Java tutorial
/* * Licensed to the Apache Software Foundation (ASF) under one * or more contributor license agreements. See the NOTICE 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 com.granule.json.utils.internal; import org.xml.sax.Attributes; import org.xml.sax.SAXException; import org.xml.sax.helpers.DefaultHandler; import java.util.logging.*; import java.util.Stack; import java.util.Properties; import java.io.OutputStream; import java.io.OutputStreamWriter; import java.io.IOException; /** * This class is a SAX entension to do conversion of XML to JSON. */ public class JSONSAXHandler extends DefaultHandler { /** * Logger code */ private static String className = "org.apache.commons.json.utils.xml.transform.impl.JSONSAXHandler"; private static Logger logger = Logger.getLogger(className, null); /** * The writer to stream the JSON text out to. */ private OutputStreamWriter osWriter = null; /** * The current JSON object being constructed from the current TAG being parsed. */ private JSONObject current = null; /** * The stack of the current JSON object position. */ private Stack previousObjects = new Stack(); /** * The toplevel containing JSON object. */ private JSONObject head = null; /** * Whether or not to render the JSON text is a compact or indented format. */ private boolean compact = false; /** * Constructor. * @param os The outputStream to write the resulting JSON to. Same as JSONSAXHander(os,false); * @throws IOException Thrown if an error occurs during streaming out, or XML read. */ public JSONSAXHandler(OutputStream os) throws IOException { if (logger.isLoggable(Level.FINER)) logger.entering(className, "JSONHander(OutputStream) <constructor>"); this.osWriter = new OutputStreamWriter(os, "UTF-8"); this.compact = true; if (logger.isLoggable(Level.FINER)) logger.exiting(className, "JSONHander(OutputStream) <constructor>"); } /** * Constructor. * @param os The outputStream to write the resulting JSON to * @param verbose Whenther or not to render the stream in a verbose (formatted), or compact form. * @throws IOException Thrown if an error occurs during streaming out, or XML read. */ public JSONSAXHandler(OutputStream os, boolean verbose) throws IOException { if (logger.isLoggable(Level.FINER)) logger.entering(className, "JSONHander(OutputStream, boolean) <constructor>"); this.osWriter = new OutputStreamWriter(os, "UTF-8"); this.compact = !verbose; if (logger.isLoggable(Level.FINER)) logger.exiting(className, "JSONHander(OutputStream, boolean) <constructor>"); } /** * This function parses an IFix top level element and all its children. */ public void startElement(String namespaceURI, String localName, String qName, Attributes attrs) throws SAXException { if (logger.isLoggable(Level.FINER)) logger.exiting(className, "startElement(String,String,String,org.xml.sax.Attributes)"); Properties props = new Properties(); int attrLength = attrs.getLength(); for (int i = 0; i < attrLength; i++) { props.put(attrs.getQName(i), attrs.getValue(i)); } JSONObject obj = new JSONObject(localName, props); if (this.head == null) { this.head = obj; this.current = head; } else { if (current != null) { this.previousObjects.push(current); this.current.addJSONObject(obj); } this.current = obj; } if (logger.isLoggable(Level.FINER)) logger.exiting(className, "startElement(String,String,String,org.xml.sax.Attributes)"); } /** * Function ends a tag in this iFix parser. */ public void endElement(String uri, String localName, String qName) throws SAXException { if (logger.isLoggable(Level.FINER)) logger.entering(className, "endElement(String,String,String)"); if (!previousObjects.isEmpty()) { this.current = (JSONObject) this.previousObjects.pop(); } else { this.current = null; } if (logger.isLoggable(Level.FINER)) logger.exiting(className, "endElement(String,String,String)"); } public void characters(char[] ch, int start, int length) throws SAXException { if (logger.isLoggable(Level.FINER)) logger.entering(className, "characters(char[], int, int)"); String str = new String(ch, start, length); if (this.current.getTagText() != null) { str = this.current.getTagText() + str; } this.current.setTagText(str); if (logger.isLoggable(Level.FINER)) logger.exiting(className, "characters(char[], int, int)"); } public void startDocument() throws SAXException { if (logger.isLoggable(Level.FINER)) logger.entering(className, "startDocument()"); startJSON(); if (logger.isLoggable(Level.FINER)) logger.exiting(className, "startDocument()"); } public void endDocument() throws SAXException { if (logger.isLoggable(Level.FINER)) logger.exiting(className, "endDocument()"); endJSON(); if (logger.isLoggable(Level.FINER)) logger.exiting(className, "endDocument()"); } /** * Method to flush out anything remaining in the buffers. */ public void flushBuffer() throws IOException { if (logger.isLoggable(Level.FINER)) logger.entering(className, "flushBuffer()"); if (this.osWriter != null) { this.osWriter.flush(); } if (logger.isLoggable(Level.FINER)) logger.exiting(className, "flushBuffer()"); } /** * Internal method to start JSON generation. */ private void startJSON() throws SAXException { if (logger.isLoggable(Level.FINER)) logger.entering(className, "startJSON()"); this.head = new JSONObject("", null); this.current = head; if (logger.isLoggable(Level.FINER)) logger.exiting(className, "startJSON()"); } /** * Internal method to end the JSON generation and to write out the resultant JSON text * and reset the internal state of the hander. */ private void endJSON() throws SAXException { if (logger.isLoggable(Level.FINER)) logger.entering(className, "endJSON()"); try { this.head.writeObject(this.osWriter, 0, true, this.compact); this.head = null; this.current = null; this.previousObjects.clear(); } catch (Exception ex) { SAXException saxEx = new SAXException(ex); saxEx.initCause(ex); throw saxEx; } if (logger.isLoggable(Level.FINER)) logger.exiting(className, "endJSON()"); } }