Java 连接MySql数据库配置

用navicat连接Mysql

1.点击连接，选择Mysql

2.输入连接名称，密码，安装Mysql时输入的密码，本人默认123456，好记

3.点击测试连接

出现上面这种情况是Mysql服务没有开启

解决方案：

任务管理器 ——服务——找到mysql服务—-右键开始

 启动服务之后，打开我们的navicat，再次测试连接，点击确定

 打开本地，新建数据库test1，新建一张表

创建表语句：

/*
 Navicat Premium Data Transfer

 Source Server         : 本地
 Source Server Type    : MySQL
 Source Server Version : 50525
 Source Host           : localhost:3306
 Source Schema         : test1

 Target Server Type    : MySQL
 Target Server Version : 50525
 File Encoding         : 65001

 Date: 24/04/2022 10:49:21
*/

SET NAMES utf8mb4;
SET FOREIGN_KEY_CHECKS = 0;

— —————————-
— Table structure for people
— —————————-
DROP TABLE IF EXISTS `people`;
CREATE TABLE `people`  (
  `id` bigint(20) NOT NULL COMMENT ‘id’,
  `name` varchar(20) CHARACTER SET utf8 COLLATE utf8_general_ci NULL DEFAULT NULL COMMENT ‘姓名’,
  `age` int(20) NULL DEFAULT NULL COMMENT ‘年龄’,
  `address` varchar(20) CHARACTER SET utf8 COLLATE utf8_general_ci NULL DEFAULT NULL COMMENT ‘地址’,
  PRIMARY KEY (`id`) USING BTREE
) ENGINE = InnoDB CHARACTER SET = utf8 COLLATE = utf8_general_ci ROW_FORMAT = Compact;

— —————————-
— Records of people
— —————————-
INSERT INTO `people` VALUES (1, ‘张三’, 20, ‘上海’);
INSERT INTO `people` VALUES (2, ‘李四’, 25, ‘北京’);
INSERT INTO `people` VALUES (3, ‘王五’, 30, ‘重庆’);

SET FOREIGN_KEY_CHECKS = 1;
 

数据库就准好了，接下来创建项目，连接数据库获取数据

创建Java项目

引入依赖：

<dependencies>
    <!-- springmvc的场景启动器 -->
    <dependency>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-web</artifactId>
        <version>2.6.5</version>
    </dependency>

    <!-- 添加lombok的依赖 -->
    <dependency>
        <groupId>org.projectlombok</groupId>
        <artifactId>lombok</artifactId>
        <version>1.18.8</version>
    </dependency>

    <!-- MySQL驱动包 -->
    <dependency>
        <groupId>mysql</groupId>
        <artifactId>mysql-connector-java</artifactId>
        <version>8.0.28</version>
    </dependency>

    <!-- Mybatis的场景启动器 -->
    <dependency>
        <groupId>org.mybatis.spring.boot</groupId>
        <artifactId>mybatis-spring-boot-starter</artifactId>
        <version>2.2.2</version>
    </dependency>

    <!-- 单元测试场景启动器 -->
    <dependency>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-test</artifactId>
        <version>2.6.5</version>
    </dependency>
</dependencies>

application.yml配置

server:
  #端口号
  port: 9527
spring:
  #数据库配置
  datasource:
    driver-class-name: com.mysql.cj.jdbc.Driver
    url: jdbc:mysql://localhost:3306/test1?useUnicode=true&characterEncoding=utf8&zeroDateTimeBehavior=convertToNull&useSSL=true&serverTimezone=GMT%2B8
    username: root
    password: 123456
# MyBatis配置
mybatis:
  mapper-locations: com/thk/mapper/*Mapper.xml

启动类：

@SpringBootApplication
public class app {
    public static void main(String[] args) {
        SpringApplication.run(app.class,args);
        System.out.println("启动成功！！！");
    }
}

实体类：

package com.thk.domain;


public class People {
    /**
     * id
     */
    private Long id;
    /**
     * 姓名
     */
    private String name;
    /**
     * 年龄
     */
    private Integer age;
    /**
     * 地址
     */
    private String address;

    public Long getId() {
        return id;
    }

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

    public String getName() {
        return name;
    }

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

    public Integer getAge() {
        return age;
    }

    public void setAge(Integer age) {
        this.age = age;
    }

    public String getAddress() {
        return address;
    }

    public void setAddress(String address) {
        this.address = address;
    }

    @Override
    public String toString() {
        return "People{" +
                "id=" + id +
                ", name='" + name + '\'' +
                ", age=" + age +
                ", address='" + address + '\'' +
                '}';
    }
    
}

Controller：

@RestController
public class PeopleController {
    @Autowired
    private IPeopleService peopleService;

    /**
     * 查询全部用户
     * @param people
     * @return
     */
    @GetMapping("/selectAll")
    public List<People> selectAll( People people) {
        return peopleService.selectAll(people);
    }
}

service接口

public interface IPeopleService {
    /**
     * 查询全部用户
     * @param people
     * @return
     */
    List<People> selectAll(People people);
}

service实现类：

@Service
public class PeopleImpl implements IPeopleService {
    @Autowired
    private PeopleMapper peopleMapper;

    /**
     * 查询全部用户
     * @param people
     * @return
     */
    public List<People> selectAll(People people) {
        return peopleMapper.selectAll(people);
    }
}

mapper接口

@Mapper
public interface PeopleMapper {
    /**
     * 查询全部用户
     * @param people
     * @return
     */
    List<People> selectAll(People people);
}

mapperxml

<?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.thk.mapper.PeopleMapper">

    <select id="selectAll" resultType="com.thk.domain.People">
        SELECT  * FROM  people
    </select>
</mapper>

启动项目：、

测试：

浏览器输入：http://localhost:9527/selectAll

浏览器数据：

数据库数据：

 浏览器显示的数据就是从数据库当中查出来的数据，项目已经成功连接到数据库了

打印运行日志：

浏览器访问成功，但是没有输出运行的日志，看不到执行的Sql语句，就很不方便

我们在application.yml配置一下就好了

# 日志配置
logging:
  level:
    com: debug
    org.springframework: warn

重启项目，再次运行

数据库连接结束，

下章预告：对数据库执行CRUD