Java tutorial
/* * Copyright 2005-2009 the original author or authors. * * 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 eu.europeana.enrichment.common; import java.io.BufferedReader; import java.io.BufferedWriter; import java.io.ByteArrayInputStream; import java.io.File; import java.io.FileFilter; import java.io.FileInputStream; import java.io.FileNotFoundException; import java.io.FileOutputStream; import java.io.FileReader; import java.io.FileWriter; import java.io.IOException; import java.io.InputStream; import java.io.InputStreamReader; import java.io.OutputStream; import java.io.UnsupportedEncodingException; import java.net.URL; import java.net.URLDecoder; import java.util.ArrayList; import java.util.Arrays; import java.util.Collection; import java.util.Enumeration; import java.util.HashSet; import java.util.LinkedList; import java.util.List; import java.util.Queue; import java.util.Set; import org.apache.commons.io.FilenameUtils; import org.apache.commons.io.filefilter.WildcardFileFilter; /** * Various utilities. * * @author Borys Omelayenko * */ public class Utils { public static List<File> expandFileTemplateFrom(File dir, String... pattern) throws IOException { List<File> files = new ArrayList<File>(); for (String p : pattern) { File fdir = new File(new File(dir, FilenameUtils.getFullPathNoEndSeparator(p)).getCanonicalPath()); if (!fdir.isDirectory()) throw new IOException("Error: " + fdir.getCanonicalPath() + ", expanded from directory " + dir.getCanonicalPath() + " and pattern " + p + " does not denote a directory"); if (!fdir.canRead()) throw new IOException("Error: " + fdir.getCanonicalPath() + " is not readable"); FileFilter fileFilter = new WildcardFileFilter(FilenameUtils.getName(p)); File[] list = fdir.listFiles(fileFilter); if (list == null) throw new IOException("Error: " + fdir.getCanonicalPath() + " does not denote a directory or something else is wrong"); if (list.length == 0) throw new IOException("Error: no files found, template " + p + " from dir " + dir.getCanonicalPath() + " where we recognised " + fdir.getCanonicalPath() + " as path and " + fileFilter + " as file mask"); for (File file : list) { if (!file.exists()) { throw new FileNotFoundException( "File not found: " + file + " resolved to " + file.getCanonicalPath()); } } files.addAll(Arrays.asList(list)); } return files; } public static String show(Collection list, String separator) { String result = ""; for (Object object : list) { if (result.length() > 0) result += separator; result += object.toString(); } return result; } /** * Returned by compareFiles. * */ public static class DiffInFiles { @Override public String toString() { return "Line" + line + ", " + strOne + " * " + strTwo; } public int line; public String strOne; public String strTwo; public DiffInFiles(int line, String strOne, String strTwo) { super(); this.line = line; this.strOne = strOne; this.strTwo = strTwo; } } /** * Compares two text files. * * @param file1 * @param file2 * @return lines where they differ */ public static List<DiffInFiles> compareFiles(File file1, File file2, int maxDiffLinesToReport) throws IOException { List<DiffInFiles> result = new ArrayList<DiffInFiles>(); BufferedReader b1 = new BufferedReader(new FileReader(file1), 64000); BufferedReader b2 = new BufferedReader(new FileReader(file2), 64000); int lineNumber = 0; while (maxDiffLinesToReport == -1 || result.size() < maxDiffLinesToReport) { String s1 = b1.readLine(); String s2 = b2.readLine(); // end of both files if (s1 == null && s2 == null) break; // one is shorter if (s1 == null) { result.add(new DiffInFiles(lineNumber, s1, s2)); } else { if (s2 == null) { result.add(new DiffInFiles(lineNumber, s1, s2)); } else { if (!s1.equals(s2)) result.add(new DiffInFiles(lineNumber, s1, s2)); } } lineNumber++; } b1.close(); b2.close(); return result; } /** * Loads a file into a string. * * @param fileName * file name * @param EOL * End-of-line string to put into the resulting string * @return * @throws FileNotFoundException * @throws IOException */ public static String loadFileToString(String fileName, String EOL) throws FileNotFoundException, IOException { BufferedReader in = new BufferedReader(new FileReader(fileName)); String result = ""; String str; while ((str = in.readLine()) != null) { result += str + EOL; } in.close(); return result; } public static void saveStringToFile(String string, String fileName) throws FileNotFoundException, IOException { BufferedWriter out = new BufferedWriter(new FileWriter(fileName)); out.append(string); out.close(); } /** * Loads a web page from an URL to a string. * * @param url * address of the page * @param EOL * End-of-line string to put into the resulting string * @return * @throws FileNotFoundException * @throws IOException */ public static String loadURLToString(String url, String EOL) throws FileNotFoundException, IOException { BufferedReader in = new BufferedReader(new InputStreamReader((new URL(url)).openStream())); String result = ""; String str; while ((str = in.readLine()) != null) { result += str + EOL; } in.close(); return result; } // public static String[] filesToString(List<File> files) throws Exception // { // String[] result = new String[files.size()]; // int i = 0; // for (File file : files) // { // result[i++] = file.getCanonicalPath(); // } // return result; // } // // public static long hashCode(String[] list) // { // return merge(list, ";").hashCode(); // } // // public static String merge(String[] list, String separator) // { // String merged = ""; // for (int i = 0; i < list.length; i++) // { // merged += ((i == 0) ? "" : separator) + list[i]; // } // return merged; // } /* * From * http://www.java-tips.org/java-se-tips/java.io/reading-a-file-into-a-byte * -array.html and adapted */ private static byte[] getBytesFromFile(File file) throws IOException { InputStream is = new FileInputStream(file); // Get the size of the file long length = file.length(); if (length > Integer.MAX_VALUE) { // File is too large throw new IOException("File is too large"); } // Create the byte array to hold the data byte[] bytes = new byte[(int) length]; // Read in the bytes int offset = 0; int numRead = 0; while (offset < bytes.length && (numRead = is.read(bytes, offset, bytes.length - offset)) >= 0) { offset += numRead; } // Ensure all the bytes have been read in if (offset < bytes.length) { throw new IOException("Could not completely read file " + file.getName()); } // Close the input stream and return bytes is.close(); return bytes; } static public byte[] readResourceFile(File src) throws IOException { if (src == null) throw new NullPointerException("Null src"); String srcPath; try { srcPath = src.getCanonicalPath(); } catch (Exception e) { throw new IOException(e.getMessage() + " on " + src.getName()); } if (srcPath.contains("!")) { // JARs // remove dire prefix if (srcPath.indexOf("file:") != srcPath.lastIndexOf("file:")) throw new IOException("Source " + srcPath + " should contain only one substring 'file:'"); srcPath = srcPath.substring(srcPath.indexOf("file:") + "file:".length()); String[] srcPaths = srcPath.split("!"); if (srcPaths.length != 2) throw new IOException( "Source " + srcPath + " should contain no '!' for plain files or just '!' for jar files."); if (srcPaths[1].startsWith("/") || srcPaths[1].startsWith("\\")) srcPaths[1] = srcPaths[1].substring(1); JarResources jr = new JarResources(srcPaths[0]); byte[] buf = jr.getResource(srcPaths[1]); if (buf == null) throw new NullPointerException("Null resource: " + srcPaths[1] + " from " + srcPaths[0]); return buf; } else { // plain files return getBytesFromFile(src); } } static public String readResourceFileAsString(String resource) throws IOException { BufferedReader br = new BufferedReader( new InputStreamReader(new ByteArrayInputStream(readResourceFile(new File(resource))))); String line; String result = ""; while ((line = br.readLine()) != null) { result += line + "\n"; } br.close(); return result; } private static InputStream readResourceFromPackage(Class theClass, String resource) throws IOException { if (theClass.getResource(resource) == null) throw new NullPointerException( "Failed to find resource for class " + theClass.getName() + " resource " + resource); String fileName = theClass.getResource(resource).getFile(); if (fileName == null) throw new NullPointerException("Failed to generate file for resource for class " + theClass.getName() + " resource " + resource); byte[] file = readResourceFile(new File(fileName)); return new ByteArrayInputStream(file); } static public String readResourceFileFromSamePackageAsString(Class theClass, String resource) throws IOException { BufferedReader br = new BufferedReader(new InputStreamReader(readResourceFromPackage(theClass, resource))); String line; String result = ""; while ((line = br.readLine()) != null) { result += line + "\n"; } br.close(); return result; } static public List<String> readResourceFileFromSamePackageAsList(Class theClass, String resource) throws IOException { BufferedReader br = new BufferedReader(new InputStreamReader(readResourceFromPackage(theClass, resource))); String line; List<String> result = new ArrayList<String>(); while ((line = br.readLine()) != null) { result.add(line); } br.close(); return result; } /** * A dirty Dutch plural -> singular converter. */ public static String getSingular(String plural) { if (plural == null) return null; String singular = plural; // if word ends with -en : cut off -en if (plural.endsWith("en")) singular = plural.substring(0, plural.length() - 2); else // if word ends with 's : cut off 's if (plural.endsWith("'s")) singular = plural.substring(0, plural.length() - 2); else // if word ends with -s : cut off -s if (plural.endsWith("s")) singular = plural.substring(0, plural.length() - 1); // then // if word ends with two similar consonant : remove one if (singular.matches("(.*)(ss|tt|qq|ww|rr|pp|dd|ff|gg|kk|ll|zz|xx|cc|vv|bb|nn|mm)$")) singular = singular.substring(0, singular.length() - 1); // if word ends with -v : remove -v and add -f if (singular.endsWith("v")) singular = singular.substring(0, singular.length() - 1) + "f"; // if word ends with -z : remove -z and add -s if (singular.endsWith("z")) singular = singular.substring(0, singular.length() - 1) + "s"; return singular; } /** * Attempts to list all the classes in the specified package as determined * by the context class loader * * @param pckgname * the package name to search * @return a list of classes that exist within that package * @throws ClassNotFoundException * if something went wrong */ public static List<Class> getClassesForPackage(String pckgname) throws ClassNotFoundException, IOException { // Set<String> list = getClassNamesPackage(pckgname); Set<String> list = new FindClasspath().getClassesForPackage(pckgname); List<Class> classes = new ArrayList<Class>(); for (String fileName : list) { classes.add(Class.forName(pckgname.length() == 0 ? fileName : (pckgname + '.' + fileName))); } return classes; } private static Set<String> getClassNamesPackage(String pckgname) throws ClassNotFoundException, IOException { // This will hold a list of directories matching the pckgname. There may // be // more than one if a package is split over multiple jars/paths Queue<File> directories = new LinkedList<File>(); try { ClassLoader cld = Thread.currentThread().getContextClassLoader(); if (cld == null) { throw new ClassNotFoundException("Can't get class loader."); } String path = pckgname.replace('.', '/'); // Ask for all resources for the path Enumeration<URL> resources = cld.getResources(path); while (resources.hasMoreElements()) { directories.add(new File(URLDecoder.decode(resources.nextElement().getPath(), "UTF-8"))); } } catch (NullPointerException x) { throw new ClassNotFoundException( pckgname + " does not appear to be a valid package (Null pointer exception)"); } catch (UnsupportedEncodingException encex) { throw new ClassNotFoundException( pckgname + " does not appear to be a valid package (Unsupported encoding)"); } catch (IOException ioex) { throw new ClassNotFoundException( "IOException was thrown when trying to get all resources for " + pckgname); } Set<String> classes = new HashSet<String>(); // For every directory identified capture all the .class files while (!directories.isEmpty()) { File directory = directories.poll(); if (directory.exists()) { // Get the list of the files contained in the package File[] files = directory.listFiles(); for (File file : files) { // we are only interested in .class files if (file.getCanonicalPath().endsWith(".class")) { String fileName = file.getPath().substring(directory.getPath().length() + 1); pckgname = file.getPath() .substring(file.getPath().indexOf(File.separator + "nl" + File.separator) + 1); pckgname = pckgname.substring(0, pckgname.lastIndexOf(File.separator)) .replaceAll("\\" + File.separator, "."); // if (!fileName.matches("(.+)\\$\\d\\.class")) // removes the .class extension classes.add(fileName.substring(0, fileName.length() - 6)); } // Add subdirs if (file.isDirectory()) { directories.add(file); } } } else { throw new ClassNotFoundException( pckgname + " (" + directory.getPath() + ") does not appear to be a valid package"); } } return classes; } public static void copy(InputStream src, File dst) throws IOException { if (src == null) throw new NullPointerException("Source should not be NULL."); if (dst == null) throw new NullPointerException("Dest should not be NULL."); OutputStream out = new FileOutputStream(dst); while (src.available() != 0) { out.write(src.read()); } out.close(); } }