SpringBoot连接PostgreSQL+MybatisPlus入门案例(代码详解)_Java

项目结构

一、java代码

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>org.example</groupid>
    <artifactid>jdservice</artifactid>
    <version>1.0-snapshot</version>
    <properties>
        <maven.compiler.source>8</maven.compiler.source>
        <maven.compiler.target>8</maven.compiler.target>
        <project.build.sourceencoding>utf-8</project.build.sourceencoding>
    </properties>
    <dependencies>
        <dependency>
            <groupid>org.springframework.boot</groupid>
            <artifactid>spring-boot-starter-web</artifactid>
            <version>2.0.3.release</version>
        </dependency>
        <dependency>
            <groupid>org.springframework.boot</groupid>
            <artifactid>spring-boot-starter</artifactid>
            <version>2.0.3.release</version>
        </dependency>
        <!-- https://mvnrepository.com/artifact/org.postgresql/postgresql -->
        <dependency>
            <groupid>org.postgresql</groupid>
            <artifactid>postgresql</artifactid>
            <version>42.6.0</version>
        </dependency>
        <dependency>
            <groupid>org.projectlombok</groupid>
            <artifactid>lombok</artifactid>
            <version>1.18.12</version>
        </dependency>
        <!--mybatis‐plus的springboot支持-->
        <dependency>
            <groupid>com.baomidou</groupid>
            <artifactid>mybatis-plus-boot-starter</artifactid>
            <version>3.1.0</version>
        </dependency>
    </dependencies>
</project>

controller层

package org.example.jd.controller;
import org.example.jd.pojo.tuser;
import org.example.jd.service.tuserservice;
import org.springframework.beans.factory.annotation.autowired;
import org.springframework.web.bind.annotation.*;
import java.util.list;
@crossorigin(origins = "http://localhost:8080")
@restcontroller
public class usercontroller {
    @autowired
    private tuserservice tuserservice;
    @postmapping("/api/userlogin")
    public string login(@requestbody tuser tuser) {
        // 实际业务逻辑处理
        string username = tuser.getusername();
        string password = tuser.getpassword();
        // 这里可以进行用户名密码验证等操作
        system.out.println("========login successful=====");
        system.out.println(username + "," + password);
        return "login successful"; // 返回登录成功信息或者其他响应
    }
    @getmapping("/api/getuserlist")
    public list<tuser> getuserlist() {
        list<tuser> tuserlist = tuserservice.getuserlist();
        return tuserlist;
    }
}

mapper层

package org.example.jd.mapper;
import com.baomidou.mybatisplus.core.mapper.basemapper;
import org.example.jd.pojo.tuser;
public interface tusermapper extends basemapper<tuser> { //参数为实体类
}

pojo层

package org.example.jd.pojo;
import com.baomidou.mybatisplus.annotation.tableid;
import com.baomidou.mybatisplus.annotation.tablename;
import lombok.allargsconstructor;
import lombok.data;
import lombok.noargsconstructor;
import java.time.localdate;
@data
@allargsconstructor
@noargsconstructor
@tablename("tuser")   //指定数据库表
public class tuser {
    @tableid(value = "uid") //指定主键
    private int uid;
    private string username;
    private string password;
    private int age;
    private string gender;
    private localdate birthday;
    private string address;
}

service层

tuserservice

package org.example.jd.service;
import org.example.jd.pojo.tuser;
import java.util.list;
public interface tuserservice {
    list<tuser> getuserlist();
}

tuserserviceimp

package org.example.jd.service;
import org.example.jd.mapper.tusermapper;
import org.example.jd.pojo.tuser;
import org.springframework.beans.factory.annotation.autowired;
import org.springframework.stereotype.service;
import java.util.list;
@service
public class tuserserviceimp implements tuserservice {
    @autowired
    private tusermapper tusermapper;
    @override
    public list<tuser> getuserlist() {
        return tusermapper.selectlist(null);
    }
}

application启动类

package org.example.jd;
import org.mybatis.spring.annotation.mapperscan;
import org.springframework.boot.springapplication;
import org.springframework.boot.autoconfigure.springbootapplication;
@springbootapplication
@mapperscan("org.example.jd.mapper") //扫描mapper层
public class application {
    public static void main(string[] args) {
        springapplication.run(application.class, args);
    }
}

tusermapper.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">
<!--namespace是mapper层对应的接口名-->
<mapper namespace="org.example.jd.mapper.tusermapper">
    <!--id是mapper层对应的接口名中对应的方法名-->
<!--    <select id="myfinduserbyid" resulttype="user">-->
<!--        select *-->
<!--        from tb_user-->
<!--        where id = #{id}-->
<!--    </select>-->
</mapper>

mybatis-config.xml

<?xml version="1.0" encoding="utf-8" ?>
<!doctype configuration
        public "-//mybatis.org//dtd config 3.0//en" "http://mybatis.org/dtd/mybatis-3-config.dtd">
<configuration>
    <!--设置驼峰匹配，mybatisplus默认开启驼峰匹配-->
    <!--    <settings>-->
    <!--        <setting name="mapunderscoretocamelcase" value="true"/>-->
    <!--    </settings>-->
</configuration>

application.yml配置文件

server:
  port: 8090
spring:
  datasource:
    url: jdbc:postgresql://localhost:5432/myjd
    username: postgres
    password: 123456
    driver-class-name: org.postgresql.driver
#设置mybatis-plus
mybatis-plus:
  config-location: classpath:mybatis/mybatis-config.xml  #配置文件
  mapper-locations: classpath:mybatis/mapper/*.xml  #设置mapper层对应的接口对应的mapper.xml的路径
  type-aliases-package: org.example.jd.pojo  #设置别名，mapper.xml中resulttype="org.example.jd.pojo.tuser"可省去包，即resulttype="tuser"
  #开启自动驼峰映射，注意：配置configuration.map-underscore-to-camel-case则不能配置config-location，可写到mybatis-config.xml中
#  configuration:
#    map-underscore-to-camel-case: true

二、sql

/*
 navicat premium data transfer
 source server         : mypgsql
 source server type    : postgresql
 source server version : 160003 (160003)
 source host           : localhost:5432
 source catalog        : myjd
 source schema         : public
 target server type    : postgresql
 target server version : 160003 (160003)
 file encoding         : 65001
 date: 19/07/2024 22:15:18
*/
-- ----------------------------
-- table structure for tuser
-- ----------------------------
drop table if exists "public"."tuser";
create table "public"."tuser" (
  "uid" int4 not null,
  "username" varchar(255) collate "pg_catalog"."default",
  "age" int4,
  "gender" varchar(1) collate "pg_catalog"."default",
  "birthday" date,
  "address" varchar(255) collate "pg_catalog"."default",
  "password" varchar(255) collate "pg_catalog"."default"
)
;
-- ----------------------------
-- records of tuser
-- ----------------------------
insert into "public"."tuser" values (1, 'jack', 24, '男', '2021-10-19', '深圳', '123');
-- ----------------------------
-- primary key structure for table tuser
-- ----------------------------
alter table "public"."tuser" add constraint "user_pkey" primary key ("uid");