【Web】Apache HttpClient & HttpAsyncClient

参考：https://www.baeldung.com/category/http/tag/httpclient/

POM配置

<dependency>
     <groupId>org.apache.httpcomponents</groupId>
     <artifactId>httpclient</artifactId>
     <version>4.5.7</version>
</dependency>
<dependency>
     <groupId>org.apache.httpcomponents</groupId>
     <artifactId>httpasyncclient</artifactId>
     <version>4.1.4</version> 
</dependency>

一、对接参数：连接超时参数

Connection Timeout (http.connection.timeout) – the time to establish the connection with the remote host
Socket Timeout (http.socket.timeout) – the time waiting for data – after establishing the connection; maximum time of inactivity between two data packets
the Connection Manager Timeout (http.connection-manager.timeout) – the time to wait for a connection from the connection manager/pool

int timeout = 5;
RequestConfig config = RequestConfig.custom()
        .setConnectTimeout(timeout * 1000)
        .setConnectionRequestTimeout(timeout * 1000)
        .setSocketTimeout(timeout * 1000)
        .build();
CloseableHttpClient client = HttpClientBuilder.create().setDefaultRequestConfig(config).build();

HttpGet getMethod = new HttpGet("http://host:8080/path"); 
HttpResponse response = httpClient.execute(getMethod); 
System.out.println( "HTTP Status of response: " + response.getStatusLine().getStatusCode());

二、Header配置

　　Since HttpClient 4.3: 通过RequestBuilder::setHeader

HttpClient client = HttpClients.custom().build();
HttpUriRequest request = RequestBuilder.get()
  .setUri(SAMPLE_URL)
  .setHeader(HttpHeaders.CONTENT_TYPE, "application/json")
  .build();
client.execute(request);

　　Before 4.3: Request.setHeader

HttpClient client = new DefaultHttpClient();
HttpGet request = new HttpGet(SAMPLE_URL);
request.setHeader(HttpHeaders.CONTENT_TYPE, "application/json");
client.execute(request);

　　设置默认Header，避免每个请求都重复设置，configure it as a default header on the Client

Header header = new BasicHeader(HttpHeaders.CONTENT_TYPE, "application/json");
List<Header> headers = Lists.newArrayList(header);
HttpClient client = HttpClients.custom().setDefaultHeaders(headers).build();
HttpUriRequest request = RequestBuilder.get().setUri(SAMPLE_URL).build();

client.execute(request);

三、请求参数

　　1. 查询的QueryParam

HttpGet httpGet = new HttpGet("https://example.com");
URI uri = new URIBuilder(httpGet.getURI())
      .addParameter("param1", "value1")
      .addParameter("param2", "value2")
      .build();
((HttpRequestBase) httpGet).setURI(uri);

CloseableHttpResponse response = client.execute(httpGet);
client.close();

　　或 BasicNameValuePair

List nameValuePairs = new ArrayList();
nameValuePairs.add(new BasicNameValuePair("param1", "value1"));
nameValuePairs.add(new BasicNameValuePair("param2", "value2"));
HttpGet httpGet = new HttpGet("https://example.com");
URI uri = new URIBuilder(httpGet.getURI())
      .addParameters(nameValuePairs)
      .build();
((HttpRequestBase) httpGet).setURI(uri);

CloseableHttpResponse response = client.execute(httpGet);
client.close();

四、POST的entity URL编码

public CloseableHttpResponse sendHttpRequest() {
    List nameValuePairs = new ArrayList();
    nameValuePairs.add(new BasicNameValuePair("param1", "value1"));
    nameValuePairs.add(new BasicNameValuePair("param2", "value2"));
    HttpPost httpPost = new HttpPost("https://example.com");
    httpPost.setEntity(new UrlEncodedFormEntity(nameValuePairs, StandardCharsets.UTF_8));
    CloseableHttpResponse response = client.execute(httpPost);
    client.close();

五、HttpAsyncClient

　　1、基础使用

CloseableHttpAsyncClient client = HttpAsyncClients.createDefault();
client.start();  // 必须先执行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();

　　2、多线程使用： PoolingNHttpClientConnectionManager

@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();
    }
}

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());
        }
    }
}

　　3. 通过代理

@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();
}

　　4. SSLCertificate

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();
}

　　5. Cookie

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();
}

　　6. 鉴权 CredentialsProvider

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();
}