Customising JIRA code

When customising JIRA, it is sometimes necessary to make code modifications. Most classes in JIRA conform to an interface (eg. the Webwork action classes, and *Manager classes), so it is possible to write your own implementation of JIRA interfaces and use yours instead of the default. This page describes the basics of how plug modified classes into JIRA with minimal pain.

Picocontainer

JIRA uses Picocontainer as a central object factory. Picocontainer is responsible for instantiating objects and resolving their constructor dependencies. This greatly simplifies code, in that any Picocontainer-instantiated object (eg. a Webwork action) can obtain an instance of another (eg. a Manager class) simply by requesting one in its constructor. PicoContainer will ensure each object required in the constructor is passed in (aka dependency injection). Eg. the ViewIssue action:

ViewIssue.java

public class ViewIssue extends AbstractViewIssue
{
    ....
    public ViewIssue(RepositoryManager repositoryManager, PermissionManager permissionManager, TrackbackManager trackbackManager,
                     ThumbnailManager thumbnailManager, SubTaskManager subTaskManager, IssueLinkManager issueLinkManager,
                     IssueLinkTypeManager issueLinkTypeManager, VoteManager voteManager, WatcherManager watcherManager,
                     PluginManager pluginManager)
    {
        super(issueLinkManager, subTaskManager);
        this.trackbackManager = trackbackManager;
        this.thumbnailManager = thumbnailManager;
        this.issueLinkTypeManager = issueLinkTypeManager;
        this.pluginManager = pluginManager;
        this.pagerManager = new PagerManager(ActionContext.getSession());
        this.repositoryManager = repositoryManager;
        this.permissionManager = permissionManager;
        this.voteManager = voteManager;
        this.watcherManager = watcherManager;
    }
    ....
}

Non-managed classes

Classes not managed by Picocontainer (eg. workflow conditions / functions, Services and Listeners, or JSP scriptlets) can still get pico-instantiated objects statically using static methods on ComponentManager. For example:

final ProjectManager projectManager = ComponentManager.getInstance().getProjectManager();
final IssueFactory = ComponentManager.getInstance().getIssueFactory();
//or
final ApplicationProperties applicationProperties = ComponentManager.getComponentInstanceOfType(ApplicationProperties.class);

Register new Picocontainer-managed classes

Picocontainer-managed classes need to be registered with Picocontainer. This happens automatically for Webwork actions, but other classes need to be registered manually. This is done in ComponentRegistrar's registerComponents() method:

ComponentManager.java

    public void registerComponents(final ComponentContainer register, final boolean startupOK)
    {
...
        register.implementation(INTERNAL, EntityUtils.class);
        register.implementation(PROVIDED, AttachmentManager.class, DefaultAttachmentManager.class);
        register.implementation(PROVIDED, AttachmentService.class, DefaultAttachmentService.class);
        register.implementation(PROVIDED, ProjectService.class, DefaultProjectService.class);
        register.implementation(PROVIDED, FieldManager.class, DefaultFieldManager.class);
        register.implementation(PROVIDED, CustomFieldManager.class, DefaultCustomFieldManager.class);
        register.implementation(PROVIDED, CustomFieldService.class, DefaultCustomFieldService.class);
        register.implementation(PROVIDED, FieldScreenManager.class, DefaultFieldScreenManager.class);
        register.implementation(INTERNAL, DefaultFieldScreenStore.class);
        register.implementation(PROVIDED, MailThreadManager.class, MailThreadManagerImpl.class);
        register.implementation(PROVIDED, CvsRepositoryUtil.class, CvsRepositoryUtilImpl.class);
        register.implementation(INTERNAL, DefaultWebAttachmentManager.class);
        register.implementation(INTERNAL, I18nBean.class);// this is a candidate for removal (may not be used - SF 08/Oct/04)
        register.implementation(PROVIDED, I18nHelper.class, I18nBean.class);
        register.implementation(PROVIDED, I18nHelper.BeanFactory.class, I18nBean.CachingFactory.class);
        register.implementation(INTERNAL, JiraLocaleUtils.class);
        register.implementation(PROVIDED, LocaleManager.class, DefaultLocaleManager.class);
        register.implementation(INTERNAL, PingUrlFilterer.class);
...
     }

Components can either by INTERNAL meaning that they will be available only to JIRA itself or PROVIDED in which case they will also be available to plugins2 plugins.

Components are generally only registered in the ComponentRegistrar, if they are required in JIRA internally. Plugin writers who wish to write to write their own components that can be injected in their plugin's classes should use the component plugin module .

If you wanted to register your overridden version of a pico-registered class, you could just register yours instead of the default in ComponentRegistrar above.

Overriding components in JIRA

Sometimes it may be necessary for a plugin writer to override a component that JIRA ships with to provide some custom behaviour. There's two ways this can be achieved. The preferred way is to provide a plugins1 component module. Alternatively one can also provide an extension pico container via a jira-application.properties property which can be used in more complex scenarios.

Overriding with a plugins1 component module

To override a component in JIRA, one simply has to declare a component module for an interface that's already been registered in JIRA. For example to override JIRA's SearchService, one could declare a plugin component like this:

<component key="searchService" name="Search Service"
               class="com.atlassian.docsprint.MySearchService">
        <interface>com.atlassian.jira.bc.issue.search.SearchService</interface>
</component>

Please note that components can only be overriden from a plugins1 component plugin module that is deployed to WEB-INF/lib. Overriding a component from a plugins2 plugin will not work.

Overriding with an extension pico-container

Since JIRA 3.0 there is another way of plugging in your customizations that avoids modifying JIRA code. In jira-application.properties, register an extension container provider:

jira.extension.container.provider = com.mycompany.jira.MyContainerProvider

In this class, you can register your own implementations of interfaces, which will be used in preference to the defaults in ComponentManager:

MyContainerProvider.java

package com.mycompany.jira;

import org.picocontainer.PicoContainer;
import org.picocontainer.defaults.DefaultPicoContainer;
import com.atlassian.jira.config.component.ProfilingComponentAdapterFactory;
import com.atlassian.jira.web.action.issue.BugAssociatorPrefs;
import com.atlassian.jira.security.PermissionManager;
import com.atlassian.jira.permission.PermissionSchemeManager;

import com.mycompany.jira.MyBugAssociatorPrefs;
import com.mycompany.jira.MyPermissionManager;
import com.mycompany.jira.MyPermissionSchemeManager;

public class MyContainerProvider implements ContainerProvider
{
    private DefaultPicoContainer container;

    public PicoContainer getContainer(PicoContainer parent)
    {
        if (container == null)
            buildContainer(parent);
        return container;
    }

    private void buildContainer(PicoContainer parent)
    {
        this.container = new DefaultPicoContainer(new ProfilingComponentAdapterFactory(), parent);
        container.registerComponentImplementation(BugAssociatorPrefs.class, MyBugAssociatorPrefs.class);
        container.registerComponentImplementation(PermissionManager.class, MyPermissionManager.class);
        container.registerComponentImplementation(PermissionSchemeManager.class, MyPermissionSchemeManager.class);
    }
}

Here we have registered our own implementations of three classes, after delegating to the default (so ours will take precedence). You can now keep MyContainerProvider and your modified com.mycompany.jira.* classes in their own jar, which can be dropped into any JIRA instance to customize it to your needs.

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