Java tutorial
/******************************************************************************* * Copyright (c) 2010-2014 SAP AG and others. * All rights reserved. This program and the accompanying materials * are made available under the terms of the Eclipse Public License v1.0 * which accompanies this distribution, and is available at * http://www.eclipse.org/legal/epl-v10.html * * Contributors: * SAP AG - initial API and implementation *******************************************************************************/ package org.eclipse.skalli.core.rest; import java.io.IOException; import java.io.Writer; import java.util.Stack; import java.util.UUID; import org.apache.commons.lang.StringUtils; import org.apache.commons.lang.time.DateFormatUtils; import org.apache.commons.lang.time.DurationFormatUtils; import org.eclipse.skalli.commons.CharacterStack; import org.eclipse.skalli.commons.FormatUtils; import org.eclipse.skalli.services.rest.RestWriter; import org.eclipse.skalli.services.rest.RestWriterBase; import org.restlet.data.MediaType; public class XMLRestWriter extends RestWriterBase implements RestWriter { private static final MediaType MEDIA_TYPE = MediaType.TEXT_XML; private static final char STATE_INITIAL = '\u03B1'; private static final char STATE_FINAL = '\u03C9'; private static final char STATE_ARRAY = 'A'; private static final char STATE_OBJECT = 'O'; private static final char STATE_ITEM = 'I'; private static final char EXPECT_OPENING_TAG = '\u03B1'; private static final char OPENING_TAG = '<'; private static final char EXPECT_TEXT_NODE = '#'; private static final char EXPECT_CLOSING_TAG = '\u03C9'; private static final String MILLIS_KEY = "millis"; //$NON-NLS-1$ private static final String ITEM = "item"; //$NON-NLS-1$ private static final String LINK_KEY = "link"; //$NON-NLS-1$ private static final String HREF_KEY = "href"; //$NON-NLS-1$ private static final String REL_KEY = "rel"; //$NON-NLS-1$ private static final String VALUE_KEY = "value"; //$NON-NLS-1$ private static final String VALUE_TAG = '<' + VALUE_KEY + '>'; private static final String VALUE_END_TAG = "</" + VALUE_KEY + '>'; //$NON-NLS-1$ private static final String XML_HEADER = "<?xml version=\"1.0\" encoding=\"UTF-8\" ?>\n"; //$NON-NLS-1$ private static final String XMLNS_PREFIX = "xmlns:"; //$NON-NLS-1$ // stack for state machine private CharacterStack states; // stack for names of nested tags private Stack<String> tags; // the current state private char state; // state that record where we are currently within a // tag, i.e. whether we are in the opening tag, // expect the text node or the begin of a new tag private char tagState; // the name of the tag we are currently in private String tag; // the name to assign to the next tag private String nextKey; // the name to assign to the next tag within an array private String nextItem; public XMLRestWriter(Writer writer, String webLocator) { this(writer, webLocator, 0); } public XMLRestWriter(Writer writer, String webLocator, int options) { super(writer, webLocator, options); states = new CharacterStack(); tags = new Stack<String>(); states.push(state = STATE_INITIAL); tagState = EXPECT_OPENING_TAG; } @Override public MediaType getMediaType() { return MEDIA_TYPE; } @Override public void flush() throws IOException { if (state != STATE_FINAL) { throw new IllegalStateException("Final state not yet reached"); } writer.flush(); } @Override public RestWriter key(String key) { nextKey = StringUtils.isNotBlank(key) ? key : null; return this; } @Override public RestWriter array() throws IOException { return array(null, null); } @Override public RestWriter array(String itemKey) throws IOException { return array(null, itemKey); } @Override public RestWriter array(String key, String itemKey) throws IOException { if (state == STATE_FINAL) { throw new IllegalStateException("Unexpeced array: Final state already reached"); } if (tagState == EXPECT_CLOSING_TAG) { throw new IllegalStateException("Unexpected array after value"); } if (state == STATE_INITIAL) { writer.append(XML_HEADER); } closeOpeningTag(); String tag = key; if (StringUtils.isBlank(tag)) { tag = nextKey; if (StringUtils.isBlank(tag)) { if (state == STATE_ITEM || state == STATE_ARRAY) { tag = nextItem; } } } nextItem = itemKey; if (StringUtils.isBlank(nextItem)) { nextItem = ITEM; } if (StringUtils.isNotBlank(tag)) { writer.append('<').append(tag); tagState = OPENING_TAG; } states.push(state = STATE_ARRAY); tags.push(tag); nextKey = null; return this; } @Override public RestWriter item() throws IOException { if (state == STATE_INITIAL) { throw new IllegalStateException("Still in initial state"); } if (tagState == EXPECT_CLOSING_TAG) { throw new IllegalStateException("Unexpected item after value"); } closeOpeningTag(); if (state != STATE_ITEM) { while (state != STATE_ARRAY) { end(); } if (state == STATE_ARRAY) { states.push(state = STATE_ITEM); tags.push(nextItem); } } return this; } @Override public RestWriter item(String itemKey) throws IOException { nextItem = StringUtils.isNotBlank(itemKey) ? itemKey : null; return item(); } @Override public RestWriter object() throws IOException { return object(null); } @Override public RestWriter object(String key) throws IOException { if (state == STATE_FINAL) { throw new IllegalStateException("Unexpeced object: Final state already reached"); } if (tagState == EXPECT_CLOSING_TAG) { throw new IllegalStateException("Unexpected object after value"); } if (state == STATE_INITIAL) { writer.append(XML_HEADER); } closeOpeningTag(); String tag = key; if (StringUtils.isBlank(tag)) { tag = nextKey; if (StringUtils.isBlank(tag)) { if (state == STATE_ITEM || state == STATE_ARRAY) { tag = nextItem; } } } if (StringUtils.isNotBlank(tag)) { writer.append('<').append(tag); tagState = OPENING_TAG; } states.push(state = STATE_OBJECT); tags.push(tag); nextKey = null; return this; } @Override public RestWriter end() throws IOException { if (state == STATE_FINAL) { throw new IllegalStateException("Final state already reached"); } if (state == STATE_INITIAL) { throw new IllegalStateException("Still in initial state"); } state = states.pop(); tag = tags.pop(); if (state == STATE_INITIAL) { throw new IllegalStateException("Still in initial state"); } if (state == STATE_ARRAY || state == STATE_OBJECT) { closeTag(); } state = states.peek(); if (state == STATE_INITIAL) { state = STATE_FINAL; } if (state == STATE_ARRAY || state == STATE_ITEM) { nextItem = tag; } return this; } @Override public RestWriter links() throws IOException { return array(); } @Override public RestWriter links(String key) throws IOException { return key(key).array(); } @Override public RestWriter link(String rel, String href) throws IOException { return object(LINK_KEY).attribute(REL_KEY, rel).attribute(HREF_KEY, href).end(); } @Override public RestWriter value(String value) throws IOException { if (state == STATE_FINAL) { throw new IllegalStateException("Unexpeced value: Final state already reached"); } boolean isItem = (state == STATE_ITEM || state == STATE_ARRAY) && StringUtils.isNotBlank(nextItem); if (isItem) { closeOpeningTag(); writer.append('<').append(nextItem).append('>'); escaped(value); writer.append('<').append('/').append(nextItem).append('>'); tagState = EXPECT_OPENING_TAG; } else if (state == STATE_OBJECT && tagState != EXPECT_CLOSING_TAG) { closeOpeningTag(); if (tagState == EXPECT_OPENING_TAG) { writer.append(VALUE_TAG); escaped(value); writer.append(VALUE_END_TAG); } else { escaped(value); } tagState = EXPECT_CLOSING_TAG; } else { throw new IllegalStateException("Unexpected value"); } nextKey = null; return this; } @Override public RestWriter value(long l) throws IOException { return value(Long.toString(l)); } @Override public RestWriter value(double d) throws IOException { return value(Double.toString(d)); } @Override public RestWriter value(Number n) throws IOException { return value(n.toString()); } @Override public RestWriter value(boolean b) throws IOException { return value(Boolean.toString(b)); } @Override public RestWriter value(UUID uuid) throws IOException { return value(uuid.toString()); } @Override public RestWriter date(long millis) throws IOException { return value(DateFormatUtils.formatUTC(millis, "yyyy-MM-dd")); //$NON-NLS-1$ } @Override public RestWriter datetime(long millis) throws IOException { return value(FormatUtils.formatUTC(millis)); } @Override public RestWriter duration(long millis) throws IOException { return value(DurationFormatUtils.formatDurationISO(millis)); } @Override public RestWriter href(Object... pathSegments) throws IOException { return value(hrefOf(pathSegments)); } @Override public RestWriter pair(String key, String value) throws IOException { if (state == STATE_FINAL) { throw new IllegalStateException("Unexpeced attribute: Final state already reached"); } if (StringUtils.isBlank(key)) { throw new IllegalStateException("Missing tag name"); } if (state == STATE_OBJECT) { closeOpeningTag(); if (StringUtils.isNotBlank(value) || isSet(ALL_MEMBERS)) { writer.append('<').append(key); if (value != null) { writer.append('>'); escaped(value); writer.append("</").append(key).append('>'); //$NON-NLS-1$ } else { writer.append("/>"); //$NON-NLS-1$ } } } else { throw new IllegalStateException("Unexpected attribute without tag"); } nextKey = null; return this; } @Override public RestWriter pair(String key, long l) throws IOException { return pair(key, Long.toString(l)); } @Override public RestWriter pair(String key, double d) throws IOException { return pair(key, Double.toString(d)); } @Override public RestWriter pair(String key, Number n) throws IOException { return pair(key, n.toString()); } @Override public RestWriter pair(String key, boolean b) throws IOException { return pair(key, Boolean.toString(b)); } @Override public RestWriter pair(String key, UUID uuid) throws IOException { return pair(key, uuid != null ? uuid.toString() : null); } @Override public RestWriter date(String key, long millis) throws IOException { return object(key).pair(MILLIS_KEY, millis).value(DateFormatUtils.formatUTC(millis, "yyyy-MM-dd")); //$NON-NLS-1$ } @Override public RestWriter datetime(String key, long millis) throws IOException { return object(key).pair(MILLIS_KEY, millis).value(FormatUtils.formatUTC(millis)); } @Override public RestWriter duration(String key, long millis) throws IOException { return object(key).pair(MILLIS_KEY, millis).value(DurationFormatUtils.formatDurationISO(millis)); } @Override public RestWriter href(String key, Object... pathSegments) throws IOException { return pair(key, hrefOf(pathSegments)); } @Override public RestWriter attribute(String key, String value) throws IOException { if (state == STATE_FINAL) { throw new IllegalStateException("Unexpeced attribute: Final state already reached"); } if (StringUtils.isBlank(key)) { throw new IllegalStateException("Missing attribute name"); } if (tagState == OPENING_TAG && value != null) { writer.append(' ').append(key).append('='); writer.append('"'); if (value != null) { escaped(value); } writer.append('"'); } else if (tagState == EXPECT_OPENING_TAG) { if (state == STATE_OBJECT) { pair(key, value); } else if (state == STATE_ARRAY || state == STATE_ITEM) { array().attribute(key, value).end(); } } else { throw new IllegalStateException("Unexpected attribute"); } nextKey = null; return this; } @Override public RestWriter attribute(String key, long l) throws IOException { return attribute(key, Long.toString(l)); } @Override public RestWriter attribute(String key, double d) throws IOException { return attribute(key, Double.toString(d)); } @Override public RestWriter attribute(String key, Number n) throws IOException { return attribute(key, n.toString()); } @Override public RestWriter attribute(String key, boolean b) throws IOException { return attribute(key, Boolean.toString(b)); } @Override public RestWriter attribute(String key, UUID uuid) throws IOException { return attribute(key, uuid != null ? uuid.toString() : null); } @Override public RestWriter namespace(String key, String value) throws IOException { attribute(StringUtils.isBlank(key) ? XMLNS_PREFIX : key, value); return this; } private void closeOpeningTag() throws IOException { if (tagState == OPENING_TAG) { writer.append('>'); tagState = EXPECT_TEXT_NODE; } } private void closeTag() throws IOException { if (state == STATE_FINAL) { throw new IllegalStateException("Final state already reached"); } if (state == STATE_INITIAL) { throw new IllegalStateException("Initial state"); } if (tagState == OPENING_TAG) { writer.append("/>"); //$NON-NLS-1$ tagState = EXPECT_OPENING_TAG; } else if (tag != null) { writer.append("</").append(tag).append('>'); //$NON-NLS-1$ tagState = EXPECT_OPENING_TAG; } } @SuppressWarnings("nls") private RestWriter escaped(String s) throws IOException { int len = s.length(); for (int i = 0; i < len; ++i) { char c = s.charAt(i); switch (c) { case '&': writer.append("&"); break; case '<': writer.append("<"); break; case '>': writer.append(">"); break; case '"': writer.append("""); break; case '\'': writer.append("'"); break; default: writer.append(c); } } return this; } }