Java tutorial
/** * Copyright 2016-2017 Amazon.com, Inc. or its affiliates. All Rights Reserved. * * Licensed under the Apache License, Version 2.0 (the "License"). * You may not use this file except in compliance with the License. * A copy of the License is located at * * http://aws.amazon.com/apache2.0 * * or in the "license" file accompanying this file. This file 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.amazonaws.mobileconnectors.pinpoint.analytics; import java.text.DateFormat; import java.text.SimpleDateFormat; import java.util.Locale; import java.util.Scanner; import java.util.TimeZone; import org.apache.commons.logging.Log; import org.apache.commons.logging.LogFactory; import org.json.JSONException; import org.json.JSONObject; import com.amazonaws.mobileconnectors.pinpoint.internal.core.PinpointContext; import com.amazonaws.mobileconnectors.pinpoint.internal.core.util.JSONBuilder; import com.amazonaws.mobileconnectors.pinpoint.internal.core.util.JSONSerializable; import com.amazonaws.mobileconnectors.pinpoint.internal.core.util.StringUtil; import static com.amazonaws.mobileconnectors.pinpoint.internal.core.util.Preconditions.checkNotNull; /** * A Session Object Mostly immutable, with the exception of its stop time. This * session object tracks whether or not it has been paused by checking the * status of it's stop time. A session's stop time is only set when the session * has been paused, and is set to -1 if it is currently running. Can be * serialized and restored for persistence. */ public class Session implements JSONSerializable { // - Session ID configuration constants -------------------------= protected static final String SESSION_ID_DATE_FORMAT = "yyyyMMdd"; protected static final String SESSION_ID_TIME_FORMAT = "HHmmssSSS"; protected static final char SESSION_ID_DELIMITER = '-'; protected static final char SESSION_ID_PAD_CHAR = '_'; protected static final int SESSION_ID_APPKEY_LENGTH = 8; protected static final int SESSION_ID_UNIQID_LENGTH = 8; private static final Log LOGGER = LogFactory.getLog(Session.class); // - JSON/Serialization constants -------------------------------= private static final String JSON_SESSION_ID_ATTR = "session_id"; private static final String JSON_START_TIME_ATTR = "start_time"; private static final String JSON_STOP_TIME_ATTR = "stop_time"; private static final int INDENTATION = 4; // - Field Declarations -----------------------------------------= private final DateFormat sessionIdTimeFormat; private final String sessionID; private final Long startTime; private Long stopTime = null; /** * CONSTRUCTOR - ACTUAL Used by SessionClient * * @param context */ protected Session(final PinpointContext context) { checkNotNull(context, "A valid PinpointContext must be provided!"); this.sessionIdTimeFormat = new SimpleDateFormat( SESSION_ID_DATE_FORMAT + SESSION_ID_DELIMITER + SESSION_ID_TIME_FORMAT, Locale.US); this.sessionIdTimeFormat.setTimeZone(TimeZone.getTimeZone("UTC")); this.startTime = System.currentTimeMillis(); this.stopTime = null; this.sessionID = this.generateSessionID(context); } /** * Used by deserealizer * * @param sessionID * @param startTime * @param stopTime */ protected Session(final String sessionID, final String startTime, final String stopTime) { this.sessionIdTimeFormat = new SimpleDateFormat( SESSION_ID_DATE_FORMAT + SESSION_ID_DELIMITER + SESSION_ID_TIME_FORMAT, Locale.US); this.sessionIdTimeFormat.setTimeZone(TimeZone.getTimeZone("UTC")); Scanner s = new Scanner(startTime); this.startTime = s.nextLong(); s = new Scanner(stopTime); this.stopTime = s.nextLong(); this.sessionID = sessionID; if (this.stopTime == Long.MIN_VALUE) { this.stopTime = null; } } /** * STATIC FACTORY * * @param context The {@link PinpointContext} * @return new Session object */ public static Session newInstance(final PinpointContext context) { return new Session(context); } /** * Re-Generates a session object that has been serialized Returns null if * the input is null * * @param serializedSession - a Session's serialization string. * @return a session object identical to the one that was serialized */ public static Session getSessionFromSerializedSession(final String serializedSession) { Session s = null; if (StringUtil.isBlank(serializedSession)) { return s; } try { final JSONObject json = new JSONObject(serializedSession); final String sessionID = json.getString(JSON_SESSION_ID_ATTR); final String startTime = json.getString(JSON_START_TIME_ATTR); final String stopTime = json.getString(JSON_STOP_TIME_ATTR); s = new Session(sessionID, startTime, stopTime); } catch (final JSONException e) { e.printStackTrace(); } return s; } /** * Session is considered paused if stopTime is not null * * @return true iff session is currently paused */ public boolean isPaused() { return (this.stopTime != null); } /** * Pauses the session object. Generates a stop time. */ public void pause() { if (!isPaused()) { this.stopTime = System.currentTimeMillis(); } } /** * Resumes the session object. Invalidates the stop time. */ public void resume() { this.stopTime = null; } /** * Calculates and returns the session's duration Returns a duration of 0 if * session is not paused or the system clock has been tampered with. * * @return session duration in milliseconds */ public Long getSessionDuration() { Long time = this.stopTime; if (time == null) { time = System.currentTimeMillis(); } if (time < this.startTime) { return 0L; } Long sessionLength = -1L; try { sessionLength = time - this.startTime; } catch (final NumberFormatException e) { LOGGER.error("error parsing session duration", e); } return sessionLength; } /** * Generates Session ID by concatenating present AppKey, UniqueID, and * <AppKey>-<UniqueID>-yyyyMMdd-HHmmssSSS * * @param context The {@link PinpointContext} * @return [String] SessionID */ public String generateSessionID(final PinpointContext context) { final String uniqID = context.getUniqueId(); final String time = this.sessionIdTimeFormat.format(this.startTime); return StringUtil.trimOrPadString(uniqID, SESSION_ID_UNIQID_LENGTH, SESSION_ID_PAD_CHAR) + SESSION_ID_DELIMITER + time; } @Override public JSONObject toJSONObject() { Long stopT = this.stopTime; if (stopT == null) { stopT = Long.MIN_VALUE; } final JSONBuilder builder = new JSONBuilder(this); builder.withAttribute(JSON_SESSION_ID_ATTR, getSessionID()); builder.withAttribute(JSON_START_TIME_ATTR, getStartTime()); builder.withAttribute(JSON_STOP_TIME_ATTR, stopT); return builder.toJSONObject(); } @Override public String toString() { final JSONObject json = toJSONObject(); try { return json.toString(INDENTATION); } catch (final JSONException e) { return json.toString(); } } public String getSessionID() { return this.sessionID; } public long getStartTime() { return this.startTime; } public Long getStopTime() { return this.stopTime; } }