Database Connection Pool

1. Customizing the database connection pool

 Public classMypool {Private intInit_count = 3; Private intMax_count = 6; Private intCurr_count = 0; PrivateLinkedlist<connection> pool =NewLinkedlist<connection>();  PublicMypool () { for(inti = 0; i < Init_count; i++) {Curr_count++;        Pool.addlast (CreateConnection ()); }    }    /*** Using the proxy class, each time the connection Close method is called, the connection is placed in the connection pool*/    PrivateConnection createconnection () {Try{class.forname ("Com.mysql.jdbc.Driver"); Connection Connection= Drivermanager.getconnection ("Jdbc:mysql:///test", "root", "juaner767"); Connection Proxy=(Connection) proxy.newproxyinstance (Connection.getclass (). getClassLoader (),//class Loader//Connection.getclass (). Getinterfaces () implements an interface that is used when the object is a concrete class                    NewClass[]{connection.class},//connection is an interface, so use it like this                    NewInvocationhandler () {//the transaction handler is automatically triggered when the connection object method is called@Override PublicObject Invoke (Object proxy, Method method, object[] args)throwsthrowable {String name=Method.getname (); Object result=NULL; //when the Close method is executed, the connection is placed in the connection pool                            if("Close". Equals (name)) {System.out.println ("Call object Monitored interface");                            Releaseconnection (connection); }Else{result=Method.invoke (connection, args); }                            returnresult;            }                    }            ); returnproxy; } Catch(Exception e) {Throw NewRuntimeException (e); }    }     PublicConnection getconnection () {Connection Connection=NULL; if(Pool.size () > 0) {Connection=Pool.removefirst (); }Else{            if(Curr_count <max_count) {Curr_count++; Connection=createconnection (); }Else {                Throw NewRuntimeException ("The maximum number of connections is currently reached, unable to get the connection!")); }        }        returnconnection; }     Public voidreleaseconnection (Connection Connection) {if(Connection = =NULL)            return; if(Pool.size () <init_count) Pool.addlast (connection); Else{            Try{connection.close (); } Catch(SQLException e) {Throw NewRuntimeException (e); } Curr_count--; }    }}

2.DBCP Connection Pool Components

DBCP is an open source connection pool implementation under the Apache Software Foundation. Using a DBCP data source, the application should add the following two jar files to the system:
Commons-dbcp.jar: Implementation of connection pooling
Commons-pool.jar: Dependency libraries for connection pooling implementations
The connection pool for Tomcat is implemented with this connection pool. The database connection pool can be used either in combination with the application server or independently by the application.

Db.properties:

Url=jdbc:mysql:///studentdriverclassname=com.mysql.jdbc.driverusername=rootpassword=juaner767initialsize= 3maxactive=6maxidle=3000

To use the DBCP connection pool:

@Test Public voidTest2 ()throwsException {//Load configuration fileProperties prop =NewProperties (); InputStream in= Demo1.class. getResourceAsStream ("Db.properties"); Prop.load (in);
DataSource DataSource=Basicdatasourcefactory.createdatasource (prop); Connection Connection=datasource.getconnection (); Connection.preparestatement ("DELETE from student_info WHERE stuid = 2008006"). Executeupdate ();    Connection.close (); }

3.C3P0 Connection Pool Components

C3P0 is an open source JDBC connection pool that implements the data source and Jndi bindings, and supports the standard extensions of the JDBC3 specification and JDBC2. The open source projects that currently use it are hibernate,spring and so on.

Set configuration file C3p0-config.xml under src:

<C3p0-config>  <Default-config>     < Propertyname= "Jdbcurl">Jdbc:mysql://localhost:3306/student</ Property>     < Propertyname= "Driverclass">Com.mysql.jdbc.Driver</ Property>     < Propertyname= "User">Root</ Property>     < Propertyname= "Password">juaner767</ Property>     < Propertyname= "Initialpoolsize">3</ Property>     < Propertyname= "Maxpoolsize">6</ Property>     < Propertyname= "MaxIdleTime">1000</ Property>  </Default-config></C3p0-config>

To use the C3P0 connection pool:

    @Test public    void Test2 () throws exception{        //auto-load configuration file for c3p0 under SRC c3p0-config.xml        Combopooleddatasource DataSource = new Combopooleddatasource ();        Connection Connection = Datasource.getconnection ();        PreparedStatement PreparedStatement  = null;        String sql = "INSERT into Student_info (stuname,telephone) VALUES (?,?) ";        PreparedStatement = connection.preparestatement (sql);        for (int i = 0;i<i++) {            preparedstatement.setstring (1, "Test" +i);            Preparedstatement.setint (2,1353356234);            Preparedstatement.executeupdate ();        }        Connection.close ();    }

4. The difference dbcp does not automatically reclaim the function of idle connections. The C3P0 has auto-recycle idle connection function. 5. Using the C3P0 connection pool in Hibernate

Configure in Hibernate.cfg.xml:

        <!--Connection Pool Configuration -        <!--Connection Pool Management class, driver management class -        < Propertyname= "Hibernate.connection.provider_class">Org.hibernate.connection.C3P0ConnectionProvider</ Property>        <!--Configuring connection pool parameter information -        < Propertyname= "Hibernate.c3p0.min_size">2</ Property>        < Propertyname= "Hibernate.c3p0.max_size">4</ Property>        < Propertyname= "Hibernate.c3p0.timeout">5000</ Property>        < Propertyname= "Hibernate.c3p0.max_statements">10</ Property>        < Propertyname= "Hibernate.c3p0.idle_test_period">30000</ Property>        < Propertyname= "Hibernate.c3p0.acquire_increment">2</ Property>

Database Connection Pool