DBCP and C3P0 database connection pool

What does a database connection pool do?

Learned the computer network know that in an internal LAN, most of the use of private addresses, in order to deal with the outside, must have a corresponding legal external address corresponds. However the number of internal users is huge, one machine an external IP is unrealistic. So there's a concept called connection pooling. Because not every user wants to surf the internet at the same time, when a user needs to surf the Internet, he can get an external IP address from the connection pool, thus access to the external network. When the user no longer needs to surf the Internet, this IP address is put back into the connection pool and can be accessed by other users. The connection pool here is primarily to address the problem of the number of IP addresses. In the database, there is also the concept of connection pooling. I think this connection pool is mainly through the reuse of the connection, thus more efficient implementation of the response to the user request. Common Java-developed connection pools are mainly dbcp and c3p0.

C3P0 Introduction:

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.

DBCP Introduction:

DBCP (database connection pool), DB connection pooling. is a Java Connection pool project on Apache and a connection pool component used by Tomcat. Use of DBCP alone requires 3 packages: Common-dbcp.jar,common-pool.jar, Common-collections.jar because establishing a database connection is a very time-consuming and resource-intensive behavior, the connection pool is pre-established with the database to make some connections, put in memory, the application needs to establish a database connection directly to the connection pool to apply for a line, run out and then put back.  

c3p0 differs from DBCP:

DBCP does not have automatic ability to reclaim idle connections  .

C3P0 has automatic recycle idle connection function.

dbcp required Jar:commons-dbcp.jar, Commons-pool.jar
c3p0 required Jar:c3p0-0.9.2.1.jar mchange-commons-java-0.2.3.4.jar

applicationcontext.xml configuration information is as follows:

<!--Configure DBCP data Source-<bean id= "DataSource2" destroy-method= "Close" class= "Org.apache.commons.dbcp.BasicDataSo Urce "> <property name=" driverclassname "value=" ${jdbc.driverclassname} "/> <property name=" url "V Alue= "${jdbc.url}"/> <property name= "username" value= "${jdbc.username}"/> <property name= "Passwo        Rd "value=" ${jdbc.password} "/> <!--the number of connections created when the pool starts--<property name=" InitialSize "value=" 5 "/> <!--The maximum number of connections that can be allocated from the pool at the same time. When set to 0, it means no limit. --<property name= "maxactive" value= "/> <!--the maximum number of idle connections that will not be released in the pool. When set to 0, it means no limit. --<property name= "Maxidle" value= "/> <!--the minimum number of connections that remain idle in the pool without creating a new connection. --<property name= "Minidle" value= "3"/> <!--Set Auto Recycle timeout connection--<property name= "Remo  Veabandoned "value=" true "/> <!--auto-reclaim time-out (in seconds)-<property name=" Removeabandonedtimeout "     Value= "/>"   <!--set the time-out error for the print connection when the auto-recycle timeout is connected--<property name= "logabandoned" value= "true"/> <!--wait timeout to The maximum time, in milliseconds, that the pool waits for the connection to be reclaimed before throwing an exception (when there is no available connection).  Set to 1 to indicate an infinite wait. --<property name= "maxwait" value= "/> </bean> <!--configuration c3p0 data Source--&lt ; Bean id= "DataSource" class= "Com.mchange.v2.c3p0.ComboPooledDataSource" destroy-method= "close" > <property nam        E= "Jdbcurl" value= "${jdbc.url}"/> <property name= "Driverclass" value= "${jdbc.driverclassname}"/>         <property name= "user" value= "${jdbc.username}"/> <property name= "password" value= "${jdbc.password}"/> <!--The maximum number of connections that are kept in the connection pool. Default:15---<property name= "maxpoolsize" value= "/>" <!--the minimum number of connections left in the connection pool. --<property name= "Minpoolsize" value= "1"/> <!--the number of connections obtained at initialization, the value should be between Minpoolsize and Maxpoolsize. Default:3--<property name= "initialpoolsize" value= "/> <!"--Maximum idle time, unused in 60 seconds, the connection is discarded. If 0, it will never be discarded. default:0--<property name= "MaxIdleTime" value= "$"/> <!--when the connection in the connection pool runs out, c3p0 the number of connections fetched at the same time. Default:3--<property name= "Acquireincrement" value= "5"/> <!--JDBC Standard parameters to control the loading of prepareds in the data source Number of tatements. However, because the pre-cached statements belong to a single connection instead of the entire connection pool.          So setting this parameter takes into account a variety of factors. If both maxstatements and maxstatementsperconnection are 0, the cache is closed. default:0--> <property name= "maxstatements" value= "0"/> <!--every 60 seconds to check for idle connections in all connection pools. default:0--<property name= "idleconnectiontestperiod" value= "/>" <!--definition to get a new connection from the database The number of repeated attempts after the failure. Default:30--<property name= "acquireretryattempts" value= "$"/> <!--getting a connection failure will cause all waiting connections The pool to get the connected thread throws an exception. However, the data source is still valid and continues to try to get the connection the next time you call Getconnection (). If set to True, the data source will declare broken and permanently shut down after attempting to acquire a connection failure.         default:false--> <property name= "Breakafteracquirefailure" value= "true"/>        <!--use it only when you need it, due to its high performance consumption. If set to true then the validity of each connection submission is officer. We recommend using methods such as Idleconnectiontestperiod or automatictesttable to improve the performance of your connectivity tests. Default:false--<property name= "Testconnectiononcheckout" value= "false"/> </bean>