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 java.util.logging.*; import java.util.Hashtable; import java.util.Enumeration; import java.util.Vector; import java.util.Properties; import java.io.IOException; import java.io.Writer; /** * This class is lightweight representation of an XML tag as a JSON object. * TODO: Look at using HashMap and collections to store the data instead of sync'ed objects. * TODO: See if the indent/newline handling could be cleaned up. the repeated checks for compact is rather ugly. * TODO: Look at maybe using the Java representation object as store for the XML data intsead of this customized object. */ public class JSONObject { /** * Logger. */ private static String className = "org.apache.commons.json.uils.xml.internal.JSONObject"; private static Logger logger = Logger.getLogger(className, null); private static final String indent = " "; /** * The JSON object name. Effectively, the XML tag name. */ private String objectName = null; /** * All basic JSON object properties. Effectively same as XML tag attributes. */ private Properties attrs = null; /** * All children JSON objects referenced. Effectively the child tags of an XML tag. */ private Hashtable jsonObjects = null; /** * Any XML freeform text to associate with the JSON object, */ private String tagText = null; /** * Constructor. * @param objectName The object (tag) name being constructed. * @param attrs A proprerties object of all the attributes present for the tag. */ public JSONObject(String objectName, Properties attrs) { this.objectName = objectName; this.attrs = attrs; this.jsonObjects = new Hashtable(); } /** * Method to add a JSON child object to this JSON object. * @param obj The child JSON object to add to this JSON object. */ public void addJSONObject(JSONObject obj) { if (logger.isLoggable(Level.FINER)) logger.entering(className, "addJSONObject(JSONObject)"); Vector vect = (Vector) this.jsonObjects.get(obj.objectName); if (vect != null) { vect.add(obj); } else { vect = new Vector(); vect.add(obj); this.jsonObjects.put(obj.objectName, vect); } if (logger.isLoggable(Level.FINER)) logger.exiting(className, "addJSONObject(JSONObject)"); } /** * Method to set any freeform text on the object. * @param str The freeform text to assign to the JSONObject */ public void setTagText(String str) { this.tagText = str; } /** * Method to get any freeform text on the object. */ public String getTagText() { return this.tagText; } /** * Method to write out the JSON formatted object. Same as calling writeObject(writer,indentDepth,contentOnly,false); * @param writer The writer to use when serializing the JSON structure. * @param indentDepth How far to indent the text for object's JSON format. * @param contentOnly Flag to debnnote whether to assign this as an attribute name, or as a nameless object. Commonly used for serializing an array. The Array itself has the name, The contents are all nameless objects * @throws IOException Trhown if an error occurs on write. */ public void writeObject(Writer writer, int indentDepth, boolean contentOnly) throws IOException { if (logger.isLoggable(Level.FINER)) logger.entering(className, "writeObject(Writer, int, boolean)"); writeObject(writer, indentDepth, contentOnly, false); if (logger.isLoggable(Level.FINER)) logger.entering(className, "writeObject(Writer, int, boolean)"); } /** * Method to write out the JSON formatted object. * @param writer The writer to use when serializing the JSON structure. * @param indentDepth How far to indent the text for object's JSON format. * @param contentOnly Flag to debnnote whether to assign this as an attribute name, or as a nameless object. Commonly used for serializing an array. The Array itself has the name, The contents are all nameless objects * @param compact Flag to denote to write the JSON in compact form. No indentions or newlines. Setting this value to true will cause indentDepth to be ignored. * @throws IOException Trhown if an error occurs on write. */ public void writeObject(Writer writer, int indentDepth, boolean contentOnly, boolean compact) throws IOException { if (logger.isLoggable(Level.FINER)) logger.entering(className, "writeObject(Writer, int, boolean, boolean)"); if (writer != null) { try { if (isEmptyObject()) { writeEmptyObject(writer, indentDepth, contentOnly, compact); } else if (isTextOnlyObject()) { writeTextOnlyObject(writer, indentDepth, contentOnly, compact); } else { writeComplexObject(writer, indentDepth, contentOnly, compact); } } catch (Exception ex) { IOException iox = new IOException("Error occurred on serialization of JSON text."); iox.initCause(ex); throw iox; } } else { throw new IOException("The writer cannot be null."); } if (logger.isLoggable(Level.FINER)) logger.entering(className, "writeObject(Writer, int, boolean, boolean)"); } /** * Internal method to write out a proper JSON attribute string. * @param writer The writer to use while serializing * @param name The attribute name to use. * @param value The value to assign to the attribute. * @param depth How far to indent the JSON text. * @param compact Flag to denote whether or not to use pretty indention, or compact format, when writing. * @throws IOException Trhown if an error occurs on write. */ private void writeAttribute(Writer writer, String name, String value, int depth, boolean compact) throws IOException { if (logger.isLoggable(Level.FINER)) logger.entering(className, "writeAttribute(Writer, String, String, int)"); if (!compact) { writeIndention(writer, depth); } try { if (!compact) { writer.write("\"" + name + "\"" + " : " + "\"" + escapeStringSpecialCharacters(value) + "\""); } else { writer.write("\"" + name + "\"" + ":" + "\"" + escapeStringSpecialCharacters(value) + "\""); } } catch (Exception ex) { IOException iox = new IOException("Error occurred on serialization of JSON text."); iox.initCause(ex); throw iox; } if (logger.isLoggable(Level.FINER)) logger.exiting(className, "writeAttribute(Writer, String, String, int)"); } /** * Internal method for doing a simple indention write. * @param writer The writer to use while writing the JSON text. * @param indentDepth How deep to indent the text. * @throws IOException Trhown if an error occurs on write. */ private void writeIndention(Writer writer, int indentDepth) throws IOException { if (logger.isLoggable(Level.FINER)) logger.entering(className, "writeIndention(Writer, int)"); try { for (int i = 0; i < indentDepth; i++) { writer.write(indent); } } catch (Exception ex) { IOException iox = new IOException("Error occurred on serialization of JSON text."); iox.initCause(ex); throw iox; } if (logger.isLoggable(Level.FINER)) logger.exiting(className, "writeIndention(Writer, int)"); } /** * Internal method to write out a proper JSON attribute string. * @param writer The writer to use while serializing * @param attrs The attributes in a properties object to write out * @param depth How far to indent the JSON text. * @param compact Whether or not to use pretty indention output, or compact output, format * @throws IOException Trhown if an error occurs on write. */ private void writeAttributes(Writer writer, Properties attrs, int depth, boolean compact) throws IOException { if (logger.isLoggable(Level.FINER)) logger.entering(className, "writeAttributes(Writer, Properties, int, boolean)"); if (attrs != null) { Enumeration props = attrs.propertyNames(); if (props != null && props.hasMoreElements()) { while (props.hasMoreElements()) { String prop = (String) props.nextElement(); writeAttribute(writer, escapeAttributeNameSpecialCharacters(prop), (String) attrs.get(prop), depth + 1, compact); if (props.hasMoreElements()) { try { if (!compact) { writer.write(",\n"); } else { writer.write(","); } } catch (Exception ex) { IOException iox = new IOException("Error occurred on serialization of JSON text."); iox.initCause(ex); throw iox; } } } } } if (logger.isLoggable(Level.FINER)) logger.exiting(className, "writeAttributes(Writer, Properties, int, boolean)"); } /** * Internal method to escape special attribute name characters, to handle things like name spaces. * @param str The string to escape the characters in. */ private String escapeAttributeNameSpecialCharacters(String str) { if (str != null) { StringBuffer strBuf = new StringBuffer(""); for (int i = 0; i < str.length(); i++) { char strChar = str.charAt(i); switch (strChar) { case ':': { strBuf.append("_ns-sep_"); break; } default: { strBuf.append(strChar); break; } } } str = strBuf.toString(); } return str; } /** * Internal method to escape special attribute name characters, to handle things like name spaces. * @param str The string to escape the characters in. */ private String escapeStringSpecialCharacters(String str) { if (logger.isLoggable(Level.FINER)) logger.exiting(className, "escapeStringSpecialCharacters(String)"); if (str != null) { StringBuffer strBuf = new StringBuffer(""); for (int i = 0; i < str.length(); i++) { char strChar = str.charAt(i); switch (strChar) { case '"': { strBuf.append("\\\""); break; } case '\t': { strBuf.append("\\t"); break; } case '\b': { strBuf.append("\\b"); break; } case '\\': { strBuf.append("\\\\"); break; } case '\f': { strBuf.append("\\f"); break; } case '\r': { strBuf.append("\\r"); break; } case '/': { strBuf.append("\\/"); break; } default: { if ((strChar >= 32) && (strChar <= 126)) { strBuf.append(strChar); } else { strBuf.append("\\u"); StringBuffer sb = new StringBuffer(Integer.toHexString(strChar)); while (sb.length() < 4) { sb.insert(0, '0'); } strBuf.append(sb.toString()); } break; } } } str = strBuf.toString(); } if (logger.isLoggable(Level.FINER)) logger.exiting(className, "escapeStringSpecialCharacters(String)"); return str; } /** * Internal method to write out all children JSON objects attached to this JSON object. * @param writer The writer to use while writing the JSON text. * @param depth The indention depth of the JSON text. * @param compact Flag to denote whether or not to write in nice indent format, or compact format. * @throws IOException Trhown if an error occurs on write. */ private void writeChildren(Writer writer, int depth, boolean compact) throws IOException { if (logger.isLoggable(Level.FINER)) logger.entering(className, "writeChildren(Writer, int, boolean)"); if (!jsonObjects.isEmpty()) { Enumeration keys = jsonObjects.keys(); while (keys.hasMoreElements()) { String objName = (String) keys.nextElement(); Vector vect = (Vector) jsonObjects.get(objName); if (vect != null && !vect.isEmpty()) { /** * Non-array versus array elements. */ if (vect.size() == 1) { if (logger.isLoggable(Level.FINEST)) logger.logp(Level.FINEST, className, "writeChildren(Writer, int, boolean)", "Writing child object: [" + objName + "]"); JSONObject obj = (JSONObject) vect.elementAt(0); obj.writeObject(writer, depth + 1, false, compact); if (keys.hasMoreElements()) { try { if (!compact) { if (!obj.isTextOnlyObject() && !obj.isEmptyObject()) { writeIndention(writer, depth + 1); } writer.write(",\n"); } else { writer.write(","); } } catch (Exception ex) { IOException iox = new IOException("Error occurred on serialization of JSON text."); iox.initCause(ex); throw iox; } } else { if (obj.isTextOnlyObject() && !compact) { writer.write("\n"); } } } else { if (logger.isLoggable(Level.FINEST)) logger.logp(Level.FINEST, className, "writeChildren(Writer, int, boolean)", "Writing array of JSON objects with attribute name: [" + objName + "]"); try { if (!compact) { writeIndention(writer, depth + 1); writer.write("\"" + objName + "\""); writer.write(" : [\n"); } else { writer.write("\"" + objName + "\""); writer.write(":["); } for (int i = 0; i < vect.size(); i++) { JSONObject obj = (JSONObject) vect.elementAt(i); obj.writeObject(writer, depth + 2, true, compact); /** * Still more we haven't handled. */ if (i != (vect.size() - 1)) { if (!compact) { if (!obj.isTextOnlyObject() && !obj.isEmptyObject()) { writeIndention(writer, depth + 2); } writer.write(",\n"); } else { writer.write(","); } } } if (!compact) { writer.write("\n"); writeIndention(writer, depth + 1); } writer.write("]"); if (keys.hasMoreElements()) { writer.write(","); } if (!compact) { writer.write("\n"); } } catch (Exception ex) { IOException iox = new IOException("Error occurred on serialization of JSON text."); iox.initCause(ex); throw iox; } } } } } if (logger.isLoggable(Level.FINER)) logger.exiting(className, "writeChildren(Writer, int, boolean)"); } /** * Method to write an 'empty' XML tag, like <F/> * @param writer The writer object to render the XML to. * @param indentDepth How far to indent. * @param contentOnly Whether or not to write the object name as part of the output * @param compact Flag to denote whether to output in a nice indented format, or in a compact format. * @throws IOException Trhown if an error occurs on write. */ private void writeEmptyObject(Writer writer, int indentDepth, boolean contentOnly, boolean compact) throws IOException { if (logger.isLoggable(Level.FINER)) logger.entering(className, "writeEmptyObject(Writer, int, boolean, boolean)"); if (!contentOnly) { if (!compact) { writeIndention(writer, indentDepth); writer.write("\"" + this.objectName + "\""); writer.write(" : true"); } else { writer.write("\"" + this.objectName + "\""); writer.write(":true"); } } else { if (!compact) { writeIndention(writer, indentDepth); writer.write("true"); } else { writer.write("true"); } } if (logger.isLoggable(Level.FINER)) logger.exiting(className, "writeEmptyObject(Writer, int, boolean, boolean)"); } /** * Method to write a text ony XML tagset, like <F>FOO</F> * @param writer The writer object to render the XML to. * @param indentDepth How far to indent. * @param contentOnly Whether or not to write the object name as part of the output * @param compact Whether or not to write the ohject in compact form, or nice indent form. * @throws IOException Trhown if an error occurs on write. */ private void writeTextOnlyObject(Writer writer, int indentDepth, boolean contentOnly, boolean compact) throws IOException { if (logger.isLoggable(Level.FINER)) logger.entering(className, "writeTextOnlyObject(Writer, int, boolean, boolean)"); if (!contentOnly) { writeAttribute(writer, this.objectName, this.tagText.trim(), indentDepth, compact); } else { if (!compact) { writeIndention(writer, indentDepth); writer.write("\"" + escapeStringSpecialCharacters(this.tagText.trim()) + "\""); } else { writer.write("\"" + escapeStringSpecialCharacters(this.tagText.trim()) + "\""); } } if (logger.isLoggable(Level.FINER)) logger.exiting(className, "writeTextOnlyObject(Writer, int, boolean, boolean)"); } /** * Method to write aa standard attribute/subtag containing object * @param writer The writer object to render the XML to. * @param indentDepth How far to indent. * @param contentOnly Whether or not to write the object name as part of the output * @param compact Flag to denote whether or not to write the object in compact form. * @throws IOException Trhown if an error occurs on write. */ private void writeComplexObject(Writer writer, int indentDepth, boolean contentOnly, boolean compact) throws IOException { if (logger.isLoggable(Level.FINER)) logger.entering(className, "writeComplexObject(Writer, int, boolean, boolean)"); boolean wroteTagText = false; if (!contentOnly) { if (logger.isLoggable(Level.FINEST)) logger.logp(Level.FINEST, className, "writeComplexObject(Writer, int, boolean, boolean)", "Writing object: [" + this.objectName + "]"); if (!compact) { writeIndention(writer, indentDepth); } writer.write("\"" + this.objectName + "\""); if (!compact) { writer.write(" : {\n"); } else { writer.write(":{"); } } else { if (logger.isLoggable(Level.FINEST)) logger.logp(Level.FINEST, className, "writeObject(Writer, int, boolean, boolean)", "Writing object contents as an anonymous object (usually an array entry)"); if (!compact) { writeIndention(writer, indentDepth); writer.write("{\n"); } else { writer.write("{"); } } if (this.tagText != null && !this.tagText.equals("") && !this.tagText.trim().equals("")) { writeAttribute(writer, "content", this.tagText.trim(), indentDepth + 1, compact); wroteTagText = true; } if (this.attrs != null && !this.attrs.isEmpty() && wroteTagText) { if (!compact) { writer.write(",\n"); } else { writer.write(","); } } writeAttributes(writer, this.attrs, indentDepth, compact); if (!this.jsonObjects.isEmpty()) { if (this.attrs != null && (!this.attrs.isEmpty() || wroteTagText)) { if (!compact) { writer.write(",\n"); } else { writer.write(","); } } else { if (!compact) { writer.write("\n"); } } writeChildren(writer, indentDepth, compact); } else { if (!compact) { writer.write("\n"); } } if (!compact) { writeIndention(writer, indentDepth); writer.write("}\n"); //writer.write("\n"); } else { writer.write("}"); } if (logger.isLoggable(Level.FINER)) logger.exiting(className, "writeComplexObject(Writer, int, boolean, boolean)"); } /** * Internal Helper method for determining if this is an empty tag inan XML document, such as <F/> * @return boolean denoting whether or not the object being written contains any attributes, tags, or text. */ private boolean isEmptyObject() { boolean retVal = false; /** * Check for no attributes */ if (this.attrs == null || (this.attrs != null && this.attrs.isEmpty())) { /** * Check for no sub-children */ if (this.jsonObjects.isEmpty()) { /** * Check for no tag text. */ if (this.tagText == null || (this.tagText != null && this.tagText.trim().equals(""))) { retVal = true; } } } return retVal; } /** * Internal Helper method for determining if this is an XML tag which contains only freeform text, like: <F>foo</F> * @return boolean denoting whether or not the object being written is a text-only XML tagset. */ private boolean isTextOnlyObject() { boolean retVal = false; /** * Check for no attributes */ if (this.attrs == null || (this.attrs != null && this.attrs.isEmpty())) { /** * Check for no sub-children */ if (this.jsonObjects.isEmpty()) { /** * Check for tag text contents. */ if (this.tagText != null && !this.tagText.trim().equals("")) { retVal = true; } } } return retVal; } }