Java tutorial
/* * Copyright (c) 2014 Michael Berkovich, http://tr8nhub.com All rights reserved. * * Permission is hereby granted, free of charge, to any person obtaining a copy * of this software and associated documentation files (the "Software"), to deal * in the Software without restriction, including without limitation the rights * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell * copies of the Software, and to permit persons to whom the Software is * furnished to do so, subject to the following conditions: * * The above copyright notice and this permission notice shall be included in * all copies or substantial portions of the Software. * * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN * THE SOFTWARE. */ package com.tr8n.core; import java.io.IOException; import java.io.StringWriter; import java.net.MalformedURLException; import java.net.URL; import java.net.URLEncoder; import java.util.ArrayList; import java.util.HashMap; import java.util.Iterator; import java.util.List; import java.util.Map; import java.util.regex.Pattern; import org.json.simple.JSONValue; import org.json.simple.parser.JSONParser; import org.json.simple.parser.ParseException; public class Utils { /** * Checks if the object is an integer or a real number * @param obj * @return */ public static boolean isNumeric(Object obj) { return obj.toString().matches("[+-]?\\d*(\\.\\d+)?"); } /** * Checks if the object is an integer * @param obj * @return */ public static boolean isInteger(Object obj) { return obj.toString().matches("[+-]?\\d*?"); } /** * Parses integer * @param obj * @return */ public static Integer parseInt(Object obj) { return Integer.parseInt("" + obj); } /** * Parses a double * @param obj * @return */ public static Double parseDouble(Object obj) { return Double.parseDouble("" + obj); } /** * Creates a regular expression from a string pattern * @param str * @return */ public static Pattern parsePattern(String str) { String regex = str; if (regex.startsWith("/")) regex = regex.substring(1, regex.length()); if (regex.endsWith("/i")) regex = regex.substring(0, regex.length() - 2); else if (regex.endsWith("/")) regex = regex.substring(0, regex.length() - 1); return Pattern.compile(regex); } /** * Creates a query string out of parameters map * @param params * @return */ public static String buildQueryString(Map<String, Object> params) throws Exception { StringBuilder sb = new StringBuilder(); Iterator<Map.Entry<String, Object>> entries = params.entrySet().iterator(); while (entries.hasNext()) { Map.Entry<String, Object> e = entries.next(); if (sb.length() > 0) { sb.append('&'); } sb.append(URLEncoder.encode((String) e.getKey(), "UTF-8")).append('=') .append(URLEncoder.encode((String) e.getValue(), "UTF-8")); } return sb.toString(); } /** * * @param path * @return * @throws MalformedURLException */ public static URL buildURL(String host, String path, Map<String, Object> params) throws Exception { StringBuilder url = new StringBuilder(); url.append(host); if (!host.endsWith("/") && !path.startsWith("/")) url.append("/"); url.append(path); if (params != null && params.keySet().size() > 0) { url.append("?"); url.append(buildQueryString(params)); } return new URL(url.toString()); } /** * Builds a URL * @param host * @param path * @return * @throws MalformedURLException */ public static URL buildURL(String host, String path) throws Exception { return buildURL(host, path, null); } /** * Builds a map out of parameters * @param data * @return */ public static Map<String, Object> buildMap(Object... data) { HashMap<String, Object> result = new HashMap<String, Object>(); if (data.length % 2 != 0) throw new IllegalArgumentException("Odd number of arguments"); String key = null; Integer step = -1; for (Object value : data) { step++; switch (step % 2) { case 0: if (value == null) throw new IllegalArgumentException("Null key value"); key = (String) value; continue; case 1: result.put(key, value); break; } } return result; } /** * Extends a map * * @param original * @param data * @return */ public static Map<String, Object> extendMap(Map<String, Object> original, Object... data) { Map<String, Object> map = new HashMap<String, Object>(original); map.putAll(buildMap(data)); return map; } /** * Builds a map out of parameters * @param data * @return */ public static Map<String, String> buildStringMap(String... data) { HashMap<String, String> result = new HashMap<String, String>(); if (data.length % 2 != 0) throw new IllegalArgumentException("Odd number of arguments"); String key = null; Integer step = -1; for (String value : data) { step++; switch (step % 2) { case 0: if (value == null) throw new IllegalArgumentException("Null key value"); key = (String) value; continue; case 1: result.put(key, value); break; } } return result; } /** * Builds a list from parameters * @param data * @return */ public static List<Object> buildList(Object... data) { List<Object> result = new ArrayList<Object>(); for (Object value : data) { result.add(value); } return result; } /** * Builds a list of Strings * @param data * @return */ public static List<String> buildStringList(String... data) { List<String> result = new ArrayList<String>(); for (String value : data) { result.add(value); } return result; } /** * Parsing JSON from string * @param jsonText * @return */ public static Object parseJSON(String jsonText) { if (jsonText == null) return null; JSONParser p = new JSONParser(); Object obj = null; try { obj = p.parse(jsonText); } catch (ParseException pe) { Tr8n.getLogger().logException(pe); return null; } return obj; } /** * Builds json from an object * * @param object * @return */ public static String buildJSON(Object object) { if (object == null) return null; StringWriter out = new StringWriter(); try { JSONValue.writeJSONString(object, out); } catch (IOException ex) { Tr8n.getLogger().logException(ex); return null; } return out.toString(); } /** * Trims all values in a list of strings * @param original * @return */ public static List<String> trimListValues(List<String> original) { List<String> trimmedList = new ArrayList<String>(); for (int i = 0; i < original.size(); i++) trimmedList.add((original.get(i).toString()).trim()); return trimmedList; } /** * Returns a value from a nested map using a specific separator * @param map * @param key * @param separator * @return */ @SuppressWarnings("unchecked") public static Object getNestedMapValue(Map<String, Object> map, String key, String separator) { String[] parts = key.split(separator); for (int i = 0; i < parts.length - 1; i++) { String part = parts[i]; Object obj = map.get(part); if (!(obj instanceof Map)) return null; map = (Map<String, Object>) obj; } return map.get(parts[parts.length - 1]); } /** * Returns a value from a nested map using a dot separator * @param map * @param key * @return */ public static Object getNestedMapValue(Map<String, Object> map, String key) { return getNestedMapValue(map, key, "\\."); } /** * * @param map * @param key * @param value * @param separator */ @SuppressWarnings("unchecked") public static void setNestedMapValue(Map<String, Object> map, String key, Object value, String separator) { String[] parts = key.split(separator); for (int i = 0; i < parts.length - 1; i++) { String part = parts[i]; Map<String, Object> child = (Map<String, Object>) map.get(part); if (child == null) { map.put(part, new HashMap<String, Object>()); child = (Map<String, Object>) map.get(part); } map = child; } map.put(parts[parts.length - 1], value); } /** * * @param map * @param key * @param value */ public static void setNestedMapValue(Map<String, Object> map, String key, Object value) { setNestedMapValue(map, key, value, "\\."); } /** * * @param objects * @param joiner * @return */ @SuppressWarnings("rawtypes") public static String join(List objects, String joiner) { return join(objects.toArray(), joiner); } /** * * @param objects * @param joiner * @return */ public static String join(Object[] objects, String joiner) { if (objects.length == 1) return objects[0].toString(); StringBuilder sb = new StringBuilder(); for (int i = 0; i < objects.length; i++) { sb.append(objects[i].toString()); if (i < objects.length - 1) sb.append(joiner); } return sb.toString(); } }