路徑@MapperScan("com.example.mapper")
package com.example;

import org.mybatis.spring.annotation.MapperScan;
import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;

@MapperScan("com.example.mapper")  //掃描 mapper接口
@SpringBootApplication
public class SpringbootMybatisApplication {

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

}

測(cè)試成功，就這樣基本框架就搭建成功了

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