liferay过滤器（二）
liferay的过滤器基本上都可以在portal-ext.properties文件里面进行设置是否使用(true or false)
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1、GZipFilter过滤器
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主要代码：
if (isCompress(request) && !isInclude(request) &&
???BrowserSnifferUtil.acceptsGzip(request) &&
???!isAlreadyFiltered(request)) {
???if (_log.isDebugEnabled()) {
????String completeURL = HttpUtil.getCompleteURL(request);
????_log.debug("Compressing " + completeURL);
???}
???request.setAttribute(SKIP_FILTER, Boolean.TRUE);
???GZipResponse gZipResponse = new GZipResponse(response);
???processFilter(GZipFilter.class, request, gZipResponse, filterChain);
???gZipResponse.finishResponse();
??}
??else {
???if (_log.isDebugEnabled()) {
????String completeURL = HttpUtil.getCompleteURL(request);
????_log.debug("Not compressing " + completeURL);
???}
???processFilter(
????GZipFilter.class, request, response, filterChain);
??}
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主要功能：截获输出进行处理，写入到真正的HttpServletResponse中（在源代码中没有找到处理的代码，压缩处理代码参看：http://blog.csdn.net/hongweigg/article/details/6197445）
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2、Header Filter过滤器
主要代码：
Enumeration<String> enu = _filterConfig.getInitParameterNames();
??while (enu.hasMoreElements()) {
???String name = enu.nextElement();
???if (name.equals(_URL_REGEX_PATTERN)) {
????continue;
???}
???String value = _filterConfig.getInitParameter(name);
???if (name.equals(_EXPIRES) && Validator.isNumber(value)) {
????int seconds = GetterUtil.getInteger(value);
????Calendar cal = new GregorianCalendar();
????cal.add(Calendar.SECOND, seconds);
????value = _dateFormat.format(cal.getTime());
???}
???// LEP-5895
???boolean addHeader = true;
???if (name.equalsIgnoreCase(HttpHeaders.CACHE_CONTROL)) {
????HttpSession session = request.getSession(false);
????if ((session == null) || session.isNew()) {
?????addHeader = false;
????}
???}
???if (addHeader) {
????response.addHeader(name, value);
???}
??}
??long lastModified = getLastModified(request);
??long ifModifiedSince = request.getDateHeader(
???HttpHeaders.IF_MODIFIED_SINCE);
??if (lastModified > 0) {
???response.setDateHeader(HttpHeaders.LAST_MODIFIED, lastModified);
???if (lastModified <= ifModifiedSince) {
????response.setDateHeader(
?????HttpHeaders.LAST_MODIFIED, ifModifiedSince);
????response.setStatus(HttpServletResponse.SC_NOT_MODIFIED);
????return;
???}
??}
功能：添加页面过期时间的参数，根据filter config属性文件中的Expires
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3、I18n 过滤器
主要代码：
String contextPath = PortalUtil.getPathContext();
??String requestURI = request.getRequestURI();
??if ((Validator.isNotNull(contextPath)) &&
???(requestURI.indexOf(contextPath) != -1)) {
???requestURI = requestURI.substring(contextPath.length());
??}
??requestURI = StringUtil.replace(
???requestURI, StringPool.DOUBLE_SLASH, StringPool.SLASH);
??String i18nLanguageId = requestURI.substring(1);
??int pos = requestURI.indexOf(StringPool.SLASH, 1);
??if (pos != -1) {
???i18nLanguageId = i18nLanguageId.substring(0, pos - 1);
??}
??if (_languageIds.contains(i18nLanguageId)) {
???return null;
??}
??String defaultLanguageId = LocaleUtil.toLanguageId(
???LocaleUtil.getDefault());
??String guestLanguageId = CookieKeys.getCookie(
???request, CookieKeys.GUEST_LANGUAGE_ID);
??if (Validator.isNull(guestLanguageId)) {
???guestLanguageId = defaultLanguageId;
??}
??if (PropsValues.LOCALE_PREPEND_FRIENDLY_URL_STYLE == 1) {
???if (!defaultLanguageId.equals(guestLanguageId)) {
????i18nLanguageId = guestLanguageId;
???}
???else {
????return null;
???}
??}
??else if (PropsValues.LOCALE_PREPEND_FRIENDLY_URL_STYLE == 2) {
???i18nLanguageId = guestLanguageId;
??}
??if (i18nLanguageId == null) {
???return null;
??}
??String i18nPath = StringPool.SLASH + i18nLanguageId;
??Locale locale = LocaleUtil.fromLanguageId(i18nLanguageId);
??if (!LanguageUtil.isDuplicateLanguageCode(locale.getLanguage())) {
???i18nPath = StringPool.SLASH + locale.getLanguage();
??}
??else {
???Locale priorityLocale = LanguageUtil.getLocale(
????locale.getLanguage());
???if (locale.equals(priorityLocale)) {
????i18nPath = StringPool.SLASH + locale.getLanguage();
???}
??}
??String redirect = contextPath + i18nPath + requestURI;
??LayoutSet layoutSet = (LayoutSet)request.getAttribute(
???WebKeys.VIRTUAL_HOST_LAYOUT_SET);
??if ((layoutSet != null) &&
???(requestURI.startsWith(_PRIVATE_GROUP_SERVLET_MAPPING) ||
??? requestURI.startsWith(_PRIVATE_USER_SERVLET_MAPPING) ||
??? requestURI.startsWith(_PUBLIC_GROUP_SERVLET_MAPPING))) {
???int x = requestURI.indexOf(StringPool.SLASH, 1);
???if (x == -1) {
????// /web
????requestURI += StringPool.SLASH;
????x = requestURI.indexOf(StringPool.SLASH, 1);
???}
???int y = requestURI.indexOf(StringPool.SLASH, x + 1);
???if (y == -1) {
????// /web/alpha
????requestURI += StringPool.SLASH;
????y = requestURI.indexOf(StringPool.SLASH, x + 1);
???}
???String groupFriendlyURL = requestURI.substring(x, y);
???Group group = layoutSet.getGroup();
???if (group.getFriendlyURL().equals(groupFriendlyURL)) {
????redirect = contextPath + i18nPath + requestURI.substring(y);
???}
??}
??String queryString = request.getQueryString();
??if (Validator.isNotNull(queryString)) {
???redirect += StringPool.QUESTION + request.getQueryString();
??}
??return redirect;
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主要功能：重新组装重定向URL(设置语言的ID)。
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4、Language过滤器
主要代码：
HttpServletRequest request, StringServletResponse stringResponse) {
??String languageId = LanguageUtil.getLanguageId(request);
??Locale locale = LocaleUtil.fromLanguageId(languageId);
??String content = stringResponse.getString();
??StringBundler sb = new StringBundler();
??Matcher matcher = _pattern.matcher(content);
??int x = 0;
??while (matcher.find()) {
???int y = matcher.start(0);
???String key = matcher.group(1);
???sb.append(content.substring(x, y));
???sb.append(StringPool.APOSTROPHE);
???String value = null;
???if (_portletConfig != null) {
????value = UnicodeLanguageUtil.get(_portletConfig, locale, key);
???}
???else {
????value = UnicodeLanguageUtil.get(locale, key);
???}
???sb.append(value);
???sb.append(StringPool.APOSTROPHE);
???x = matcher.end(0);
??}
??sb.append(content.substring(x));
??return sb.toString();
功能：取得语言的id，根据id设置语言name，写到response中
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5、Minifier过滤器
主要代码：
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