Thymeleaf plugin does not work in STS 4.9.0 (Eclipse 2020-12)

[manueljordan]

Hello Thymelead Developers

Having:

and the Thymeleaf plugin

For a Spring Boot (2.4.1) app with Thymeleaf, doing the following

Does not work (BTW - the Error Log view shows nothing)

Having the following header:

Now in some point randomly appears:

And the Plugin does not work how is expected.

Now sure what could be.

[manueljordan]

Some times when the Add Thymeleaf Nature is triggered manually it shows

[user20161119]

the same version as you,got this error after install plugin

[manueljordan]

Thanks for that figure, yes. I think that I got the same message but I didn't take a screenshot about that

[kaiwinter]

The root cause here is this exception:

Caused by: java.lang.ClassNotFoundException: javax.activation.DataSource cannot be found by org.thymeleaf.extras.eclipse.core_3.0.0.202005310144
	at org.eclipse.osgi.internal.loader.BundleLoader.findClass(BundleLoader.java:519)
	at org.eclipse.osgi.internal.loader.ModuleClassLoader.loadClass(ModuleClassLoader.java:170)
	at java.base/java.lang.ClassLoader.loadClass(ClassLoader.java:521)

JDK 11 misses this package but STS requires JDK 11. So I think this plugin has to be updated to be JDK 11 compatible. This issue is a duplicate of #100. Unfortunately I couldn't manage to build and test this plugin.

[ultraq]

I thought I managed to fix up the Java 11 issues back in #84 (and many related issues to that) by bundling javax.activation and friends with the plugin 🤔 I'll check the build again and try w/ STS this time since you're saying it requires JDK11 now (I have a bunch of JDKs on my machine so I'm not always sure what Eclipse is using what JDK).

[kaiwinter]

Thanks for your reply 😃 Here is an example of my SpringToolSuite4.ini which is pretty identical to eclipse.ini. The -vm arg defines the JDK which gets used for running eclipse/STS:

-vm
C:/dev/Java/jdk-11.0.6+10/bin
-startup
plugins/org.eclipse.equinox.launcher_1.6.200.v20210416-2027.jar
--launcher.library
plugins/org.eclipse.equinox.launcher.win32.win32.x86_64_1.2.200.v20210429-1609
-product
org.springframework.boot.ide.branding.sts4
--launcher.defaultAction
openFile
-vmargs
-javaagent:C:\dev\eclipse\sts-4.5.1.RELEASE\lombok.jar
-Dosgi.requiredJavaVersion=11
-Dosgi.dataAreaRequiresExplicitInit=true
-Xms512m
-Xmx6000m
--illegal-access=permit
--add-modules=ALL-SYSTEM

[ultraq]

Had a look at this, and I think STS won't work with this plugin any more. Even after looking into the bundled javax.activation JAR, I'm getting build errors everywhere using STS. It seems that, as of STS 4.8.0, they started moving to a different editor for web development to something called Wild Web Developer (spring-projects/sts4#354). This plugin was written atop the Eclipse's Web Tools Platform (WTP) project instead, which ships as part of the "Eclipse for Java and Web developers" edition from the Eclipse website.

Thymeleaf support in WWD would be a much bigger project than simply fixing the bundled JARs... 🤔

[kaiwinter]

Ah ok I see. Well that's bad news. I was always hoping this plugin may be extended to provide an even better Thymeleaf integration in Eclipse.

[manueljordan]

I think STS would give support (for integration for both) - I don't see a reason to isolate thymeleaf plugin