Apache druid

Druid是Java语言中最好的数据库连接池。Druid能够提供强大的监控和扩展功能。

快速开始

maven

<dependency><groupId>com.alibaba</groupId><artifactId>druid</artifactId><version>1.2.15</version>
</dependency>

配置

DruidDataSource大部分属性都是参考DBCP的，如果你原来就是使用DBCP，迁移是十分方便的。

 <bean id="dataSource" class="com.alibaba.druid.pool.DruidDataSource" init-method="init" destroy-method="close"> <property name="url" value="${jdbc_url}" /><property name="username" value="${jdbc_user}" /><property name="password" value="${jdbc_password}" /><property name="filters" value="stat" /><property name="maxActive" value="20" /><property name="initialSize" value="1" /><property name="maxWait" value="6000" /><property name="minIdle" value="1" /><property name="timeBetweenEvictionRunsMillis" value="60000" /><property name="minEvictableIdleTimeMillis" value="300000" /><property name="testWhileIdle" value="true" /><property name="testOnBorrow" value="false" /><property name="testOnReturn" value="false" /><property name="poolPreparedStatements" value="true" /><property name="maxOpenPreparedStatements" value="20" /><property name="asyncInit" value="true" /></bean>

这个是 spring 的配置，其实配置上就是一个 POJO

实战例子

mysql 数据准备

建表语句

use test;CREATE TABLE "users" ("id" int(11) NOT NULL,"username" varchar(255) NOT NULL,"email" varchar(255) NOT NULL,PRIMARY KEY ("id")
) ENGINE=InnoDB DEFAULT CHARSET=utf8 |

插入数据

insert into users (id, username, email) values (1, 'u-1', '1@email.com');
insert into users (id, username, email) values (2, 'u-2', '2@email.com');
insert into users (id, username, email) values (3, 'u-3', '3@email.com');

数据确认：

mysql> select * from users;
+----+----------+-------------+
| id | username | email       |
+----+----------+-------------+
|  1 | u-1      | 1@email.com |
|  2 | u-2      | 2@email.com |
|  3 | u-3      | 3@email.com |
+----+----------+-------------+
3 rows in set (0.00 sec)

数据库准备

maven 引入

<!-- MySQL JDBC Driver -->
<dependency><groupId>mysql</groupId><artifactId>mysql-connector-java</artifactId><version>5.1.47</version> <!-- 或者最新版本 -->
</dependency>
<dependency><groupId>com.alibaba</groupId><artifactId>druid</artifactId><version>1.2.15</version>
</dependency>

入门代码

package com.github.houbb.calcite.learn.mysql;import com.alibaba.druid.pool.DruidDataSource;import java.sql.Connection;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.sql.Statement;/*** druid 整合 mysql 使用* @author 老马啸西风*/
public class DruidMySQLExample {public static void main(String[] args) {// 初始化 Druid 数据源DruidDataSource dataSource = new DruidDataSource();dataSource.setUrl("jdbc:mysql://localhost:3306/test?useUnicode=true&characterEncoding=utf-8&useSSL=false&serverTimezone=UTC");dataSource.setUsername("admin");dataSource.setPassword("123456");Connection conn = null;Statement stmt = null;ResultSet rs = null;try {// 从连接池获取数据库连接conn = dataSource.getConnection();// 创建 Statement 对象stmt = conn.createStatement();// 执行 SQL 查询rs = stmt.executeQuery("SELECT * FROM users");// 遍历结果集while (rs.next()) {// 处理每一行数据int id = rs.getInt("id");String username = rs.getString("username");String email = rs.getString("email");// 输出到控制台System.out.println("ID: " + id + ", username: " + username+ ", email: " + email);}} catch (SQLException e) {e.printStackTrace();} finally {// 关闭资源try {if (rs != null) rs.close();if (stmt != null) stmt.close();if (conn != null) conn.close();} catch (SQLException e) {e.printStackTrace();}}}}

输出如下：

ID: 1, username: u-1, email: 1@email.com
ID: 2, username: u-2, email: 2@email.com
ID: 3, username: u-3, email: 3@email.com