[ http://issues.apache.org/jira/browse/DERBY-668?page=comments#action_12359106 ]
Andrew McIntyre commented on DERBY-668: --------------------------------------- Class.getResource() doesn't return the .class file itself, it returns the URL of the location from which the class in question has already been loaded. This is used to determine the actual location of the loaded class, whether it was loaded by the extensions mechanism or from the classpath. Because we're just asking for the location of the file, I don't believe there are any security manager issues. If we tried to load the class from the URL, that might be a problem if we don't have sufficient permissions to access the class. > SysInfo can give misleading information when JDBC jars are loaded from > jre/lib/ext > ---------------------------------------------------------------------------------- > > Key: DERBY-668 > URL: http://issues.apache.org/jira/browse/DERBY-668 > Project: Derby > Type: Bug > Components: Build tools > Versions: 10.1.1.0 > Reporter: Bryan Pendleton > Priority: Minor > Attachments: Derby-668.diff, derby-668-2.diff, derby-668-3.diff > > There is a section in the SysInfo tool's output titled "Derby Information", > which prints location and version information for the major Derby jars. Here > is an example of that output: > --------- Derby Information -------- > JRE - JDBC: J2SE 1.4.2 - JDBC 3.0 > [/home/bpendleton/src/derby-subversion/trunk/jars/insane/derby.jar] 10.2.0.0 > alpha - (315052M) > [/home/bpendleton/src/derby-subversion/trunk/jars/insane/derbytools.jar] > 10.2.0.0 alpha - (315052M) > [/home/bpendleton/src/derby-subversion/trunk/jars/insane/derbynet.jar] > 10.2.0.0 alpha - (315052M) > [/home/bpendleton/src/derby-subversion/trunk/jars/insane/derbyclient.jar] > 10.2.0.0 alpha - (315052M) > [/home/bpendleton/downloads/derby/db2jcc/lib/db2jcc.jar] 2.4 - (17) > [/home/bpendleton/downloads/derby/db2jcc/lib/db2jcc_license_c.jar] 2.4 - (17) > Unfortunately, this tool can be fooled if you arrange for one of these jar > files to be loaded from a magic location like $JAVA_HOME/jre/lib/ext. > For example, I had (accidentally) placed an old version of db2jcc.jar into > $JAVA_HOME/jre/lib/ext. When I ran SysInfo, it printed out: > --------- Derby Information -------- > JRE - JDBC: J2SE 1.4.2 - JDBC 3.0 > [/home/bpendleton/src/derby-subversion/trunk/jars/insane/derby.jar] 10.2.0.0 > alpha - (315052M) > [/home/bpendleton/src/derby-subversion/trunk/jars/insane/derbytools.jar] > 10.2.0.0 alpha - (315052M) > [/home/bpendleton/src/derby-subversion/trunk/jars/insane/derbynet.jar] > 10.2.0.0 alpha - (315052M) > [/home/bpendleton/src/derby-subversion/trunk/jars/insane/derbyclient.jar] > 10.2.0.0 alpha - (315052M) > [/home/bpendleton/downloads/derby/db2jcc/lib/db2jcc.jar] 1.0 - (581) > [/home/bpendleton/downloads/derby/db2jcc/lib/db2jcc_license_c.jar] 1.0 - (581) > However, the "1.0 (581)" information actually came from > $JAVA_HOME/jre/lib/ext/db2jcc.jar, NOT from > /home/bpendleton/downloads/derby/db2jcc/lib/db2jcc.jar. > It would be nice if SysInfo could detect the difference between a jar file > being loaded via the application class loader using $CLASSPATH, and a jar > file being loaded via the system class loader using JDK library extensions. > To reproduce the problem, simply: > 1) Place an older version of db2jcc.jar into $JAVA_HOME/jre/lib/ext > 2) Place a newer version of db2jcc.jar into your $CLASSPATH > 3) Run SysInfo. You will see that it prints the name of the jarfile from > $CLASSPATH, but the version info from the JDK copy. -- This message is automatically generated by JIRA. - If you think it was sent incorrectly contact one of the administrators: http://issues.apache.org/jira/secure/Administrators.jspa - For more information on JIRA, see: http://www.atlassian.com/software/jira
