1. 概述
在本教程中，我们将说明Apache HttpAsyncClient的最常见用例-从基本用法到如何设置代理、如何使用SSL证书以及最后如何使用异步客户端进行身份验证。
2. 简单示例
首先，让我们看看如何在一个简单的示例中使用HttpAsyncClient发送一个GET请求：
@Test
void whenUseHttpAsyncClient_thenCorrect() throws InterruptedException, ExecutionException, IOException {
final SimpleHttpRequest request = SimpleRequestBuilder.get(HOST_WITH_COOKIE)
.build();
final CloseableHttpAsyncClient client = HttpAsyncClients.custom()
.build();
client.start();
final Future<SimpleHttpResponse> future = client.execute(request, null);
final HttpResponse response = future.get();
assertThat(response.getCode(), equalTo(200));
client.close();
}
请注意，我们需要在使用异步客户端之前启动它；否则，我们将得到以下异常：
java.lang.IllegalStateException: Request cannot be executed; I/O reactor status: INACTIVE
at o.a.h.u.Asserts.check(Asserts.java:46)
at o.a.h.i.n.c.CloseableHttpAsyncClientBase.
ensureRunning(CloseableHttpAsyncClientBase.java:90)
3. 使用HttpAsyncClient实现多线程
现在让我们看看如何使用HttpAsyncClient同时执行多个请求。
在以下示例中，我们使用HttpAsyncClient向3个不同的主机发送3个GET请求。
3.1 对于HttpAsyncClient 5.x
@Test
void whenUseMultipleHttpAsyncClient_thenCorrect() throws Exception {
final IOReactorConfig ioReactorConfig = IOReactorConfig
.custom()
.build();
final CloseableHttpAsyncClient client = HttpAsyncClients.custom()
.setIOReactorConfig(ioReactorConfig)
.build();
client.start();
final String[] toGet = { "http://www.google.com/", "http://www.apache.org/", "http://www.bing.com/" };
final GetThread[] threads = new GetThread[toGet.length];
for (int i = 0; i < threads.length; i++) {
final HttpGet request = new HttpGet(toGet[i]);
threads[i] = new GetThread(client, request);
}
for (final GetThread thread : threads) {
thread.start();
}
for (final GetThread thread : threads) {
thread.join();
}
}
下面是我们处理响应的GetThread实现：
static class GetThread extends Thread {
private final CloseableHttpAsyncClient client;
private final HttpContext context;
private final HttpGet request;
GetThread(final CloseableHttpAsyncClient client, final HttpGet request) {
this.client = client;
context = HttpClientContext.create();
this.request = request;
}
@Override
public void run() {
try {
final Future<HttpResponse> future = client.execute(request, context, null);
final HttpResponse response = future.get();
assertThat(response.getStatusLine().getStatusCode(), equalTo(200));
} catch (final Exception ex) {
System.out.println(ex.getLocalizedMessage());
}
}
}
3.2 对于HttpAsyncClient4.5
@Test
void whenUseMultipleHttpAsyncClient_thenCorrect() throws Exception {
final ConnectingIOReactor ioReactor = new DefaultConnectingIOReactor();
final PoolingNHttpClientConnectionManager cm = new PoolingNHttpClientConnectionManager(ioReactor);
final CloseableHttpAsyncClient client = HttpAsyncClients.custom().setConnectionManager(cm).build();
client.start();
final String[] toGet = { "http://www.google.com/", "http://www.apache.org/", "http://www.bing.com/" };
final GetThread[] threads = new GetThread[toGet.length];
for (int i = 0; i < threads.length; i++) {
final HttpGet request = new HttpGet(toGet[i]);
threads[i] = new GetThread(client, request);
}
for (final GetThread thread : threads) {
thread.start();
}
for (final GetThread thread : threads) {
thread.join();
}
}
4. 使用HttpAsyncClient代理
让我们看看如何使用HttpAsyncClient设置和使用代理。
在下面的示例中，我们通过代理发送HTTP GET请求。
4.1 对于HttpAsyncClient 5.x
@Test
void whenUseProxyWithHttpClient_thenCorrect() throws Exception {
final HttpHost proxy = new HttpHost("127.0.0.1", GetRequestMockServer.serverPort);
DefaultProxyRoutePlanner routePlanner = new DefaultProxyRoutePlanner(proxy);
final CloseableHttpAsyncClient client = HttpAsyncClients.custom()
.setRoutePlanner(routePlanner)
.build();
client.start();
final SimpleHttpRequest request = new SimpleHttpRequest("GET" ,HOST_WITH_PROXY);
final Future<SimpleHttpResponse> future = client.execute(request, null);
final HttpResponse response = future.get();
assertThat(response.getCode(), equalTo(200));
client.close();
}
4.2 对于HttpAsyncClient 4.5
@Test
void whenUseProxyWithHttpClient_thenCorrect() throws Exception {
final CloseableHttpAsyncClient client = HttpAsyncClients.createDefault();
client.start();
final HttpHost proxy = new HttpHost("127.0.0.1", GetRequestMockServer.serverPort);
final RequestConfig config = RequestConfig.custom().setProxy(proxy).build();
final HttpGet request = new HttpGet(HOST_WITH_PROXY);
request.setConfig(config);
final Future<HttpResponse> future = client.execute(request, null);
final HttpResponse response = future.get();
assertThat(response.getStatusLine().getStatusCode(), equalTo(200));
client.close();
}
5. 使用HttpAsyncClient的SSL证书
现在，让我们看看如何使用SSL证书和HttpAsyncClient。
在以下示例中，我们配置HttpAsyncClient以接收所有证书：
5.1 对于HttpAsyncClient 5.x
@Test
void whenUseSSLWithHttpAsyncClient_thenCorrect() throws Exception {
final TrustStrategy acceptingTrustStrategy = (certificate, authType) -> true;
final SSLContext sslContext = SSLContexts.custom()
.loadTrustMaterial(null, acceptingTrustStrategy)
.build();
final TlsStrategy tlsStrategy = ClientTlsStrategyBuilder.create()
.setHostnameVerifier(NoopHostnameVerifier.INSTANCE)
.setSslContext(sslContext)
.build();
final PoolingAsyncClientConnectionManager cm = PoolingAsyncClientConnectionManagerBuilder.create()
.setTlsStrategy(tlsStrategy)
.build();
final CloseableHttpAsyncClient client = HttpAsyncClients.custom()
.setConnectionManager(cm)
.build();
client.start();
final SimpleHttpRequest request = new SimpleHttpRequest("GET",HOST_WITH_SSL);
final Future<SimpleHttpResponse> future = client.execute(request, null);
final HttpResponse response = future.get();
assertThat(response.getCode(), equalTo(200));
client.close();
}
5.2 对于HttpAsyncClient 4.5
@Test
void whenUseSSLWithHttpAsyncClient_thenCorrect() throws Exception {
final TrustStrategy acceptingTrustStrategy = (certificate, authType) -> true;
final SSLContext sslContext = SSLContexts.custom()
.loadTrustMaterial(null, acceptingTrustStrategy)
.build();
final CloseableHttpAsyncClient client = HttpAsyncClients.custom()
.setSSLHostnameVerifier(NoopHostnameVerifier.INSTANCE)
.setSSLContext(sslContext).build();
client.start();
final HttpGet request = new HttpGet(HOST_WITH_SSL);
final Future<HttpResponse> future = client.execute(request, null);
final HttpResponse response = future.get();
assertThat(response.getStatusLine().getStatusCode(), equalTo(200));
client.close();
}
6. 在HttpAsyncClient中使用Cookie
接下来，让我们看看如何在HttpAsyncClient中使用Cookie。
在下面的示例中，我们在发送请求之前设置了一个Cookie值。
6.1 对于HttpAsyncClient 5.x
@Test
void whenUseCookiesWithHttpAsyncClient_thenCorrect() throws Exception {
final BasicCookieStore cookieStore = new BasicCookieStore();
final BasicClientCookie cookie = new BasicClientCookie(COOKIE_NAME, "1234");
cookie.setDomain(COOKIE_DOMAIN);
cookie.setPath("/");
cookieStore.addCookie(cookie);
final CloseableHttpAsyncClient client = HttpAsyncClients.custom().build();
client.start();
final SimpleHttpRequest request = new SimpleHttpRequest("GET" ,HOST_WITH_COOKIE);
final HttpContext localContext = new BasicHttpContext();
localContext.setAttribute(HttpClientContext.COOKIE_STORE, cookieStore);
final Future<SimpleHttpResponse> future = client.execute(request, localContext, null);
final HttpResponse response = future.get();
assertThat(response.getCode(), equalTo(200));
client.close();
}
6.2 对于HttpAsyncClient 4.5
@Test
void whenUseCookiesWithHttpAsyncClient_thenCorrect() throws Exception {
final BasicCookieStore cookieStore = new BasicCookieStore();
final BasicClientCookie cookie = new BasicClientCookie(COOKIE_NAME, "1234");
cookie.setDomain(COOKIE_DOMAIN);
cookie.setPath("/");
cookieStore.addCookie(cookie);
final CloseableHttpAsyncClient client = HttpAsyncClients.custom().build();
client.start();
final HttpGet request = new HttpGet(HOST_WITH_COOKIE);
final HttpContext localContext = new BasicHttpContext();
localContext.setAttribute(HttpClientContext.COOKIE_STORE, cookieStore);
final Future<HttpResponse> future = client.execute(request, localContext, null);
final HttpResponse response = future.get();
assertThat(response.getStatusLine().getStatusCode(), equalTo(200));
client.close();
}
7. 使用HttpAsyncClient进行身份验证
接下来，让我们看看如何使用HttpAsyncClient进行身份验证。
在下面的示例中，我们使用CredentialsProvider通过基本身份验证访问主机。
7.1 对于HttpAsyncClient 5.x
@Test
void whenUseAuthenticationWithHttpAsyncClient_thenCorrect() throws Exception {
final BasicCredentialsProvider credsProvider = new BasicCredentialsProvider();
final UsernamePasswordCredentials credentials =
new UsernamePasswordCredentials(DEFAULT_USER, DEFAULT_PASS.toCharArray());
credsProvider.setCredentials(new AuthScope(URL_SECURED_BY_BASIC_AUTHENTICATION, 80) ,credentials);
final CloseableHttpAsyncClient client = HttpAsyncClients
.custom()
.setDefaultCredentialsProvider(credsProvider).build();
final SimpleHttpRequest request = new SimpleHttpRequest("GET" ,URL_SECURED_BY_BASIC_AUTHENTICATION);
client.start();
final Future<SimpleHttpResponse> future = client.execute(request, null);
final HttpResponse response = future.get();
assertThat(response.getCode(), equalTo(200));
client.close();
}
7.2 对于HttpAsyncClient 4.5
@Test
public void whenUseAuthenticationWithHttpAsyncClient_thenCorrect() throws Exception {
CredentialsProvider provider = new BasicCredentialsProvider();
UsernamePasswordCredentials creds = new UsernamePasswordCredentials("user", "pass");
provider.setCredentials(AuthScope.ANY, creds);
CloseableHttpAsyncClient client =
HttpAsyncClients.custom().setDefaultCredentialsProvider(provider).build();
client.start();
HttpGet request = new HttpGet("http://localhost:8080");
Future<HttpResponse> future = client.execute(request, null);
HttpResponse response = future.get();
assertThat(response.getStatusLine().getStatusCode(), equalTo(200));
client.close();
}
8. 总结
在本文中，我们阐述了异步Apache Http客户端的各种用例。
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