ResourceLoader.java

package com.github.agiledon.sisyphus.util;

import com.google.common.base.Charsets;
import com.google.common.base.Joiner;
import com.google.common.base.Predicate;
import com.google.common.base.Strings;
import com.google.common.collect.Iterables;
import com.google.common.collect.Lists;
import com.google.common.io.Files;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

import java.io.File;
import java.io.IOException;
import java.util.List;

import static com.github.agiledon.sisyphus.util.ResourceFilePath.compensatePath;
import static com.github.agiledon.sisyphus.util.ResourceFilePath.getAbsolutePath;
import static com.google.common.collect.Lists.newArrayList;

public final class ResourceLoader {
    private ResourceLoader() {}

    private static Logger logger = LoggerFactory.getLogger(ResourceLoader.class);
    private static final String COMMENT_INDICATOR = "#";
    private static final String SECTION_INDICATOR = "///";

    public static String loadResource(String resourceName) {
        List<String> resource = loadResourceAsLines(resourceName);
        return Joiner.on("\n").join(resource);
    }

    public static List<String> loadResourceAsLines(String resourceName) {
        try {
            File file = new File(getAbsolutePath(compensatePath(resourceName)));
            List<String> strings = Files.readLines(file, Charsets.UTF_8);
            return filterInvalidLines(strings);
        } catch (IOException e) {
            return logAndReturnEmptyList(resourceName);
        } catch (Exception e) {
            return logAndReturnEmptyList(resourceName);
        }
    }

    public static List<List<String>> loadResources(String resourceName) {
        return ListUtil.partition(loadResourceAsLines(resourceName), new Predicates<String>() {
            @Override
            public boolean apply(String element) {
                return element.trim().startsWith(SECTION_INDICATOR);
            }
        });
    }

    private static List<String> logAndReturnEmptyList(String resourceName) {
        logger.warn("Failed to read file {}.", resourceName);
        return newArrayList();
    }

    private static List<String> filterInvalidLines(Iterable<String> lines) {
        Iterable<String> filteredLines = Iterables.filter(lines, new Predicate<String>() {
            @Override
            public boolean apply(String line) {
                return notSpaceLine(line) && notComment(line);
            }
        });
        return Lists.newArrayList(filteredLines);
    }

    private static boolean notComment(String line) {
        return !line.trim().startsWith(COMMENT_INDICATOR);
    }

    private static boolean notSpaceLine(String line) {
        return !Strings.isNullOrEmpty(line.trim());
    }


}