Tomcat, classloaders and plugins
I'd like to add a plugin system to my Tomcat webapp. To experiment I've added a small Plugin interface to the webapp and I've implemented it in MyPlugin which is not a part of the deployed war. The webapp reads a config file and uses reflection to initialize the plugins.
Everything works as expected if I copy the jar containing MyPlugin into webapps/mywebapp/WEB-INF/lib. However, if I do this then the plugin is overwritten on the next deploy.
I tried moving the jar into a separate directory outside of the unpacked war and then pointing shared.loader in conf/catalina.properties there, but now I get an exception that MyPlugin cannot be cast to Plugin. Apparently the interface and the class are loaded using different classloaders.
What's the best way to solve this problem?
java tomcat classloader
asked Nov 13 '18 at 6:20
terratinkah
183
add a comment |
I'd like to add a plugin system to my Tomcat webapp. To experiment I've added a small Plugin interface to the webapp and I've implemented it in MyPlugin which is not a part of the deployed war. The webapp reads a config file and uses reflection to initialize the plugins.
Everything works as expected if I copy the jar containing MyPlugin into webapps/mywebapp/WEB-INF/lib. However, if I do this then the plugin is overwritten on the next deploy.
I tried moving the jar into a separate directory outside of the unpacked war and then pointing shared.loader in conf/catalina.properties there, but now I get an exception that MyPlugin cannot be cast to Plugin. Apparently the interface and the class are loaded using different classloaders.
What's the best way to solve this problem?
java tomcat classloader
asked Nov 13 '18 at 6:20
terratinkah
183
add a comment |
I'd like to add a plugin system to my Tomcat webapp. To experiment I've added a small Plugin interface to the webapp and I've implemented it in MyPlugin which is not a part of the deployed war. The webapp reads a config file and uses reflection to initialize the plugins.
Everything works as expected if I copy the jar containing MyPlugin into webapps/mywebapp/WEB-INF/lib. However, if I do this then the plugin is overwritten on the next deploy.
I tried moving the jar into a separate directory outside of the unpacked war and then pointing shared.loader in conf/catalina.properties there, but now I get an exception that MyPlugin cannot be cast to Plugin. Apparently the interface and the class are loaded using different classloaders.
What's the best way to solve this problem?
java tomcat classloader
asked Nov 13 '18 at 6:20
terratinkah
183
I'd like to add a plugin system to my Tomcat webapp. To experiment I've added a small Plugin interface to the webapp and I've implemented it in MyPlugin which is not a part of the deployed war. The webapp reads a config file and uses reflection to initialize the plugins.
Everything works as expected if I copy the jar containing MyPlugin into webapps/mywebapp/WEB-INF/lib. However, if I do this then the plugin is overwritten on the next deploy.
I tried moving the jar into a separate directory outside of the unpacked war and then pointing shared.loader in conf/catalina.properties there, but now I get an exception that MyPlugin cannot be cast to Plugin. Apparently the interface and the class are loaded using different classloaders.
What's the best way to solve this problem?
java tomcat classloader
java tomcat classloader
asked Nov 13 '18 at 6:20
terratinkah
183
asked Nov 13 '18 at 6:20
terratinkah
183
asked Nov 13 '18 at 6:20
terratinkah
183
asked Nov 13 '18 at 6:20
terratinkah
183
asked Nov 13 '18 at 6:20
terratinkah
183
183
add a comment |
add a comment |
0
active
oldest
votes
Your Answer
StackExchange.ifUsing("editor", function () {
StackExchange.using("externalEditor", function () {
StackExchange.using("snippets", function () {
StackExchange.snippets.init();
});
});
}, "code-snippets");
StackExchange.ready(function() {
var channelOptions = {
tags: "".split(" "),
id: "1"
};
initTagRenderer("".split(" "), "".split(" "), channelOptions);
StackExchange.using("externalEditor", function() {
// Have to fire editor after snippets, if snippets enabled
if (StackExchange.settings.snippets.snippetsEnabled) {
StackExchange.using("snippets", function() {
createEditor();
});
}
else {
createEditor();
}
});
function createEditor() {
StackExchange.prepareEditor({
heartbeatType: 'answer',
autoActivateHeartbeat: false,
convertImagesToLinks: true,
noModals: true,
showLowRepImageUploadWarning: true,
reputationToPostImages: 10,
bindNavPrevention: true,
postfix: "",
imageUploader: {
brandingHtml: "Powered by u003ca class="icon-imgur-white" href="https://imgur.com/"u003eu003c/au003e",
contentPolicyHtml: "User contributions licensed under u003ca href="https://creativecommons.org/licenses/by-sa/3.0/"u003ecc by-sa 3.0 with attribution requiredu003c/au003e u003ca href="https://stackoverflow.com/legal/content-policy"u003e(content policy)u003c/au003e",
allowUrls: true
},
onDemand: true,
discardSelector: ".discard-answer"
,immediatelyShowMarkdownHelp:true
});
}
});
Sign up or log in
StackExchange.ready(function () {
StackExchange.helpers.onClickDraftSave('#login-link');
});
Sign up using Google
Sign up using Facebook
Sign up using Email and Password
Post as a guest
Required, but never shown
StackExchange.ready(
function () {
StackExchange.openid.initPostLogin('.new-post-login', 'https%3a%2f%2fstackoverflow.com%2fquestions%2f53274949%2ftomcat-classloaders-and-plugins%23new-answer', 'question_page');
}
);
Post as a guest
Required, but never shown
0
active
oldest
votes
0
active
oldest
votes
active
oldest
votes
active
oldest
votes
Thanks for contributing an answer to Stack Overflow!
- Please be sure to answer the question. Provide details and share your research!
But avoid …
- Asking for help, clarification, or responding to other answers.
- Making statements based on opinion; back them up with references or personal experience.
To learn more, see our tips on writing great answers.
Some of your past answers have not been well-received, and you're in danger of being blocked from answering.
Please pay close attention to the following guidance:
- Please be sure to answer the question. Provide details and share your research!
But avoid …
- Asking for help, clarification, or responding to other answers.
- Making statements based on opinion; back them up with references or personal experience.
To learn more, see our tips on writing great answers.
Sign up or log in
StackExchange.ready(function () {
StackExchange.helpers.onClickDraftSave('#login-link');
});
Sign up using Google
Sign up using Facebook
Sign up using Email and Password
Post as a guest
Required, but never shown
StackExchange.ready(
function () {
StackExchange.openid.initPostLogin('.new-post-login', 'https%3a%2f%2fstackoverflow.com%2fquestions%2f53274949%2ftomcat-classloaders-and-plugins%23new-answer', 'question_page');
}
);
Post as a guest
Required, but never shown
Sign up or log in
StackExchange.ready(function () {
StackExchange.helpers.onClickDraftSave('#login-link');
});
Sign up using Google
Sign up using Facebook
Sign up using Email and Password
Post as a guest
Required, but never shown
Sign up or log in
StackExchange.ready(function () {
StackExchange.helpers.onClickDraftSave('#login-link');
});
Sign up using Google
Sign up using Facebook
Sign up using Email and Password
Post as a guest
Required, but never shown
Sign up or log in
StackExchange.ready(function () {
StackExchange.helpers.onClickDraftSave('#login-link');
});
Sign up using Google
Sign up using Facebook
Sign up using Email and Password
Sign up using Google
Sign up using Facebook
Sign up using Email and Password
Post as a guest
Required, but never shown
Required, but never shown
Required, but never shown
Required, but never shown
Required, but never shown
Required, but never shown
Required, but never shown
Required, but never shown
Required, but never shown
