[Java知识库]spring-boot完整项目搭建

新建一个maven项目

• 先给读者看下结构，可以后面再回头看
  
• 其次插件必装MyBatisX
• 选装中文包Chinese(Simplified) Language Pack

依赖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 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>2.6.4</version>
        <relativePath/> <!-- lookup parent from repository -->
    </parent>
    <groupId>com.example</groupId>
    <artifactId>demo3</artifactId>
    <version>0.0.1-SNAPSHOT</version>
    <name>demo3</name>
    <description>demo3</description>
    <properties>
        <java.version>1.8</java.version>
    </properties>
    <dependencies>
        <!--        spring-boot-->
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter</artifactId>
        </dependency>
        <!--        test-->
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-test</artifactId>
            <scope>test</scope>
        </dependency>
        <!--        web-->
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-web</artifactId>
        </dependency>
        <!--        mybatis-plus-->
        <dependency>
            <groupId>com.baomidou</groupId>
            <artifactId>mybatis-plus-boot-starter</artifactId>
            <version>3.5.1</version>
        </dependency>
        <!--        mysql-->
        <dependency>
            <groupId>mysql</groupId>
            <artifactId>mysql-connector-java</artifactId>
        </dependency>
        <!--        lombok-->
        <dependency>
            <groupId>org.projectlombok</groupId>
            <artifactId>lombok</artifactId>
        </dependency>
        <!--        日志-->
        <dependency>
            <groupId>org.slf4j</groupId>
            <artifactId>slf4j-api</artifactId>
            <version>1.7.21</version>
        </dependency>
        <dependency>
            <groupId>org.slf4j</groupId>
            <artifactId>slf4j-log4j12</artifactId>
            <version>1.7.21</version>
        </dependency>
    </dependencies>

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

</project>

配置application.yml

server:
  port: 8086

spring:
  datasource:
    driver-class-name: com.mysql.cj.jdbc.Driver
    username: root
    password: 123456
    url: jdbc:mysql://localhost:3306/llx?useUnicode=true&characterEncoding=UTF-8&serverTimeZone=UTC

  ##配置数据初始化
  sql:
    ##项目一运行就执行下面目录文件(首先执行user.sql->再到user-data.sql)
    init:
      schema-locations: classpath*:sql/*sql
      data-locations: classpath*:sql/data/*sql

mybatis-plus:
  ## 指定mapper扫描路径
  mapper-locations: classpath*:mapper/*.xml
  ## 表前缀
  global-config:
    db-config:
      table-prefix: tb_

主启动类com/llx/App

package com.llx;

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

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

表resource/sql/user.sql

CREATE TABLE IF NOT Exists tb_user (
    id INT(20) NOT NULL COMMENT '主键id',
    username VARCHAR(30) NULL DEFAULT NULL COMMENT '姓名',
    age INT(11) NULL DEFAULT NULL COMMENT '年龄',
    email VARCHAR(50) NULL DEFAULT NULL COMMENT '邮箱',
    PRIMARY KEY(id)
);

表数据resource/sql/data/user-data.sql

replace into tb_user(id,user_name,age,email) values
(1,'Jone',18,'test1@qq.com'),
(2,'Jone',22,'test2@qq.com'),
(3,'Jone',23,'test3@qq.com'),
(4,'Jone',12,'test4@qq.com'),
(5,'Jone',34,'test5@qq.com')

实体类com/llx/Bean/User

package com.llx.Bean;

import com.baomidou.mybatisplus.annotation.TableField;
import com.baomidou.mybatisplus.annotation.TableName;
import lombok.Data;

@Data // set、get、toString
@TableName("user") // 指定表名
public class User {
    @TableField("id") // 对应数据库表中字段名称
    private Integer id;
    // 假如数据库表中字段为user_name则自动转为userName这种驼峰命名
    private String userName;
    private String email;
    private Integer age;
}

分页功能类com/llx/config/MybatisPlusConfig

package com.llx.config;

import com.baomidou.mybatisplus.extension.plugins.MybatisPlusInterceptor;
import com.baomidou.mybatisplus.extension.plugins.inner.PaginationInnerInterceptor;
import org.mybatis.spring.annotation.MapperScan;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;

@Configuration
@MapperScan("com.llx.mapper") //指定扫描包
public class MybatisPlusConfig {

    @Bean
    public MybatisPlusInterceptor mybatisPlusInterceptor(){
        // 分页插件
        MybatisPlusInterceptor mybatisPlusInterceptor = new MybatisPlusInterceptor();
        mybatisPlusInterceptor.addInnerInterceptor(new PaginationInnerInterceptor());
        return mybatisPlusInterceptor;
    }
}

com/llx/mapper/UserMapper

package com.llx.mapper;

import com.baomidou.mybatisplus.core.mapper.BaseMapper;
import com.llx.Bean.User;

import java.util.List;

public interface UserMapper extends BaseMapper<User> {
    // 自定义mapper查询
    List<User> findUserGtAge(int age);
}

com/llx/service/UserService

package com.llx.service;

import com.baomidou.mybatisplus.core.conditions.query.LambdaQueryWrapper;
import com.baomidou.mybatisplus.extension.plugins.pagination.Page;
import com.llx.Bean.User;
import com.llx.mapper.UserMapper;
import lombok.extern.slf4j.Slf4j;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Service;

import java.util.List;

@Service
@Slf4j
public class UserService {
    @Autowired
    private UserMapper userMapper;

    // LambdaQueryWrapper查询所有
    public List<User> findAll() {
        return userMapper.selectList(new LambdaQueryWrapper<>());
    }

    // LambdaQueryWrapper分页查询
    public List<User> findPage(Integer current, Integer pageSize) {
        Page<User> page = new Page(current, pageSize);
        Page<User> userPage = userMapper.selectPage(page, new LambdaQueryWrapper<>());
        log.info("total:{}", userPage.getTotal());
        log.info("pages:{}", userPage.getPages());
        return userPage.getRecords();
    }

    // 自定义mapper查询
    public List<User> findAge(Integer age) {
        return userMapper.findUserGtAge(age);
//下面是使用LambdaQueryWrapper的写法
//return userMapper.selectList(new LambdaQueryWrapper<>().gt(User::getAge,20));
    }
}

com/llx/controller/UserController

package com.llx.controller;

import com.llx.Bean.User;
import com.llx.service.UserService;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RequestParam;
import org.springframework.web.bind.annotation.RestController;

import java.util.List;

@RestController
@RequestMapping("user")
public class UserController {

    @Autowired
    private UserService userService;
    // 通过LambdaQueryWrapper去查询
    @GetMapping("/findAll")
    public List<User> findAll(){
        return userService.findAll();
    }
    // 通过LambdaQueryWrapper去查询
    @GetMapping("/findPage")
    public List<User> findPage(@RequestParam("page") Integer page,
                               @RequestParam("pageSize") Integer pageSize){
        return userService.findPage(page,pageSize);
    }
    // 自定义mapper去查询
    @GetMapping("/findAge")
    public List<User> findAge(Integer age){
        System.out.println(age);
        return userService.findAge(age);
    }


}

resource/mapper/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.llx.mapper.UserMapper">
    <select id="findUserGtAge" parameterType="int" resultType="com.llx.Bean.User">
        select * from tb_user where age = #{age}
    </select>
</mapper>