java - 如何创建全局查找上下文？

Question

我正在制作一个 Openide 应用程序，它使用多个窗口来查看同一个文档，并且我想制作它，以便在每个窗口中启用保存按钮（如果已启用）。我怎么做？

Answer 1

这很容易，您可以自己实现ContextGlobalProvider. 这两个 来源可以帮助您做到这一点。

使用这些资源，我能够创建两个不同版本的CentralLookup. 这是您的“上下文”不变时的第一个：

@ServiceProvider(service = ContextGlobalProvider.class,
    //this next arg is nessesary if you want yours to be the default
    supersedes = "org.netbeans.modules.openide.windows.GlobalActionContextImpl")
public class CentralLookup implements ContextGlobalProvider{
    private final InstanceContent content = new InstanceContent();
    private final Lookup lookup = new AbstractLookup(content);
    public CentralLookup() {}

    public void add(Object instance){
        content.add(instance);
    }

    public void remove(Object instance){
        content.remove(instance);
    }

    public static CentralLookup getInstance() {
        return CentralLookupHolder.INSTANCE;
    }

    // this is apperently only called once...
    @Override
    public Lookup createGlobalContext() {
        return lookup;
    }
    private static class CentralLookupHolder {
        //private static final CentralLookup INSTANCE = new CentralLookup();
        private static final CentralLookup INSTANCE = Lookup.getDefault().lookup(CentralLookup.class);
    }
}

如果您想要一个随当前上下文或“文档”而变化的内容，请使用以下命令：

    @ServiceProvider(service = ContextGlobalProvider.class,
    //this next arg is nessesary if you want yours to be the default
    supersedes = "org.netbeans.modules.openide.windows.GlobalActionContextImpl")
public class CentralLookup implements ContextGlobalProvider, Lookup.Provider{
    public CentralLookup() {}

    public void add(Object instance){
        getCurrentDocument().content.add(instance);
    }

    public void remove(Object instance){
        getCurrentDocument().content.remove(instance);
    }

    public static CentralLookup getInstance() {
        return CentralLookupHolder.INSTANCE;
    }

    // this is apperently only called once...
    @Override
    public Lookup createGlobalContext() {
        return Lookups.proxy(this);
    }

    @Override
    public Lookup getLookup(){
        return getCurrentDocument().lookup;
    }
    /**
     * Refresh which lookup is current.  Call this after changing the current document
     */
    public void updateLookupCurrent(){
        Utilities.actionsGlobalContext().lookup(ActionMap.class);
    }
    private static class CentralLookupHolder {
        //private static final CentralLookup INSTANCE = new CentralLookup();
        private static final CentralLookup INSTANCE = Lookup.getDefault().lookup(CentralLookup.class);
    }
}