my applet can't connect to database

[liana lim]

my applet can't connect to my mysql database. i put my applet class and database in 1 server.

i use this code to connect the database

  Connection cn=null;
        try {
 
            Class.forName("org.gjt.mm.mysql.Driver").newInstance();
        } catch (IllegalAccessException ex) {
            Logger.getLogger(NewJApplet.class.getName()).log(Level.SEVERE, null, ex);
        }
        cn = (Connection) DriverManager.getConnection("jdbc:mysql://" + compname + ":3306/" + dbname, username, password);  

and here's the error

  Oct 17, 2008 8:28:22 AM javaapplication3.NewJApplet init
SEVERE: null
com.mysql.jdbc.exceptions.jdbc4.CommunicationsException: Communications link failure
 
Last packet sent to the server was 0 ms ago.
at sun.reflect.NativeConstructorAccessorImpl.newInstance0(Native Method)
at sun.reflect.NativeConstructorAccessorImpl.newInstance(Unknown Source)
at sun.reflect.DelegatingConstructorAccessorImpl.newInstance(Unknown Source)
at java.lang.reflect.Constructor.newInstance(Unknown Source)
at com.mysql.jdbc.Util.handleNewInstance(Util.java:406)
at com.mysql.jdbc.SQLError.createCommunicationsException(SQLError.java:1074)
at com.mysql.jdbc.ConnectionImpl.createNewIO(ConnectionImpl.java:2104)
at com.mysql.jdbc.ConnectionImpl.<init>(ConnectionImpl.java:729)
at com.mysql.jdbc.JDBC4Connection.<init>(JDBC4Connection.java:46)
at sun.reflect.NativeConstructorAccessorImpl.newInstance0(Native Method)
at sun.reflect.NativeConstructorAccessorImpl.newInstance(Unknown Source)
at sun.reflect.DelegatingConstructorAccessorImpl.newInstance(Unknown Source)
at java.lang.reflect.Constructor.newInstance(Unknown Source)
at com.mysql.jdbc.Util.handleNewInstance(Util.java:406)
at com.mysql.jdbc.ConnectionImpl.getInstance(ConnectionImpl.java:302)
at com.mysql.jdbc.NonRegisteringDriver.connect(NonRegisteringDriver.java:283)
at java.sql.DriverManager.getConnection(Unknown Source)
at java.sql.DriverManager.getConnection(Unknown Source)
at javaapplication3.NewJApplet.Connect(NewJApplet.java:74)
at javaapplication3.NewJApplet.init(NewJApplet.java:44)
at sun.applet.AppletPanel.run(Unknown Source)
at java.lang.Thread.run(Unknown Source)
Caused by: java.net.SocketException: java.security.AccessControlException: access denied (java.net.SocketPermission 192.168.71.50:3306 connect,resolve)
at com.mysql.jdbc.StandardSocketFactory.unwrapExceptionToProperClassAndThrowIt(StandardSocketFactory.java:407)
at com.mysql.jdbc.StandardSocketFactory.connect(StandardSocketFactory.java:268)
at com.mysql.jdbc.MysqlIO.<init>(MysqlIO.java:276)
at com.mysql.jdbc.ConnectionImpl.createNewIO(ConnectionImpl.java:2027)
... 15 more  

can anyone tell me how to fix it??

[Ulf Dittmer]

Applets are only allowed to connect to the server they were served from. If the database is on some other server, then the applet needs to be signed. See HowCanAnAppletReadFilesOnTheLocalFileSystem for more detail.

[liana lim]

i already did it. my applet and my database are on same server

[liana lim]

I already add java policy on client side with this :

grant codeBase "http://192.168.71.50/-" {
permission java.security.AllPermission;
};

it still can't connect database. help please....

[Ulf Dittmer]

Policy files can be tricky. Make sure that the one you're making changes to is really being used.

As an aside, you should remove the ".newInstance()" call in the driver initialization.

[Tim Holloway]

There could also be a firewall issue.

Look back in the forum archives about 2 weeks and I've covered this before. Including a rant why most applets have no business operating in 2-tier mode and opening their own JDBC connections.

[atul anand]

grant {
permission java.lang.RuntimePermission
"accessClassInPackage.sun.jdbc.odbc";
permission java.util.PropertyPermission
"file.encoding", "read";
};

save this to txt file say ... grantacc.txt


and to command prompt write this'

appletviewer -J-Djava.security.policy=grantacc.txt ur_file.html