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.hbs.common.josn; import java.io.BufferedReader; import java.io.ByteArrayInputStream; import java.io.IOException; import java.io.InputStream; import java.io.PrintWriter; import java.io.Reader; import java.io.Writer; import java.lang.reflect.Method; import java.util.ArrayList; import java.util.Collection; import java.util.LinkedList; import java.util.List; import java.util.regex.Pattern; import java.util.zip.GZIPOutputStream; import javax.servlet.http.HttpServletRequest; import javax.servlet.http.HttpServletResponse; import org.apache.commons.logging.Log; import org.apache.commons.logging.LogFactory; import com.hbs.common.josn.annotations.SMDMethod; /** * Wrapper for JSONWriter with some utility methods. */ public class JSONUtil { final static String RFC3339_FORMAT = "yyyy-MM-dd HH:mm:ss"; private static final Log log = LogFactory.getLog(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) throws JSONException { JSONWriter writer = new JSONWriter(); writer.setIgnoreHierarchy(ignoreHierarchy); return writer.write(object, excludeProperties, includeProperties); } /** * 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 * @return JSON string * @throws JSONException */ public static String serialize(Object object, Collection<Pattern> excludeProperties, Collection<Pattern> includeProperties, boolean ignoreHierarchy, boolean enumAsBean) throws JSONException { JSONWriter writer = new JSONWriter(); writer.setIgnoreHierarchy(ignoreHierarchy); writer.setEnumAsBean(enumAsBean); return writer.write(object, excludeProperties, includeProperties); } /** * 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) throws IOException, JSONException { writer.write(serialize(object, excludeProperties, includeProperties, true)); } /** * 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 = null; 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(HttpServletResponse response, String encoding, boolean wrapWithComments, String serializedJSON, boolean smd, boolean gzip, String contentType) throws IOException { String json = serializedJSON == null ? "" : serializedJSON; if (wrapWithComments) { StringBuilder sb = new StringBuilder("/* "); sb.append(json); sb.append(" */"); json = sb.toString(); } if (log.isDebugEnabled()) { log.debug("[JSON]" + json); } if (contentType == null) { contentType = "application/json"; } response.setContentType((smd ? "application/json-rpc;charset=" : contentType + ";charset=") + encoding); if (gzip) { response.addHeader("Content-Encoding", "gzip"); GZIPOutputStream out = null; InputStream in = null; try { out = new GZIPOutputStream(response.getOutputStream()); in = new ByteArrayInputStream(json.getBytes()); 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(encoding).length); PrintWriter out = response.getWriter(); out.print(json); } } public static List<String> asList(String commaDelim) { if ((commaDelim == null) || (commaDelim.trim().length() == 0)) return null; List<String> list = new ArrayList<String>(); String[] split = commaDelim.split(","); for (int i = 0; i < split.length; i++) { String trimmed = split[i].trim(); if (trimmed.length() > 0) { list.add(trimmed); } } return list; } /** * 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 * * 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 * * 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. * * 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 */ @SuppressWarnings("unchecked") 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; } static boolean isGzipInRequest(HttpServletRequest request) { String header = request.getHeader("Accept-Encoding"); return header != null && header.indexOf("gzip") >= 0; } }