Druid database connection pool details

Recommended reading ：JDBC Detailed explanation

summary

1. Database connection pool is a container , To be responsible for the distribution of 、 Manage database connections (Connection);
2. It allows applications to reuse an existing database connection , Instead of building a new ;
3. Release database connection with idle time exceeding the maximum idle time to avoid missing database connection caused by no free database connection ;

It can be understood by analogy with thread pool .

advantage
1. Resource reuse
2. Improve system response speed
3. Avoid missing database connections

Connection pool is to create some connections at the beginning （Connection） Objects stored . When users need to connect to the database , You don't need to create your own connection , You only need to get a connection from the connection pool for use , Return the connection object to the connection pool after use ; In this way, we can reuse resources , It also saves time for frequent connection creation and connection destruction , Thus, the response speed of the system is improved .

Common database connection pool ： DBCP、C3P0、Druid
Now we use more Druid, Its performance will be better than the other two .

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 .

Database connection pool implementation

Standard interface ：DataSource
official (SUN) Database connection pool standard interface provided , This interface is implemented by a third-party organization . This interface provides the function of obtaining connection ：Connection getConnection()

Then you don't need to pass DriverManager Object acquisition Connection object , But through the connection pool （DataSource） obtain Connection object .

Driud Usage flow

1. Import jar package druid-1.1.12.jar
2. Define configuration file druid.properties
3. Load profile
4. Get database connection pool object
5. Get the connection

Code example

The configuration file
druid.properties

driverClassName=com.mysql.jdbc.Driver
url=jdbc:mysql://127.0.0.1:3306/sd?useSSL=false&useServerPrepStmts=true
username=root
password=root
#  The number of initial connections 
initialSize=5
#  maximum connection 
maxActive=10
#  Maximum waiting time 
maxWait=3000

Java Code

public static void main(String[] args) throws Exception {
    
        //1. Import jar package 
        //2. Define configuration file 
        //3.  Load profile 
        Properties prop=new Properties();
        prop.load(new FileInputStream("C:\\Users\\ Sven \\Desktop\\Java\\demo\\index\\src\\druid.properties"));

        //4.  Get connection pool object 
        DataSource dataSource= DruidDataSourceFactory.createDataSource(prop);

        //5.  Get database connection  Connection
        Connection conn=dataSource.getConnection();

        //6. Operating the database 
        String sql = "select * from st";
        Statement stmt=conn.createStatement();
        ResultSet rs = stmt.executeQuery(sql);
        while (rs.next()) {
    
            int id = rs.getInt("id");
            String name = rs.getString("name");
            int age = rs.getInt("age");
            System.out.println(id + " " + name + " " + age);
        }

    }

Recommended reading ：JDBC Detailed explanation