Thanks for the info. I have a few questions which are embedded below:
André van Toly wrote:
Hi,
Op 9-nov-2005, om 23:07 heeft Benjamin Slade het volgende geschreven:
Can someone point me to some resources for setting up Tomcat so that
servlets/JSP's can connect to a local MySQL database?
The instructions for configuring Connector/J don't seem to match the
setup of my tomcat/conf/server.xml file. Specifically, the
Connector/J web page talks about adding:
Inside the <Context> tag of the conf/server.xml file, but there is no
<Context> tag in my conf/server.xml. Should I add one? Or should I
add these XML tags to the tomcat/conf/context.xml? Where can I find
documentation on the structure of the server.xml and context.xml
files? The Apache Tomcat Configuration Reference web page doesn't
have much and neither does the Database question in the Tomcat FAQ.
Yes, you need to add a context to your [tomcat]/conf/server.xml. For
example for Tomcat's ROOT context the configuration could look like:
<Context path="" docBase="ROOT">
<Resource
name="jdbc/TestDB
auth="Container"
type="javax.sql.DataSource"
maxActive="100"
maxIdle="30"
maxWait="10000"
username="username"
password="password"
driverClassName="com.mysql.jdbc.Driver"
url="jdbc:mysql://localhost:3306/databasename?autoReconnect=true"
/>
</Context>
The ROOT context is the webapp called ROOT :-) which we'll be at
http://localhost:8080
For the <Context> tag above:
Using the docBase of "ROOT" is only when placing servlets into a single
ROOT directory, right? I'd prefer to set things up with a servlet/JSP
in it's own web application directory, because that's how most app's run
in real life.
So instead, I'm going to leave out the path="" docBase="ROOT" and I'm
going to put the <Context> tag into my
$CATALINA_HOME/webapps//MyApps//WEB-INF/web.xml file, near the end
(where /MyApps/ is the directory for my test servlet/JSP). Is this
correct, will it work? (The answer seems to be "no". See below)
On the other hand, if I wanted to add the above <Context> tag to my
server.xml, where do I add it in the file? The web page
http://tomcat.apache.org/tomcat-5.5-doc/jndi-datasource-examples-howto.html
says:
Add this in between the |</Context>| tag of the examples context and
the |</Host>| tag closing the localhost definition. If there is no
such tag, you can add one as illustrated in the Context
(http://tomcat.apache.org/tomcat-5.5-doc/config/context.html) and Host
(http://tomcat.apache.org/tomcat-5.5-doc/config/host.html)
configuration references, and repeated below for your convenience.
Both of those web pages are involved architecture reference pages, so
unless I hear from someone else on this mailing list, I'll spend the
next few hours wading through them.
Your webapp configuration [tomcat]/webapps/ROOT/WEB-INF/web.xml should
have a reference to the resource and in this example has to look like
this:
<resource-ref>
<description>DB Connection</description>
<res-ref-name>jdbc/TestDB</res-ref-name>
<res-type>javax.sql.DataSource</res-type>
<res-auth>Container</res-auth>
</resource-ref>
Now you can try the example at point 4. of the 'MySQL DBCP Example':
http://tomcat.apache.org/tomcat-5.5-doc/jndi-datasource-examples-howto.html
Remember to install the taglib's the example requires. And you should
of course have a MySQL jdbc driver (f.e.
mysql-connector-java-3.1.10-bin.jar) installed in [tomcat]/common/lib.
I haven't used taglibs before so I'll have to figure out how to install
them.
In the meantime, I tried running the servlet:
<%
DataSource ds=null;
Context ctx = new InitialContext();
if(ctx == null )
throw new Exception("Boom - No Context");
ds=(DataSource)ctx.lookup("java:comp/env/jdbc/TestDB");
if(ds == null )
throw new Exception("Boom - No Datasource");
Connection conn=ds.getConnection();
Statement stmt=conn.createStatement();
ResultSet rs=stmt.executeQuery("select 'Hello World'");
if (rs.next()){
%><%=rs.getString(1)%><%
}
%>
But I get the error "Cannot create JDBC driver of class '' for connect
URL 'null'" apparently resulting from the ds.getConnection() call.
Success.
---André
The Apache Tomcat Configuration Reference: The Context Container web
page seems to have lots of information, but it seems like a lot of
reference detail. I just need a database "Hello World" example.
I'm a newbie so I'm not familiar with the structure/semantics of the
server.xml and context.xml files. Also, I haven't gotten around to
learning how JNDI works. I was sort of hoping to do a "Hello World"
database JSP before delving into all of the system guts.
Thanks
Ben Slade
--André van Toly
web http://www.toly.nl mobile +31(0)627233562
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