com.google.mr4c.content.RelativeContentFactory.java Source code

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Here is the source code for com.google.mr4c.content.RelativeContentFactory.java

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/**
  * Copyright 2014 Google Inc. All rights reserved.
  * 
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
  * You may obtain a copy of the License at
  * 
  *     http://www.apache.org/licenses/LICENSE-2.0
  * 
  * Unless required by applicable law or agreed to in writing, software
  * distributed under the License is distributed on an "AS IS" BASIS,
  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
  * See the License for the specific language governing permissions and
  * limitations under the License.
*/

package com.google.mr4c.content;

import com.google.mr4c.config.category.MR4CConfig;
import com.google.mr4c.config.category.Category;
import com.google.mr4c.config.category.CoreConfig;

import java.io.IOException;
import java.io.InputStream;
import java.io.FileInputStream;
import java.io.OutputStream;
import java.io.FileOutputStream;
import java.io.File;
import java.net.URI;

import org.apache.commons.lang3.StringUtils;

import org.apache.hadoop.fs.Path;

public class RelativeContentFactory extends AbstractContentFactory implements ContentFactory {

    private static File s_defaultWD = new File(System.getProperty("user.dir")); // working directory at JVM startup

    public static File getWorkingDirectory() {
        String confWD = MR4CConfig.getDefaultInstance().getCategory(Category.CORE)
                .getProperty(CoreConfig.PROP_ROOT_DIR);
        return StringUtils.isEmpty(confWD) ? s_defaultWD : new File(confWD);
    }

    public static File toFile(URI uri) {
        return toFile(uri, getWorkingDirectory());
    }

    public static File toFile(URI uri, File parent) {
        if (!"rel".equals(uri.getScheme())) {
            throw new IllegalArgumentException("Expecting a relative file URI [" + uri + "]");
        }
        // Doing this because File won't take a URI with a relative path
        String path = uri.getSchemeSpecificPart();
        return new File(parent, path);
    }

    public static URI toRelativeFileURI(File file) {
        return toRelativeFileURI(file, getWorkingDirectory());
    }

    public static URI toRelativeFileURI(File file, File ancestor) {
        String path = toRelativeFilePath(file, ancestor);
        return URI.create("rel:" + path);
    }

    public static String toRelativeFilePath(File file, File ancestor) {
        checkRelated(file, ancestor);
        URI fileUri = file.toURI();
        URI ancestorUri = ancestor.toURI();
        URI relativeUri = ancestorUri.relativize(fileUri);
        return relativeUri.getPath();
    }

    public InputStream readContentAsStream(URI uri) throws IOException {
        File file = toFile(uri);
        return new FileInputStream(file);
    }

    public long getContentLength(URI uri) throws IOException {
        File file = toFile(uri);
        return file.length();
    }

    public OutputStream getOutputStreamForContent(URI uri) throws IOException {
        File file = toFile(uri);
        return new FileOutputStream(file);
    }

    public void ensureParentExists(URI uri) throws IOException {
        File file = toFile(uri);
        LocalContentFactory.ensureParentExists(file);
    }

    public boolean exists(URI uri) throws IOException {
        File file = toFile(uri);
        return file.exists();
    }

    public boolean deleteContent(URI uri) throws IOException {
        File file = toFile(uri);
        return file.delete();
    }

    public Path toPath(URI uri) {
        File file = toFile(uri);
        return new Path(file.toURI());
    }

    private static void checkRelated(File file, File ancestor) {
        if (!file.getAbsolutePath().startsWith(ancestor.getAbsolutePath())) {
            throw new IllegalStateException(String.format("[%s] is not a decendent of [%s]", file, ancestor));
        }
    }

}