1.数据准备

drop table if exists account;
create table if not exists account
(id    int primary key auto_increment,name  varchar(10),money double(10, 2)
);
insert into account(name, money)
values ('张三', 1000),('李四', 1000);

2.pom.xml文件中引用druid

<dependency><groupId>com.alibaba</groupId><artifactId>druid</artifactId><version>1.1.10</version>
</dependency>

3. 在resource目录下创建druid.properties配置文件

driverClassName=com.mysql.cj.jdbc.Driver
url=jdbc:mysql:///db1?useServerPrepStmts=true
username=root
password=root1234
# 初始化连接数量
initialSize=5
# 最大连接数量
maxActive=10
# 最大等待时间
maxWait=3000

4. 编写java代码

// 加载配置文件
Properties prop = new Properties();
prop.load(Main.class.getClassLoader().getResourceAsStream("druid.properties"));// 获取连接池对象
DataSource dataSource = DruidDataSourceFactory.createDataSource(prop);
// 获取数据库连接对象
Connection connection = dataSource.getConnection();String sql = "select * from account";
PreparedStatement prepareStatement = connection.prepareStatement(sql);ResultSet resultSet = prepareStatement.executeQuery();while (resultSet.next()) {int id = resultSet.getInt("id");String name = resultSet.getString("name");double money = resultSet.getDouble("money");System.out.println("id = " + id + " , name = " + name + " , money = " + money);
}
// 释放资源
resultSet.close();
prepareStatement.close();
connection.close();

参考文献

1. 黑马程序员JavaWeb基础教程