Tomcat: Defining Jndi Resources, accessing the database

The JDBC resource in Tomcat is designed using Jndi to configure JDBC resources in Tomcat and learn how to configure Jndi resources. The following is a JDBC resource to illustrate how to use Tomcat's resource services.

1. Define JNDI Resources

Can be defined as a global resource, or it can be defined as a resource for a Web context.

Scenario 1: Define the JNDI resource in context:

To define a resource, to use <resource>, define a JDBC resource as follows:

<Context><ResourceAuth= "Container"name= "Jdbc/mysql_jdbctest"type= "Javax.sql.DataSource"Driverclassname= "Com.mysql.jdbc.Driver"username= "Cloudlink"Password= "Cloudlink"Maxidle= "2"maxwait= "the"URL= "Jdbc:mysql:192.168.2.92:3306/jdbctest?useencoding=utf-8"maxactive= "4"/></Context>

Scenario 2:

Defines a global Jndi resource, defined in the <GlobalNamingResource> of Tomcat/conf/server.xml.

The following is a definition of a global resource, which is placed in <GlobalNamingResource>.

<Globalnamingresource><ResourceAuth= "Container"name= "Jdbc_test_1"type= "Javax.sql.DataSource"Driverclassname= "Com.mysql.jdbc.Driver"username= "Cloudlink"Password= "Cloudlink"Maxidle= "2"maxwait= "the"URL= "Jdbc:mysql:192.168.2.92:3306/jdbctest?useencoding=utf-8"maxactive= "4"/></Globalnamingresource>

Then in the <Context> link global resources:

< Context >     <  Globalname type/> </  Context>

in this way, a global resource is linked to a context.

2. Defining a reference to a Jndi resource in a Web application

In Web. XML, declare which Jndi resources to reference.

<Resource-ref>    <Res-ref-name>Jdbc/mysql_jdbctest</Res-ref-name><Res-type>Javax.sql.DataSource</Res-ref-name><Res-auth>Container</Res-ref-name></Resource-ref>

when a reference to a JNDI resource is defined in a Web application, the corresponding resource can be found in the Web application based on that reference.

3. Using Jndi resources in Web applications

 Public voidGet (HttpServletRequest request, httpservletresponse response)throwsexception{Context Context=NewInitialContext (); Context Envcontext= (Context) context.lookup ("java:/com/env "); DataSource DS= (DataSource) envcontext.lookup ("jdbc/mysql_jdbctest "); Connection Conn=ds.getconnection (); Statement stmt=conn.createstatement (); String SQL="Select UserID, username, age from User"; ResultSet RS=stmt.executequery (SQL); PrintWriter out=Response.getwriter (); while (Rs.next ()) {out.println (rs.getstring (1) + "\ T" +rs.getstring (2) + "\ T" +rs.getint (3) + "<br>");   } rs.close ();   Stmt.close ();   Conn.close ();   Out.flush (); Out.close ();}

4, create the corresponding database, table

Insert data:

Insert  into User Values (' Hello1 ', ' name1 ',);

  

5. Start Tomcat and test.

Before you start Tomcat, you need to add the JDBC driver for MySQL under Tomcat/lib.

Tomcat: Defining Jndi Resources, accessing the database