MySQL learning record 13 database connection pool, pooling technology, DBCP, c3p0

MySQL Learning record 13 Database connection pool 、 Pool technology 、DBCP、C3P0

13.1 Database connection pool

13.1.1 Pool technology

In a nutshell , Is to save a lot of resources in advance , For a rainy day .
Due to our database connection → completion of enforcement → Releasing this process will waste system resources , Pooling technology prepares some resources in advance , Let the database connect to these resources prepared in advance .
for instance , Suppose the bank does not have pooling Technology , Every time I open the door , Serve only one person , Then close the door , Repeat the above steps for the next person . And if you have pooling Technology , There is a salesman waiting there after opening the door , Only the server is shut down , The salesman just went offline . How many salesmen are needed ？ This is it. “ Minimum connections ”, Generally, it is the number of commonly used connections , The maximum number of connections is the maximum load limit of the service , Those who exceed the maximum number of connections can only queue .

Open source data source implementation ( Use immediately )：

• DBCP
• C3P0
• Druid: Alibaba

After using these database connection pools , We don't need to write the code to connect to the database in the project development

13.1.2DBCP

Needed jar package ：commons-dbcp-1.4 、commons-pool-1.6

dbcpconfig.properties：

driverClassName=com.mysql.jdbc.Driver
url=jdbc:mysql://localhost:3306/jdbcstudy?useUnicode=true&characterEncoding=utf8&useSSL=false
username=root
password=123456
#<!--  Initialize connection  -->
initialSize=10
# Maximum number of connections 
maxActive=50
#<!--  Maximum free connection  -->
maxIdle=20
#<!--  Minimum free connection  -->
minIdle=5
#<!--  Timeout wait time in milliseconds  6000 millisecond /1000 be equal to 60 second  -->
maxWait=60000
#JDBC The format of the connection attribute attribute attached to the driver when establishing the connection must be as follows ：【 Property name =property;】
# Be careful ："user"  And  "password"  Two attributes are explicitly passed , So there's no need to include them .
connectionProperties=useUnicode=true;characterEncoding=UTF8
# Specifies the automatic commit of connections created by the connection pool （auto-commit） state .
defaultAutoCommit=true
#driver default  Specifies the read-only... Of the connection created by the connection pool （read-only） state .
# If the value is not set , be “setReadOnly” Method will not be called .（ Some drivers do not support read-only mode , Such as ：Informix）
defaultReadOnly=
#driver default  Specify the transaction level of the connection created by the connection pool （TransactionIsolation）.
# The available values are one of the following ：（ Details visible javadoc.）NONE,READ_UNCOMMITTED, READ_COMMITTED, REPEATABLE_READ, SERIALIZABLE
defaultTransactionIsolation=READ_UNCOMMITTED

import org.apache.commons.dbcp.BasicDataSourceFactory;

import javax.sql.DataSource;
import java.io.InputStream;
import java.sql.*;
import java.util.Properties;

public class JdbcUtils_DBCP {
    

    private static DataSource dataSource = null;

    static {
    
        try {
    
            InputStream in = JdbcUtils_DBCP.class.getClassLoader().getResourceAsStream("dbcpconfig.properties");
            Properties properties = new Properties();
            properties.load(in);

            // create data source   Factory mode , Create objects 
            dataSource = BasicDataSourceFactory.createDataSource(properties);

        } catch (Exception e) {
    
            e.printStackTrace();
        }
    }

    // Get the connection 
    public static Connection getConnection() throws SQLException {
    
        return dataSource.getConnection();  // Get the connection from the data source 
    }

    // Release the connection 
    public static void release(Connection conn, Statement st, ResultSet rs) throws SQLException {
    
        if (rs != null) {
    
            rs.close();
        }
        if (st != null) {
    
            st.close();
        }
        if (conn != null) {
    
            conn.close();
        }
    }
}

import java.sql.*;

public class TestDBCP {
    
    public static void main(String[] args) throws SQLException {
    
        Connection conn = null;
        PreparedStatement st = null;

        try {
    
            conn = JdbcUtils_DBCP.getConnection();  // Get database connection , So it's connected , Don't write those configurations anymore 

            // difference   Use ? Instead of parameters 
            String sql = "INSERT INTO users(id,`NAME`,`PASSWORD`,`email`,`birthday`)" + "VALUES(?,?,?,?,?)";
            st = conn.prepareStatement(sql);// precompile sql, First write sql, Don't execute 

            // Assign parameters manually 
            st.setInt(1, 4);
            st.setString(2, "haha");
            st.setString(3, "123456");
            st.setString(4, "[email protected]");
            // Be careful  sql.Date
            // util.Date
            st.setDate(5, new java.sql.Date(new java.util.Date().getTime()));

            // perform 
            int i = st.executeUpdate();  // hold sql Statement is thrown in and executed ,i Is the number of rows affected 
            if (i > 0) {
    
                System.out.println(" Insert the success !");
            }

        } catch (SQLException e) {
    
            e.printStackTrace();
        } finally {
    
            JdbcUtils_DBCP.release(conn, st, null);
        }
    }
}

13.1.3C3P0

Needed jar package ：c3p0-0.9.5.5 、mchange-commons-java-0.2.19

c3p0-config.xml：

<?xml version="1.0" encoding="UTF-8"?>

<c3p0-config>
    <!--
    c3p0 Default （ Default ） To configure 
     If in code "ComboPooledDataSource ds=new ComboPooledDataSource();" This means that you are using c3p0 Default （ Default ）
    -->
    <default-config>
        <property name="driverClass">com.mysql.jdbc.Driver</property>
        <property name="jdbcUrl">jdbc:mysql://localhost:3306/jdbcstudy?useUnicode=true&amp;characterEncoding=utf8&amp;
            useSSL=false
        </property>
        <property name="user">root</property>
        <property name="password">123456</property>

        <property name="acquiredIncrement">5</property>
        <property name="initialPoolSize">10</property>
        <property name="minPoolSize">5</property>
        <property name="maxPoolSize">20</property>
    </default-config>

    <!--
        c3p0 Named configuration for 
         If in code "ComboPooledDataSource ds=new ComboPooledDataSource("MySQL");" This means that you are using mysql Default （ Default ）
        -->
    <named-config name="MySQL">
        <property name="driverClass">com.mysql.jdbc.Driver</property>
        <property name="jdbcUrl">jdbc:mysql://localhost:3306/jdbcstudy?useUnicode=true&amp;characterEncoding=utf8&amp;useSSL=false&amp;autoReconnect=true&amp;failOverReadOnly=false
        </property>
        <property name="user">root</property>
        <property name="password">123456</property>
        <property name="acquiredIncrement">5</property>
        <property name="initialPoolSize">10</property>
        <property name="minPoolSize">5</property>
        <property name="maxPoolSize">20</property>
    </named-config>

</c3p0-config>

import com.mchange.v2.c3p0.ComboPooledDataSource;
import org.apache.commons.dbcp.BasicDataSourceFactory;

import javax.sql.DataSource;
import java.io.InputStream;
import java.sql.Connection;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.sql.Statement;
import java.util.Properties;

public class JdbcUtils_C3P0 {
    

    private static ComboPooledDataSource dataSource = null;

    static {
    
        try {
    

            // Code version configuration , Not recommended 
// dataSource = new ComboPooledDataSource();
// dataSource.setDriverClass();
// dataSource.setUser();
// dataSource.setPassword();
// dataSource.setJdbcUrl();
//
// dataSource.setMaxPoolSize();
            // create data source   Factory mode , Create objects 
            dataSource = new ComboPooledDataSource("MySQL");// Configuration file writing 

        } catch (Exception e) {
    
            e.printStackTrace();
        }
    }

    // Get the connection 
    public static Connection getConnection() throws SQLException {
    
        return dataSource.getConnection();  // Get the connection from the data source 
    }

    // Release the connection 
    public static void release(Connection conn, Statement st, ResultSet rs) throws SQLException {
    
        if (rs != null) {
    
            rs.close();
        }
        if (st != null) {
    
            st.close();
        }
        if (conn != null) {
    
            conn.close();
        }
    }
}

import java.sql.Connection;
import java.sql.Date;
import java.sql.PreparedStatement;
import java.sql.SQLException;

public class TestC3P0 {
    
    public static void main(String[] args) throws SQLException {
    
        Connection conn = null;
        PreparedStatement st = null;

        try {
    
            conn = JdbcUtils_C3P0.getConnection();

            // difference   Use ? Instead of parameters 
            String sql = "INSERT INTO users(id,`NAME`,`PASSWORD`,`email`,`birthday`)" + "VALUES(?,?,?,?,?)";
            st = conn.prepareStatement(sql);// precompile sql, First write sql, Don't execute 

            // Assign parameters manually 
            st.setInt(1, 5);
            st.setString(2, "baba");
            st.setString(3, "123456");
            st.setString(4, "[email protected]");
            // Be careful  sql.Date
            // util.Date
            st.setDate(5, new Date(new java.util.Date().getTime()));

            // perform 
            int i = st.executeUpdate();  // hold sql Statement is thrown in and executed ,i Is the number of rows affected 
            if (i > 0) {
    
                System.out.println(" Insert the success !");
            }

        } catch (SQLException e) {
    
            e.printStackTrace();
        } finally {
    
            JdbcUtils_C3P0.release(conn, st, null);
        }
    }
}

No matter what data source is used , The essence is the same ,DateSource The interface will not change , The method won't change .