java数据库访问（一）—JDBC方式

jdbc方式是最基本的访问数据库的方式，仅需要数据库驱动即可，本次连接的是mysql数据库，故仅需要mysql的驱动，pom.xml配置如下：

<!-- https://mvnrepository.com/artifact/mysql/mysql-connector-java -->
        <dependency>
            <groupId>mysql</groupId>
            <artifactId>mysql-connector-java</artifactId>
            <version>5.1.6</version>
        </dependency>

mysql驱动是对java jdbc各个接口的具体实现，以Connection为例，下面是具体的类关系：

本次要查询的数据库有如下数据：

工程是单纯的spring工程，为了后边方便继续集成spring data JPA以及Mybatis等，spring配置文件如下：

<?xml version="1.0" encoding="UTF-8"?>
<beans xmlns="http://www.springframework.org/schema/beans"
    xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
    xmlns:context="http://www.springframework.org/schema/context"
    xsi:schemaLocation="
     http://www.springframework.org/schema/context
     http://www.springframework.org/schema/context/spring-context-2.5.xsd  
     http://www.springframework.org/schema/beans
     https://www.springframework.org/schema/beans/spring-beans.xsd">
    <!-- 配置组件自动扫描装配路径及筛选条件 -->
    <context:component-scan base-package="com.*"/>
</beans>

JdbcService代码示例如下：

package com.test.database;

import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.ResultSet;
import java.sql.Statement;

import org.springframework.stereotype.Service;

@Service
public class JdbcService {

    String url = "jdbc:mysql://localhost:3306/test";
    String username = "root";
    String password = "root";

    public void testJdbc() throws Exception {
        //加载mysql驱动
        Class.forName("com.mysql.jdbc.Driver");
        Connection connection = DriverManager.getConnection(url, username, password);
        Statement statement = connection.createStatement();
        String sql = "select * from user";
        ResultSet resultSet = statement.executeQuery(sql);
        while(resultSet.next()) {
        System.out.println(resultSet.getInt("id"));
        System.out.println(resultSet.getString("name"));
        System.out.println(resultSet.getString("password"));
        }
        resultSet.close();
        statement.close();
        connection.close();
    }
}

测试类如下：

package com.test;

import org.springframework.beans.BeansException;
import org.springframework.context.ApplicationContext;
import org.springframework.context.support.ClassPathXmlApplicationContext;

import com.test.database.JdbcService;

public class Main {

    public static void main(String[] args) throws BeansException, Exception {
        ApplicationContext context = new ClassPathXmlApplicationContext("spring-context.xml");
        context.getBean(JdbcService.class).testJdbc();
    }
}

打印结果为：

1
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