使用需要引入jar包，maven项目引入如下： `<dependency> <groupId>org.apache.httpcomponents</groupId> <artifactId>httpclient</artifactId> <version>4.5</version> </dependency>
org.apache.httpcomponents httpcore 4.4.4 ` org.apache.httpcomponents httpmime 4.5
使用方法，代码如下：
package com.test;import java.io.File;import java.io.IOException;import java.security.KeyManagementException;import java.security.KeyStoreException;import java.security.NoSuchAlgorithmException;import java.util.Iterator;import java.util.List;import java.util.Map;import org.apache.http.HttpEntity;import org.apache.http.HttpStatus;import org.apache.http.client.config.RequestConfig;import org.apache.http.client.methods.CloseableHttpResponse;import org.apache.http.client.methods.HttpGet;import org.apache.http.client.methods.HttpPost;import org.apache.http.config.Registry;import org.apache.http.config.RegistryBuilder;import org.apache.http.conn.socket.ConnectionSocketFactory;import org.apache.http.conn.socket.PlainConnectionSocketFactory;import org.apache.http.conn.ssl.SSLConnectionSocketFactory;import org.apache.http.conn.ssl.SSLContextBuilder;import org.apache.http.conn.ssl.TrustSelfSignedStrategy;import org.apache.http.entity.ContentType;import org.apache.http.entity.StringEntity;import org.apache.http.entity.mime.MultipartEntityBuilder;import org.apache.http.entity.mime.content.FileBody;import org.apache.http.entity.mime.content.StringBody;import org.apache.http.impl.client.CloseableHttpClient;import org.apache.http.impl.client.DefaultHttpRequestRetryHandler;import org.apache.http.impl.client.HttpClients;import org.apache.http.impl.conn.PoolingHttpClientConnectionManager;import org.apache.http.util.EntityUtils;/** * * @author zengh * @date 2016年10月19日 上午11:27:25 * */public class HttpClientUtil { // utf-8字符编码 public static final String CHARSET_UTF_8 = "utf-8"; // HTTP内容类型。 public static final String CONTENT_TYPE_TEXT_HTML = "text/xml"; // HTTP内容类型。相当于form表单的形式，提交数据 public static final String CONTENT_TYPE_FORM_URL = "application/x-www-form-urlencoded"; // HTTP内容类型。相当于form表单的形式，提交数据 public static final String CONTENT_TYPE_JSON_URL = "application/json;charset=utf-8"; // 连接管理器 private static PoolingHttpClientConnectionManager pool; // 请求配置 private static RequestConfig requestConfig; static { try { //System.out.println("初始化HttpClientTest~~~开始"); SSLContextBuilder builder = new SSLContextBuilder(); builder.loadTrustMaterial(null, new TrustSelfSignedStrategy()); SSLConnectionSocketFactory sslsf = new SSLConnectionSocketFactory( builder.build()); // 配置同时支持 HTTP 和 HTPPS Registry socketFactoryRegistry = RegistryBuilder. create().register( "http", PlainConnectionSocketFactory.getSocketFactory()).register( "https", sslsf).build(); // 初始化连接管理器 pool = new PoolingHttpClientConnectionManager( socketFactoryRegistry); // 将最大连接数增加到200，实际项目最好从配置文件中读取这个值 pool.setMaxTotal(200); // 设置最大路由 pool.setDefaultMaxPerRoute(2); // 根据默认超时限制初始化requestConfig int socketTimeout = 10000; int connectTimeout = 10000; int connectionRequestTimeout = 10000; requestConfig = RequestConfig.custom().setConnectionRequestTimeout( connectionRequestTimeout).setSocketTimeout(socketTimeout).setConnectTimeout( connectTimeout).build(); //System.out.println("初始化HttpClientTest~~~结束"); } catch (NoSuchAlgorithmException e) { e.printStackTrace(); } catch (KeyStoreException e) { e.printStackTrace(); } catch (KeyManagementException e) { e.printStackTrace(); } // 设置请求超时时间 requestConfig = RequestConfig.custom().setSocketTimeout(50000).setConnectTimeout(50000) .setConnectionRequestTimeout(50000).build(); } public static CloseableHttpClient getHttpClient() { CloseableHttpClient httpClient = HttpClients.custom() // 设置连接池管理 .setConnectionManager(pool) // 设置请求配置 .setDefaultRequestConfig(requestConfig) // 设置重试次数 .setRetryHandler(new DefaultHttpRequestRetryHandler(0, false)) .build(); return httpClient; } /** * 发送Post请求 * * @param httpPost * @return */ private static String sendHttpPost(HttpPost httpPost) { CloseableHttpClient httpClient = null; CloseableHttpResponse response = null; // 响应内容 String responseContent = null; try { // 创建默认的httpClient实例. httpClient = getHttpClient(); // 配置请求信息 httpPost.setConfig(requestConfig); // 执行请求 response = httpClient.execute(httpPost); // 得到响应实例 HttpEntity entity = response.getEntity(); // 可以获得响应头 // Header[] headers = response.getHeaders(HttpHeaders.CONTENT_TYPE); // for (Header header : headers) { // System.out.println(header.getName()); // } // 得到响应类型 // System.out.println(ContentType.getOrDefault(response.getEntity()).getMimeType()); // 判断响应状态 if (response.getStatusLine().getStatusCode() >= 300) { throw new Exception( "HTTP Request is not success, Response code is " + response.getStatusLine().getStatusCode()); } if (HttpStatus.SC_OK == response.getStatusLine().getStatusCode()) { responseContent = EntityUtils.toString(entity, CHARSET_UTF_8); EntityUtils.consume(entity); } } catch (Exception e) { e.printStackTrace(); } finally { try { // 释放资源 if (response != null) { response.close(); } } catch (IOException e) { e.printStackTrace(); } } return responseContent; } /** * 发送Get请求 * * @param httpGet * @return */ private static String sendHttpGet(HttpGet httpGet) { CloseableHttpClient httpClient = null; CloseableHttpResponse response = null; // 响应内容 String responseContent = null; try { // 创建默认的httpClient实例. httpClient = getHttpClient(); // 配置请求信息 httpGet.setConfig(requestConfig); // 执行请求 response = httpClient.execute(httpGet); // 得到响应实例 HttpEntity entity = response.getEntity(); // 可以获得响应头 // Header[] headers = response.getHeaders(HttpHeaders.CONTENT_TYPE); // for (Header header : headers) { // System.out.println(header.getName()); // } // 得到响应类型 // System.out.println(ContentType.getOrDefault(response.getEntity()).getMimeType()); // 判断响应状态 if (response.getStatusLine().getStatusCode() >= 300) { throw new Exception( "HTTP Request is not success, Response code is " + response.getStatusLine().getStatusCode()); } if (HttpStatus.SC_OK == response.getStatusLine().getStatusCode()) { responseContent = EntityUtils.toString(entity, CHARSET_UTF_8); EntityUtils.consume(entity); } } catch (Exception e) { e.printStackTrace(); } finally { try { // 释放资源 if (response != null) { response.close(); } } catch (IOException e) { e.printStackTrace(); } } return responseContent; } /** * 发送 post请求 * * @param httpUrl * 地址 */ public static String sendHttpPost(String httpUrl) { // 创建httpPost HttpPost httpPost = new HttpPost(httpUrl); return sendHttpPost(httpPost); } /** * 发送 get请求 * * @param httpUrl */ public static String sendHttpGet(String httpUrl) { // 创建get请求 HttpGet httpGet = new HttpGet(httpUrl); return sendHttpGet(httpGet); } /** * 发送 post请求（带文件） * * @param httpUrl * 地址 * @param maps * 参数 * @param fileLists * 附件 */ public static String sendHttpPost(String httpUrl, Map maps, List fileLists) { HttpPost httpPost = new HttpPost(httpUrl);// 创建httpPost MultipartEntityBuilder meBuilder = MultipartEntityBuilder.create(); if (maps != null) { for (String key : maps.keySet()) { meBuilder.addPart(key, new StringBody(maps.get(key), ContentType.TEXT_PLAIN)); } } if (fileLists != null) { for (File file : fileLists) { FileBody fileBody = new FileBody(file); meBuilder.addPart("files", fileBody); } } HttpEntity reqEntity = meBuilder.build(); httpPost.setEntity(reqEntity); return sendHttpPost(httpPost); } /** * 发送 post请求 * * @param httpUrl * 地址 * @param params * 参数(格式:key1=value1&key2=value2) * */ public static String sendHttpPost(String httpUrl, String params) { HttpPost httpPost = new HttpPost(httpUrl);// 创建httpPost try { // 设置参数 if (params != null && params.trim().length() > 0) { StringEntity stringEntity = new StringEntity(params, "UTF-8"); stringEntity.setContentType(CONTENT_TYPE_FORM_URL); httpPost.setEntity(stringEntity); } } catch (Exception e) { e.printStackTrace(); } return sendHttpPost(httpPost); } /** * 发送 post请求 * * @param maps * 参数 */ public static String sendHttpPost(String httpUrl, Map maps) { String parem = convertStringParamter(maps); return sendHttpPost(httpUrl, parem); } /** * 发送 post请求 发送json数据 * * @param httpUrl * 地址 * @param paramsJson * 参数(格式 json) * */ public static String sendHttpPostJson(String httpUrl, String paramsJson) { HttpPost httpPost = new HttpPost(httpUrl);// 创建httpPost try { // 设置参数 if (paramsJson != null && paramsJson.trim().length() > 0) { StringEntity stringEntity = new StringEntity(paramsJson, "UTF-8"); stringEntity.setContentType(CONTENT_TYPE_JSON_URL); httpPost.setEntity(stringEntity); } } catch (Exception e) { e.printStackTrace(); } return sendHttpPost(httpPost); } /** * 发送 post请求 发送xml数据 * * @param httpUrl 地址 * @param paramsXml 参数(格式 Xml) * */ public static String sendHttpPostXml(String httpUrl, String paramsXml) { HttpPost httpPost = new HttpPost(httpUrl);// 创建httpPost try { // 设置参数 if (paramsXml != null && paramsXml.trim().length() > 0) { StringEntity stringEntity = new StringEntity(paramsXml, "UTF-8"); stringEntity.setContentType(CONTENT_TYPE_TEXT_HTML); httpPost.setEntity(stringEntity); } } catch (Exception e) { e.printStackTrace(); } return sendHttpPost(httpPost); } /** * 将map集合的键值对转化成：key1=value1&key2=value2 的形式 * * @param parameterMap * 需要转化的键值对集合 * @return 字符串 */ public static String convertStringParamter(Map parameterMap) { StringBuffer parameterBuffer = new StringBuffer(); if (parameterMap != null) { Iterator iterator = parameterMap.keySet().iterator(); String key = null; String value = null; while (iterator.hasNext()) { key = (String) iterator.next(); if (parameterMap.get(key) != null) { value = (String) parameterMap.get(key); } else { value = ""; } parameterBuffer.append(key).append("=").append(value); if (iterator.hasNext()) { parameterBuffer.append("&"); } } } return parameterBuffer.toString(); } public static void main(String[] args) throws Exception { System.out.println(sendHttpGet("http://www.baidu.com")); }}