Connection pool examples

Author: AndriiPiatakha

online-store.persistence/pom.xml

@@ -19,6 +19,26 @@
 			<artifactId>mysql-connector-java</artifactId>
 			<version>8.0.28</version>
 		</dependency>
+
+		<dependency>
+			<groupId>org.apache.commons</groupId>
+			<artifactId>commons-dbcp2</artifactId>
+			<version>2.9.0</version>
+		</dependency>
+
+		<dependency>
+			<groupId>c3p0</groupId>
+			<artifactId>c3p0</artifactId>
+			<version>0.9.1.2</version>
+		</dependency>
+
+		<dependency>
+			<groupId>com.zaxxer</groupId>
+			<artifactId>HikariCP</artifactId>
+			<version>5.0.1</version>
+		</dependency>
+
+
 	</dependencies>
 
 

online-store.persistence/src/main/java/com/itbulls/learnit/onlinestore/persistence/utils/connectionpools/C3p0Demo.java

@@ -0,0 +1,41 @@
+package com.itbulls.learnit.onlinestore.persistence.utils.connectionpools;
+
+import java.beans.PropertyVetoException;
+import java.sql.Connection;
+import java.sql.SQLException;
+
+import org.apache.commons.dbcp2.BasicDataSource;
+
+import com.mchange.v2.c3p0.ComboPooledDataSource;
+
+public class C3p0Demo {
+
+	private static ComboPooledDataSource cpds = new ComboPooledDataSource();
+
+    static {
+        try {
+            cpds.setDriverClass("com.mysql.cj.jdbc.Driver");
+            cpds.setJdbcUrl("jdbc:mysql://localhost:3306/learn_it_db");
+            cpds.setUser("root");
+            cpds.setPassword("root");
+            cpds.setMaxIdleTime(100);
+            cpds.setMaxStatementsPerConnection(10);
+        } catch (PropertyVetoException e) {
+            // handle the exception
+        }
+    }
+    
+    public static Connection getConnection() throws SQLException {
+        return cpds.getConnection();
+    }
+	
+	public static void main(String[] args) throws SQLException {
+		Connection conn = getConnection();
+		try (conn) {
+			System.out.println(conn);
+		}
+		System.out.println(conn);
+	}
+
+
+}

online-store.persistence/src/main/java/com/itbulls/learnit/onlinestore/persistence/utils/connectionpools/DbcpDemo.java

@@ -0,0 +1,35 @@
+package com.itbulls.learnit.onlinestore.persistence.utils.connectionpools;
+
+import java.sql.Connection;
+import java.sql.SQLException;
+
+import org.apache.commons.dbcp2.BasicDataSource;
+
+public class DbcpDemo {
+
+	private static BasicDataSource ds = new BasicDataSource();
+
+	static {
+		ds.setUrl("jdbc:mysql://localhost:3306/learn_it_db");
+		ds.setUsername("root");
+		ds.setPassword("root");
+		ds.setMinIdle(3);
+		ds.setTimeBetweenEvictionRunsMillis(1000);
+		ds.setMaxIdle(20);
+		ds.setMaxOpenPreparedStatements(200);
+	}
+
+	public static Connection getConnection() throws SQLException {
+		return ds.getConnection();
+	}
+	
+	public static void main(String[] args) throws SQLException {
+		Connection conn = getConnection();
+		try (conn) {
+			System.out.println(conn);
+		}
+		System.out.println(conn);
+	}
+
+
+}

online-store.persistence/src/main/java/com/itbulls/learnit/onlinestore/persistence/utils/connectionpools/HikaricpDemo.java

@@ -0,0 +1,38 @@
+package com.itbulls.learnit.onlinestore.persistence.utils.connectionpools;
+
+import java.sql.Connection;
+import java.sql.SQLException;
+
+import org.apache.commons.dbcp2.BasicDataSource;
+
+import com.zaxxer.hikari.HikariConfig;
+import com.zaxxer.hikari.HikariDataSource;
+
+public class HikaricpDemo {
+
+	private static HikariConfig config = new HikariConfig();
+	private static HikariDataSource ds;
+
+	static {
+		config.setJdbcUrl("jdbc:mysql://localhost:3306/learn_it_db");
+		config.setUsername("root");
+		config.setPassword("root");
+		config.addDataSourceProperty("cachePrepStmts", "true");
+		config.addDataSourceProperty("prepStmtCacheSize", "100");
+		config.addDataSourceProperty("prepStmtCacheSqlLimit", "2048");
+		ds = new HikariDataSource(config);
+	}
+
+	public static Connection getConnection() throws SQLException {
+		return ds.getConnection();
+	}
+
+	public static void main(String[] args) throws SQLException {
+		Connection conn = getConnection();
+		try (conn) {
+			System.out.println(conn);
+		}
+		System.out.println(conn);
+	}
+
+}

online-store.web/src/main/java/com/itbulls/learnit/onlinestore/web/servlets/ConnectionPoolDemoServlet.java

@@ -0,0 +1,58 @@
+package com.itbulls.learnit.onlinestore.web.servlets;
+
+import jakarta.servlet.http.HttpServlet;
+import java.io.IOException;
+import java.sql.Connection;
+import java.sql.SQLException;
+
+import javax.naming.Context;
+import javax.naming.InitialContext;
+import javax.naming.NamingException;
+
+import javax.sql.DataSource;
+
+import jakarta.annotation.Resource;
+import jakarta.servlet.ServletException;
+import jakarta.servlet.annotation.WebServlet;
+import jakarta.servlet.http.HttpServletRequest;
+import jakarta.servlet.http.HttpServletResponse;
+
+@WebServlet("/cp-demo")
+public class ConnectionPoolDemoServlet extends HttpServlet {
+	
+	private DataSource ds1;
+	
+	@Resource(name = "jdbc/connpool")
+    private DataSource ds2;
+	
+	protected void doGet(HttpServletRequest request, HttpServletResponse response)
+			throws ServletException, IOException {
+
+		InitialContext initialContext;
+		try {
+			initialContext = new InitialContext();
+			Context context = (Context) initialContext.lookup("java:comp/env");
+			DataSource ds1 = (DataSource) context.lookup("jdbc/connpool");	
+			
+			Connection conn1 = getConnection(ds1);
+			Connection conn2 = getConnection(ds2);
+			
+			try (conn1; conn2) {
+				System.out.println("Connection 1 from DS1:\t" + conn1);
+				System.out.println("Connection 2 from DS2:\t" + conn2);
+			}
+			
+			System.out.println("Connection 1 from DS1 after closure:\t" + conn1);
+			System.out.println("Connection 2 from DS2 after closure:\t" + conn2);
+			
+			System.out.println("DS1 equals DS2:\t" + ds1.equals(ds2));
+		} catch (NamingException | SQLException e) {
+			e.printStackTrace();
+		}
+	}
+	
+	private Connection getConnection(DataSource ds) throws SQLException {
+		return ds.getConnection();
+	}
+
+}

online-store.web/src/main/webapp/META-INF/context.xml

@@ -0,0 +1,44 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<context>
+  
+
+    <Resource name="jdbc/connpool" 
+    		auth="Container" 
+    		type="javax.sql.DataSource"
+            maxActive="5" 
+            maxIdle="5" 
+            maxWait="10000"
+            maxAge="10000"
+            username="root" 
+            password="root" 
+            driverClassName="com.mysql.cj.jdbc.Driver"
+            url="jdbc:mysql://localhost:3306/learn_it_db"/>
+    
+    <!-- Description of all other attributes - https://tomcat.apache.org/tomcat-7.0-doc/jdbc-pool.html  -->
+    
+    <!-- maxActive: Maximum number of database connections in pool. Make sure you
+         configure your mysqld max_connections large enough to handle
+         all of your db connections. Set to -1 for no limit.
+         -->
+
+    <!-- maxIdle: Maximum number of idle database connections to retain in pool.
+         Set to -1 for no limit.  See also the DBCP documentation on this
+         and the minEvictableIdleTimeMillis configuration parameter.
+         -->
+
+    <!-- maxWait: Maximum time to wait for a database connection to become available
+         in ms, in this example 10 seconds. An Exception is thrown if
+         this timeout is exceeded.  Set to -1 to wait indefinitely.
+         -->
+
+    <!-- username and password: MySQL username and password for database connections  -->
+
+    <!-- driverClassName: Class name for the old mm.mysql JDBC driver is
+         org.gjt.mm.mysql.Driver - we recommend using Connector/J though.
+         Class name for the official MySQL Connector/J driver is com.mysql.jdbc.Driver.
+         -->
+
+    <!-- url: The JDBC connection url for connecting to your MySQL database.
+         -->
+
+</context>