HttpClient是Apache Jakarta Common下的子项目，用来提供高效的、最新的、功能丰富的支持HTTP协议的客户端编程工具包，并且它支持HTTP协议最新的版本和建议。HttpClient已经应用在很多的项目中，比如Apache Jakarta上很著名的另外两个开源项目Cactus和HTMLUnit都使用了HttpClient。
HttpClient通俗的讲就是模拟了浏览器的行为，如果我们需要在后端向某一地址提交数据获取结果，就可以使用HttpClient.
关于HttpClient（原生）具体的使用不属于我们这里的学习内容，我们这里这里为了简化HttpClient的使用，提供了工具类HttpClient（对原生HttpClient进行了封装）
依赖
<!--httpclient支持--><dependency><groupId>org.apache.httpcomponents</groupId><artifactId>httpclient</artifactId></dependency>
HttpClient工具类代码：
public class HttpClient {private String url;private Map<String, String> param;private int statusCode;private String content;private String xmlParam;private boolean isHttps;public boolean isHttps() {return isHttps;}public void setHttps(boolean isHttps) {this.isHttps = isHttps;}public String getXmlParam() {return xmlParam;}public void setXmlParam(String xmlParam) {this.xmlParam = xmlParam;}public HttpClient(String url, Map<String, String> param) {this.url = url;this.param = param;}public HttpClient(String url) {this.url = url;}public void setParameter(Map<String, String> map) {param = map;}public void addParameter(String key, String value) {if (param == null)param = new HashMap<String, String>();param.put(key, value);}public void post() throws ClientProtocolException, IOException {HttpPost http = new HttpPost(url);setEntity(http);execute(http);}public void put() throws ClientProtocolException, IOException {HttpPut http = new HttpPut(url);setEntity(http);execute(http);}public void get() throws ClientProtocolException, IOException {if (param != null) {StringBuilder url = new StringBuilder(this.url);boolean isFirst = true;for (String key : param.keySet()) {if (isFirst) {url.append("?");}else {url.append("&");}url.append(key).append("=").append(param.get(key));}this.url = url.toString();}HttpGet http = new HttpGet(url);execute(http);}/*** set http post,put param*/private void setEntity(HttpEntityEnclosingRequestBase http) {if (param != null) {List<NameValuePair> nvps = new LinkedList<NameValuePair>();for (String key : param.keySet()) {nvps.add(new BasicNameValuePair(key, param.get(key))); // 参数}http.setEntity(new UrlEncodedFormEntity(nvps, Consts.UTF_8)); // 设置参数}if (xmlParam != null) {http.setEntity(new StringEntity(xmlParam, Consts.UTF_8));}}private void execute(HttpUriRequest http) throws ClientProtocolException,IOException {CloseableHttpClient httpClient = null;try {if (isHttps) {SSLContext sslContext = new SSLContextBuilder().loadTrustMaterial(null, new TrustStrategy() {// 信任所有@Overridepublic boolean isTrusted(X509Certificate[] chain,String authType)throws CertificateException {return true;}}).build();SSLConnectionSocketFactory sslsf = new SSLConnectionSocketFactory(sslContext);httpClient = HttpClients.custom().setSSLSocketFactory(sslsf).build();} else {httpClient = HttpClients.createDefault();}CloseableHttpResponse response = httpClient.execute(http);try {if (response != null) {if (response.getStatusLine() != null) {statusCode = response.getStatusLine().getStatusCode();}HttpEntity entity = response.getEntity();// 响应内容content = EntityUtils.toString(entity, Consts.UTF_8);}} finally {response.close();}} catch (Exception e) {e.printStackTrace();} finally {httpClient.close();}}public int getStatusCode() {return statusCode;}public String getContent() throws ParseException, IOException {return content;}}
HttpClient工具类使用的步骤
HttpClient client=new HttpClient(请求的url地址);client.setHttps(true);//是否是https协议client.setXmlParam(xmlParam);//发送的xml数据client.post();//执行post请求String result = client.getContent(); //获取结果
