Java tutorial
/* * $Id$ * * 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.wxxr.nirvana.json; import com.opensymphony.xwork2.util.TextParseUtil; import com.opensymphony.xwork2.util.WildcardUtil; import com.opensymphony.xwork2.util.logging.Logger; import com.opensymphony.xwork2.util.logging.LoggerFactory; import com.wxxr.nirvana.json.annotations.SMDMethod; import org.apache.commons.lang3.StringUtils; import javax.servlet.http.HttpServletRequest; import javax.servlet.http.HttpServletResponse; import java.io.*; import java.lang.reflect.Method; import java.util.*; import java.util.regex.Pattern; import java.util.zip.GZIPOutputStream; /** * Wrapper for JSONWriter with some utility methods. */ public class JSONUtil { public final static String RFC3339_FORMAT = "yyyy-MM-dd'T'HH:mm:ss"; private static final Logger LOG = LoggerFactory.getLogger(JSONUtil.class); /** * Serializes an object into JSON. * * @param object * to be serialized * @return JSON string * @throws JSONException */ public static String serialize(Object object) throws JSONException { JSONWriter writer = new JSONWriter(); return writer.write(object); } /** * Serializes an object into JSON, excluding any properties matching any of * the regular expressions in the given collection. * * @param object * to be serialized * @param excludeProperties * Patterns matching properties to exclude * @param ignoreHierarchy * whether to ignore properties defined on base classes of the * root object * @return JSON string * @throws JSONException */ public static String serialize(Object object, Collection<Pattern> excludeProperties, Collection<Pattern> includeProperties, boolean ignoreHierarchy, boolean excludeNullProperties) throws JSONException { JSONWriter writer = new JSONWriter(); writer.setIgnoreHierarchy(ignoreHierarchy); return writer.write(object, excludeProperties, includeProperties, excludeNullProperties); } /** * Serializes an object into JSON, excluding any properties matching any of * the regular expressions in the given collection. * * @param object * to be serialized * @param excludeProperties * Patterns matching properties to exclude * @param ignoreHierarchy * whether to ignore properties defined on base classes of the * root object * @param enumAsBean * whether to serialized enums a Bean or name=value pair * @param defaultDateFormat * date format used to serialize dates * @return JSON string * @throws JSONException */ public static String serialize(Object object, Collection<Pattern> excludeProperties, Collection<Pattern> includeProperties, boolean ignoreHierarchy, boolean enumAsBean, boolean excludeNullProperties, String defaultDateFormat) throws JSONException { JSONWriter writer = new JSONWriter(); writer.setIgnoreHierarchy(ignoreHierarchy); writer.setEnumAsBean(enumAsBean); writer.setDateFormatter(defaultDateFormat); return writer.write(object, excludeProperties, includeProperties, excludeNullProperties); } /** * Serializes an object into JSON to the given writer. * * @param writer * Writer to serialize the object to * @param object * object to be serialized * @throws IOException * @throws JSONException */ public static void serialize(Writer writer, Object object) throws IOException, JSONException { writer.write(serialize(object)); } /** * Serializes an object into JSON to the given writer, excluding any * properties matching any of the regular expressions in the given * collection. * * @param writer * Writer to serialize the object to * @param object * object to be serialized * @param excludeProperties * Patterns matching properties to ignore * @throws IOException * @throws JSONException */ public static void serialize(Writer writer, Object object, Collection<Pattern> excludeProperties, Collection<Pattern> includeProperties, boolean excludeNullProperties) throws IOException, JSONException { writer.write(serialize(object, excludeProperties, includeProperties, true, excludeNullProperties)); } /** * Deserializes a object from JSON * * @param json * string in JSON * @return desrialized object * @throws JSONException */ public static Object deserialize(String json) throws JSONException { JSONReader reader = new JSONReader(); return reader.read(json); } /** * Deserializes a object from JSON * * @param reader * Reader to read a JSON string from * @return deserialized object * @throws JSONException * when IOException happens */ public static Object deserialize(Reader reader) throws JSONException { // read content BufferedReader bufferReader = new BufferedReader(reader); String line; StringBuilder buffer = new StringBuilder(); try { while ((line = bufferReader.readLine()) != null) { buffer.append(line); } } catch (IOException e) { throw new JSONException(e); } return deserialize(buffer.toString()); } public static void writeJSONToResponse(SerializationParams serializationParams) throws IOException { StringBuilder stringBuilder = new StringBuilder(); if (StringUtils.isNotBlank(serializationParams.getSerializedJSON())) stringBuilder.append(serializationParams.getSerializedJSON()); if (StringUtils.isNotBlank(serializationParams.getWrapPrefix())) stringBuilder.insert(0, serializationParams.getWrapPrefix()); else if (serializationParams.isWrapWithComments()) { stringBuilder.insert(0, "/* "); stringBuilder.append(" */"); } else if (serializationParams.isPrefix()) stringBuilder.insert(0, "{}&& "); if (StringUtils.isNotBlank(serializationParams.getWrapSuffix())) stringBuilder.append(serializationParams.getWrapSuffix()); String json = stringBuilder.toString(); if (LOG.isDebugEnabled()) { LOG.debug("[JSON]" + json); } HttpServletResponse response = serializationParams.getResponse(); // status or error code if (serializationParams.getStatusCode() > 0) response.setStatus(serializationParams.getStatusCode()); else if (serializationParams.getErrorCode() > 0) response.sendError(serializationParams.getErrorCode()); // content type response.setContentType( serializationParams.getContentType() + ";charset=" + serializationParams.getEncoding()); if (serializationParams.isNoCache()) { response.setHeader("Cache-Control", "no-cache"); response.setHeader("Expires", "0"); response.setHeader("Pragma", "No-cache"); } if (serializationParams.isGzip()) { response.addHeader("Content-Encoding", "gzip"); GZIPOutputStream out = null; InputStream in = null; try { out = new GZIPOutputStream(response.getOutputStream()); in = new ByteArrayInputStream(json.getBytes(serializationParams.getEncoding())); byte[] buf = new byte[1024]; int len; while ((len = in.read(buf)) > 0) { out.write(buf, 0, len); } } finally { if (in != null) in.close(); if (out != null) { out.finish(); out.close(); } } } else { response.setContentLength(json.getBytes(serializationParams.getEncoding()).length); PrintWriter out = response.getWriter(); out.print(json); } } public static Set<String> asSet(String commaDelim) { if ((commaDelim == null) || (commaDelim.trim().length() == 0)) return null; return TextParseUtil.commaDelimitedStringToSet(commaDelim); } /** * List visible methods carrying the * * @SMDMethod annotation * * @param ignoreInterfaces * if true, only the methods of the class are examined. If false, * annotations on every interfaces' methods are examined. */ @SuppressWarnings("unchecked") public static Method[] listSMDMethods(Class clazz, boolean ignoreInterfaces) { final List<Method> methods = new LinkedList<Method>(); if (ignoreInterfaces) { for (Method method : clazz.getMethods()) { SMDMethod smdMethodAnnotation = method.getAnnotation(SMDMethod.class); if (smdMethodAnnotation != null) { methods.add(method); } } } else { // recurse the entire superclass/interface hierarchy and add in // order encountered JSONUtil.visitInterfaces(clazz, new JSONUtil.ClassVisitor() { public boolean visit(Class aClass) { for (Method method : aClass.getMethods()) { SMDMethod smdMethodAnnotation = method.getAnnotation(SMDMethod.class); if ((smdMethodAnnotation != null) && !methods.contains(method)) { methods.add(method); } } return true; } }); } Method[] methodResult = new Method[methods.size()]; return methods.toArray(methodResult); } /** * Realizes the visit(Class) method called by vistInterfaces for all * encountered classes/interfaces */ public static interface ClassVisitor { /** * Called when a new interface/class is encountered * * @param aClass * the encountered class/interface * @return true if the recursion should continue, false to stop * recursion immediately */ @SuppressWarnings("unchecked") boolean visit(Class aClass); } /** * Visit all the interfaces realized by the specified object, its * superclasses and its interfaces <p/> Visitation is performed in the * following order: aClass aClass' interfaces the interface's superclasses * (interfaces) aClass' superclass superclass' interfaces superclass' * interface's superclasses (interfaces) super-superclass and so on <p/> The * Object base class is base excluded. Classes/interfaces are only visited * once each * * @param aClass * the class to start recursing upwards from * @param visitor * this vistor is called for each class/interface encountered * @return true if all classes/interfaces were visited, false if it was * exited early as specified by a ClassVisitor result */ @SuppressWarnings("unchecked") public static boolean visitInterfaces(Class aClass, ClassVisitor visitor) { List<Class> classesVisited = new LinkedList<Class>(); return visitUniqueInterfaces(aClass, visitor, classesVisited); } /** * Recursive method to visit all the interfaces of a class (and its * superclasses and super-interfaces) if they haven't already been visited. * <p/> Always visits itself if it hasn't already been visited * * @param thisClass * the current class to visit (if not already done so) * @param classesVisited * classes already visited * @param visitor * this vistor is called for each class/interface encountered * @return true if recursion can continue, false if it should be aborted */ private static boolean visitUniqueInterfaces(Class thisClass, ClassVisitor visitor, List<Class> classesVisited) { boolean okayToContinue = true; if (!classesVisited.contains(thisClass)) { classesVisited.add(thisClass); okayToContinue = visitor.visit(thisClass); if (okayToContinue) { Class[] interfaces = thisClass.getInterfaces(); int index = 0; while ((index < interfaces.length) && (okayToContinue)) { okayToContinue = visitUniqueInterfaces(interfaces[index++], visitor, classesVisited); } if (okayToContinue) { Class superClass = thisClass.getSuperclass(); if ((superClass != null) && (!Object.class.equals(superClass))) { okayToContinue = visitUniqueInterfaces(superClass, visitor, classesVisited); } } } } return okayToContinue; } public static boolean isGzipInRequest(HttpServletRequest request) { String header = request.getHeader("Accept-Encoding"); return (header != null) && (header.indexOf("gzip") >= 0); } public static final String REGEXP_PATTERN = "regexp"; public static final String WILDCARD_PATTERN = "wildcard"; /* package */ static final String SPLIT_PATTERN = "split"; /* package */ static final String JOIN_STRING = "join"; /* package */ static final String ARRAY_BEGIN_STRING = "array-begin"; /* package */ static final String ARRAY_END_STRING = "array-end"; /* package */ static Map<String, Map<String, String>> getIncludePatternData() { Map<String, Map<String, String>> includePatternData = new HashMap<String, Map<String, String>>(); Map<String, String> data = new HashMap<String, String>(); data.put(REGEXP_PATTERN, "\\\\\\."); data.put(WILDCARD_PATTERN, "\\."); includePatternData.put(SPLIT_PATTERN, data); data = new HashMap<String, String>(); data.put(REGEXP_PATTERN, "\\."); data.put(WILDCARD_PATTERN, "."); includePatternData.put(JOIN_STRING, data); data = new HashMap<String, String>(); data.put(REGEXP_PATTERN, "\\["); data.put(WILDCARD_PATTERN, "["); includePatternData.put(ARRAY_BEGIN_STRING, data); data = new HashMap<String, String>(); data.put(REGEXP_PATTERN, "\\]"); data.put(WILDCARD_PATTERN, "]"); includePatternData.put(ARRAY_END_STRING, data); return includePatternData; } private static final Map<String, Map<String, String>> defaultIncludePatternData = getIncludePatternData(); public static List<Pattern> processIncludePatterns(Set<String> includePatterns, String type) { return processIncludePatterns(includePatterns, type, defaultIncludePatternData); } /* package */ static List<Pattern> processIncludePatterns(Set<String> includePatterns, String type, Map<String, Map<String, String>> includePatternData) { if (includePatterns != null) { List<Pattern> results = new ArrayList<Pattern>(includePatterns.size()); Map<String, String> existingPatterns = new HashMap<String, String>(); for (String pattern : includePatterns) { processPattern(results, existingPatterns, pattern, type, includePatternData); } return results; } else { return null; } } private static void processPattern(List<Pattern> results, Map<String, String> existingPatterns, String pattern, String type, Map<String, Map<String, String>> includePatternData) { // Compile a pattern for each *unique* "level" of the object // hierarchy specified in the regex. String[] patternPieces = pattern.split(includePatternData.get(SPLIT_PATTERN).get(type)); String patternExpr = ""; for (String patternPiece : patternPieces) { patternExpr = processPatternPiece(results, existingPatterns, patternExpr, patternPiece, type, includePatternData); } } private static String processPatternPiece(List<Pattern> results, Map<String, String> existingPatterns, String patternExpr, String patternPiece, String type, Map<String, Map<String, String>> includePatternData) { if (patternExpr.length() > 0) { patternExpr += includePatternData.get(JOIN_STRING).get(type); } patternExpr += patternPiece; // Check for duplicate patterns so that there is no overlap. if (!existingPatterns.containsKey(patternExpr)) { existingPatterns.put(patternExpr, patternExpr); if (isIndexedProperty(patternPiece, type, includePatternData)) { addPattern(results, patternExpr.substring(0, patternExpr.lastIndexOf(includePatternData.get(ARRAY_BEGIN_STRING).get(type))), type); } addPattern(results, patternExpr, type); } return patternExpr; } /** * Add a pattern that does not have the indexed property matching (ie. list\[\d+\] becomes list). */ private static boolean isIndexedProperty(String patternPiece, String type, Map<String, Map<String, String>> includePatternData) { return patternPiece.endsWith(includePatternData.get(ARRAY_END_STRING).get(type)); } private static void addPattern(List<Pattern> results, String pattern, String type) { results.add(REGEXP_PATTERN.equals(type) ? Pattern.compile(pattern) : WildcardUtil.compileWildcardPattern(pattern)); if (LOG.isTraceEnabled()) { LOG.trace("Adding include " + (REGEXP_PATTERN.equals(type) ? "property" : "wildcard") + " expression: " + pattern); } } }