org.apache.oodt.commons.util.Utility Maven / Gradle / Ivy
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// Licensed to the Apache Software Foundation (ASF) under one or more contributor
// license agreements. See the NOTICE.txt file distributed with this work for
// additional information regarding copyright ownership. The ASF licenses this
// file to you 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 org.apache.oodt.commons.util;
import java.io.BufferedInputStream;
import java.io.File;
import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;
import java.util.HashSet;
import java.util.Iterator;
import java.util.Properties;
import java.util.StringTokenizer;
/** Miscellaneous utilities.
*
* This class contains various miscellaneous functions as static methods.
*
* @author Kelly
*/
public class Utility {
/** Load properties from a resource.
*
* This loads properties from the given resource (relative to the given class)
* into the given properties object. If any error occurs, this method prints a
* message to stderr but otherwise takes no special action.
*
* You typically use this to merge properties for your application into the
* System properties by calling this method as follows:
*
Utility.loadProperties(System.getProperties(), MyClass.class,
* "MyClass.properties");
This adds the properties from the file
* MyClass.properties (which must exist in the same directory as the
* file MyClass.class, whether in the filesystem or in a jar) into
* the system properties. You can then fetch these properties from anywhere in
* your program with System.getProperty(String),
* Integer.getInteger, etc.
*
* You can also use the method to load properties into a newly created
* properties object that you provide. This keeps your properties separate, but
* then you have to pass a properties object all over the place, and you can't
* take advantage of non-String properties through methods like
* Long#getLong(String), etc.
*
* @param props The properties object to load.
* @param clazz The class used to locate the resource.
* @param resourceName The name of the resource.
*/
public static void loadProperties(Properties props, final Class clazz, final String resourceName) {
BufferedInputStream in = null;
try {
in = new BufferedInputStream(clazz.getResourceAsStream(resourceName));
props.load(in);
} catch (IOException ex) {
System.err.println("I/O exception while loading \"" + resourceName + "\": " + ex.getMessage());
} finally {
if (in != null) try {
in.close();
} catch (IOException ignore) {}
}
}
/** Parse a list.
*
* This yields an iterator created from a list where commas (and optional leading
* and trailing whitespace) separate each element. Each element will occur only
* once in the iterator regardless of how many times it appeared in the string.
*
* @param list The list to parse.
* @return The iterator over unique elements in the list.
*/
public static Iterator parseCommaList(final String list) {
if (list == null) return new Iterator() {
public boolean hasNext() {
return false;
}
public Object next() {
throw new java.util.NoSuchElementException("There weren't ANY elements in this iterator, ever");
}
public void remove() {
throw new UnsupportedOperationException("Can't remove elements from this iterator");
}
};
HashSet set = new HashSet();
StringTokenizer tokens = new StringTokenizer(list, ",");
while (tokens.hasMoreTokens())
set.add(tokens.nextToken().trim());
return set.iterator();
}
/** Asynchronously redirect an input stream onto an output stream.
*
* The output stream is never closed.
*
* @param in Input stream to redirect.
* @param out Where to redirect in.
*/
public static void redirect(final InputStream in, final OutputStream out) {
new Thread() {
public void run() {
try {
byte[] buf = new byte[1024];
for (;;) {
int numRead = in.read(buf);
if (numRead == -1) {
in.close();
break;
}
out.write(buf, 0, numRead);
}
} catch (IOException ex) {
try {
in.close();
} catch (IOException ignore) {}
}
}
}.start();
}
/** Log statistics on memory to stderr.
*
* @param msg Text to include in log.
*/
public static void logMemoryStats(String msg) {
Runtime rt = Runtime.getRuntime();
System.err.println(msg + ": total=" + (rt.totalMemory() / 1024) + "KB, free=" + (rt.freeMemory() / 1024) + "KB");
}
/** Check string s is numeric. Numeric strings include 5.7, -3.9, 14.981E16, etc.
*
* @param s Text to be checked.
* @return True is s is a numeric string.
*/
public static boolean isNumeric(String s) {
try {
Double.parseDouble(s);
} catch (NumberFormatException ex) {
return false;
}
return true;
}
/**
* Delete a file or directory. If file references a directory, it
* recursively deletes all the directory tree.
*
* @param file File, directory, or other filesystem artifact to delete.
* @return True if file was deleted, false otherwise.
*/
public static boolean delete(File file) {
if (file.isDirectory()) {
File[] entries = file.listFiles();
for (int i = 0; i < entries.length; ++i)
if (!delete(entries[i]))
return false;
}
return file.delete();
}
/**
* This method will escape any single quotes found in the input string
* and return the escaped string. This will ready the string for
* insertion into a database. The single quote is escaped by inserting
* an additional single quote in front of it in the string. If some
* considerate developer has already escaped the single quotes in the
* input string, this method will essentially do nothing.
*
* @param inputString The string to be escaped.
* @return The escaped string.
*/
public static String escapeSingleQuote(String inputString) {
int index = inputString.indexOf('\'');
if (index == -1) {
return (inputString);
}
String outputString = inputString;
while (index != -1) {
// If the single quote is the last character in the string or
// the next character is not another single quote, insert a
// single quote in front of the current single quote.
if ((index == (outputString.length() - 1)) || (outputString.charAt(index + 1) != '\'')) {
outputString = outputString.substring(0, index) + "'" + outputString.substring(index);
}
// If we are not at the end of the string, check for another
// single quote.
if ((index + 2) <= (outputString.length() - 1)) {
index = outputString.indexOf('\'', index + 2);
}
else {
index = -1;
}
}
return (outputString);
}
}