正常的和数据库交互获取数据

.gitignore

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+.idea
+*.iml
+# Created by .ignore support plugin (hsz.mobi)
+### Maven template
+target/
+pom.xml.tag
+pom.xml.releaseBackup
+pom.xml.versionsBackup
+pom.xml.next
+release.properties
+dependency-reduced-pom.xml
+buildNumber.properties
+.mvn/timing.properties
+.mvn/wrapper/maven-wrapper.jar
+

pom.xml

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+<?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>
+
+    <parent>
+        <groupId>org.springframework.boot</groupId>
+        <artifactId>spring-boot-starter-parent</artifactId>
+        <version>2.3.12.RELEASE</version>
+        <relativePath />
+    </parent>
+
+    <groupId>com.mashibing</groupId>
+    <artifactId>read_write_lock</artifactId>
+    <version>1.0-SNAPSHOT</version>
+
+
+    <dependencies>
+        <dependency>
+            <groupId>org.springframework.boot</groupId>
+            <artifactId>spring-boot-starter-web</artifactId>
+        </dependency>
+        <dependency>
+            <groupId>mysql</groupId>
+            <artifactId>mysql-connector-java</artifactId>
+            <version>5.1.47</version>
+        </dependency>
+        <dependency>
+            <groupId>org.mybatis.spring.boot</groupId>
+            <artifactId>mybatis-spring-boot-starter</artifactId>
+            <version>2.2.2</version>
+        </dependency>
+        <dependency>
+            <groupId>org.projectlombok</groupId>
+            <artifactId>lombok</artifactId>
+        </dependency>
+    </dependencies>
+
+</project>

src/main/java/com/mashibing/ReadWriteLockStarterApp.java

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+package com.mashibing;
+
+import org.mybatis.spring.annotation.MapperScan;
+import org.springframework.boot.SpringApplication;
+import org.springframework.boot.autoconfigure.SpringBootApplication;
+
+/**
+ * @author zjw
+ * @description
+ */
+@SpringBootApplication
+@MapperScan(basePackages = "com.mashibing.mapper")
+public class ReadWriteLockStarterApp {
+
+    public static void main(String[] args) {
+        SpringApplication.run(ReadWriteLockStarterApp.class,args);
+    }
+}

src/main/java/com/mashibing/controller/AirController.java

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+package com.mashibing.controller;
+
+import com.mashibing.entity.Air;
+import com.mashibing.service.AirService;
+import org.springframework.beans.factory.annotation.Autowired;
+import org.springframework.web.bind.annotation.GetMapping;
+import org.springframework.web.bind.annotation.PathVariable;
+import org.springframework.web.bind.annotation.RestController;
+
+/**
+ * @author zjw
+ * @description
+ */
+@RestController
+public class AirController {
+
+    @Autowired
+    private AirService airService;
+
+    @GetMapping("/air/{id}")
+    public Air getById(@PathVariable Long id){
+        return airService.getById(id);
+    }
+}

src/main/java/com/mashibing/entity/Air.java

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+package com.mashibing.entity;
+
+import lombok.Data;
+
+/**
+ * @author zjw
+ * @description
+ */
+@Data
+public class Air {
+
+    private Long id;
+
+    private int pm25;
+
+    private String monitoringStation;
+}

src/main/java/com/mashibing/mapper/AirMapper.java

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+package com.mashibing.mapper;
+
+import com.mashibing.entity.Air;
+import org.apache.ibatis.annotations.Param;
+import org.apache.ibatis.annotations.Select;
+
+/**
+ * @author zjw
+ * @description
+ */
+public interface AirMapper {
+
+    @Select("select * from air where id = #{id}")
+    Air findById(@Param("id") Long id);
+}

src/main/java/com/mashibing/service/AirService.java

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+package com.mashibing.service;
+
+import com.mashibing.entity.Air;
+
+/**
+ * @author zjw
+ * @description
+ */
+public interface AirService {
+    Air getById(Long id);
+}

src/main/java/com/mashibing/service/impl/AirServiceImpl.java

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+package com.mashibing.service.impl;
+
+import com.mashibing.entity.Air;
+import com.mashibing.mapper.AirMapper;
+import com.mashibing.service.AirService;
+import org.springframework.beans.factory.annotation.Autowired;
+import org.springframework.stereotype.Service;
+
+/**
+ * @author zjw
+ * @description
+ */
+@Service
+public class AirServiceImpl  implements AirService {
+
+    @Autowired
+    private AirMapper airMapper;
+
+    @Override
+    public Air getById(Long id) {
+        Air air = airMapper.findById(id);
+        return air;
+    }
+}

src/main/resources/application.yml

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+spring:
+  datasource:
+    driver-class-name: com.mysql.jdbc.Driver
+    url: jdbc:mysql://localhost:3306/air
+
+mybatis:
+  configuration:
+    map-underscore-to-camel-case: true