Java tutorial
/* Copyright 2016 Arnaud Guyon 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 fr.arnaudguyon.xmltojsonlib; import android.support.annotation.IntRange; import android.support.annotation.NonNull; import android.util.Xml; import org.json.JSONArray; import org.json.JSONException; import org.json.JSONObject; import org.xmlpull.v1.XmlSerializer; import java.io.IOException; import java.io.InputStream; import java.io.StringReader; import java.io.StringWriter; import java.text.DecimalFormat; import java.text.DecimalFormatSymbols; import java.util.HashSet; import java.util.Iterator; import java.util.Locale; import javax.xml.transform.OutputKeys; import javax.xml.transform.Source; import javax.xml.transform.Transformer; import javax.xml.transform.TransformerFactory; import javax.xml.transform.stream.StreamResult; import javax.xml.transform.stream.StreamSource; /** * Converts JSON to XML */ public class JsonToXml { private static final int DEFAULT_INDENTATION = 3; // TODO: Set up Locale in the builder private static final DecimalFormat DECIMAL_FORMAT = new DecimalFormat("0", DecimalFormatSymbols.getInstance(Locale.ENGLISH)); public static class Builder { private JSONObject mJson; private HashSet<String> mForcedAttributes = new HashSet<>(); private HashSet<String> mForcedContent = new HashSet<>(); /** * Constructor * @param jsonObject a JSON object */ public Builder(@NonNull JSONObject jsonObject) { mJson = jsonObject; } /** * Constructor * @param inputStream InputStream containing the JSON */ public Builder(@NonNull InputStream inputStream) { this(FileReader.readFileFromInputStream(inputStream)); } /** * Constructor * @param jsonString String containing the JSON */ public Builder(String jsonString) { try { mJson = new JSONObject(jsonString); } catch (JSONException exception) { exception.printStackTrace(); } } /** * Force a TAG to be an attribute of the parent TAG * @param path Path for the attribute, using format like "/parentTag/childTag/childTagAttribute" * @return the Builder */ public Builder forceAttribute(String path) { mForcedAttributes.add(path); return this; } /** * Force a TAG to be the content of its parent TAG * @param path Path for the content, using format like "/parentTag/contentTag" * @return the Builder */ public Builder forceContent(String path) { mForcedContent.add(path); return this; } /** * Creates the JsonToXml object * @return a JsonToXml instance */ public JsonToXml build() { return new JsonToXml(mJson, mForcedAttributes, mForcedContent); } } private JSONObject mJson; private HashSet<String> mForcedAttributes; private HashSet<String> mForcedContent; private JsonToXml(@NonNull JSONObject jsonObject, @NonNull HashSet<String> forcedAttributes, HashSet<String> forcedContent) { mJson = jsonObject; mForcedAttributes = forcedAttributes; mForcedContent = forcedContent; } /** * * @return the XML */ @Override public String toString() { Node rootNode = new Node(null, ""); prepareObject(rootNode, mJson); return nodeToXML(rootNode); } /** * * @return the formatted XML with a default indent (3 spaces) */ public String toFormattedString() { return toFormattedString(DEFAULT_INDENTATION); } /** * * @param indent size of the indent (number of spaces) * @return the formatted XML */ public String toFormattedString(@IntRange(from = 0) int indent) { String input = toString(); try { Source xmlInput = new StreamSource(new StringReader(input)); StringWriter stringWriter = new StringWriter(); StreamResult xmlOutput = new StreamResult(stringWriter); TransformerFactory transformerFactory = TransformerFactory.newInstance(); Transformer transformer = transformerFactory.newTransformer(); transformer.setOutputProperty(OutputKeys.INDENT, "yes"); transformer.setOutputProperty("{http://xml.apache.org/xslt}indent-amount", "" + indent); transformer.transform(xmlInput, xmlOutput); return xmlOutput.getWriter().toString(); } catch (Exception e) { throw new RuntimeException(e); // TODO: do my own } } private String nodeToXML(Node node) { XmlSerializer serializer = Xml.newSerializer(); StringWriter writer = new StringWriter(); try { serializer.setOutput(writer); serializer.startDocument("UTF-8", true); nodeToXml(serializer, node); serializer.endDocument(); return writer.toString(); } catch (IOException e) { throw new RuntimeException(e); // TODO: do my own } } private void nodeToXml(XmlSerializer serializer, Node node) throws IOException { String nodeName = node.getName(); if (nodeName != null) { serializer.startTag("", nodeName); for (Node.Attribute attribute : node.getAttributes()) { serializer.attribute("", attribute.mKey, attribute.mValue); } String nodeContent = node.getContent(); if (nodeContent != null) { serializer.text(nodeContent); } } for (Node subNode : node.getChildren()) { nodeToXml(serializer, subNode); } if (nodeName != null) { serializer.endTag("", nodeName); } } private void prepareObject(Node node, JSONObject json) { Iterator<String> keyterator = json.keys(); while (keyterator.hasNext()) { String key = keyterator.next(); Object object = json.opt(key); if (object != null) { if (object instanceof JSONObject) { JSONObject subObject = (JSONObject) object; String path = node.getPath() + "/" + key; Node subNode = new Node(key, path); node.addChild(subNode); prepareObject(subNode, subObject); } else if (object instanceof JSONArray) { JSONArray array = (JSONArray) object; prepareArray(node, key, array); } else { String path = node.getPath() + "/" + key; // JSON numbers are represented either Integer or Double (IEEE 754) // Long may be represented in scientific notation because they are stored as Double // This workaround attempts to represent Long and Double objects accordingly String value; if (object instanceof Double) { double d = (double) object; // If it is a Long if (d % 1 == 0) { value = Long.toString((long) d); } else { // TODO: Set up number of decimal digits per attribute in the builder // Set only once. Represent all double numbers up to 20 decimal digits if (DECIMAL_FORMAT.getMaximumFractionDigits() == 0) { DECIMAL_FORMAT.setMaximumFractionDigits(20); } value = DECIMAL_FORMAT.format(d); } } else { // Integer, Boolean and String are handled here value = object.toString(); } if (isAttribute(path)) { node.addAttribute(key, value); } else if (isContent(path)) { node.setContent(value); } else { Node subNode = new Node(key, node.getPath()); subNode.setContent(value); node.addChild(subNode); } } } } } private void prepareArray(Node node, String key, JSONArray array) { int count = array.length(); String path = node.getPath() + "/" + key; for (int i = 0; i < count; ++i) { Node subNode = new Node(key, path); Object object = array.opt(i); if (object != null) { if (object instanceof JSONObject) { JSONObject jsonObject = (JSONObject) object; prepareObject(subNode, jsonObject); } else if (object instanceof JSONArray) { JSONArray subArray = (JSONArray) object; prepareArray(subNode, key, subArray); } else { String value = object.toString(); subNode.setName(key); subNode.setContent(value); } } node.addChild(subNode); } } private boolean isAttribute(String path) { return mForcedAttributes.contains(path); } private boolean isContent(String path) { return mForcedContent.contains(path); } }