HttpClient依赖jar包：
<dependency> <groupId>org.apache.httpcomponents</groupId> <artifactId>httpclient</artifactId> <version>4.5.2</version> </dependency>
写一个发送请求的工具类HttpUtil
package com.bs.utils; import java.io.BufferedReader; import java.io.IOException; import java.io.InputStreamReader; import java.net.URI; import java.net.URISyntaxException; import java.util.ArrayList; import java.util.Iterator; import java.util.List; import java.util.Map; import org.apache.http.HttpEntity; import org.apache.http.HttpResponse; import org.apache.http.HttpStatus; import org.apache.http.NameValuePair; import org.apache.http.ParseException; import org.apache.http.StatusLine; import org.apache.http.client.ClientProtocolException; import org.apache.http.client.HttpClient; import org.apache.http.client.entity.UrlEncodedFormEntity; 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.client.utils.URIBuilder; import org.apache.http.entity.StringEntity; import org.apache.http.impl.client.CloseableHttpClient; import org.apache.http.impl.client.DefaultHttpClient; import org.apache.http.impl.client.HttpClients; import org.apache.http.message.BasicNameValuePair; import org.apache.http.protocol.HTTP; import org.apache.http.util.EntityUtils; import org.apache.log4j.Logger; /** * HttpClient工具类 */ public class HttpUtil { private static Logger logger = Logger.getLogger(HttpUtil.class); /** * get请求 * @return */ public static String doGet(String url) { try { HttpClient client = new DefaultHttpClient(); //发送get请求 HttpGet request = new HttpGet(url); HttpResponse response = client.execute(request); /**请求发送成功，并得到响应**/ if (response.getStatusLine().getStatusCode() == HttpStatus.SC_OK) { /**读取服务器返回过来的json字符串数据**/ String strResult = EntityUtils.toString(response.getEntity()); return strResult; } } catch (IOException e) { e.printStackTrace(); } return null; } /**get请求(用于key-value格式的参数,且带有header请求头) * @param url * @param map 请求的参数map<key,value>键值对 * @param headerKey headers Key * @param headerValue headers Value * @return */ public static String doGet(String url,Map<String, String> map,String headerKey,String headerValue) { // 获取连接客户端工具 CloseableHttpClient httpClient = HttpClients.createDefault(); String entityStr = null; CloseableHttpResponse response = null; try { /* * 由于GET请求的参数都是拼装在URL地址后方，所以我们要构建一个URL，带参数 */ URIBuilder uriBuilder = new URIBuilder(url); /** 第一种添加参数的形式 */ /*uriBuilder.addParameter("name", "root"); uriBuilder.addParameter("password", "123456");*/ for (Map.Entry<String, String> entry : map.entrySet()) { uriBuilder.addParameter(entry.getKey(), entry.getValue()); } /** 第二种添加参数的形式 */ /* List<NameValuePair> list = new LinkedList<>(); BasicNameValuePair param1 = new BasicNameValuePair("startTime", "2019-1-1 00:00:00"); BasicNameValuePair param2 = new BasicNameValuePair("endTime", "2019-1-9 00:00:00"); list.add(param1); list.add(param2); uriBuilder.setParameters(list);*/ // 根据带参数的URI对象构建GET请求对象 HttpGet httpGet = new HttpGet(uriBuilder.build()); /* * 添加请求头信息 */ // 浏览器表示 httpGet.addHeader("User-Agent", "Mozilla/5.0 (Windows; U; Windows NT 5.1; en-US; rv:1.7.6)"); // 传输的类型 httpGet.addHeader("Content-Type", "application/x-www-form-urlencoded"); //header的<key,value> httpGet.setHeader(headerKey, headerValue); // 执行请求 response = httpClient.execute(httpGet); // 获得响应的实体对象 HttpEntity entity = response.getEntity(); // 使用Apache提供的工具类进行转换成字符串 entityStr = EntityUtils.toString(entity, "UTF-8"); } catch (ClientProtocolException e) { System.err.println("Http协议出现问题"); e.printStackTrace(); } catch (ParseException e) { System.err.println("解析错误"); e.printStackTrace(); } catch (URISyntaxException e) { System.err.println("URI解析异常"); e.printStackTrace(); } catch (IOException e) { System.err.println("IO异常"); e.printStackTrace(); } finally { // 释放连接 if (null != response) { try { response.close(); httpClient.close(); } catch (IOException e) { System.err.println("释放连接出错"); e.printStackTrace(); } } } return entityStr; } /** * post请求(用于key-value格式的参数) * @param url * @param params * @return */ public static String doPost(String url, Map params){ BufferedReader in = null; try { // 定义HttpClient HttpClient client = new DefaultHttpClient(); // 实例化HTTP方法 HttpPost request = new HttpPost(); request.setURI(new URI(url)); //设置参数 List<NameValuePair> nvps = new ArrayList<NameValuePair>(); for (Iterator iter = params.keySet().iterator(); iter.hasNext();) { String name = (String) iter.next(); String value = String.valueOf(params.get(name)); nvps.add(new BasicNameValuePair(name, value)); //System.out.println(name +"-"+value); } request.setEntity(new UrlEncodedFormEntity(nvps,HTTP.UTF_8)); HttpResponse response = client.execute(request); int code = response.getStatusLine().getStatusCode(); if(code == 200){ //请求成功 in = new BufferedReader(new InputStreamReader(response.getEntity() .getContent(),"utf-8")); StringBuffer sb = new StringBuffer(""); String line = ""; String NL = System.getProperty("line.separator"); while ((line = in.readLine()) != null) { sb.append(line + NL); } in.close(); return sb.toString(); } else{ // System.out.println("状态码：" + code); return null; } } catch(Exception e){ e.printStackTrace(); return null; } } /** * post请求（用于请求json格式的参数） * @param url * @param params * @return */ public static String doPost(String url, String params) throws Exception { CloseableHttpClient httpclient = HttpClients.createDefault(); HttpPost httpPost = new HttpPost(url);// 创建httpPost httpPost.setHeader("Accept", "application/json"); httpPost.setHeader("Content-Type", "application/json"); String charSet = "UTF-8"; StringEntity entity = new StringEntity(params, charSet); httpPost.setEntity(entity); CloseableHttpResponse response = null; try { response = httpclient.execute(httpPost); StatusLine status = response.getStatusLine(); int state = status.getStatusCode(); if (state == HttpStatus.SC_OK) { HttpEntity responseEntity = response.getEntity(); String jsonString = EntityUtils.toString(responseEntity); return jsonString; } else{ logger.error("请求返回:"+state+"("+url+")"); } } finally { if (response != null) { try { response.close(); } catch (IOException e) { e.printStackTrace(); } } try { httpclient.close(); } catch (IOException e) { e.printStackTrace(); } } return null; } }