《穿越SpringBoot 》第四章-SpringBoot 访问数据库 | 第1节- SpringBoot 使用原生JDBC

SpringBoot 使用 JDBC Template

前题

借助：IntelliJ IDEA，Maven构建工具，以及基于SpringBoot 2.3.4。

官人如需使用 IDEA 请阅读教程：IntelliJ IDEA

背景

Spring Framework对数据库的操作在JDBC上面做了深层次的封装，通过依赖注入功能，可以将DataSource注册到JdbcTemplate之中，使我们可以轻易的完成对象关系映射，并有助于规避常见的错误，在SpringBoot中我们可以很轻松的使用它。

使用

目录结构

在这里插入图片描述

pom.xml 依赖

Spring JDBC 的依赖包，使用 spring-boot-starter-jdbc 或 spring-boot-starter-data-jpa 将会自动获得HikariCP依赖,此外此项目还用到如下依赖。

<?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>2.3.4.RELEASE</version>
		<relativePath/> <!-- lookup parent from repository -->
	</parent>
	<groupId>com.example</groupId>
	<artifactId>jdbc</artifactId>
	<version>0.0.1-SNAPSHOT</version>
	<name>jdbc</name>
	<description>Demo project for Spring Boot</description>

	<properties>
		<java.version>1.8</java.version>
	</properties>

	<dependencies>
<!--jdbc-->
		<dependency>
			<groupId>org.springframework.boot</groupId>
			<artifactId>spring-boot-starter-jdbc</artifactId>
		</dependency>
<!--web	-->
		<dependency>
			<groupId>org.springframework.boot</groupId>
			<artifactId>spring-boot-starter-web</artifactId>
		</dependency>
<!--mysql-->
		<dependency>
			<groupId>mysql</groupId>
			<artifactId>mysql-connector-java</artifactId>
			<scope>runtime</scope>
		</dependency>

		<dependency>
			<groupId>org.springframework.boot</groupId>
			<artifactId>spring-boot-starter-thymeleaf</artifactId>
		</dependency>
		<dependency>
			<groupId>org.springframework.boot</groupId>
			<artifactId>spring-boot-configuration-processor</artifactId>
			<optional>true</optional>
		</dependency>
		<dependency>
			<groupId>org.projectlombok</groupId>
			<artifactId>lombok</artifactId>
			<optional>true</optional>
		</dependency>
		<dependency>
			<groupId>org.springframework.boot</groupId>
			<artifactId>spring-boot-starter-test</artifactId>
			<scope>test</scope>
			<exclusions>
				<exclusion>
					<groupId>org.junit.vintage</groupId>
					<artifactId>junit-vintage-engine</artifactId>
				</exclusion>
			</exclusions>
		</dependency>
	</dependencies>

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

application.properties配置文件

在application.properties中添加如下配置。值得注意的是，SpringBoot默认会自动配置DataSource，它将优先采用HikariCP连接池.

如果没有该依赖的情况则选取tomcat-jdbc，如果前两者都不可用最后选取Commons DBCP2。通过spring.datasource.type属性可以指定其它种类的连接池

server.port=9090
spring.datasource.username=root
spring.datasource.password=root
spring.datasource.url=jdbc:mysql:///test?serverTimezone=GMT%2B8&useUnicode=true&characterEncoding=utf-8

查看默认数据源：

package com.example.jdbc;

import org.junit.jupiter.api.Test;
import org.junit.runner.RunWith;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.boot.test.context.SpringBootTest;
import org.springframework.test.context.junit4.SpringRunner;
import javax.sql.DataSource;
import java.sql.Connection;
import java.sql.SQLException;

@RunWith(SpringRunner.class)
@SpringBootTest
class JdbcApplicationTests {
    
    
	@Autowired
	DataSource dataSource;

	@Test
	void contextLoads() throws SQLException {
    
    
		//查看默认数据源
		System.out.println(dataSource.getClass());
		Connection connection = dataSource.getConnection();
		System.out.println(connection);
		connection.close();
	}
}

class com.zaxxer.hikari.HikariDataSource
2020-10-18 13:21:21.481  INFO 3412 --- [           main] com.zaxxer.hikari.HikariDataSource       : HikariPool-1 - Starting...
2020-10-18 13:21:21.698  INFO 3412 --- [           main] com.zaxxer.hikari.HikariDataSource       : HikariPool-1 - Start completed.
HikariProxyConnection@392795843 wrapping com.mysql.cj.jdbc.ConnectionImpl@411c6d44

创建表

-- ----------------------------
-- Table structure for user
-- ----------------------------
DROP TABLE IF EXISTS `user`;
CREATE TABLE `user`  (
  `id` int(11) NOT NULL AUTO_INCREMENT,
  `name` varchar(255) CHARACTER SET utf8 COLLATE utf8_general_ci NULL DEFAULT NULL,
  `password` varchar(255) CHARACTER SET utf8 COLLATE utf8_general_ci NULL DEFAULT NULL,
  `age` int(11) NULL DEFAULT NULL,
  PRIMARY KEY (`id`) USING BTREE
) ENGINE = InnoDB AUTO_INCREMENT = 6 CHARACTER SET = utf8 COLLATE = utf8_general_ci ROW_FORMAT = Compact;

-- ----------------------------
-- Records of user
-- ----------------------------
INSERT INTO `user` VALUES (1, '测试1', '111', 20);
INSERT INTO `user` VALUES (2, '测试2', '222', 11);
INSERT INTO `user` VALUES (3, '测试3', '333', 25);
INSERT INTO `user` VALUES (4, '测试4', '444', 17);
INSERT INTO `user` VALUES (5, '测试5', '555', 12);

编写User 实体类

package com.example.jdbc.domain;
import lombok.Data;
@Data
public class User {
    
    
    private Integer id;
    private String name;
    private String password;
    private Integer age;
}

编写DemoController类

package com.example.jdbc.controller;
import com.example.jdbc.domain.User;
import com.example.jdbc.service.UserService;
import org.springframework.stereotype.Controller;
import org.springframework.ui.Model;
import org.springframework.web.bind.annotation.GetMapping;
import javax.annotation.Resource;
import java.util.List;

@Controller
public class DemoController {
    
    
    @Resource
    private UserService userService;

    @GetMapping("/demo1")
    public String demo1(Model model){
    
    
        List<User> users = userService.queryAll();
        System.out.println(users);
        model.addAttribute("user",users);
        return "index";
    }
}

编写index.html

<!DOCTYPE html>
<html xmlns:th="http://www.thymeleaf.org">
<head>
    <meta charset="UTF-8">
    <title>Title</title>
</head>
<link rel="stylesheet" href="style.css">
<body>
<h1>测试SpringBoot 使用jdbcTemplate</h1>
    <ul>
        <li th:each="u : ${user}" th:object="${u}">
            <div>
                <span th:text="*{name}">水果</span>
                <span th:text="${u.age}">价格</span>
            </div>
        </li>
    </ul>
</body>
</html>

编写Service 层

package com.example.jdbc.service;

import com.example.jdbc.domain.User;
import java.util.List;
public interface UserService {
    
    
    List<User> queryAll();
}

package com.example.jdbc.service.impl;

import com.example.jdbc.dao.UserDao;
import com.example.jdbc.domain.User;
import com.example.jdbc.service.UserService;
import org.springframework.stereotype.Service;
import javax.annotation.Resource;
import java.util.List;
@Service
public class UserServiceImpl implements UserService {
    
    
    @Resource
    private UserDao userDao;
    @Override
    public List<User> queryAll() {
    
    
        List<User> users = userDao.queryAll();
        return users;
    }
}

编写Dao层

package com.example.jdbc.dao;

import com.example.jdbc.domain.User;

import java.util.List;
public interface UserDao {
    
    
    List<User> queryAll();
}

package com.example.jdbc.dao.impl;

import com.example.jdbc.dao.UserDao;
import com.example.jdbc.domain.User;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.jdbc.core.BeanPropertyRowMapper;
import org.springframework.jdbc.core.JdbcTemplate;
import org.springframework.stereotype.Repository;

import java.util.List;

@Repository
public class UserDaoImpl implements UserDao {
    
    
    @Autowired
    private JdbcTemplate jdbcTemplate;

    public List<User> queryAll(){
    
    
        List<User> user =jdbcTemplate.query("select *from user",new BeanPropertyRowMapper<User>(User.class));
        return user;
    }
}

测试

执行：http://localhost:9090/demo1
在这里插入图片描述

总结:

本节只写了JdbcTemplate的一种操作，详细请参考：JdbcTemplate API文档

待完善…

本教程基于最新的spring-boot-starter-parent：2.3.4RELEASE编写,目前很多大佬都写过关于SpringBoot的教程了，如有雷同，请多多包涵.