tomcat: how can i place parameters in web.xml and fetch them in my application?
I would like to store db connection information in the application web.xml file and to fetch it in the application. i read somewhere that it's possible 开发者_如何学运维i just don't know how.
any ideas?
thanks!
1) Depending on your Application server or Container-Managed server, CREATE a Connection Pool.
2) Link your resource pool in your web.xml
e.g. (Tomcat 5.5 and higher).
I have an Example_DS (Datasource) in my connection pool, and here I share it in my web.xml
<resource-ref>
<description>Database Connection for Example</description>
<res-ref-name>jdbc/Example_DS</res-ref-name>
<res-type>javax.sql.DataSource</res-type>
<res-auth>Container</res-auth>
<res-sharing-scope>Shareable</res-sharing-scope>
</resource-ref>
This matches my resource created on context.xml (found in META-INF folder) on my web application. Still using Tomcat.
<Resource name="jdbc/Example_DS" auth="Container" type="javax.sql.DataSource"
maxActive="100" maxIdle="30" maxWait="10000"
username="YOURUSERNAMEHERE" password="YOURPASSWORDHERE" driverClassName="com.mysql.jdbc.Driver"
url="jdbc:mysql://localhost:3306/DATABASEHERE?autoReconnect=true"
removeAbandoned="true" removeAbandonedTimeout="60" logAbandoned="true"
testOnBorrow="true" validationQuery="SELECT 1" />
Clearly, you can see I'm using MySQL here.
<Resource />
allows you to create a connection pool (in Tomcat)
In JBoss....
1) Create a Example_DS.xml file where Example is the name of your datasource.
E.g.
<?xml version="1.0" encoding="UTF-8"?>
<datasources>
<local-tx-datasource>
<jndi-name>Example_DS</jndi-name>
<connection-url>jdbc:mysql://localhost:3306/DATABASEHERE?autoReconnect=true</connection-url>
<driver-class>com.mysql.jdbc.Driver</driver-class>
<user-name>YOURUSERNAMEHERE</user-name>
<password>YOURPASSWORDHERE</password>
<min-pool-size>0</min-pool-size>
<max-pool-size>100</max-pool-size>
<idle-timeout-minutes>2</idle-timeout-minutes>
<track-statements>false</track-statements>
</local-tx-datasource>
</datasources>
Then user the <resource-ref>
that I gave up earlier to map it to your DS in Jboss. Deploy your DS.xml file in /server/default/deploy/ folder and restart JBoss.
Once you're done, then you can call it in Java using Context.
You add them as a context-param
to your web.xml:
<context-param>
<description>My variable</description>
<param-name>variable.name</param-name>
<param-value>value</param-value>
</context-param>
Then within your servlet, you call getInitParameter()
on your ServletContext:
String variable = getServletContext().getInitParameter("variable.name");
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