我想在使用Spring RestTemplate访问https的REST API时利用持久化的http连接。然而,我不能使其工作,因为每个请求都会创建一个新的连接并进行SSL握手。 是否可以在RestTemplate中使用可重用的https连接,如果可以,如何配置它?
我设置了一个RestTemplate来进行https请求。这样可以正常工作。 但是我注意到日志中每个请求都会进行一个新的SSL握手。
我在测试中如下设置了RestTemplate:
@Before
public void setupPersistentHttpConnectionBackedRestTemplate() {
final SSLConnectionSocketFactory sslSocketFactory = new SSLConnectionSocketFactory(
sslContext,
new String[] { "TLSv1.2" },
null,
SSLConnectionSocketFactory.getDefaultHostnameVerifier());
final Registry<ConnectionSocketFactory> registry = RegistryBuilder.<ConnectionSocketFactory>create()
.register("https", sslSocketFactory)
.build();
final PoolingHttpClientConnectionManager connectionManager = new PoolingHttpClientConnectionManager(registry);
final CloseableHttpClient httpClient = HttpClients.custom()
.setSSLSocketFactory(sslSocketFactory)
.setConnectionManager(connectionManager)
.build();
final HttpComponentsClientHttpRequestFactory requestFactory = new HttpComponentsClientHttpRequestFactory();
requestFactory.setHttpClient(httpClient);
restTemplate.getRestTemplate().setRequestFactory(requestFactory);
}
然后我使用这个RestTemplate进行多次调用,像这样:
ResponseEntity<String> response = restTemplate.exchange("/tomcat/sleep?millis={millis}", HttpMethod.GET, HttpEntity.EMPTY, String.class, SLEEP_DURATION);
我调查了Spring MVC和Apache的代码,并注意到以下信息。 在Spring RestTemplate的execute方法中,首先创建一个新的请求,然后执行该请求并返回结果。
ClientHttpRequest request = createRequest(url, method);
if (requestCallback != null) {
requestCallback.doWithRequest(request);
}
response = request.execute();
handleResponse(url, method, response);
return (responseExtractor != null ? responseExtractor.extractData(response) : null);
这反过来又会调用HttpComponentsClientHttpRequestFactory,每次都会创建一个新的http context:
@Override
public ClientHttpRequest createRequest(URI uri, HttpMethod httpMethod) throws IOException {
HttpClient client = getHttpClient();
HttpUriRequest httpRequest = createHttpUriRequest(httpMethod, uri);
postProcessHttpRequest(httpRequest);
HttpContext context = createHttpContext(httpMethod, uri);
if (context == null) {
context = HttpClientContext.create();
}
...
在请求执行调用期间跟踪调用链时,我最终会进入Apache MainClientExec。在那里,它尝试基于路由和上下文用户令牌重复使用连接。执行请求后,从上下文中检索用户令牌并存储以供进一步查找。
@Override
public CloseableHttpResponse execute(
final HttpRoute route,
final HttpRequestWrapper request,
final HttpClientContext context,
final HttpExecutionAware execAware) throws IOException, HttpException {
...
Object userToken = context.getUserToken();
final ConnectionRequest connRequest = connManager.requestConnection(route, userToken);
...
if (userToken == null) {
userToken = userTokenHandler.getUserToken(context);
context.setAttribute(HttpClientContext.USER_TOKEN, userToken);
}
if (userToken != null) {
connHolder.setState(userToken);
}
...
在https连接的情况下,用户令牌从SSL主体中检索,而SSL主体则从SSL证书中获取它。
@Override
public Object getUserToken(final HttpContext context) {
...
if (userPrincipal == null) {
final HttpConnection conn = clientContext.getConnection();
if (conn.isOpen() && conn instanceof ManagedHttpClientConnection) {
final SSLSession sslsession = ((ManagedHttpClientConnection) conn).getSSLSession();
if (sslsession != null) {
userPrincipal = sslsession.getLocalPrincipal();
}
}
}
public Principal getLocalPrincipal() {
if (this.cipherSuite.keyExchange != KeyExchange.K_KRB5 && this.cipherSuite.keyExchange != KeyExchange.K_KRB5_EXPORT) {
return this.localCerts == null ? null : this.localCerts[0].getSubjectX500Principal();
} else {
return this.localPrincipal == null ? null : this.localPrincipal;
}
}
PoolingHttpClientConnectionManager旨在基于路由和状态(其中包含用户令牌)尝试返回可重用的连接。
但由于RestTemplate每次都会从头开始进行新的请求,因此用户令牌会丢失,PoolingHttpClientConnectionManager无法找到可重用的连接,因此每次都会创建一个新的连接。
我希望RestTemplate可以创建一个可重用该连接的请求,而不是每次都创建一个新的连接。