Apache Tomcat 5.5 Servlet/JSP 容器

Apache Tomcat Configuration Reference

The GlobalNamingResources Component

The GlobalNamingResources element defines the global JNDI resources for the Server.

These resources are listed in the server's global JNDI resource context. This context is distinct from the per-web-application JNDI contexts described in the JNDI Resources HOW-TO. The resources defined in this element are not visible in the per-web-application contexts unless you explicitly link them with <ResourceLink> elements.

Attributes

Nested Components

Special Features

Environment Entries
You can configure named values that will be made visible to all web applications as environment entry resources by nesting <Environment> entries inside this element. For example, you can create an environment entry like this:
<GlobalNamingResources ...>
  ...
  <Environment name="maxExemptions" value="10"
         type="java.lang.Integer" override="false"/>
  ...
</GlobalNamingResources>
This is equivalent to the inclusion of the following element in the web application deployment descriptor (/WEB-INF/web.xml):
<env-entry>
  <env-entry-name>maxExemptions</env-entry-name>
  <env-entry-value>10</env-entry-value>
  <env-entry-type>java.lang.Integer</env-entry-type>
</env-entry>
but does not require modification of the deployment descriptor to customize this value.

The valid attributes for an <Environment> element are as follows:

Attribute Description
description
Optional, human-readable description of this environment entry.

name
The name of the environment entry to be created, relative to the java:comp/env context.

override
Set this to false if you do not want an <env-entry> for the same environment entry name, found in the web application deployment descriptor, to override the value specified here. By default, overrides are allowed.

type
The fully qualified Java class name expected by the web application for this environment entry. Must be one of the legal values for <env-entry-type> in the web application deployment descriptor: java.lang.Boolean, java.lang.Byte, java.lang.Character, java.lang.Double, java.lang.Float, java.lang.Integer, java.lang.Long, java.lang.Short, or java.lang.String.

value
The parameter value that will be presented to the application when requested from the JNDI context. This value must be convertable to the Java type defined by the type attribute.
Resource Definitions
You can declare the characteristics of resources to be returned for JNDI lookups of <resource-ref> and <resource-env-ref> elements in the web application deployment descriptor by defining them in this element and then linking them with <ResourceLink> elements in the <Context> element. You MUST also define any other needed parameters using attributes on the Resource element, to configure the object factory to be used (if not known to Tomcat already), and the properties used to configure that object factory.

For example, you can create a resource definition like this:
<GlobalNamingResources ...>
  ...
  <Resource name="jdbc/EmployeeDB" auth="Container"
            type="javax.sql.DataSource"
     description="Employees Database for HR Applications"/>
  ...
</GlobalNamingResources>
This is equivalent to the inclusion of the following element in the web application deployment descriptor (/WEB-INF/web.xml):
<resource-ref>
  <description>Employees Database for HR Applications</description>
  <res-ref-name>jdbc/EmployeeDB</res-ref-name>
  <res-ref-type>javax.sql.DataSource</res-ref-type>
  <res-auth>Container</res-auth>
</resource-ref>
but does not require modification of the deployment descriptor to customize this value.

The valid attriutes for a <Resource> element are as follows:

Attribute Description
auth
Specify whether the web Application code signs on to the corresponding resource manager programatically, or whether the Container will sign on to the resource manager on behalf of the application. The value of this attribute must be Application or Container. This attribute is required if the web application will use a <resource-ref> element in the web application deployment descriptor, but is optional if the application uses a <resource-env-ref> instead.

description
Optional, human-readable description of this resource.

name
The name of the resource to be created, relative to the java:comp/env context.

scope
Specify whether connections obtained through this resource manager can be shared. The value of this attribute must be Shareable or Unshareable. By default, connections are assumed to be shareable.

type
The fully qualified Java class name expected by the web application when it performs a lookup for this resource.
Resource Links
Use <ResourceLink> elements to link resources from the global context into per-web-application contexts. Here is an example of making a custom factory available to a web applications, based on the example definition in the JNDI Resource HOW-TO:
      
        <Context>
          <ResourceLink 
            name="bean/MyBeanFactory"
            global="bean/MyBeanFactory"
            type="com.mycompany.MyBean"
          />
        </Context>
      
    
Transaction

You can declare the characteristics of the UserTransaction to be returned for JNDI lookup for java:comp/UserTransaction. You MUST define an object factory class to instantiate this object as well as the needed resource parameters as attributes of the Transaction element, and the properties used to configure that object factory.

The valid attributes for the <Transaction> element are as follows:

Attribute Description
factory
The class name for the JNDI object factory.