Java JDBC - How to connect to Oracle using tnsnames.ora

Question

tnsnames.ora file contains the Databases and the their description (host + port).

• Is it possible to esta

Answer 1

Well, in some GUIs the TNS driver configuration is simply not implemented or not working (NetBeans for example :-) )

https://netbeans.org/bugzilla/show_bug.cgi?id=231526

There is simple workaround here. You can take the entry directly from the tnsnames.ora file and attach it to the jdbc driver string as following:

Example from using odbc7.jar (Oracle 12c JDBC driver for JDK 7) to connect to Oracle 11gR2 RAC cluster:

jdbc:oracle:thin:@(DESCRIPTION=(ADDRESS_LIST=(ADDRESS=(PROTOCOL= TCP)(HOST=hostA)(PORT= 1522))(ADDRESS=(PROTOCOL=TCP)(HOST=hostB)(PORT=1521)))(SOURCE_ROUTE=yes)(CONNECT_DATA=(SERVICE_NAME=DatabaseService)))

Be aware of putting double :: characters in the end as host:port:service, if you will put :: in the end like this:

jdbc:oracle:thin:@(DESCRIPTION=(ADDRESS_LIST=(ADDRESS=(PROTOCOL= TCP)(HOST=hostA)(PORT= 1522))(ADDRESS=(PROTOCOL=TCP)(HOST=hostB)(PORT=1521)))(SOURCE_ROUTE=yes)(CONNECT_DATA=(SERVICE_NAME=DatabaseService)))::

You will end up with "NL Exception was generated" exception.

Another approach is to configure following property: System.setProperty("oracle.net.tns_admin","C:/app/product/11.2.0/client_1/NETWORK/ADMIN");

Of course, instead of hardcoded value, you can for example set up environment variable in your operating system like ORACLE_TNS_ADMIN and then reference it:

System.setProperty("oracle.net.tns_admin",System.getenv("ORACLE_TNS_ADMIN"));

or pass it to java process via -D switch on linux:

-Doracle.net.tns_admin=$ORACLE_TNS_ADMIN

and windows:as

-Doracle.net.tns_admin=%ORACLE_TNS_ADMIN%

Once our application is aware of TNS config file, we can connect by reference service name in TNSNAMES.ora file as in this full example:

 // tell the driver where to look for the TNSNAMES.ORA file
System.setProperty(
          "oracle.net.tns_admin",
          "C:/app/product/11.2.0/client_1/NETWORK/ADMIN");

// ORCL is net service name from the TNSNAMES.ORA file
String dbURL = "jdbc:oracle:thin:@ORCL";

// load the driver
Class.forName("oracle.jdbc.OracleDriver");

Connection conn = null;
Statement stmt = null;

try {
  conn = DriverManager.getConnection(dbURL,
                                     "your_username",
                                     "your_password");

  stmt = conn.createStatement();

  ResultSet rs = stmt.executeQuery("SELECT dummy FROM dual");