Apache HTTPASYNCCLIENT教程

2019-08-29 1044 words 3 minutes

Contents

1. 概述

在本教程中，我们将说明 Apache HttpAsyncClient最常见的用例——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例子中使用HttpAsyncClient——发送一个 GET 请求：

@Test
public void whenUseHttpAsyncClient_thenCorrect() throws Exception {
    CloseableHttpAsyncClient client = HttpAsyncClients.createDefault();
    client.start();
    HttpGet request = new HttpGet("http://www.google.com");
    
    Future<HttpResponse> future = client.execute(request, null);
    HttpResponse response = future.get();
    assertThat(response.getStatusLine().getStatusCode(), equalTo(200));
    client.close();
}

注意我们需要在使用之前如何启动异步客户端；没有它，我们会得到以下异常：

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 进行多线程

现在——让我们看看如何使用HttpAsyncClient同时执行多个请求。

在下面的示例中——我们使用HttpAsyncClient和PoolingNHttpClientConnectionManager向三个不同的主机发送三个 GET 请求：

@Test
public void whenUseMultipleHttpAsyncClient_thenCorrect() throws Exception {
    ConnectingIOReactor ioReactor = new DefaultConnectingIOReactor();
    PoolingNHttpClientConnectionManager cm = 
      new PoolingNHttpClientConnectionManager(ioReactor);
    CloseableHttpAsyncClient client = 
      HttpAsyncClients.custom().setConnectionManager(cm).build();
    client.start();
    
    String[] toGet = { 
        "http://www.google.com/", 
        "http://www.apache.org/", 
        "http://www.bing.com/" 
    };
    GetThread[] threads = new GetThread[toGet.length];
    for (int i = 0; i < threads.length; i++) {
        HttpGet request = new HttpGet(toGet[i]);
        threads[i] = new GetThread(client, request);
    }
    for (GetThread thread : threads) {
        thread.start();
    }
    for (GetThread thread : threads) {
        thread.join();
    }
}

这是我们处理响应的GetThread实现：

static class GetThread extends Thread {
    private CloseableHttpAsyncClient client;
    private HttpContext context;
    private HttpGet request;
    public GetThread(CloseableHttpAsyncClient client,HttpGet req){
        this.client = client;
        context = HttpClientContext.create();
        this.request = req;
    }
    @Override
    public void run() {
        try {
            Future<HttpResponse> future = client.execute(request, context, null);
            HttpResponse response = future.get();
            assertThat(response.getStatusLine().getStatusCode(), equalTo(200));
        } catch (Exception ex) {
            System.out.println(ex.getLocalizedMessage());
        }
    }
}

4. 使用HttpAsyncClient 的代理

接下来——让我们看看如何通过HttpAsyncClient设置和使用代理。

在以下示例中——我们通过代理发送 HTTP GET 请求：

@Test
public void whenUseProxyWithHttpClient_thenCorrect() throws Exception {
    CloseableHttpAsyncClient client = HttpAsyncClients.createDefault();
    client.start();
    
    HttpHost proxy = new HttpHost("74.50.126.248", 3127);
    RequestConfig config = RequestConfig.custom().setProxy(proxy).build();
    HttpGet request = new HttpGet("https://issues.apache.org/");
    request.setConfig(config);
    
    Future<HttpResponse> future = client.execute(request, null);
    HttpResponse response = future.get();
    
    assertThat(response.getStatusLine().getStatusCode(), equalTo(200));
    client.close();
}

5. 带有SSL 证书的HttpAsyncClient

现在 - 让我们看看如何将SSL 证书与HttpAsyncClient一起使用。

在以下示例中 - 我们将HttpAsyncClient配置为接受所有证书：

@Test
public void whenUseSSLWithHttpAsyncClient_thenCorrect() throws Exception {
    TrustStrategy acceptingTrustStrategy = new TrustStrategy() {
        public boolean isTrusted(X509Certificate[] certificate,  String authType) {
            return true;
        }
    };
    SSLContext sslContext = SSLContexts.custom()
      .loadTrustMaterial(null, acceptingTrustStrategy).build();
    CloseableHttpAsyncClient client = HttpAsyncClients.custom()
      .setSSLHostnameVerifier(SSLConnectionSocketFactory.ALLOW_ALL_HOSTNAME_VERIFIER)
      .setSSLContext(sslContext).build();
    client.start();
    
    HttpGet request = new HttpGet("https://mms.nw.ru/");
    Future<HttpResponse> future = client.execute(request, null);
    HttpResponse response = future.get();
    
    assertThat(response.getStatusLine().getStatusCode(), equalTo(200));
    client.close();
}

6. 使用Cookie的HttpAsyncClient

接下来——让我们看看如何在HttpAsyncClient中使用 cookie 。

在下面的例子中——我们在发送请求之前设置了一个 cookie 值：

@Test
public void whenUseCookiesWithHttpAsyncClient_thenCorrect() throws Exception {
    BasicCookieStore cookieStore = new BasicCookieStore();
    BasicClientCookie cookie = new BasicClientCookie("JSESSIONID", "1234");
    cookie.setDomain(".github.com");
    cookie.setPath("/");
    cookieStore.addCookie(cookie);
    
    CloseableHttpAsyncClient client = HttpAsyncClients.custom().build();
    client.start();
    
    HttpGet request = new HttpGet("http://www.github.com");
    HttpContext localContext = new BasicHttpContext();
    localContext.setAttribute(HttpClientContext.COOKIE_STORE, cookieStore);
    Future<HttpResponse> future = client.execute(request, localContext, null);
    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。

在以下示例中——我们使用CredentialsProvider通过基本身份验证访问主机：

@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();
}