🚧 数据库相关功能

README.md

@@ -1 +1,87 @@
-# Springboot3和JDK17的基础脚手架
+# Springboot3和JDK17的基础脚手架 - 数据库分支
+
+
+
+## 基础依赖
+- MySQL
+- MyBatis-Plus 3.5.15  这个版本是SpringBoot3支持的最高版本
+- jsqlparser 在MyBatis-Plus 3.5.9以后的版本，插件部分开始修改为可选依赖，所以这里手动增加。
+
+> 引入 MyBatis-Plus 之后请不要再次引入 MyBatis 以及 mybatis-spring-boot-starter和MyBatis-Spring，以避免因版本差异导致的问题。
+
+```xml
+<dependency>
+    <groupId>com.mysql</groupId>
+    <artifactId>mysql-connector-j</artifactId>
+    <scope>runtime</scope>
+</dependency>
+
+<dependency>
+    <groupId>com.baomidou</groupId>
+    <artifactId>mybatis-plus-spring-boot3-starter</artifactId>
+    <version>3.5.15</version>
+</dependency>
+
+<dependency>
+    <groupId>com.baomidou</groupId>
+    <artifactId>mybatis-plus-jsqlparser</artifactId>
+    <version>3.5.14</version>
+    <scope>compile</scope>
+</dependency>
+```
+
+
+
+## Druid数据源配置详解
+- [官方WIKI](https://github.com/alibaba/druid/wiki/%E9%A6%96%E9%A1%B5)
+
+### Druid多数据源说明
+添加配置
+```properties
+spring.datasource.url=
+spring.datasource.username=
+spring.datasource.password=
+
+# Druid 数据源配置，继承spring.datasource.* 配置，相同则覆盖
+spring.datasource.druid.initial-size=5
+spring.datasource.druid.max-active=5
+
+# Druid 数据源 1 配置，继承spring.datasource.druid.* 配置，相同则覆盖
+spring.datasource.druid.one.max-active=10
+spring.datasource.druid.one.max-wait=10000
+
+
+# Druid 数据源 2 配置，继承spring.datasource.druid.* 配置，相同则覆盖
+
+spring.datasource.druid.two.max-active=20
+spring.datasource.druid.two.max-wait=20000
+
+```
+
+# Druid 数据源配置，继承spring.datasource.* 配置，相同则覆盖
+
+```properties
+spring.datasource.druid.initial-size=5
+spring.datasource.druid.max-active=5
+```
+
+# Druid 数据源 1 配置，继承spring.datasource.druid.* 配置，相同则覆盖
+```properties
+
+
+spring.datasource.druid.one.max-active=10
+spring.datasource.druid.one.max-wait=10000
+```
+
+# Druid 数据源 2 配置，继承spring.datasource.druid.* 配置，相同则覆盖
+```properties
+spring.datasource.druid.two.max-active=20
+spring.datasource.druid.two.max-wait=20000
+```
+
+强烈注意：**Spring Boot 2.X** 版本不再支持配置继承，多数据源的话每个数据源的所有配置都需要单独配置，否则配置不会生效
+
+
+
+## MyBatis-Plus配置详解
+- [官网文档](https://baomidou.com/introduce/)

pom.xml

@@ -14,6 +14,8 @@
         <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
         <project.reporting.outputEncoding>UTF-8</project.reporting.outputEncoding>
         <spring-boot.version>3.5.9</spring-boot.version>
+        <druid.version>1.2.27</druid.version>
+        <mybatis-plus.version>3.5.15</mybatis-plus.version>
     </properties>
 
 
@@ -40,7 +42,35 @@
             <artifactId>spring-boot-starter-test</artifactId>
             <scope>test</scope>
         </dependency>
+
+        <!-- MySQL相关Maven依赖 -->
+        <dependency>
+            <groupId>com.mysql</groupId>
+            <artifactId>mysql-connector-j</artifactId>
+            <scope>runtime</scope>
+        </dependency>
+
+        <dependency>
+            <groupId>com.baomidou</groupId>
+            <artifactId>mybatis-plus-spring-boot3-starter</artifactId>
+            <version>${mybatis-plus.version}</version>
+        </dependency>
+
+        <dependency>
+            <groupId>com.baomidou</groupId>
+            <artifactId>mybatis-plus-jsqlparser</artifactId>
+            <version>${mybatis-plus.version}</version>
+            <scope>compile</scope>
+        </dependency>
+        <dependency>
+            <groupId>com.alibaba</groupId>
+            <artifactId>druid-spring-boot-3-starter</artifactId>
+            <version>${druid.version}</version>
+        </dependency>
+
+
     </dependencies>
+
     <dependencyManagement>
         <dependencies>
             <dependency>

src/main/java/com/yongfeng/lg/springboot3jdk17/Application.java

@@ -1,9 +1,11 @@
 package com.yongfeng.lg.springboot3jdk17;
 
+import org.mybatis.spring.annotation.MapperScan;
 import org.springframework.boot.SpringApplication;
 import org.springframework.boot.autoconfigure.SpringBootApplication;
 
 @SpringBootApplication
+@MapperScan("com.yongfeng.lg.springboot3jdk17.mapper") // 必须配置，扫描mapper包
 public class Application {
 
     public static void main(String[] args) {

src/main/java/com/yongfeng/lg/springboot3jdk17/controller/UserController.java

@@ -0,0 +1,57 @@
+package com.yongfeng.lg.springboot3jdk17.controller;
+
+import com.baomidou.mybatisplus.core.conditions.query.LambdaQueryWrapper;
+import com.baomidou.mybatisplus.extension.plugins.pagination.Page;
+import com.yongfeng.lg.springboot3jdk17.entity.User;
+import com.yongfeng.lg.springboot3jdk17.service.UserService;
+import org.springframework.beans.factory.annotation.Autowired;
+import org.springframework.web.bind.annotation.*;
+import java.util.List;
+
+@RestController
+@RequestMapping("/user")
+public class UserController {
+
+    @Autowired
+    private UserService userService;
+
+
+    // 1. 新增用户
+    @PostMapping("/save")
+    public boolean save(@RequestBody User user) {
+        return userService.save(user);
+    }
+
+    // 2. 根据ID查询用户
+    @GetMapping("/{id}")
+    public User getById(@PathVariable Long id) {
+        return userService.getById(id);
+    }
+
+    // 3. 查询所有用户
+    @GetMapping("/list")
+    public List<User> list() {
+        return userService.list();
+    }
+
+    // 4. 分页查询用户 (MP分页插件生效)
+    @GetMapping("/page")
+    public Page<User> page(@RequestParam Integer current, @RequestParam Integer size) {
+        Page<User> page = new Page<>(current, size);
+        return userService.page(page);
+    }
+
+    // 5. 条件查询：根据年龄查询
+    @GetMapping("/listByAge/{age}")
+    public List<User> listByAge(@PathVariable Integer age) {
+        LambdaQueryWrapper<User> wrapper = new LambdaQueryWrapper<>();
+        wrapper.gt(User::getAge, age); // 年龄大于指定值
+        return userService.list(wrapper);
+    }
+
+    // 6. 删除用户
+    @DeleteMapping("/{id}")
+    public boolean remove(@PathVariable Long id) {
+        return userService.removeById(id);
+    }
+}

src/main/java/com/yongfeng/lg/springboot3jdk17/entity/User.java

@@ -0,0 +1,57 @@
+package com.yongfeng.lg.springboot3jdk17.entity;
+
+import com.baomidou.mybatisplus.annotation.IdType;
+import com.baomidou.mybatisplus.annotation.TableField;
+import com.baomidou.mybatisplus.annotation.TableId;
+import com.baomidou.mybatisplus.annotation.TableName;
+import com.yongfeng.lg.springboot3jdk17.enums.SexEnum;
+import lombok.Data;
+import java.io.Serializable;
+import java.time.LocalDateTime;
+
+/**
+ * 数据库表对应的实体类 (示例：用户表 user)
+ */
+@Data // lombok注解，自动生成get/set/toString/equals等方法
+@TableName("user") // 对应数据库的表名
+public class User implements Serializable {
+
+    private static final long serialVersionUID = 1L;
+
+    // 自增主键
+    @TableId(type = IdType.AUTO)
+    private Long id;
+
+    // 用户名 (数据库字段：user_name)
+    @TableField("user_name")
+    private String userName;
+
+    // 密码
+    @TableField("password")
+    private String password;
+
+    // 年龄
+    @TableField("age")
+    private Integer age;
+
+    // 性别  使用枚举值
+    @TableField("sex")
+    private SexEnum sex;
+
+
+    // 邮箱
+    @TableField("email")
+    private String email;
+
+    // 创建时间
+    @TableField("create_time")
+    private LocalDateTime createTime;
+
+    // 更新时间
+    @TableField("update_time")
+    private LocalDateTime updateTime;
+
+    // 逻辑删除字段 (0=未删除，1=已删除)
+    @TableField("deleted")
+    private Integer deleted;
+}

src/main/java/com/yongfeng/lg/springboot3jdk17/enums/SexEnum.java

@@ -0,0 +1,26 @@
+package com.yongfeng.lg.springboot3jdk17.enums;
+
+import com.baomidou.mybatisplus.annotation.EnumValue;
+import lombok.AllArgsConstructor;
+import lombok.Getter;
+
+/**
+ * MyBatis-Plus使用枚举示例
+ */
+
+@Getter
+@AllArgsConstructor
+public enum SexEnum {
+    PRIMARY(1, "小学"),
+    SECONDARY(2, "中学"),
+    HIGH(3, "高中");
+
+    // 枚举属性使用 @EnumValue 注解，
+    // 指定枚举值在数据库中存储的实际值。
+    // 支持枚举类中的任意字段，如序号或编码。
+    // 标记数据库存的值是code
+    @EnumValue
+    private final int code;
+
+    private final String desc;
+}

src/main/java/com/yongfeng/lg/springboot3jdk17/mapper/UserMapper.java

@@ -0,0 +1,16 @@
+package com.yongfeng.lg.springboot3jdk17.mapper;
+
+
+import com.baomidou.mybatisplus.core.mapper.BaseMapper;
+import com.yongfeng.lg.springboot3jdk17.entity.User;
+import org.apache.ibatis.annotations.Mapper;
+
+/**
+ * MP的Mapper接口，继承BaseMapper即可，无需写任何方法
+ * BaseMapper<User> 中的泛型是对应的实体类
+ */
+//@Mapper // 可选，因为主启动类加了@MapperScan，二选一即可
+public interface UserMapper extends BaseMapper<User> {
+
+    // 自定义的Mapper可以在这里面写，对应Mapper XML文件
+}

src/main/java/com/yongfeng/lg/springboot3jdk17/service/UserService.java

@@ -0,0 +1,12 @@
+package com.yongfeng.lg.springboot3jdk17.service;
+
+
+import com.baomidou.mybatisplus.extension.service.IService;
+import com.yongfeng.lg.springboot3jdk17.entity.User;
+
+/**
+ * 业务层接口，继承MP的IService
+ */
+public interface UserService extends IService<User> {
+
+}

src/main/java/com/yongfeng/lg/springboot3jdk17/service/impl/UserServiceImpl.java

@@ -0,0 +1,16 @@
+package com.yongfeng.lg.springboot3jdk17.service.impl;
+
+
+import com.baomidou.mybatisplus.extension.service.impl.ServiceImpl;
+import com.yongfeng.lg.springboot3jdk17.entity.User;
+import com.yongfeng.lg.springboot3jdk17.mapper.UserMapper;
+import com.yongfeng.lg.springboot3jdk17.service.UserService;
+import org.springframework.stereotype.Service;
+
+/**
+ * 业务层实现类，继承ServiceImpl，注入Mapper即可
+ */
+@Service
+public class UserServiceImpl extends ServiceImpl<UserMapper, User> implements UserService {
+
+}

src/main/resources/application.properties

@@ -1,3 +1,53 @@
-# 端口号
+# Web服务端口号
 server.port=8080
+# 配置数据源类型为Druid
+spring.datasource.type=com.alibaba.druid.pool.DruidDataSource
+# druid相关配置文件
+# MySQL8.x 驱动类，固定值；如果是MySQL5.7，改成 com.mysql.jdbc.Driver
+spring.datasource.druid.driver-class-name=com.mysql.cj.jdbc.Driver
+# 数据库连接地址
+spring.datasource.druid.url=jdbc:mysql://10.232.112.35:3306/springboot3-jdk17?useUnicode=true&characterEncoding=utf8&zeroDateTimeBehavior=convertToNull&useSSL=false&serverTimezone=Asia/Shanghai
+# 数据库名
+spring.datasource.druid.username=root
+# 数据库密码
+spring.datasource.druid.password=-w9M627JZeYo5p^3lbH0mqDa
+# 初始化连接数
+spring.datasource.druid.initial-size=5
+# 最小空闲连接数
+spring.datasource.druid.min-idle=5
+# 最大活跃连接数
+spring.datasource.druid.max-active=20
+# 获取连接的最大等待时间(ms)
+spring.datasource.druid.max-wait=60000
+# 检测空闲连接的间隔时间
+spring.datasource.druid.time-between-eviction-runs-millis=60000
+# 空闲连接的存活时间
+spring.datasource.druid.min-evictable-idle-time-millis=300000
+# 检测连接是否有效
+spring.datasource.druid.validation-query=SELECT 1 FROM DUAL
+# 空闲时检测连接有效性
+spring.datasource.druid.test-while-idle=true
+# 获取连接时不检测（提升性能）但是可能存在使用了废弃的会话
+spring.datasource.druid.test-on-borrow=false
+# 归还连接时不检测（提升性能）
+spring.datasource.druid.test-on-return=false
+#  开启PSCache
+spring.datasource.druid.pool-prepared-statements=true
+spring.datasource.druid.max-pool-prepared-statement-per-connection-size=20
 
+# MyBatis-Plus配置文件
+# 配置Mapper.xml映射文件的路径
+mybatis-plus.mapper-locations=classpath:mapper/**/*.xml
+# 配置实体类的包别名，简化Mapper中的实体类引用
+mybatis-plus.type-aliases-package=com.example.demo.entity
+#  主键策略：AUTO(自增)，也可以用雪花算法 (分布式唯一ID，推荐)
+mybatis-plus.global-config.db-config.id-type=AUTO
+# 逻辑删除字段配置（可选）
+mybatis-plus.global-config.db-config.logic-delete-field=deleted
+# 配合逻辑删除字段  1代表删除
+mybatis-plus.global-config.db-config.logic-delete-value=1
+mybatis-plus.global-config.db-config.logic-not-delete-value=0
+
+mybatis-plus.configuration.map-underscore-to-camel-case=true
+mybatis-plus.configuration.log-impl=org.apache.ibatis.logging.stdout.StdOutImpl
+mybatis-plus.configuration.cache-enabled=false