Java tutorial
/* * 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 org.apache.accumulo.monitor.servlets; import java.io.IOException; import java.util.Collections; import java.util.List; import javax.servlet.http.Cookie; import javax.servlet.http.HttpServletRequest; import javax.servlet.http.HttpServletResponse; import org.apache.accumulo.core.Constants; import org.apache.accumulo.core.zookeeper.ZooUtil; import org.apache.accumulo.monitor.Monitor; import org.apache.accumulo.server.master.state.DeadServerList; import org.apache.accumulo.server.monitor.LogService; import org.apache.accumulo.server.problems.ProblemReports; import org.apache.accumulo.server.problems.ProblemType; import org.apache.commons.httpclient.util.HttpURLConnection; import org.apache.log4j.Logger; public class OperationServlet extends BasicServlet { private static final long serialVersionUID = 1L; @Override protected String getTitle(HttpServletRequest req) { return "Operations"; } @Override public void doGet(HttpServletRequest req, HttpServletResponse resp) throws IOException { // Verify that this is the active Monitor instance if (!isActiveMonitor()) { resp.sendError(HttpURLConnection.HTTP_UNAVAILABLE, STANDBY_MONITOR_MESSAGE); return; } String redir = null; List<Cookie> cookiesToSet = Collections.emptyList(); try { String operation = req.getParameter("action"); redir = req.getParameter("redir"); if (operation != null) { for (Class<?> subclass : OperationServlet.class.getClasses()) { Object t; try { t = subclass.newInstance(); } catch (Exception e) { continue; } if (t instanceof WebOperation) { WebOperation op = (WebOperation) t; if (op.getClass().getSimpleName().equalsIgnoreCase(operation + "Operation")) { cookiesToSet = op.execute(req, log); break; } } } } } catch (Throwable t) { log.error(t, t); } finally { try { for (Cookie c : cookiesToSet) { resp.addCookie(c); } resp.sendRedirect(sanitizeRedirect(redir)); resp.flushBuffer(); } catch (Throwable t) { log.error(t, t); } } } private static String sanitizeRedirect(final String url) { if (url == null || url.isEmpty() || url.contains("\r") || url.contains("\n")) { // prevent HTTP response splitting return "/"; } return url.startsWith("/") ? url : ("/" + url); } private interface WebOperation { List<Cookie> execute(HttpServletRequest req, Logger log) throws Exception; } public static class RefreshOperation implements WebOperation { @Override public List<Cookie> execute(HttpServletRequest req, Logger log) { String value = req.getParameter("value"); return Collections.singletonList( new Cookie("page.refresh.rate", value == null ? "5" : BasicServlet.encode(value))); } } public static class ClearLogOperation implements WebOperation { @Override public List<Cookie> execute(HttpServletRequest req, Logger log) { LogService.getInstance().clear(); return Collections.emptyList(); } } public static class ClearTableProblemsOperation implements WebOperation { @Override public List<Cookie> execute(HttpServletRequest req, Logger log) { String table = req.getParameter("table"); try { ProblemReports.getInstance(Monitor.getContext()).deleteProblemReports(table); } catch (Exception e) { log.error("Failed to delete problem reports for table " + table, e); } return Collections.emptyList(); } } public static class ClearProblemOperation implements WebOperation { @Override public List<Cookie> execute(HttpServletRequest req, Logger log) { String table = req.getParameter("table"); String resource = req.getParameter("resource"); String ptype = req.getParameter("ptype"); try { ProblemReports.getInstance(Monitor.getContext()).deleteProblemReport(table, ProblemType.valueOf(ptype), resource); } catch (Exception e) { log.error("Failed to delete problem reports for table " + table, e); } return Collections.emptyList(); } } public static class SortTableOperation implements WebOperation { @Override public List<Cookie> execute(HttpServletRequest req, Logger log) throws IOException { String page = req.getParameter("page"); String table = req.getParameter("table"); String asc = req.getParameter("asc"); String col = req.getParameter("col"); if (table == null || page == null || (asc == null && col == null)) return Collections.emptyList(); page = BasicServlet.encode(page); table = BasicServlet.encode(table); if (asc == null) { col = BasicServlet.encode(col); return Collections .singletonList(new Cookie("tableSort." + page + "." + table + "." + "sortCol", col)); } else { asc = BasicServlet.encode(asc); return Collections .singletonList(new Cookie("tableSort." + page + "." + table + "." + "sortAsc", asc)); } } } public static class ToggleLegendOperation implements WebOperation { @Override public List<Cookie> execute(HttpServletRequest req, Logger log) throws Exception { String page = req.getParameter("page"); String table = req.getParameter("table"); String show = req.getParameter("show"); if (table == null || page == null || show == null) return Collections.emptyList(); page = BasicServlet.encode(page); table = BasicServlet.encode(table); show = BasicServlet.encode(show); return Collections.singletonList(new Cookie("tableLegend." + page + "." + table + "." + "show", show)); } } public static class ClearDeadServerOperation implements WebOperation { @Override public List<Cookie> execute(HttpServletRequest req, Logger log) { String server = req.getParameter("server"); // a dead server should have a uniq address: a logger or tserver DeadServerList obit = new DeadServerList( ZooUtil.getRoot(Monitor.getContext().getInstance()) + Constants.ZDEADTSERVERS); obit.delete(server); return Collections.emptyList(); } } }