Java tutorial
/* * Copyright 2012 LinkedIn Corp. * * Licensed 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 azkaban.webapp.servlet; import java.io.IOException; import java.util.ArrayList; import java.util.HashMap; import java.util.List; import java.util.Map; import javax.servlet.ServletConfig; import javax.servlet.ServletException; import javax.servlet.http.Cookie; import javax.servlet.http.HttpServlet; import javax.servlet.http.HttpServletRequest; import javax.servlet.http.HttpServletResponse; import org.joda.time.DateTime; import org.joda.time.format.DateTimeFormat; import org.joda.time.format.DateTimeFormatter; import azkaban.server.AzkabanServer; import azkaban.server.HttpRequestUtils; import azkaban.server.session.Session; import azkaban.utils.Props; import azkaban.utils.JSONUtils; import azkaban.utils.WebUtils; import azkaban.webapp.AzkabanWebServer; import azkaban.webapp.plugin.PluginRegistry; import azkaban.webapp.plugin.ViewerPlugin; import azkaban.webapp.plugin.TriggerPlugin; /** * Base Servlet for pages */ public abstract class AbstractAzkabanServlet extends HttpServlet { private static final DateTimeFormatter ZONE_FORMATTER = DateTimeFormat.forPattern("z"); private static final String AZKABAN_SUCCESS_MESSAGE = "azkaban.success.message"; private static final String AZKABAN_WARN_MESSAGE = "azkaban.warn.message"; private static final String AZKABAN_FAILURE_MESSAGE = "azkaban.failure.message"; private static final long serialVersionUID = -1; public static final String DEFAULT_LOG_URL_PREFIX = "predefined_log_url_prefix"; public static final String LOG_URL_PREFIX = "log_url_prefix"; public static final String HTML_TYPE = "text/html"; public static final String XML_MIME_TYPE = "application/xhtml+xml"; public static final String JSON_MIME_TYPE = "application/json"; protected static final WebUtils utils = new WebUtils(); private AzkabanServer application; private String name; private String label; private String color; private List<ViewerPlugin> viewerPlugins; private List<TriggerPlugin> triggerPlugins; /** * To retrieve the application for the servlet * * @return */ public AzkabanServer getApplication() { return application; } @Override public void init(ServletConfig config) throws ServletException { application = (AzkabanServer) config.getServletContext() .getAttribute(AzkabanServletContextListener.AZKABAN_SERVLET_CONTEXT_KEY); if (application == null) { throw new IllegalStateException("No batch application is defined in the servlet context!"); } Props props = application.getServerProps(); name = props.getString("azkaban.name", ""); label = props.getString("azkaban.label", ""); color = props.getString("azkaban.color", "#FF0000"); if (application instanceof AzkabanWebServer) { AzkabanWebServer server = (AzkabanWebServer) application; viewerPlugins = PluginRegistry.getRegistry().getViewerPlugins(); triggerPlugins = new ArrayList<TriggerPlugin>(server.getTriggerPlugins().values()); } } /** * Checks for the existance of the parameter in the request * * @param request * @param param * @return */ public boolean hasParam(HttpServletRequest request, String param) { return HttpRequestUtils.hasParam(request, param); } /** * Retrieves the param from the http servlet request. Will throw an exception * if not found * * @param request * @param name * @return * @throws ServletException */ public String getParam(HttpServletRequest request, String name) throws ServletException { return HttpRequestUtils.getParam(request, name); } /** * Retrieves the param from the http servlet request. * * @param request * @param name * @param default * * @return */ public String getParam(HttpServletRequest request, String name, String defaultVal) { return HttpRequestUtils.getParam(request, name, defaultVal); } /** * Returns the param and parses it into an int. Will throw an exception if not * found, or a parse error if the type is incorrect. * * @param request * @param name * @return * @throws ServletException */ public int getIntParam(HttpServletRequest request, String name) throws ServletException { return HttpRequestUtils.getIntParam(request, name); } public int getIntParam(HttpServletRequest request, String name, int defaultVal) { return HttpRequestUtils.getIntParam(request, name, defaultVal); } public long getLongParam(HttpServletRequest request, String name) throws ServletException { return HttpRequestUtils.getLongParam(request, name); } public long getLongParam(HttpServletRequest request, String name, long defaultVal) { return HttpRequestUtils.getLongParam(request, name, defaultVal); } public Map<String, String> getParamGroup(HttpServletRequest request, String groupName) throws ServletException { return HttpRequestUtils.getParamGroup(request, groupName); } /** * Returns the session value of the request. * * @param request * @param key * @param value */ protected void setSessionValue(HttpServletRequest request, String key, Object value) { request.getSession(true).setAttribute(key, value); } /** * Adds a session value to the request * * @param request * @param key * @param value */ @SuppressWarnings({ "unchecked", "rawtypes" }) protected void addSessionValue(HttpServletRequest request, String key, Object value) { List l = (List) request.getSession(true).getAttribute(key); if (l == null) l = new ArrayList(); l.add(value); request.getSession(true).setAttribute(key, l); } /** * Sets an error message in azkaban.failure.message in the cookie. This will * be used by the web client javascript to somehow display the message * * @param response * @param errorMsg */ protected void setErrorMessageInCookie(HttpServletResponse response, String errorMsg) { Cookie cookie = new Cookie(AZKABAN_FAILURE_MESSAGE, errorMsg); cookie.setPath("/"); response.addCookie(cookie); } /** * Sets a warning message in azkaban.warn.message in the cookie. This will * be used by the web client javascript to somehow display the message * * @param response * @param warnMsg */ protected void setWarnMessageInCookie(HttpServletResponse response, String errorMsg) { Cookie cookie = new Cookie(AZKABAN_WARN_MESSAGE, errorMsg); cookie.setPath("/"); response.addCookie(cookie); } /** * Sets a message in azkaban.success.message in the cookie. This will be used * by the web client javascript to somehow display the message * * @param response * @param errorMsg */ protected void setSuccessMessageInCookie(HttpServletResponse response, String message) { Cookie cookie = new Cookie(AZKABAN_SUCCESS_MESSAGE, message); cookie.setPath("/"); response.addCookie(cookie); } /** * Retrieves a success message from a cookie. azkaban.success.message * * @param request * @return */ protected String getSuccessMessageFromCookie(HttpServletRequest request) { Cookie cookie = getCookieByName(request, AZKABAN_SUCCESS_MESSAGE); if (cookie == null) { return null; } return cookie.getValue(); } /** * Retrieves a warn message from a cookie. azkaban.warn.message * * @param request * @return */ protected String getWarnMessageFromCookie(HttpServletRequest request) { Cookie cookie = getCookieByName(request, AZKABAN_WARN_MESSAGE); if (cookie == null) { return null; } return cookie.getValue(); } /** * Retrieves a success message from a cookie. azkaban.failure.message * * @param request * @return */ protected String getErrorMessageFromCookie(HttpServletRequest request) { Cookie cookie = getCookieByName(request, AZKABAN_FAILURE_MESSAGE); if (cookie == null) { return null; } return cookie.getValue(); } /** * Retrieves a cookie by name. Potential issue in performance if a lot of * cookie variables are used. * * @param request * @return */ protected Cookie getCookieByName(HttpServletRequest request, String name) { Cookie[] cookies = request.getCookies(); if (cookies != null) { for (Cookie cookie : cookies) { if (name.equals(cookie.getName())) { return cookie; } } } return null; } /** * Creates a new velocity page to use. With session. * * @param req * @param resp * @param template * @return */ protected Page newPage(HttpServletRequest req, HttpServletResponse resp, Session session, String template) { Page page = new Page(req, resp, application.getVelocityEngine(), template); page.add("azkaban_name", name); page.add("azkaban_label", label); page.add("azkaban_color", color); page.add("utils", utils); page.add("timezone", ZONE_FORMATTER.print(System.currentTimeMillis())); page.add("currentTime", (new DateTime()).getMillis()); if (session != null && session.getUser() != null) { page.add("user_id", session.getUser().getUserId()); } page.add("context", req.getContextPath()); String errorMsg = getErrorMessageFromCookie(req); page.add("error_message", errorMsg == null || errorMsg.isEmpty() ? "null" : errorMsg); setErrorMessageInCookie(resp, null); String warnMsg = getWarnMessageFromCookie(req); page.add("warn_message", warnMsg == null || warnMsg.isEmpty() ? "null" : warnMsg); setWarnMessageInCookie(resp, null); String successMsg = getSuccessMessageFromCookie(req); page.add("success_message", successMsg == null || successMsg.isEmpty() ? "null" : successMsg); setSuccessMessageInCookie(resp, null); // @TODO, allow more than one type of viewer. For time sake, I only install // the first one if (viewerPlugins != null && !viewerPlugins.isEmpty()) { page.add("viewers", viewerPlugins); } if (triggerPlugins != null && !triggerPlugins.isEmpty()) { page.add("triggerPlugins", triggerPlugins); } return page; } /** * Creates a new velocity page to use. * * @param req * @param resp * @param template * @return */ protected Page newPage(HttpServletRequest req, HttpServletResponse resp, String template) { Page page = new Page(req, resp, application.getVelocityEngine(), template); page.add("azkaban_name", name); page.add("azkaban_label", label); page.add("azkaban_color", color); page.add("timezone", ZONE_FORMATTER.print(System.currentTimeMillis())); page.add("currentTime", (new DateTime()).getMillis()); page.add("context", req.getContextPath()); // @TODO, allow more than one type of viewer. For time sake, I only install // the first one if (viewerPlugins != null && !viewerPlugins.isEmpty()) { page.add("viewers", viewerPlugins); ViewerPlugin plugin = viewerPlugins.get(0); page.add("viewerName", plugin.getPluginName()); page.add("viewerPath", plugin.getPluginPath()); } if (triggerPlugins != null && !triggerPlugins.isEmpty()) { page.add("triggers", triggerPlugins); } return page; } /** * Writes json out to the stream. * * @param resp * @param obj * @throws IOException */ protected void writeJSON(HttpServletResponse resp, Object obj) throws IOException { writeJSON(resp, obj, false); } protected void writeJSON(HttpServletResponse resp, Object obj, boolean pretty) throws IOException { resp.setContentType(JSON_MIME_TYPE); JSONUtils.toJSON(obj, resp.getOutputStream(), true); } /** * Retrieve the Azkaban application * * @param config * @return */ public static AzkabanWebServer getApp(ServletConfig config) { AzkabanWebServer app = (AzkabanWebServer) config.getServletContext() .getAttribute(AzkabanServletContextListener.AZKABAN_SERVLET_CONTEXT_KEY); if (app == null) { throw new IllegalStateException("No batch application is defined in the servlet context!"); } else { return app; } } public static String createJsonResponse(String status, String message, String action, Map<String, Object> params) { HashMap<String, Object> response = new HashMap<String, Object>(); response.put("status", status); if (message != null) { response.put("message", message); } if (action != null) { response.put("action", action); } if (params != null) { response.putAll(params); } return JSONUtils.toJSON(response); } }