Java tutorial
/* * Copyright (c) 2005-2010, WSO2 Inc. (http://www.wso2.org) All Rights Reserved. * * WSO2 Inc. 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 org.wso2.carbon.registry.app; import org.apache.commons.logging.Log; import org.apache.commons.logging.LogFactory; import org.wso2.carbon.registry.core.ActionConstants; import org.wso2.carbon.registry.core.Collection; import org.wso2.carbon.registry.core.RegistryConstants; import org.wso2.carbon.registry.core.Resource; import org.wso2.carbon.registry.core.exceptions.RegistryException; import org.wso2.carbon.registry.core.secure.AuthorizationFailedException; import org.wso2.carbon.registry.core.session.CurrentSession; import org.wso2.carbon.registry.core.session.UserRegistry; import org.wso2.carbon.registry.core.utils.AuthorizationUtils; import org.wso2.carbon.registry.core.utils.RegistryUtils; import javax.servlet.ServletOutputStream; import javax.servlet.http.HttpServlet; import javax.servlet.http.HttpServletRequest; import javax.servlet.http.HttpServletResponse; import java.io.IOException; import java.io.InputStream; import java.io.PrintWriter; import java.net.HttpURLConnection; import java.net.URI; import java.net.URISyntaxException; import java.net.URLDecoder; /** * Implementation of a servlet to handle requests having /registry/resource/. This will provide the * raw resource so that it could be accessed as via a valid URL. */ public class ResourceServlet extends HttpServlet { private static final Log log = LogFactory.getLog(ResourceServlet.class); /** * Logic that will be executed for a get request. * * @param request the HTTP Servlet request. * @param response the HTTP Servlet response. * * @throws IOException if an error occurred. */ protected void doGet(HttpServletRequest request, HttpServletResponse response) throws IOException { try { String uri = request.getRequestURI(); int idx = uri.indexOf("resource"); String path = uri.substring(idx + 8); if (path == null) { String msg = "Could not get the resource content. Path is not specified."; log.error(msg); response.setStatus(HttpURLConnection.HTTP_BAD_REQUEST); return; } Resource resource; try { UserRegistry registry = Utils.getRegistry(request); try { path = new URI(path).normalize().toString(); } catch (URISyntaxException e) { log.error("Unable to normalize requested resource path: " + path, e); } String decodedPath = URLDecoder.decode(path, RegistryConstants.DEFAULT_CHARSET_ENCODING); CurrentSession.setUserRealm(registry.getUserRealm()); CurrentSession.setUser(registry.getUserName()); try { if (!AuthorizationUtils.authorize( RegistryUtils.getAbsolutePath(registry.getRegistryContext(), decodedPath), ActionConstants.GET)) { response.setStatus(HttpURLConnection.HTTP_UNAUTHORIZED); response.setHeader("WWW-Authenticate", "Basic realm=\"WSO2-Registry\""); return; } resource = registry.get(decodedPath); } finally { CurrentSession.removeUserRealm(); CurrentSession.removeUser(); } } catch (AuthorizationFailedException e) { log.error(e.getMessage()); response.setStatus(HttpURLConnection.HTTP_UNAUTHORIZED); response.setHeader("WWW-Authenticate", "Basic realm=\"WSO2-Registry\""); return; } catch (RegistryException e) { String msg = "Error retrieving the resource " + path + ". " + e.getMessage(); log.error(msg, e); throw e; } if (resource instanceof Collection) { String msg = "Could not get the resource content. Path " + path + " refers to a collection."; log.error(msg); response.setStatus(HttpURLConnection.HTTP_NOT_IMPLEMENTED); return; } // date based conditional get long ifModifiedSinceValue = request.getDateHeader("If-Modified-Since"); long lastModifiedValue = resource.getLastModified().getTime(); if (ifModifiedSinceValue > 0) { // convert the time values from milliseconds to seconds ifModifiedSinceValue /= 1000; lastModifiedValue /= 1000; /* condition to check we have latest updates in terms of dates */ if (ifModifiedSinceValue >= lastModifiedValue) { /* no need to response with data */ response.setStatus(HttpURLConnection.HTTP_NOT_MODIFIED); return; } } response.setDateHeader("Last-Modified", lastModifiedValue); // eTag based conditional get String ifNonMatchValue = request.getHeader("if-none-match"); String currentETag = Utils.calculateEntityTag(resource); if (ifNonMatchValue != null) { if (ifNonMatchValue.equals(currentETag)) { /* the version is not modified */ response.setStatus(HttpURLConnection.HTTP_NOT_MODIFIED); return; } } response.setHeader("ETag", currentETag); if (resource.getMediaType() != null && resource.getMediaType().length() > 0) { response.setContentType(resource.getMediaType()); } else { response.setHeader("Content-Disposition", "attachment; filename=" + RegistryUtils.getResourceName(path)); response.setContentType("application/download"); } InputStream contentStream = null; if (resource.getContent() != null) { contentStream = resource.getContentStream(); } if (contentStream != null) { try { ServletOutputStream servletOutputStream = response.getOutputStream(); byte[] contentChunk = new byte[RegistryConstants.DEFAULT_BUFFER_SIZE]; int byteCount; while ((byteCount = contentStream.read(contentChunk)) != -1) { servletOutputStream.write(contentChunk, 0, byteCount); } response.flushBuffer(); servletOutputStream.flush(); } finally { contentStream.close(); } } else { Object content = resource.getContent(); if (content != null) { if (content instanceof byte[]) { ServletOutputStream servletOutputStream = response.getOutputStream(); servletOutputStream.write((byte[]) content); response.flushBuffer(); servletOutputStream.flush(); } else { PrintWriter writer = response.getWriter(); writer.write(content.toString()); writer.flush(); } } } resource.discard(); } catch (RegistryException e) { String msg = "Failed to get resource content. " + e.getMessage(); log.error(msg, e); response.setStatus(HttpURLConnection.HTTP_INTERNAL_ERROR); } } }