Three ways to implement a C3P0 connection pool

Jar Package used:

Mysql-connector-java-5.1.30-bin.jar

C3p0-0.9.5.2.jar

Mchange-commons-java-0.2.11.jar

set parameters directly:

C3p0inner.java

Package Com.song.c3p0.db.inner;
Import java.sql.Connection;
Import java.sql.PreparedStatement;
Import Java.sql.ResultSet;

Import java.sql.SQLException;

Import Com.mchange.v2.c3p0.ComboPooledDataSource;
	
	public class C3p0inner {private static Combopooleddatasource ds; Static initialization blocks are initialized static{try {ds = new Combopooleddatasource ();//create Connection Pool instance Ds.setdriverclass ("Com.mysql.jdbc.Driv ER ");//Set the driver Ds.setjdbcurl (" jdbc:mysql://localhost:3306/cloudhospital ") required to connect to the database,//Set the URL of the connection database Ds.setuser (" Root ");//Set the user name of the connection database Ds.setpassword (" admin ");//Set the password of the connection database Ds.setmaxpoolsize (40);//Set the maximum number of connections for the connection pool Ds.setm Inpoolsize (2);//Set the minimum number of connections for the connection pool ds.setinitialpoolsize (10);//Set the initial connection pool connection number ds.setmaxstatements (100);//Set the cache state of the connection pool
		The maximum number of ment} catch (Exception e) {e.printstacktrace ();
	}}//Gets the connection to the specified database public static Combopooleddatasource getinstance () {return DS; }//Returns a connection from the connection pool public static Connection getconnection () {Connection conn = Null
		try {conn = ds.getconnection ();
		} catch (Exception e) {e.printstacktrace ();
	} return conn;
			}//release resource public static void Realeaseresource (ResultSet rs,preparedstatement ps,connection conn) {if (null! = RS) {
			try {rs.close ();
			} catch (SQLException e) {e.printstacktrace ();
			}} if (null! = PS) {try {ps.close ();
			} catch (SQLException e) {e.printstacktrace ();
		}} try {conn.close ();
		} catch (SQLException e) {e.printstacktrace (); }
	}
}

C3p0innermain.java

Package Com.song.c3p0.db.inner;
Import java.sql.Connection;
Import java.sql.PreparedStatement;
Import Java.sql.ResultSet;

Import java.sql.SQLException;  public class C3p0innermain {public PreparedStatement setstatement (Connection conn,string sql) {PreparedStatement PS =
		Null
		try {PS = conn.preparestatement (SQL);
		} catch (SQLException e) {e.printstacktrace ();
	} return PS; Public PreparedStatement Setparameter (PreparedStatement ps,object...values) {try {if (null! = values) {for (i
				NT i=1;i<=values.length;i++) {ps.setobject (I, values[i-1]);
		}}} catch (Exception e) {e.printstacktrace ();
	} return PS;
		public static void Main (string[] args) {Connection conn = null;
		PreparedStatement PS = null;
		ResultSet rs = null;
			
			try {conn = c3p0inner.getconnection ();
			
			C3p0innermain C3p0innermain = new C3p0innermain ();
			
			String sql = "SELECT * from Tb_user WHERE ID <?"; PS = C3p0innermain.setstatement (conn, SQL);
			
			PS = C3p0innermain.setparameter (PS, New object[]{20});
			
			rs = Ps.executequery ();
				while (Rs.next ()) {Object OB = Rs.getobject (1);
				Object name = Rs.getobject (4);
			System.out.println ("ID:" + ob + ", Name:" + name ");
		}} catch (Exception e) {e.printstacktrace ();
		}finally{//Release Resources C3p0inner.realeaseresource (RS, PS, conn);
 }
	}
}

To set parameters with a configuration file:

1. Get the parameters from the configuration file

Config.properties

Driverclass = com.mysql.jdbc.Driver
jdbcurl = jdbc:mysql://localhost:3306/cloudhospital
User = root
Password = Admin
maxpoolsize =
minpoolsize = 2
initialpoolsize = 5
maxstatements =
maxidletime = 100

C3p0properties.java

Package com.song.c3p0.db.properties;
Import java.sql.Connection;

Import java.util.Properties;

Import Com.mchange.v2.c3p0.ComboPooledDataSource;
	
	public class C3p0properties {private Combopooleddatasource CPDs;
	
	private static c3p0properties c3p0properties;
	static{c3p0properties = new C3p0properties ();
			
			Public c3p0properties () {try {CPDs = new Combopooleddatasource ();
			Load Config file properties props = new properties ();
			
			Props.load (C3P0Properties.class.getClassLoader (). getResourceAsStream ("config.properties"));
			Cpds.setdriverclass (Props.getproperty ("Driverclass"));
			Cpds.setjdbcurl (Props.getproperty ("Jdbcurl"));
			Cpds.setuser (Props.getproperty ("User"));
			
			Cpds.setpassword (Props.getproperty ("Password"));
			Cpds.setmaxpoolsize (Integer.parseint (Props.getproperty ("maxpoolsize"));
			Cpds.setminpoolsize (Integer.parseint (Props.getproperty ("minpoolsize"));
			Cpds.setinitialpoolsize (Integer.parseint (Props.getproperty ("initialpoolsize")); CPDs. Setmaxstatements (Integer.parseint (Props.getproperty ("maxstatements")));
			
		Cpds.setmaxidletime (Integer.parseint (Props.getproperty ("MaxIdleTime"));
		} catch (Exception e) {e.printstacktrace ();
	}} public static C3p0properties getinstance () {return c3p0properties;
		} public Connection getconnection () {Connection conn = null;
		try {conn = cpds.getconnection ();
		} catch (Exception e) {e.printstacktrace ();
	} return conn;
 }
}

C3popropertiesmain.java

Package com.song.c3p0.db.properties;
Import java.sql.Connection;
Import java.sql.PreparedStatement;
Import Java.sql.ResultSet;

Import java.sql.SQLException; public class C3popropertiesmain {public PreparedStatement getpreparestatement (Connection conn,string sql) {PREPAREDST
		Atement PS = null;
		try {PS = conn.preparestatement (SQL);
		} catch (SQLException e) {e.printstacktrace ();
	} return PS; Public PreparedStatement setpreparestatementparameter (preparedstatement ps,object ... values) {try {if (null! =
				Values) {for (int i = 1; I <= values.length; i++) {Ps.setobject (I, values[i-1]);
		}}} catch (SQLException e) {e.printstacktrace ();
	} return PS;
			}//release resource public static void Realeaseresource (ResultSet rs,preparedstatement ps,connection conn) {if (null! = RS) {
			try {rs.close ();
			} catch (SQLException e) {e.printstacktrace ();
			}} if (null! = PS) {try {ps.close ();
} catch (SQLException e) {				E.printstacktrace ();
		}} try {conn.close ();
		} catch (SQLException e) {e.printstacktrace ();
		}} public static void Main (string[] args) {Connection conn = null;
		PreparedStatement PS = null;
		ResultSet rs = null;
			
			try {conn = C3p0properties.getinstance (). getconnection ();
			
			String sql = "SELECT * from Tb_user WHERE ID <?";
			
			C3popropertiesmain c3p0instance = new C3popropertiesmain ();
			PS = c3p0instance.getpreparestatement (conn, SQL);
			
			C3p0instance.setpreparestatementparameter (PS, New object[]{20});
			
			rs = Ps.executequery ();
				while (Rs.next ()) {Object obj1 = rs.getobject (1);
				
				Object Obj4 = Rs.getobject (4);
			System.out.println ("ID:" + obj1 + ", NAME:" + obj4);
		}} catch (SQLException e) {e.printstacktrace ();
		}finally{//Release Resources C3popropertiesmain.realeaseresource (RS, PS, conn);
 }
	}
}

2. Do not explicitly get the parameters from the configuration file

C3p0.properties

C3p0.driverclass = com.mysql.jdbc.Driver
c3p0.jdbcurl = jdbc:mysql://localhost:3306/cloudhospital
C3p0.user = root
c3p0.password = admin
c3p0.maxpoolsize =
c3p0.minpoolsize = 3
c3p0.maxstatements =
C3p0.maxidletime = 150

C3p0propertiessimplify.java

Package com.song.c3p0.db.properties;

Import java.sql.Connection;

Import Com.mchange.v2.c3p0.ComboPooledDataSource;

public class C3p0propertiessimplify {
	
	private static c3p0propertiessimplify c3p0propertiessimplify;
	
	Private Combopooleddatasource CPDs;
	
	static{
		c3p0propertiessimplify = new C3p0propertiessimplify ();
	}

	Public c3p0propertiessimplify () {
		CPDs = new Combopooleddatasource ();
	}
	
	public static c3p0propertiessimplify getinstance () {
		return c3p0propertiessimplify;
	}
	
	Public Connection getconnection () {
		Connection conn = null;
		try {
			conn = cpds.getconnection ();
		} catch (Exception e) {
			e.printstacktrace ();
		}
		return conn;
	}
}

C3p0propertiessimplifymain.java

Package com.song.c3p0.db.properties;
Import java.sql.Connection;
Import java.sql.PreparedStatement;
Import Java.sql.ResultSet;

Import java.sql.SQLException; public class C3p0propertiessimplifymain {public PreparedStatement createstatement (Connection conn,string sql) {Prepar
		Edstatement PS = null;
		try {PS = conn.preparestatement (SQL);
		} catch (SQLException e) {e.printstacktrace ();
	} return PS; Public PreparedStatement setparameters (PreparedStatement ps,object...values) {try {if (null! = values) {for (
				int i=1;i<=values.length;i++) {ps.setobject (I, values[i-1]);
		}}} catch (Exception e) {e.printstacktrace ();
	} return PS;
		public static void Main (string[] args) {Connection conn = null;
		PreparedStatement PS = null;
		ResultSet rs = null;
			
			try {conn = C3p0propertiessimplify.getinstance (). getconnection ();
			C3p0propertiessimplifymain c3p0instance = new C3p0propertiessimplifymain (); String sql = "SELECT * from" Tb_user WHERE ID <?
			";
			PS = c3p0instance.createstatement (conn, SQL);
			
			PS = C3p0instance.setparameters (PS, New object[]{20});
			rs = Ps.executequery ();
				while (Rs.next ()) {Object obj1 = rs.getobject (1);
				
				Object Obj4 = Rs.getobject (4);
			System.out.println ("ID:" + obj1 + ", Name:" + obj4);
					}} catch (Exception e) {}finally{try {if (null! = rs) {try {rs.close ();
					} catch (SQLException e) {e.printstacktrace ();
					}} if (null! = PS) {try {ps.close ();
					} catch (SQLException e) {e.printstacktrace ();
				}} try {conn.close ();
				} catch (SQLException e) {e.printstacktrace ();
			}} catch (Exception E2) {e2.printstacktrace ();
 }
		}
	}
}

To set parameters with an XML file:C3p0-config.xml

<?xml version= "1.0" encoding= "UTF-8"?>
<c3p0-config>
	<named-config name= "Myc3p0xml" >
		<property name= "Driverclass" >com.mysql.jdbc.Driver</property>
		<property name= "Jdbcurl" >jdbc:mysql://localhost:3306/cloudhospital</property>
		<property name= "user" >root</ property>
		<property name= "password" >admin</property>
		<property name= "Maxpoolsize" > 20</property>
		<property name= "minpoolsize" >3</property>
		<property name= " Maxstatements ">30</property>
		<property name=" MaxIdleTime ">150</property>
	</ Named-config>
</c3p0-config>

C3p0xmlsimplify.java

Package com.song.c3p0.db.xml;
Import java.sql.Connection;
Import java.sql.PreparedStatement;
Import Java.sql.ResultSet;

Import java.sql.SQLException;

Import Com.mchange.v2.c3p0.ComboPooledDataSource;

	public class C3p0xmlsimplify {private static c3p0xmlsimplify c3p0xmlsimplify;
	
	Private Combopooleddatasource CPDs;
	static{c3p0xmlsimplify = new C3p0xmlsimplify ();
	} public C3p0xmlsimplify () {CPDs = new Combopooleddatasource ("Myc3p0xml");
	} public static C3p0xmlsimplify getinstance () {return c3p0xmlsimplify;
		} public Connection getconnection () {Connection conn = null;
		try {conn = cpds.getconnection ();
		} catch (Exception e) {e.printstacktrace ();
	} return conn;
		} public static PreparedStatement setstatement (Connection conn, String sql) {PreparedStatement PS = null;
		try {PS = conn.preparestatement (SQL);
		} catch (SQLException e) {e.printstacktrace ();
	} return PS; } public static PreparedStatement setsqlparameters (PreparEdstatement ps,object...values) {try {if (null! = values) {for (int i = 1; I <= values.length; i++) {p
				S.setobject (i, values[i-1]);
		}}} catch (Exception e) {e.printstacktrace ();
	} return PS;
				} public static void Releasesources (Connection conn, PreparedStatement PS, ResultSet rs) {if (null! = rs) {try {
			Rs.close ();
			} catch (Exception e) {e.printstacktrace ();
			}} if (null! = PS) {try {ps.close ();
			} catch (Exception e) {e.printstacktrace ();
			}} if (null! = conn) {try {conn.close ();
			} catch (Exception e) {e.printstacktrace ();
 }
		}
	}
}

C3p0xmlsimplifymain.java

Package com.song.c3p0.db.xml;

Import java.sql.Connection;
Import java.sql.PreparedStatement;
Import Java.sql.ResultSet;

public class C3p0xmlsimplifymain {public

	static void Main (string[] args) {
		Connection conn = null;
		PreparedStatement PS = null;
		ResultSet rs = null;
		try {
			conn = C3p0xmlsimplify.getinstance (). getconnection ();
			
			String sql = "SELECT * from Tb_user WHERE ID <?";
			PS = c3p0xmlsimplify.setstatement (conn, SQL);
			PS = C3p0xmlsimplify.setsqlparameters (PS, New object[]{20});
			
			rs = Ps.executequery ();
			
			while (Rs.next ()) {
				Object obj1 = rs.getobject (1);
				Object Obj4 = Rs.getobject (4);
				
				System.out.println ("ID:" + obj1 + ", Name:" + obj4);
			}
		} catch (Exception e) {
			e.printstacktrace ();
		} finally{
			c3p0xmlsimplify.releasesources (conn, PS, RS);}}}