Eclipse 2020-06 JDK 11, GWT project cannot connect to Oracle Database

[Yibin Li]

I just upgrade my Eclipse to 2020-06 and Java JDK 11

My Oracle client on my PC is Oracle 11.2. There is ojdbc6_g.jar is in C:\Oracle\product\11.2.0\client_1\jdbc\lib

I created a new GWT Web Application

In Data connection module, I copied or Java 8 DB Connection code here

1. I tried

OracleDataSource ods2 = new OracleDataSource();

String url = "jdbc:oracle:thin:@/server:port/service";

 ods2.setURL(url);

 ods2.setUser(appsettings.getString("username"));

  ods2.setPassword( appsettings.getString("pwd")  );

It can compile. But when I debug the connection

Line : OracleDataSource ods2 = new OracleDataSource(); throws exception

[ERROR] Found resouce but unrecognized URL format: 'jrt:/java.sql/javax/sql/DataSource.class'.

2. Then I try another way to connect to t DB

Connection con=DriverManager.getConnection(  "jdbc:oracle:thin:@server:port","username","pwd");  

It throws :

java.lang.NoClassDefFoundError: org/ietf/jgss/GSSException

at java.base/java.lang.Class.forName0(Native Method)

at java.base/java.lang.Class.forName(Class.java:315)

at oracle.net.ano.Ano.init(Unknown Source)

at oracle.net.ns.NSProtocol.connect(NSProtocol.java:284)

at oracle.jdbc.driver.T4CConnection.connect(T4CConnection.java:1407)

at oracle.jdbc.driver.T4CConnection.logon(T4CConnection.java:328)

at oracle.jdbc.driver.PhysicalConnection.<init>(PhysicalConnection.java:535)

at oracle.jdbc.driver.T4CConnection.<init>(T4CConnection.java:218)

at oracle.jdbc.driver.T4CDriverExtension.getConnection(T4CDriverExtension.java:29)

at oracle.jdbc.driver.OracleDriver.connect(OracleDriver.java:528)

at java.sql/java.sql.DriverManager.getConnection(DriverManager.java:677)

at java.sql/java.sql.DriverManager.getConnection(DriverManager.java:228)

Any suggestions or comments

Thank you for your help

Yibin Li

[Yibin Li]

Also Console prints

[WARN] Server class 'org.ietf.jgss.GSSException' could not be found in the web app, but was found on the system classpath

   [ERROR] Found resouce but unrecognized URL format: 'jrt:/java.security.jgss/org/ietf/jgss/GSSException.class'

[Jens]

[WARN] Server class 'org.ietf.jgss.GSSException' could not be found in the web app, but was found on the system classpath

   [ERROR] Found resouce but unrecognized URL format: 'jrt:/java.security.jgss/org/ietf/jgss/GSSException.class'

JRT urls are available since Java 9 and the embedded Jetty 9.2.x that GWT provides does not understand these kinds of URLs.

For complex GWT apps the recommendation is to not use the embedded Jetty provided by GWT. Instead use GWT CodeServer to serve GWT client code during development and your own Jetty server to deploy your server side code to. You need at least Jetty 9.4.7 and not higher than Jetty 10.x because Jetty 11.x uses the new Jakarta EE namespace which GWT server side code does not support.

Also see: https://github.com/gwtproject/gwt/issues/9582

[Yibin Li]

Jens,

I will try this approach

Almost each UI is working as GWT 2.5. But not DB connection. I deployed the code to my test server and use DB datasource on server, everything is working. The only obstacle is DB connection.

Thank you for your reply.

[Yibin Li]

I changed the JDK to Java 8 and everything is working. 

The same DB connection code can connect to DB

Eclipse 2020-06

1. NO GWT

    Java11 can connect to DB

2. With GWT

   Java 11 cannot connection to DB