我想通过https访问REST api时,使用Spring RestTemplate使用持久的http连接。我不能使它工作;将为每个请求创建一个新的连接,并且每次都会进行SSL握手。是否可以使用RestTemplate通过https建立可重用的连接,如果可以,如何配置它?
我设置了RestTemplate来通过https发出请求。可以正常工作。但是,我在日志中注意到,每个请求都会发生新的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);
}
然后我像这样使用RestTemplate打了几个电话:
ResponseEntity<String> response = restTemplate.exchange("/tomcat/sleep?millis={millis}", HttpMethod.GET, HttpEntity.EMPTY, String.class, SLEEP_DURATION);
我研究了spring-mvc和apache的代码,并注意以下内容。在Spring RestTemplate execute方法中,创建一个新请求,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);
依次是调用HttpComponentsClientHttpRequestFactory,每次都会在其中创建新的http上下文:
@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遵循调用链时,我最终遇到了Apache MainClientExec。在那里,它尝试根据路由和上下文用户令牌重用连接。执行请求后,将从上下文中检索用户令牌并存储以进行进一步查找。
@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);
}
...
在使用https连接的情况下,将从SSL主体中检索用户令牌,而从SSL证书中检索用户令牌:
@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尝试根据路由和状态(已存储用户令牌的状态)返回可重用的连接。
但是由于RestTemplate每次都以具有新上下文的新请求开始,因此,uset令牌丢失,并且PoolingHttpClientConnectionManager无法找到可重用的连接,因此每次都创建一个新的连接。
我希望RestRemplate可以创建一个重用该连接的请求,而不是每次都创建一个新请求。
@Override
protected HttpContext createHttpContext(HttpMethod httpMethod, URI uri) {
HttpClientContext context = HttpClientContext.create();
context.setUserToken(userToken);
return context;
}