HttpClient 是 Apache Jakarta Common 下的子項目，可以用來提供高效的、最新的、功能豐富的支持 HTTP 協議的客戶端編程工具包，並且它支持 HTTP 協議最新的版本和建議。
使用HttpClient發送請求、接收響應很簡單，一般需要如下幾步即可：
- 創建CloseableHttpClient對象。
- 創建請求方法的實例，並指定請求URL。如果需要發送GET請求，創建HttpGet對象；如果需要發送POST請求，創建HttpPost對象。
- 如果需要發送請求參數，可可調用setEntity(HttpEntity entity)方法來設置請求參數。setParams方法已過時（4.4.1版本）。
- 調用HttpGet、HttpPost對象的setHeader(String name, String value)方法設置header信息，或者調用setHeaders(Header[] headers)設置一組header信息。
- 調用CloseableHttpClient對象的execute(HttpUriRequest request)發送請求，該方法返回一個CloseableHttpResponse。
- 調用HttpResponse的getEntity()方法可獲取HttpEntity對象，該對象包裝了服務器的響應內容。程序可通過該對象獲取服務器的響應內容；調用CloseableHttpResponse的getAllHeaders()、getHeaders(String name)等方法可獲取服務器的響應頭。
- 釋放連接。無論執行方法是否成功，都必須釋放連接
具體代碼如下(HttpClient-4.4.1)：
/** * 簡單httpclient實例 * * @author arron * @date 2015年11月11日 下午6:36:49 * @version 1.0 */ public class SimpleHttpClientDemo { /** * 模擬請求 * * @param url 資源地址 * @param map 參數列表 * @param encoding 編碼 * @return * @throws ParseException * @throws IOException */ public static String send(String url, Map<String,String> map,String encoding) throws ParseException, IOException{ String body = ""; //創建httpclient對象 CloseableHttpClient client = HttpClients.createDefault(); //創建post方式請求對象 HttpPost httpPost = new HttpPost(url); //裝填參數 List<NameValuePair> nvps = new ArrayList<NameValuePair>(); if(map!=null){ for (Entry<String, String> entry : map.entrySet()) { nvps.add(new BasicNameValuePair(entry.getKey(), entry.getValue())); } } //設置參數到請求對象中 httpPost.setEntity(new UrlEncodedFormEntity(nvps, encoding)); System.out.println("請求地址："+url); System.out.println("請求參數："+nvps.toString()); //設置header信息 //指定報文頭【Content-type】、【User-Agent】 httpPost.setHeader("Content-type", "application/x-www-form-urlencoded"); httpPost.setHeader("User-Agent", "Mozilla/4.0 (compatible; MSIE 5.0; Windows NT; DigExt)"); //執行請求操作，並拿到結果（同步阻塞） CloseableHttpResponse response = client.execute(httpPost); //獲取結果實體 HttpEntity entity = response.getEntity(); if (entity != null) { //按指定編碼轉換結果實體為String類型 body = EntityUtils.toString(entity, encoding); } EntityUtils.consume(entity); //釋放鏈接 response.close(); return body; } }
對於HTTPS的訪問，采取繞過證書的策略：
/** * 繞過驗證 * * @return * @throws NoSuchAlgorithmException * @throws KeyManagementException */ public static SSLContext createIgnoreVerifySSL() throws NoSuchAlgorithmException, KeyManagementException { SSLContext sc = SSLContext.getInstance("SSLv3"); // 實現一個X509TrustManager接口，用於繞過驗證，不用修改里面的方法 X509TrustManager trustManager = new X509TrustManager() { @Override public void checkClientTrusted( java.security.cert.X509Certificate[] paramArrayOfX509Certificate, String paramString) throws CertificateException { } @Override public void checkServerTrusted( java.security.cert.X509Certificate[] paramArrayOfX509Certificate, String paramString) throws CertificateException { } @Override public java.security.cert.X509Certificate[] getAcceptedIssuers() { return null; } }; sc.init(null, new TrustManager[] { trustManager }, null); return sc; }
然后修改原來的send方法：
/** * 模擬請求 * * @param url 資源地址 * @param map 參數列表 * @param encoding 編碼 * @return * @throws NoSuchAlgorithmException * @throws KeyManagementException * @throws IOException * @throws ClientProtocolException */ public static String send(String url, Map<String,String> map,String encoding) throws KeyManagementException, NoSuchAlgorithmException, ClientProtocolException, IOException { String body = ""; //采用繞過驗證的方式處理https請求 SSLContext sslcontext = createIgnoreVerifySSL(); // 設置協議http和https對應的處理socket鏈接工廠的對象 Registry<ConnectionSocketFactory> socketFactoryRegistry = RegistryBuilder.<ConnectionSocketFactory>create() .register("http", PlainConnectionSocketFactory.INSTANCE) .register("https", new SSLConnectionSocketFactory(sslcontext)) .build(); PoolingHttpClientConnectionManager connManager = new PoolingHttpClientConnectionManager(socketFactoryRegistry); HttpClients.custom().setConnectionManager(connManager); //創建自定義的httpclient對象 CloseableHttpClient client = HttpClients.custom().setConnectionManager(connManager).build(); // CloseableHttpClient client = HttpClients.createDefault(); //創建post方式請求對象 HttpPost httpPost = new HttpPost(url); //裝填參數 List<NameValuePair> nvps = new ArrayList<NameValuePair>(); if(map!=null){ for (Entry<String, String> entry : map.entrySet()) { nvps.add(new BasicNameValuePair(entry.getKey(), entry.getValue())); } } //設置參數到請求對象中 httpPost.setEntity(new UrlEncodedFormEntity(nvps, encoding)); System.out.println("請求地址："+url); System.out.println("請求參數："+nvps.toString()); //設置header信息 //指定報文頭【Content-type】、【User-Agent】 httpPost.setHeader("Content-type", "application/x-www-form-urlencoded"); httpPost.setHeader("User-Agent", "Mozilla/4.0 (compatible; MSIE 5.0; Windows NT; DigExt)"); //執行請求操作，並拿到結果（同步阻塞） CloseableHttpResponse response = client.execute(httpPost); //獲取結果實體 HttpEntity entity = response.getEntity(); if (entity != null) { //按指定編碼轉換結果實體為String類型 body = EntityUtils.toString(entity, encoding); } EntityUtils.consume(entity); //釋放鏈接 response.close(); return body; }
但是，如果是自己用jdk或者其他工具生成的證書，還是希望用其他方式認證自簽名的證書，這篇文章就來分享一下如何設置信任自簽名的證書。當然你也可以參考官網示例中。
要想信任自簽名的證書，必須得知道密鑰庫的路徑及密鑰庫的密碼。然后加載到程序來才可以。具體代碼如下：
/** * 設置信任自簽名證書 * * @param keyStorePath 密鑰庫路徑 * @param keyStorepass 密鑰庫密碼 * @return */ public static SSLContext custom(String keyStorePath, String keyStorepass){ SSLContext sc = null; FileInputStream instream = null; KeyStore trustStore = null; try { trustStore = KeyStore.getInstance(KeyStore.getDefaultType()); instream = new FileInputStream(new File(keyStorePath)); trustStore.load(instream, keyStorepass.toCharArray()); // 相信自己的CA和所有自簽名的證書 sc = SSLContexts.custom().loadTrustMaterial(trustStore, new TrustSelfSignedStrategy()).build(); } catch (KeyStoreException | NoSuchAlgorithmException| CertificateException | IOException | KeyManagementException e) { e.printStackTrace(); } finally { try { instream.close(); } catch (IOException e) { } } return sc; }
然后修改原來的send方法：
/** * 模擬請求 * * @param url 資源地址 * @param map 參數列表 * @param encoding 編碼 * @return * @throws ParseException * @throws IOException * @throws KeyManagementException * @throws NoSuchAlgorithmException * @throws ClientProtocolException */ public static String send(String url, Map<String,String> map,String encoding) throws ClientProtocolException, IOException { String body = ""; //tomcat是我自己的密鑰庫的密碼，你可以替換成自己的 //如果密碼為空，則用"nopassword"代替 SSLContext sslcontext = custom("D:\\keys\\wsriakey", "tomcat"); // 設置協議http和https對應的處理socket鏈接工廠的對象 Registry<ConnectionSocketFactory> socketFactoryRegistry = RegistryBuilder.<ConnectionSocketFactory>create() .register("http", PlainConnectionSocketFactory.INSTANCE) .register("https", new SSLConnectionSocketFactory(sslcontext)) .build(); PoolingHttpClientConnectionManager connManager = new PoolingHttpClientConnectionManager(socketFactoryRegistry); HttpClients.custom().setConnectionManager(connManager); //創建自定義的httpclient對象 CloseableHttpClient client = HttpClients.custom().setConnectionManager(connManager).build(); // CloseableHttpClient client = HttpClients.createDefault(); //創建post方式請求對象 HttpPost httpPost = new HttpPost(url); //裝填參數 List<NameValuePair> nvps = new ArrayList<NameValuePair>(); if(map!=null){ for (Entry<String, String> entry : map.entrySet()) { nvps.add(new BasicNameValuePair(entry.getKey(), entry.getValue())); } } //設置參數到請求對象中 httpPost.setEntity(new UrlEncodedFormEntity(nvps, encoding)); System.out.println("請求地址："+url); System.out.println("請求參數："+nvps.toString()); //設置header信息 //指定報文頭【Content-type】、【User-Agent】 httpPost.setHeader("Content-type", "application/x-www-form-urlencoded"); httpPost.setHeader("User-Agent", "Mozilla/4.0 (compatible; MSIE 5.0; Windows NT; DigExt)"); //執行請求操作，並拿到結果（同步阻塞） CloseableHttpResponse response = client.execute(httpPost); //獲取結果實體 HttpEntity entity = response.getEntity(); if (entity != null) { //按指定編碼轉換結果實體為String類型 body = EntityUtils.toString(entity, encoding); } EntityUtils.consume(entity); //釋放鏈接 response.close(); return body; }