Apache HttpClient4使用教程

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基于HttpClient 4.5.2

1. 执行GET请求

   CloseableHttpClient httpClient = HttpClients.custom()
                   .build();
   CloseableHttpResponse response = httpClient.execute(new HttpGet("https://www.baidu.com"));
   System.out.println(EntityUtils.toString(response.getEntity()));
   

2. 执行POST请求

   1. 提交form表单参数

      CloseableHttpClient httpClient = HttpClients.custom()
              .build();
      HttpPost httpPost = new HttpPost("https://www.explame.com");
      List<NameValuePair> formParams = new ArrayList<NameValuePair>();
      //表单参数
      formParams.add(new BasicNameValuePair("name1", "value1"));
      formParams.add(new BasicNameValuePair("name2", "value2"));
      UrlEncodedFormEntity entity = new UrlEncodedFormEntity(formParams, "utf-8");
      httpPost.setEntity(entity);
      CloseableHttpResponse response = httpClient.execute(httpPost);
      System.out.println(EntityUtils.toString(response.getEntity()));
      

   2. 提交payload参数

      CloseableHttpClient httpClient = HttpClients.custom()
                  .build();
      HttpPost httpPost = new HttpPost("https://www.explame.com");
      StringEntity entity = new StringEntity("{\"id\": \"1\"}");
      httpPost.setEntity(entity);
      CloseableHttpResponse response = httpClient.execute(httpPost);
      System.out.println(EntityUtils.toString(response.getEntity()));
      

   3. post上传文件

      CloseableHttpClient httpClient = HttpClients.custom()
              .build();
      HttpPost httpPost = new HttpPost("https://www.example.com");
      MultipartEntityBuilder multipartEntityBuilder = MultipartEntityBuilder.create();
      //要上传的文件
      multipartEntityBuilder.addBinaryBody("file", new File("temp.txt"));
      httpPost.setEntity(multipartEntityBuilder.build());
      CloseableHttpResponse response = httpClient.execute(httpPost);
      System.out.println(EntityUtils.toString(response.getEntity()));
      

   4. post提交multipart/form-data类型参数

      CloseableHttpClient httpClient = HttpClients.custom()
              .build();
      HttpPost httpPost = new HttpPost("https://www.example.com");
      MultipartEntityBuilder multipartEntityBuilder = MultipartEntityBuilder.create();
      multipartEntityBuilder.addTextBody("username","wycm");
      multipartEntityBuilder.addTextBody("passowrd","123");
      //文件
      multipartEntityBuilder.addBinaryBody("file", new File("temp.txt"));
      httpPost.setEntity(multipartEntityBuilder.build());
      CloseableHttpResponse response = httpClient.execute(httpPost);
      System.out.println(EntityUtils.toString(response.getEntity()));
      

3. 设置User-Agent

       CloseableHttpClient httpClient = HttpClients.custom()
               .setUserAgent("Mozilla/5.0")
               .build();
       CloseableHttpResponse response = httpClient.execute(new HttpGet("https://www.baidu.com"));
       System.out.println(EntityUtils.toString(response.getEntity()));
   

4. 设置重试处理器
   当请求超时, 会自动重试，最多3次

   HttpRequestRetryHandler retryHandler = (exception, executionCount, context) -> {
       if (executionCount >= 3) {
           return false;
       }
       if (exception instanceof InterruptedIOException) {
           return true;
       }
       if (exception instanceof UnknownHostException) {
           return true;
       }
       if (exception instanceof ConnectTimeoutException) {
           return true;
       }
       if (exception instanceof SSLException) {
           return true;
       }
       HttpClientContext clientContext = HttpClientContext.adapt(context);
       HttpRequest request = clientContext.getRequest();
       boolean idempotent = !(request instanceof HttpEntityEnclosingRequest);
       if (idempotent) {
           return true;
       }
       return false;
   };
   CloseableHttpClient httpClient = HttpClients.custom()
           .setRetryHandler(retryHandler)
           .build();
   httpClient.execute(new HttpGet("https://www.baidu.com"));
   

5. 重定向策略

   1. HttpClient默认情况
      会对302、307的GET和HEAD请求以及所有的303状态码做重定向处理
   2. 关闭自动重定向

      CloseableHttpClient httpClient = HttpClients.custom()
               //关闭httpclient重定向
              .disableRedirectHandling()
              .build();
      

   3. POST支持302状态码重定向

      CloseableHttpClient httpClient = HttpClients.custom()
          //post 302支持重定向
          .setRedirectStrategy(new LaxRedirectStrategy())
          .build();
      CloseableHttpResponse response = httpClient.execute(new HttpPost("https://www.explame.com"));
      System.out.println(EntityUtils.toString(response.getEntity()));
      

6. 定制cookie

   • 方式一：通过addHeader方式设置（不推荐这种方式）

         CloseableHttpClient httpClient = HttpClients.custom()
                 .build();
         HttpGet httpGet = new HttpGet("http://www.example.com");
         httpGet.addHeader("Cookie", "name=value");
         httpClient.execute(httpGet);
     

     由于HttpClient默认会维护cookie状态。如果这个请求response中有Set-Cookie头，那下次请求的时候httpclient默认会把这个Cookie带上。并且会新建一行header。如果再遇到
     httpGet.addHeader("Cookie", "name=value");
     那么下次请求则会有两行name为Cookie的header。

   • 方式二：通过CookieStore的方式，以浏览器中的cookie为例（推荐）

     //此处直接粘贴浏览器cookiefinal String RAW_COOKIES = "name1=value1; name2=value2";final CookieStore cookieStore = new BasicCookieStore();for (String rawCookie : RAW_COOKIES.split("; ")){    String[] s = rawCookie.split("=");    BasicClientCookie cookie = new BasicClientCookie(s[0], s[1]);    cookie.setDomain("baidu.com");    cookie.setPath("/");    cookie.setSecure(false);    cookie.setAttribute("domain", "baidu.com");    Calendar calendar = Calendar.getInstance();    calendar.add(Calendar.DAY_OF_MONTH, +5);    cookie.setExpiryDate(calendar.getTime());    cookieStore.addCookie(cookie);}CloseableHttpClient httpClient = HttpClients.custom()        .setDefaultCookieStore(cookieStore)        .build();httpClient.execute(new HttpGet("https://www.baidu.com"));

     这种方式把定制的cookie交给httpclient维护。

7. cookie管理

   • 方式一：初始化HttpClient时，传入一个自己CookieStore对象

     CookieStore cookieStore = new BasicCookieStore();
     CloseableHttpClient httpClient = HttpClients.custom()
             .setDefaultCookieStore(cookieStore)
             .build();
     httpClient.execute(new HttpGet("https://www.baidu.com"));
     //请求一次后,清理cookie再发起一次新的请求
     cookieStore.clear();
     httpClient.execute(new HttpGet("https://www.baidu.com"));
     

   • 方式二：每次执行请求的时候传入自己的HttpContext对象

     //注:HttpClientContext不是线程安全的，不要多个线程维护一个HttpClientContext
     HttpClientContext httpContext = HttpClientContext.create();
     CloseableHttpClient httpClient = HttpClients.custom()
             .build();
     httpClient.execute(new HttpGet("https://www.baidu.com"), httpContext);
     //请求一次后,清理cookie再发起一次新的请求
     httpContext.getCookieStore().clear();
     httpClient.execute(new HttpGet("https://www.baidu.com"));
     

8. http代理的配置

   CloseableHttpClient httpClient = HttpClients.custom()
           //设置代理
           .setRoutePlanner(new DefaultProxyRoutePlanner(new HttpHost("localhost", 8888)))
           .build();
   CloseableHttpResponse response = httpClient.execute(new HttpGet("http://www.example.com"));
   System.out.println(EntityUtils.toString(response.getEntity()));
   

9. SSL配置

   //默认信任
   SSLContext sslContext = SSLContexts.custom()
           .loadTrustMaterial(KeyStore.getInstance(KeyStore.getDefaultType())
                   , (chain, authType) -> true).build();
   Registry<ConnectionSocketFactory> socketFactoryRegistry =
           RegistryBuilder.<ConnectionSocketFactory>create()
                   .register("http", new SocketProxyPlainConnectionSocketFactory())
                   .register("https", new SocketProxySSLConnectionSocketFactory(sslContext))
                   .build();
   CloseableHttpClient httpClient = HttpClients.custom()
           .setConnectionManager(new PoolingHttpClientConnectionManager(socketFactoryRegistry))
           .build();
   HttpClientContext httpClientContext = HttpClientContext.create();
   httpClientContext.setAttribute("socks.address", new InetSocketAddress("127.0.0.1", 1086));
   CloseableHttpResponse response = httpClient.execute(new HttpGet("https://httpbin.org/ip"), httpClientContext);
   System.out.println(EntityUtils.toString(response.getEntity()));
   

10. socket代理配置

    static class SocketProxyPlainConnectionSocketFactory extends PlainConnectionSocketFactory{
        @Override
        public Socket createSocket(final HttpContext context) {
            InetSocketAddress socksAddr = (InetSocketAddress) context.getAttribute("socks.address");
            if (socksAddr != null){
                Proxy proxy = new Proxy(Proxy.Type.SOCKS, socksAddr);
                return new Socket(proxy);
            } else {
                return new Socket();
            }
        }
    }
    static class SocketProxySSLConnectionSocketFactory extends SSLConnectionSocketFactory {
        public SocketProxySSLConnectionSocketFactory(final SSLContext sslContext) {
            super(sslContext, NoopHostnameVerifier.INSTANCE);
        }
    
        @Override
        public Socket createSocket(final HttpContext context) {
            InetSocketAddress socksAddr = (InetSocketAddress) context.getAttribute("socks.address");
            if (socksAddr != null){
                Proxy proxy = new Proxy(Proxy.Type.SOCKS, socksAddr);
                return new Socket(proxy);
            } else {
                return new Socket();
            }
        }
    
    }
    /**
     * socket代理配置
     */
    public static void socketProxy() throws Exception {
        //默认信任
        SSLContext sslContext = SSLContexts.custom()
                .loadTrustMaterial(KeyStore.getInstance(KeyStore.getDefaultType())
                        , (X509Certificate[] chain, String authType) -> true).build();
        Registry<ConnectionSocketFactory> socketFactoryRegistry =
                RegistryBuilder.<ConnectionSocketFactory>create()
                        .register("http", new SocketProxyPlainConnectionSocketFactory())
                        .register("https", new SocketProxySSLConnectionSocketFactory(sslContext))
                        .build();
        CloseableHttpClient httpClient = HttpClients.custom()
                .setConnectionManager(new PoolingHttpClientConnectionManager(socketFactoryRegistry))
                .build();
        HttpClientContext httpClientContext = HttpClientContext.create();
        httpClientContext.setAttribute("socks.address", new InetSocketAddress("127.0.0.1", 1086));
        CloseableHttpResponse response = httpClient.execute(new HttpGet("https://httpbin.org/ip"), httpClientContext);
        System.out.println(EntityUtils.toString(response.getEntity()));
    }
    

11. 下载文件

    CloseableHttpClient httpClient = HttpClients.custom().build();
    CloseableHttpResponse response = httpClient.execute(new HttpGet("https://www.example.com"));
    InputStream is = response.getEntity().getContent();
    Files.copy(is, new File("temp.png").toPath(), StandardCopyOption.REPLACE_EXISTING);
    
    

最后

• 完整Demo源码下载地址:https://github.com/wycm/HttpClientDemo

版权声明
作者：wycm
出处：https://blog.csdn.net/vwycm/article/details/88638996
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