SweetHome.java

package ru.abishev;

import java.io.ByteArrayOutputStream;
import java.io.File;
import java.io.FileInputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;
import java.net.MalformedURLException;
import java.net.URL;
import java.util.ArrayList;
import java.util.List;

public class SweetHome {
    public static <T> List<T> union(List<T> l1, List<T> l2) {
        List<T> result = new ArrayList<T>();
        result.addAll(l1);
        result.addAll(l2);
        return result;
    }

    public static File root() {
        return new File(".");
    }

    public static URL safeUrl(String url) {
        try {
            return new URL(url);
        } catch (MalformedURLException e) {
            throw new RuntimeException(e);
        }
    }

    public static String urlContent(URL url) throws IOException {
        InputStream input = url.openStream();
        ByteArrayOutputStream output = new ByteArrayOutputStream();
        pump(input, output);
        input.close();
        return output.toString();
    }

    public static String content(File file) {
        try {
            FileInputStream input = new FileInputStream(file);
            ByteArrayOutputStream output = new ByteArrayOutputStream();
            pump(input, output);
            input.close();
            return output.toString();
        } catch (IOException e) {
            throw new RuntimeException(e);
        }
    }

    public static List<File> files(File root) {
        List<File> result = new ArrayList<File>();
        collectFiles(root, result);
        return result;
    }

    private static void collectFiles(File file, List<File> result) {
        if (file.isFile()) {
            result.add(file);
        } else {
            for (File inner : file.listFiles()) {
                collectFiles(inner, result);
            }
        }
    }

    public static List<File> files(String... paths) {
        List<File> result = new ArrayList<File>();
        for (String path : paths) {
            result.add(new File(path));
        }
        return result;
    }

    public static List<File> withExtension(String ext, List<File> files) {
        List<File> result = new ArrayList<File>();
        for (File file : files) {
            if (file.getName().endsWith(ext)) {
                result.add(file);
            }
        }
        return result;
    }

    public static void pump(InputStream input, OutputStream output) throws IOException {
        // todo: use byte[] Luke
        int b;
        while ((b = input.read()) != -1) {
            output.write(b);
        }
    }
}