pt.up.fe.specs.library.IoUtils.java Source code

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Here is the source code for pt.up.fe.specs.library.IoUtils.java

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/**
 * Copyright 2015 SPeCS.
 * 
 * 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. under the License.
 */

package pt.up.fe.specs.library;

import java.io.BufferedReader;
import java.io.File;
import java.io.FileNotFoundException;
import java.io.IOException;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.nio.charset.Charset;

import com.google.common.io.Files;

public class IoUtils {

    /**
     * Default CharSet used in file operations.
     */
    final public static String DEFAULT_CHAR_SET = "UTF-8";

    /**
     * Helper method for Guava Files.toString, which uses the default Charset
     * and throws an unchecked exception.
     * 
     * @param file
     * @return
     */
    public static String read(File file) {
        try {
            return Files.toString(file, Charset.defaultCharset());
        } catch (IOException e) {
            throw new RuntimeException("Could not read file '" + file + "'", e);
        }
    }

    /**
     * Reads a stream to a String. The stream is closed after it is read.
     * 
     * @param inputStream
     * @return
     */
    public static String read(InputStream inputStream) {
        StringBuilder stringBuilder = new StringBuilder();

        // Try to read the contents of the input stream into the StringBuilder
        // Using 'finally' style 2 as described in
        // http://www.javapractices.com/topic/TopicAction.do?Id=25
        try (final BufferedReader bufferedReader = new BufferedReader(
                new InputStreamReader(inputStream, DEFAULT_CHAR_SET))) {

            // Read first character. It can't be cast to "char", otherwise the
            // -1 will be converted in a character.
            // First test for -1, then cast.
            int intChar = bufferedReader.read();
            while (intChar != -1) {
                char character = (char) intChar;
                stringBuilder.append(character);
                intChar = bufferedReader.read();
            }

        } catch (FileNotFoundException ex) {
            Log.warn("FileNotFoundException", ex);
            stringBuilder = new StringBuilder(0);
        } catch (IOException ex) {
            Log.warn("IOException", ex);
            stringBuilder = new StringBuilder(0);
        }

        return stringBuilder.toString();
    }

    public static InputStream resourceToStream(String resourceName) {
        // Obtain the current classloader
        ClassLoader classLoader = IoUtils.class.getClassLoader();

        // Load the file as a resource
        InputStream stream = classLoader.getResourceAsStream(resourceName);
        if (stream == null) {
            Log.warn("Could not load resource '" + resourceName + "'.");

        }

        return stream;
    }

    /**
     * Given the name of a resource, returns a String with the contents of the
     * resource.
     * 
     * @param resourceName
     * @return a string with the contents of the resource
     */
    public static String getResource(String resourceName) {
        try (InputStream inputStream = IoUtils.resourceToStream(resourceName)) {
            if (inputStream == null) {
                Log.warn("Could not get InputStream.");
                return null;
            }

            return IoUtils.read(inputStream);

        } catch (IOException e) {
            Log.warn("Could not open resource '" + resourceName + "'", e);
            return "";
        }
    }

    /**
     * Helper method for Guava Files.write, which uses the default Charset and
     * throws an unchecked exception.
     * 
     * @param contents
     * @param file
     */
    public static void write(CharSequence contents, File file) {
        try {
            Files.write(contents, file, Charset.defaultCharset());
        } catch (IOException e) {
            throw new RuntimeException("Could not write file '" + file + "'", e);
        }
    }
}