/*
* Copyright (c) 2002-2012 Alibaba Group Holding Limited.
* 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.
* 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.alibaba.citrus.service.requestcontext.session.store.cookie.impl;
import static com.alibaba.citrus.util.ArrayUtil.*;
import static com.alibaba.citrus.util.Assert.*;
import static com.alibaba.citrus.util.CollectionUtil.*;
import static com.alibaba.citrus.util.StringUtil.*;
import java.util.List;
import java.util.Map;
import javax.servlet.http.Cookie;
import javax.servlet.http.HttpServletRequest;
import com.alibaba.citrus.service.requestcontext.session.ExactMatchesOnlySessionStore;
import com.alibaba.citrus.service.requestcontext.session.store.cookie.AbstractCookieStore;
import com.alibaba.citrus.service.requestcontext.session.valueencoder.SessionValueEncoder;
import com.alibaba.citrus.service.requestcontext.session.valueencoder.impl.SimpleValueEncoder;
import com.alibaba.citrus.util.ToStringBuilder;
import com.alibaba.citrus.util.ToStringBuilder.MapBuilder;
/**
* 将Session状态保存在cookie中。
* <ul>
* <li>每个store只能保存一个值。</li>
* <li>将仅有的session attribute value用<code>SessionValueEncoder</code>编码成字符串。</li>
* </ul>
*
* @author Michael Zhou
*/
public class SingleValuedCookieStoreImpl extends AbstractCookieStore implements ExactMatchesOnlySessionStore {
private String[] attrNames;
private SessionValueEncoder[] encoders;
public void initAttributeNames(String[] attrNames) {
this.attrNames = attrNames;
assertTrue(attrNames.length <= 1, "Session store %s supports only 1 mapping to attribute name", getName());
}
public void setValueEncoders(SessionValueEncoder[] encoders) {
this.encoders = encoders;
}
@Override
protected void init() throws Exception {
if (isEmptyArray(encoders)) {
encoders = new SessionValueEncoder[] { createDefaultSessionValueEncoder() };
}
}
protected SessionValueEncoder createDefaultSessionValueEncoder() throws Exception {
SimpleValueEncoder simpleValueEncoder = new SimpleValueEncoder();
simpleValueEncoder.afterPropertiesSet();
return simpleValueEncoder;
}
public Iterable<String> getAttributeNames(String sessionID, StoreContext storeContext) {
State state = getState(storeContext);
return state.attributes.keySet();
}
public Object loadAttribute(String attrName, String sessionID, StoreContext storeContext) {
State state = getState(storeContext);
return state.attributes.get(attrName);
}
public void invalidate(String sessionID, StoreContext storeContext) {
State state = getState(storeContext);
if (!isSurvivesInInvalidating()) {
state.attributes.clear();
}
}
public void commit(Map<String, Object> modifiedAttrs, String sessionID, StoreContext storeContext) {
State state = getState(storeContext);
if (state.cookieCommitted) {
return;
}
state.cookieCommitted = true;
String attrName = attrNames[0];
if (modifiedAttrs.containsKey(attrName)) {
Object attrValue = modifiedAttrs.get(attrName);
if (attrValue == null) {
if (log.isDebugEnabled()) {
log.debug("Remove from session: {}", attrName);
}
state.attributes.remove(attrName);
} else {
if (log.isDebugEnabled()) {
log.debug("Set to session: {} = {}", attrName, attrValue);
}
state.attributes.put(attrName, attrValue);
}
}
String cookieState = null;
if (!state.attributes.isEmpty()) {
try {
cookieState = encoders[0].encode(state.attributes.get(attrName), storeContext);
} catch (Exception e) {
log.warn("Failed to encode session state", e);
}
}
cookieState = trimToEmpty(cookieState);
writeCookie(storeContext.getSessionRequestContext().getResponse(), getName(), cookieState);
}
/** 取得cookie store的状态。 */
private State getState(StoreContext storeContext) {
State state = (State) storeContext.getState();
if (state == null) {
state = new State();
storeContext.setState(state);
}
ensureCookieLoading(state, storeContext.getSessionRequestContext().getRequest(), storeContext);
return state;
}
/** 确保cookie被装载。 */
private void ensureCookieLoading(State state, HttpServletRequest request, StoreContext storeContext) {
if (state.cookieLoaded) {
return;
}
state.cookieLoaded = true;
// 读取cookie
state.requestCookieValue = readCookie(request);
// 依次使用所有encoders，试着对cookieValue解码，如果失败，则返回空表
// 如果成功，则返回单值map。
state.attributes = decodeCookieValue(state.requestCookieValue, storeContext);
}
/** 读取cookies。 */
private String readCookie(HttpServletRequest request) {
Cookie[] cookies = request.getCookies();
if (cookies == null) {
cookies = new Cookie[0];
}
// 扫描cookie。
String cookieValue = null;
for (Cookie cookie : cookies) {
String cookieName = cookie.getName();
if (getName().equals(cookieName)) {
cookieValue = cookie.getValue();
if (log.isDebugEnabled()) {
log.debug("[{}] Loading cookie: {}[length={}]={}", new Object[] { getStoreName(), getName(),
cookie.getValue().length(), cookie.getValue() });
}
break;
}
}
return cookieValue;
}
private Map<String, Object> decodeCookieValue(String cookieValue, StoreContext storeContext) {
Map<String, Object> attrs = createHashMap(4);
if (cookieValue == null) {
return attrs; // empty map
}
List<Exception> encoderExceptions = null;
for (SessionValueEncoder encoder : encoders) {
try {
attrs.put(attrNames[0], encoder.decode(cookieValue, storeContext));
log.debug("Succeeded decoding cookieValue using {}", encoder);
break;
} catch (Exception e) {
if (encoderExceptions == null) {
encoderExceptions = createLinkedList();
}
encoderExceptions.add(e);
log.trace("Failure decoding cookieValue using {}: {}", encoder, e.getMessage());
}
}
// 如果失败，记录日志
if (attrs.isEmpty() && encoderExceptions != null) {
if (log.isWarnEnabled()) {
ToStringBuilder buf = new ToStringBuilder();
buf.append("Failed to decode cookie value: ").append(cookieValue);
int i = 0;
for (Exception e : encoderExceptions) {
buf.format("\n Encoder #%d - %s threw %s", i + 1, encoders[i].getClass().getSimpleName(), e);
}
log.warn(buf.toString());
}
} else {
if (log.isDebugEnabled()) {
int attrCount = attrs.size();
ToStringBuilder buf = new ToStringBuilder();
buf.format("Found %d attributes:", attrCount);
if (!attrs.isEmpty()) {
buf.append(new MapBuilder().setPrintCount(true).setSortKeys(true).appendAll(attrs));
}
log.debug(buf.toString());
}
}
return attrs;
}
@Override
protected void toString(MapBuilder mb) {
super.toString(mb);
mb.append("encoders", encoders);
}
/** 存放cookie的状态。 */
private class State {
private boolean cookieLoaded;
private boolean cookieCommitted;
private String requestCookieValue;
private Map<String, Object> attributes;
}
}