java 数据源

1、 Install Your JDBC Driver
Use of the JDBC Data Sources JNDI Resource Factory requires that you make an appropriate JDBC driver available to both Tomcat internal classes and to your web application. This is most easily accomplished by installing the driver’s JAR file(s) into the $CATALINA_HOME/lib directory, which makes the driver available both to the resource factory and to your application.
2、Declare Your Resource Requirements
Next, modify the web application deployment descriptor (/WEB-INF/web.xml) to declare the JNDI name under which you will look up preconfigured data source. By convention, all such names should resolve to the jdbc subcontext (relative to the standard java:comp/env naming context that is the root of all provided resource factories. A typical web.xmlentry might look like this:

<resource-ref>
  <description>
    Resource reference to a factory for java.sql.Connection
    instances that may be used for talking to a particular
    database that is configured in the <Context>
    configuration for the web application.
  </description>
  <res-ref-name>
    jdbc/EmployeeDB
  </res-ref-name>
  <res-type>
    javax.sql.DataSource
  </res-type>
  <res-auth>
    Container
  </res-auth>
</resource-ref>

3、 Code Your Application’s Use Of This Resource

    Context initCtx = new InitialContext();
    Context envCtx = (Context) initCtx.lookup("java:comp/env");
    DataSource ds = (DataSource)
      envCtx.lookup("jdbc/EmployeeDB");
    Connection conn = ds.getConnection();
    use this connection to access the database ...
    conn.close();

4、To configure Tomcat’s resource factory, add an element like this to the <Context>element for the web application.

<Context >
  <Resource name="jdbc/EmployeeDB"
            auth="Container"
            type="javax.sql.DataSource"
            username="dbusername"
            password="dbpassword"
            driverClassName="org.hsql.jdbcDriver"
            url="jdbc:HypersonicSQL:database"
            maxTotal="8"
            maxIdle="4"/>
</Context>