Database connection pool & Druid usage

Introduction to database connection pool

● The database connection pool is a container , To be responsible for the distribution of 、 Manage database connections
● It allows applications to reuse an existing database connection , Instead of building a new
● Release database connection with idle time exceeding the maximum idle time to avoid missing database connection caused by no free database connection
● benefits ：
* Resource reuse
* Improve system response speed
* Avoid missing database connections

Database connection pool implementation

● Standard interface ：DataSource
* official （SUN） Database connection pool standard interface provided , This interface is implemented by a third-party organization .
* function ： Get the connection

● Common database connection pool ：
*DBCP
*C3P0
*Druid
●Druid( Druid ）
*Druid Connection pool is an open source database connection pool project of Alibaba
* Powerful , Excellent performance , yes Java One of the best database connection pools in language

Driud Use steps

1、 Import jar package druid-1.1.12.jar

Database connection pool druid Of jar Download from Bao official website : https://mvnrepository.com/artifact/com.alibaba/druid
* Put it jar Import the package into the current module directory and set the current module to be valid

2、 Define configuration file

 

* Properties of a profile : https://github.com/alibaba/druid/wiki/DruidDataSource%E9%85%8D%E7%BD%AE%E5%B1%9E%E6%80%A7%E5%88%97%E8%A1%A8​​​​​​​
（druid.properties The configuration file ）

driverClassName=com.mysql.cj.jdbc.Driver
url=jdbc:mysql://127.0.0.1:3306/byshop?serverTimezone=PRC
username=root
password=123456
// Initialize the number of connections ( Initial application in container 5 individual )
initialSize=5
// Minimum number of connection pools 
minIdle=1
// maximum connection 
maxActive=10
// Maximum waiting time (10 Second ) An error will be reported after timeout 
maxWait=10000
timeBetweenEvictionRunsMillis=6000
// The minimum time that a connection remains idle without being evicted 
minEvictableIdleTimeMillis=300000
testWhileIdle=true
// Used to check whether the connection is valid SQL, The requirement is a query statement , Commonly used select 'x'. If validationQuery by null,testOnBorrow、testOnReturn、testWhileIdle It doesn't work .
validationQuery=select 1

3、 Load profile
4、 Get database connection pool object
5、 Get the connection

import com.alibaba.druid.pool.DruidDataSourceFactory;

import javax.sql.DataSource;
import java.io.FileInputStream;
import java.sql.Connection;
import java.util.Properties;

public class Druid {
    public static void main(String[] args) throws Exception {
        // Load profile ——Properties Object load configuration file 
        Properties prop=new Properties();
        prop.load(new FileInputStream("src/druid.properties"));
        // Get connection pool object 
         DataSource dataSource=DruidDataSourceFactory.createDataSource(prop);
        // Get the corresponding database connection 
        Connection conn=dataSource.getConnection();
        System.out.println(conn);
    }
}

result ：(JDBC A connection object of )