Apache HttpClient4使用教程

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默认状况
      会对30二、307的GET和HEAD请求以及全部的303状态码作重定向处理
   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：经过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);
     因为HttpClient默认会维护cookie状态。若是这个请求response中有Set-Cookie头，那下次请求的时候httpclient默认会把这个Cookie带上。而且会新建一行header。若是再遇到
     httpGet.addHeader("Cookie", "name=value");
     那么下次请求则会有两行name为Cookie的header。
   • 方式二：经过CookieStore的方式，以浏览器中的cookie为例（推荐）
     //此处直接粘贴浏览器cookie final 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，传入一个本身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本身的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
做者：wycm
出处：https://www.cnblogs.com/w-y-c-m/p/9237335.html
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