<Context>
    <Resource name="jdbc/BookStoreDB"
              auth="Container"
              type="javax.sql.DataSource"
              driverClassName="com.mysql.jdbc.Driver"
              url="jdbc:mysql://localhost:3306/BookStoreDB" />
</Context>

<resource-ref>
    <res-ref-name>jdbc/BookStoreDB</res-ref-name>
    <res-type>javax.sql.DataSource</res-type>
    <res-auth>Container</res-auth>
</resource-ref>

<context-param>
    <param-name>DATABASE_NAME</param-name>
    <param-value>jdbc/BookStoreDB</param-value>
</context-param>

Context initCtx = new InitialContext();
Context envCtx = (Context) initCtx.lookup("java:comp/env");
DataSource ds = (DataSource) envCtx.lookup(name);   //name это DATABASE_NAME
connection = ds.getConnection();