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18.1 Basic Steps in Using JDBC

463

ing a fully qualified class name (i.e., one that includes package names) and

loads the corresponding class. This call could throw a 

ClassNotFound 

Exception

, so should be inside a 

try

/

catch

 block. Here is an example:

try {

Class.forName("connect.microsoft.MicrosoftDriver");

Class.forName("oracle.jdbc.driver.OracleDriver");

Class.forName("com.sybase.jdbc.SybDriver");

} catch(ClassNotFoundException cnfe) {

System.err.println("Error loading driver: " + cnfe);

}

One of the beauties of the JDBC approach is that the database server

requires no changes whatsoever. Instead, the JDBC driver (which is on the

client) translates calls written in the Java programming language into the spe 

cific format required by the server. This approach means that you have to

obtain a JDBC driver specific to the database you are using; you will need to

check its documentation for the fully qualified class name to use. Most data 

base vendors supply free JDBC drivers for their databases, but there are

many third party vendors of drivers for older databases. For an up to date

list, see 

http://java.sun.com/products/jdbc/drivers.html

. Many of

these driver vendors supply free trial versions (usually with an expiration date

or with some limitations on the number of simultaneous connections), so it is

easy to learn JDBC without paying for a driver.

In principle, you can use 

Class.forName

 for any class in your 

CLASSPATH

.

In practice, however, most JDBC driver vendors distribute their drivers

inside JAR files. So, be sure to include the path to the JAR file in your

CLASSPATH

 setting.

Define the Connection URL

Once you have loaded the JDBC driver, you need to specify the location of

the database server. URLs referring to databases use the 

jdbc:

 protocol and

have the server host, port, and database name (or reference) embedded

within the URL. The exact format will be defined in the documentation that

comes with the particular driver, but here are two representative examples:

String host = "dbhost.yourcompany.com";

String dbName = "someName";

int port = 1234;

String oracleURL = "jdbc:oracle:thin:@" + host + 

":" + port + ":" + dbName;

String sybaseURL = "jdbc:sybase:Tds:" + host  + 

":" + port + ":" + "?SERVICENAME=" + dbName;

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