9.5 Finder

Finder resolves imported objects and fragment processors, and provides resource and class loaders. The default DatawayFinder loads classpath resources and constructs objects by reflection. Extend it to connect application lookup rules.

Implement a Finder

This implementation checks an application object Map before falling back to default behavior. Type lookup uses the class name as its Map key.

ApplicationFinder.java

package com.example.dataway;

import java.util.Map;
import net.hasor.dataway.service.DatawayFinder;

public class ApplicationFinder extends DatawayFinder {
    private final Map<String, ?> beans;

    public ApplicationFinder(Map<String, ?> beans) {
        this.beans = beans;
    }

    @Override
    public Object findBean(String name) throws ClassNotFoundException {
        Object bean = this.beans.get(name);
        if (bean != null) {
            return bean;
        }
        return super.findBean(name);
    }

    @Override
    public Object findBean(Class<?> type) {
        Object bean = this.beans.get(type.getName());
        if (bean != null) {
            return type.cast(bean);
        }
        return super.findBean(type);
    }
}

Configure lookup and loaders

import java.util.Map;
import com.example.dataway.ApplicationFinder;
import com.example.dataway.GreetingUdf;
import net.hasor.cobble.loader.providers.ClassPathResourceLoader;

GreetingUdf greeting = new GreetingUdf();
ApplicationFinder finder = new ApplicationFinder(Map.of(
        "app.greeting", greeting,
        GreetingUdf.class.getName(), greeting));

config.finder(finder)
        .resourceLoader(ClassPathResourceLoader.INSTANCE)
        .classLoader(ApplicationFinder.class.getClassLoader());

Call from a script

import 'app.greeting' as greeting;
return greeting('Dataway');

Returns "Hello Dataway". See Custom functions for GreetingUdf.

Lookup order and loaders

Explicit importSource, library and fragment registrations take precedence; missing registrations delegate to Finder. The default Finder rejects unknown fragments.

resourceLoader handles resources such as scripts; classLoader loads Java types and SPI implementations. Pass a custom ResourceLoader to resourceLoader(...). Both setters apply to DatawayFinder and subclasses. Direct Finder implementations supply their own loaders.

Replacing Finder also switches loaders; DatawayConfig getters read the current Finder. Set Finder before configuring its loaders.