The setup and application of Tomcat database connection pool

Data | database | database connection

1. Place the database driver jar file in the common/lib of Tomcat;

2. Set up the data source in Server.xml, take the MySQL database for example, as follows:
Join in the <GlobalNamingResources> </GlobalNamingResources> node,
<resource
Name= "Jdbc/dbpool"
Type= "Javax.sql.DataSource"
password= "Root"
Driverclassname= "Com.mysql.jdbc.Driver"
Maxidle= "2"
maxwait= "5000"
Username= "Root"
Url= "Jdbc:mysql://127.0.0.1:3306/test"
Maxactive= "4"/>
Attribute Description: Name, data source names, usually "jdbc/xxx" format;
Type, "Javax.sql.DataSource";
Password, database user password;
Driveclassname, database driven;
Maxidle, maximum idle number, maximum idle time of database connection. More than idle time, the database company
The connection is marked as unavailable and then released. A set of 0 means no limit.
Maxactive, the maximum number of database connections for the connection pool. A set of 0 means no limit.
Maxwait, the maximum connection waiting time is established. If you exceed this time, you will receive an exception. Set to-1 indicates
Unlimited.

3. Set the data source reference in the Web.xml of your Web application, as follows:
Join in the <web-app></web-app> node,
<resource-ref>
<description>mysql DB Connection pool</description>
<res-ref-name>jdbc/DBPool</res-ref-name>
<res-type>javax.sql.DataSource</res-type>
<res-auth>Container</res-auth>
<res-sharing-scope>Shareable</res-sharing-scope>
</resource-ref>
Sub-node Description: description, descriptive information;
Res-ref-name, refer to the name of the data source, the attribute name of the previous step;
Res-type, resource type, "Javax.sql.DataSource";
Res-auth, "Container";
Res-sharing-scope, "shareable";

4. Set the data source link in the context.xml of the Web application as follows:
Join in the <Context></Context> node,
<resourcelink
Name= "Jdbc/dbpool"
Type= "Javax.sql.DataSource"
Global= "Jdbc/dbpool"/>
Attribute Description: Name, the property name value with steps 2nd and 3rd, and the Res-ref-name value of the child node;
Type, also take "Javax.sql.DataSource";
Global, with the name value.

At this point, the settings are complete, and the following is how to use the database connection pool.
1. Set up a connection pool class, Dbpool.java, to create a connection pool with the following code:
Import Javax.naming.Context;
Import Javax.naming.InitialContext;
Import javax.naming.NamingException;
Import Javax.sql.DataSource;

public class Dbpool {
private static DataSource pool;
static {
Context env = NULL;
try {
env = (context) new InitialContext (). Lookup ("java:comp/env");
Pool = (DataSource) env.lookup ("Jdbc/dbpool");
if (pool==null)
System.err.println ("' Dbpool ' is a unknown DataSource");
catch (Namingexception ne) {
Ne.printstacktrace ();
}
}
public static DataSource Getpool () {
return pool;
}
}

2. In the class or JSP page where you want to use the database operation, you can use Dbpool.getpool (). getconnection () to get a connection object and then do the database operation, and finally don't forget to call the Close () method on the Connection object , note: Instead of closing the connection, this connection is put back into the database connection pool.