原文地址：https://www.jianshu.com/p/17885c1e1c79
Springboot RestTemplate Cookie回话保持功能源码阅读
RestTemplate 配置通过HttpClientBuilder.create()方法初始化配置信息其中Cookie是默认打开的可以通过disableCookieManagement()方法禁用Cookie回话保持功能
/** * Rest client filter * @return */ @Bean(name = "restClient") public RestTemplate getRestClient() { CloseableHttpClient build = HttpClientBuilder.create().disableCookieManagement().useSystemProperties().build(); RestTemplate restClient = new RestTemplate(new HttpComponentsClientHttpRequestFactory(build)); // set message converters List<HttpMessageConverter<?>> messageConverters = new ArrayList<HttpMessageConverter<?>>(); // set string converter messageConverters.add(new StringHttpMessageConverter()); // set json converter messageConverters.add(new MappingJackson2HttpMessageConverter()); // set form converter messageConverters.add(new FormHttpMessageConverter()); restClient.setMessageConverters(messageConverters); // return object return restClient; } HttpClientBuilder部分源码
public CloseableHttpClient build() { b.addAll( new RequestDefaultHeaders(defaultHeaders), new RequestContent(), new RequestTargetHost(), new RequestClientConnControl(), new RequestUserAgent(userAgentCopy), new RequestExpectContinue()); // 禁用Cookie后，RequestAddCookie拦截器将不再处理请求信息 if (!cookieManagementDisabled) { b.add(new RequestAddCookies()); } // 禁用Cookie后，ResponseProcessCookies拦截器将不再处理响应信息 if (!cookieManagementDisabled) { b.add(new ResponseProcessCookies()); } } ResponseProcessCookies源码主要处理Http响应后的Cookie信息，将响应请求头信息中的Set-Cookie，Set-Cookie2保存在CookieStore中。
注：Set-Cookie2此功能已过时。虽然它可能在某些浏览器中仍然有效，但它的使用是不鼓励的，因为它可以在任何时候被删除。尽量避免使用它。过时的Set-Cookie2HTTP 响应标头用于从服务器向用户代理发送 cookie，但已被规范所弃用。Set-Cookie改为使用。
@Contract(threading = ThreadingBehavior.IMMUTABLE) public class ResponseProcessCookies implements HttpResponseInterceptor { private final Log log = LogFactory.getLog(getClass()); public ResponseProcessCookies() { super(); } @Override public void process(final HttpResponse response, final HttpContext context) throws HttpException, IOException { Args.notNull(response, "HTTP request"); Args.notNull(context, "HTTP context"); final HttpClientContext clientContext = HttpClientContext.adapt(context); // Obtain actual CookieSpec instance final CookieSpec cookieSpec = clientContext.getCookieSpec(); if (cookieSpec == null) { this.log.debug("Cookie spec not specified in HTTP context"); return; } // 获取已经存储的Cookie信息 final CookieStore cookieStore = clientContext.getCookieStore(); if (cookieStore == null) { this.log.debug("Cookie store not specified in HTTP context"); return; } // 获取Http请求后响应的Cookie信息 final CookieOrigin cookieOrigin = clientContext.getCookieOrigin(); if (cookieOrigin == null) { this.log.debug("Cookie origin not specified in HTTP context"); return; } // 读取响应的Set-Cookie请求头信息 HeaderIterator it = response.headerIterator(SM.SET_COOKIE); // 将Set-Cookie写入本地 processCookies(it, cookieSpec, cookieOrigin, cookieStore); // 查看cookie规范是否支持cookie版本控制。 if (cookieSpec.getVersion() > 0) { // 读取响应的Set-Cookie2 请求头信息 it = response.headerIterator(SM.SET_COOKIE2); // 将Set-Cookie2写入本地 processCookies(it, cookieSpec, cookieOrigin, cookieStore); } } private void processCookies( final HeaderIterator iterator, final CookieSpec cookieSpec, final CookieOrigin cookieOrigin, final CookieStore cookieStore) { while (iterator.hasNext()) { final Header header = iterator.nextHeader(); try { final List<Cookie> cookies = cookieSpec.parse(header, cookieOrigin); for (final Cookie cookie : cookies) { try { // 检查Host Domain 过期时间等数据，如果数据不符合会抛出MalformedCookieException cookieSpec.validate(cookie, cookieOrigin); // 写入CookieStore中保持 cookieStore.addCookie(cookie); if (this.log.isDebugEnabled()) { this.log.debug("Cookie accepted [" + formatCooke(cookie) + "]"); } } catch (final MalformedCookieException ex) { if (this.log.isWarnEnabled()) { this.log.warn("Cookie rejected [" + formatCooke(cookie) + "] " + ex.getMessage()); } } } } catch (final MalformedCookieException ex) { if (this.log.isWarnEnabled()) { this.log.warn("Invalid cookie header: \"" + header + "\". " + ex.getMessage()); } } } } } RequestAddCookies 源码 1.查找当前Domain下的Cookie信息存储在matchedCookies中 2.检查是否Cookie超时 3.匹配Domain信息，将符合该Domain的Cookie取出存储在matchedCookies中 4.如果有过期Cookie需要清理(超过当前时间的Cookie都清理掉)。5.Header添加Cookie信息(Cookie,Cookie2)
@Contract(threading = ThreadingBehavior.IMMUTABLE) public class RequestAddCookies implements HttpRequestInterceptor { private final Log log = LogFactory.getLog(getClass()); public RequestAddCookies() { super(); } @Override public void process(final HttpRequest request, final HttpContext context) throws HttpException, IOException { Args.notNull(request, "HTTP request"); Args.notNull(context, "HTTP context"); final String method = request.getRequestLine().getMethod(); // 忽略http connect方法 if (method.equalsIgnoreCase("CONNECT")) { return; } final HttpClientContext clientContext = HttpClientContext.adapt(context); // 读取CookieStore中的Cookie信息(在ResponseProcessCookies写入的) final CookieStore cookieStore = clientContext.getCookieStore(); if (cookieStore == null) { this.log.debug("Cookie store not specified in HTTP context"); return; } // Obtain the registry of cookie specs final Lookup<CookieSpecProvider> registry = clientContext.getCookieSpecRegistry(); if (registry == null) { this.log.debug("CookieSpec registry not specified in HTTP context"); return; } // Obtain the target host, possibly virtual (required) final HttpHost targetHost = clientContext.getTargetHost(); if (targetHost == null) { this.log.debug("Target host not set in the context"); return; } // Obtain the route (required) final RouteInfo route = clientContext.getHttpRoute(); if (route == null) { this.log.debug("Connection route not set in the context"); return; } final RequestConfig config = clientContext.getRequestConfig(); String policy = config.getCookieSpec(); if (policy == null) { policy = CookieSpecs.DEFAULT; } if (this.log.isDebugEnabled()) { this.log.debug("CookieSpec selected: " + policy); } URI requestURI = null; if (request instanceof HttpUriRequest) { requestURI = ((HttpUriRequest) request).getURI(); } else { try { requestURI = new URI(request.getRequestLine().getUri()); } catch (final URISyntaxException ignore) { } } final String path = requestURI != null ? requestURI.getPath() : null; final String hostName = targetHost.getHostName(); int port = targetHost.getPort(); if (port < 0) { port = route.getTargetHost().getPort(); } final CookieOrigin cookieOrigin = new CookieOrigin( hostName, port >= 0 ? port : 0, !TextUtils.isEmpty(path) ? path : "/", route.isSecure()); // Get an instance of the selected cookie policy final CookieSpecProvider provider = registry.lookup(policy); if (provider == null) { if (this.log.isDebugEnabled()) { this.log.debug("Unsupported cookie policy: " + policy); } return; } final CookieSpec cookieSpec = provider.create(clientContext); // Get all cookies available in the HTTP state final List<Cookie> cookies = cookieStore.getCookies(); // 查找当前Domain下的Cookie信息存储在matchedCookies中 final List<Cookie> matchedCookies = new ArrayList<Cookie>(); final Date now = new Date(); boolean expired = false; for (final Cookie cookie : cookies) { // 检查是否Cookie超时 if (!cookie.isExpired(now)) { //匹配Domain信息，将符合该Domain的Cookie取出存储在matchedCookies中。 if (cookieSpec.match(cookie, cookieOrigin)) { if (this.log.isDebugEnabled()) { this.log.debug("Cookie " + cookie + " match " + cookieOrigin); } // 存储在matchedCookies matchedCookies.add(cookie); } } else { if (this.log.isDebugEnabled()) { this.log.debug("Cookie " + cookie + " expired"); } //标记Cookie过期 expired = true; } } // 如果有过期Cookie需要清理(超过当前时间的Cookie都清理掉)。 if (expired) { cookieStore.clearExpired(now); } // 如果匹配到Cookie数据 if (!matchedCookies.isEmpty()) { final List<Header> headers = cookieSpec.formatCookies(matchedCookies); // 将Cookie加入Http请求头中 for (final Header header : headers) { // 实际上Header中存储的信息为：（Cookie:TOKEN=8CB982A185805907846DB042C469104；JSESSIONID=282294701B045845915AF1466B84527D） request.addHeader(header); } } final int ver = cookieSpec.getVersion(); if (ver > 0) { // 获取Cookie2的请求信息（Cookie2:TOKEN=8CB982A185805907846DB042C469104；JSESSIONID=282294701B045845915AF1466B84527D） final Header header = cookieSpec.getVersionHeader(); if (header != null) { // 将Cookie2加入Http请求头中 request.addHeader(header); } } // Stick the CookieSpec and CookieOrigin instances to the HTTP context // so they could be obtained by the response interceptor context.setAttribute(HttpClientContext.COOKIE_SPEC, cookieSpec); context.setAttribute(HttpClientContext.COOKIE_ORIGIN, cookieOrigin); } }