Re: Why class not found?
| От | Nick Fankhauser |
|---|---|
| Тема | Re: Why class not found? |
| Дата | |
| Msg-id | NEBBLAAHGLEEPCGOBHDGGEDHFKAA.nickf@ontko.com обсуждение исходный текст |
| Ответ на | Why class not found? (Michael Hanna <zen@hwcn.org>) |
| Список | pgsql-jdbc |
Michael- A common problem in moving from code executed from the command line to servlets is that the servlets are all executed by the tomcat user (often www-data or apache by default). This confuses people because the classpath looks fine from the command line, but that isn't the environment your code runs from. To make sure that Tomcat sees the jdbc driver, either add it to the class path in the .profile for that users, or better, place the driver (or a link to it) in /usr/share/tomcat/lib. (I'm assuming you are on linux here.) Hope this helps- -Nick -------------------------------------------------------------------------- Nick Fankhauser nickf@ontko.com Phone 1.765.935.4283 Fax 1.765.962.9788 Ray Ontko & Co. Software Consulting Services http://www.ontko.com/ > -----Original Message----- > From: pgsql-jdbc-owner@postgresql.org > [mailto:pgsql-jdbc-owner@postgresql.org]On Behalf Of Michael Hanna > Sent: Saturday, August 24, 2002 7:16 AM > To: pgsql-jdbc@postgresql.org > Subject: [JDBC] Why class not found? > > > OK, thanks to all regarding my previous Exceptions question. > > New problem: I'm getting a ClassNotFoundException from this line: > > Class.forName("org.postgresql.Driver"); //load the driver > > However I do import this package and I'm certain it's in my classpath: > > [taoki:~] michael% $CLASSPATH > /System/Library/Frameworks/JavaVM.framework/Versions/1.3.1/Classes > /classes. > jar:/usr/local/jakarta- > tomcat-4.0.3/common/lib/servlet.jar:/usr/local/pgsql/share/java/pg > jdbc2.jar: > ./: Command not found. > [taoki:~] michael% > > Also that HelloPostgresql.class by Mr. Fankhauser works fine.. > > Any ideas... > > here's the whole code: > > -- > > Rigby.java > > -- > > // Copyright Michael Hanna 2002 > // do not use without permission of author > > import java.io.*; > import javax.servlet.*; > import javax.servlet.http.*; > import java.sql.*; // All we need for JDBC > > public class Rigby extends HttpServlet { > > public void doGet(HttpServletRequest request, HttpServletResponse > response)throws IOException, ServletException > { > PrintWriter out; > DBThing dbt; > ResultSet results; > > String database = "rigby"; > String username = "postgres"; > String password = "postgres"; > > response.setContentType("text/html"); > out = response.getWriter(); > out.println("<html>"); > out.println("<body>"); > out.println("<head>"); > out.println("<title>Rigby</title>"); > out.println("</head>"); > out.println("<body>"); > out.println("<h1>Contents of friends:</h1>"); > > try { > Class.forName("org.postgresql.Driver"); //load the driver > out.println("<B>Inside try</B>"); > dbt = new DBThing(database, username, password); > results = dbt.queryDB("select * from friends"); > > if (results != null) > { > out.println("<B>id" + "First Name" +"Surname" + "Email" + > "Phone"+"Bday</B>"); > while (results.next()) > { > out.println(results.getInt("id") + > results.getString("firstname") + results.getString("surname")+ > results.getString("email")+results.getInt("tel")+results.getString > ("date") + > "\n"); > } > } > else { > out.println("The friends database is empty.<br>"); > } > results.close(); > > } catch (ClassNotFoundException cnf) { > out.println("***Exception:\n"+cnf); > cnf.printStackTrace(); > } catch (SQLException se) { > out.println("***Exception:\n"+se); > se.printStackTrace(); > } > out.println("hey2"); > out.println("</body>"); > out.println("</html>"); > > > /* > try { > new DBThing(database, user, password); > } catch (ClassNotFoundException cnfe) { > throw new IOException("Could not instantiate driver: " + > cnfe.getMessage()); > } catch (SQLException se) { > throw new IOException("Unable to connect to database or work > with it: " + se.getMessage()); > } > */ > > } > } > > -- > > DBThing.java > > > -- > > // Copyright Michael Hanna 2002 > // do not use without permission of author > > import java.sql.*; // All we need for JDBC > import java.lang.*; > > public class DBThing > { > Connection db; // A connection to the database > Statement sql; // Our statement to run queries with > DatabaseMetaData dbmd; // This is basically info the driver > delivers > // about the DB it just connected to. I use > // it to get the DB version to confirm the > // connection in this example. > > public DBThing(String database, String username, String password) > throws ClassNotFoundException, SQLException > { > > Class.forName("org.postgresql.Driver"); //load the driver > > db = DriverManager.getConnection("jdbc:postgresql:"+database, > username, > password); //connect to the db > > dbmd = db.getMetaData(); //get MetaData to confirm connection > System.out.println("Connection to > "+dbmd.getDatabaseProductName()+" "+ > dbmd.getDatabaseProductVersion()+" > successful.\n"); > > sql = db.createStatement(); //create a statement that we > can use later > > } > > public ResultSet queryDB(String query) throws SQLException > { > ResultSet rs; > rs = sql.executeQuery(query); // try to query DB > return rs; > } > } > > > ---------------------------(end of broadcast)--------------------------- > TIP 4: Don't 'kill -9' the postmaster >
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