Java tutorial
/* * * Copyright (C) 2015 Dmytro Grygorenko <dmitrygrig@gmail.com> * * This program is free software: you can redistribute it and/or modify * it under the terms of the GNU General Public License as published by * the Free Software Foundation, either version 3 of the License, or * (at your option) any later version. * * This program is distributed in the hope that it will be useful, * but WITHOUT ANY WARRANTY; without even the implied warranty of * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the * GNU General Public License for more details. * * You should have received a copy of the GNU General Public License * along with this program. If not, see <http://www.gnu.org/licenses/>. */ package cloudnet.util; import java.lang.reflect.Array; import java.lang.reflect.Field; import java.util.HashMap; import org.apache.commons.math3.util.FastMath; /** * More info here: http://stackoverflow.com/questions/603013/dumping-a-java-objects-properties * * @author Dmytro Grygorenko <dmitrygrig(at)gmail.com> */ public class Dumper { private static final Dumper instance = new Dumper(); protected static Dumper getInstance() { return instance; } class DumpContext { int maxDepth = 0; int maxArrayElements = 0; int callCount = 0; HashMap<String, String> ignoreList = new HashMap<>(); HashMap<Object, Integer> visited; DumpContext() { this.visited = new HashMap<>(); } } public static String dump(Object o) { return dump(o, 0, 0, null); } public static String dump(Object o, int maxDepth, int maxArrayElements, String[] ignoreList) { DumpContext ctx = Dumper.getInstance().new DumpContext(); ctx.maxDepth = maxDepth; ctx.maxArrayElements = maxArrayElements; if (ignoreList != null) { for (int i = 0; i < Array.getLength(ignoreList); i++) { int colonIdx = ignoreList[i].indexOf(':'); if (colonIdx == -1) { ignoreList[i] = ignoreList[i] + ":"; } ctx.ignoreList.put(ignoreList[i], ignoreList[i]); } } return dump(o, ctx); } /** * * @param o * @param ctx * @return */ protected static String dump(Object o, DumpContext ctx) { if (o == null) { return "<null>"; } ctx.callCount++; StringBuilder tabs = new StringBuilder(); for (int k = 0; k < ctx.callCount; k++) { tabs.append("\t"); } StringBuilder buffer = new StringBuilder(); Class oClass = o.getClass(); String oSimpleName = getSimpleNameWithoutArrayQualifier(oClass); if (ctx.ignoreList.get(oSimpleName + ":") != null) { return "<Ignored>"; } if (oClass.isArray()) { buffer.append("\n"); buffer.append(tabs.toString().substring(1)); buffer.append("[\n"); int rowCount = ctx.maxArrayElements == 0 ? Array.getLength(o) : FastMath.min(ctx.maxArrayElements, Array.getLength(o)); for (int i = 0; i < rowCount; i++) { buffer.append(tabs.toString()); try { Object value = Array.get(o, i); buffer.append(dumpValue(value, ctx)); } catch (Exception e) { buffer.append(e.getMessage()); } if (i < Array.getLength(o) - 1) { buffer.append(","); } buffer.append("\n"); } if (rowCount < Array.getLength(o)) { buffer.append(tabs.toString()); buffer.append(Array.getLength(o) - rowCount + " more array elements..."); buffer.append("\n"); } buffer.append(tabs.toString().substring(1)); buffer.append("]"); } else { buffer.append("\n"); buffer.append(tabs.toString().substring(1)); buffer.append("{\n"); buffer.append(tabs.toString()); buffer.append("hashCode: " + o.hashCode()); buffer.append("\n"); while (oClass != null && oClass != Object.class) { Field[] fields = oClass.getDeclaredFields(); if (ctx.ignoreList.get(oClass.getSimpleName()) == null) { if (oClass != o.getClass()) { buffer.append(tabs.toString().substring(1)); buffer.append(" Inherited from superclass " + oSimpleName + ":\n"); } for (int i = 0; i < fields.length; i++) { String fSimpleName = getSimpleNameWithoutArrayQualifier(fields[i].getType()); String fName = fields[i].getName(); fields[i].setAccessible(true); buffer.append(tabs.toString()); buffer.append(fName + "(" + fSimpleName + ")"); buffer.append("="); if (ctx.ignoreList.get(":" + fName) == null && ctx.ignoreList.get(fSimpleName + ":" + fName) == null && ctx.ignoreList.get(fSimpleName + ":") == null) { try { Object value = fields[i].get(o); buffer.append(dumpValue(value, ctx)); } catch (Exception e) { buffer.append(e.getMessage()); } buffer.append("\n"); } else { buffer.append("<Ignored>"); buffer.append("\n"); } } oClass = oClass.getSuperclass(); oSimpleName = oClass.getSimpleName(); } else { oClass = null; oSimpleName = ""; } } buffer.append(tabs.toString().substring(1)); buffer.append("}"); } ctx.callCount--; return buffer.toString(); } private static String dumpValue(Object value, DumpContext ctx) { if (value == null) { return "<null>"; } if (value.getClass().isPrimitive() || value.getClass() == java.lang.Short.class || value.getClass() == java.lang.Long.class || value.getClass() == java.lang.String.class || value.getClass() == java.lang.Integer.class || value.getClass() == java.lang.Float.class || value.getClass() == java.lang.Byte.class || value.getClass() == java.lang.Character.class || value.getClass() == java.lang.Double.class || value.getClass() == java.lang.Boolean.class || value.getClass() == java.util.Date.class || value.getClass().isEnum()) { return value.toString(); } else { Integer visitedIndex = ctx.visited.get(value); if (visitedIndex == null) { ctx.visited.put(value, ctx.callCount); if (ctx.maxDepth == 0 || ctx.callCount < ctx.maxDepth) { return dump(value, ctx); } else { return "<Reached max recursion depth>"; } } else { return "<Previously visited - see hashCode " + value.hashCode() + ">"; } } } private static String getSimpleNameWithoutArrayQualifier(Class clazz) { String simpleName = clazz.getSimpleName(); int indexOfBracket = simpleName.indexOf('['); if (indexOfBracket != -1) { return simpleName.substring(0, indexOfBracket); } return simpleName; } }