在实际开发过程中，我们经常需要调用对方提供的接口或测试自己写的接口是否合适。很多项目都会封装规定好本身项目的接口规范，所以大多数需要去调用对方提供的接口或第三方接口（短信、天气等）
①通过JDK网络类Java.net.HttpURLConnection；
②通过common封装好的HttpClient；
③通过Apache封装好的CloseableHttpClient；
④通过SpringBoot-RestTemplate；
一、通过SpringBoot-RestTemplate方式（其余几种的集大成者）
目前可以采用的调用第三方接口有：
- delete() ： 在特定的URL上对资源执行HTTP DELETE操作
- exchange() ： 在URL上执行特定的HTTP方法，返回包含对象的ResponseEntity，这个对象是从响应体中映射得到的
- execute() ： 在URL上执行特定的HTTP方法，返回一个从响应体映射得到的对象
- getForEntity() ：发送一个HTTP GET请求，返回的ResponseEntity包含了响应体所映射成的对象
- getForObject() ：发送一个HTTP GET请求，返回的请求体将映射为一个对象
- postForEntity() ：POST 数据到一个URL，返回包含一个对象的ResponseEntity，这个对象是从响应体中映射得到的
- postForObject()： POST 数据到一个URL，返回根据响应体匹配形成的对象
- headForHeaders() ：发送HTTP HEAD请求，返回包含特定资源URL的HTTP头
- optionsForAllow() ：发送HTTP OPTIONS请求，返回对特定URL的Allow头信息
- postForLocation() ：POST 数据到一个URL，返回新创建资源的URL
- put() ：PUT 资源到特定的URL
1.1、RestTemplateConfig.java类
import org.springframework.context.annotation.Bean;import org.springframework.context.annotation.Configuration;import org.springframework.http.client.ClientHttpRequestFactory;import org.springframework.http.client.SimpleClientHttpRequestFactory;import org.springframework.web.client.RestTemplate; @Configurationpublic class RestTemplateConfig { @Bean public RestTemplate restTemplate(ClientHttpRequestFactory factory){ return new RestTemplate(factory); } @Bean public ClientHttpRequestFactory simpleClientHttpRequestFactory(){ SimpleClientHttpRequestFactory factory = new SimpleClientHttpRequestFactory(); factory.setConnectTimeout(15000); factory.setReadTimeout(5000); return factory; }}1.2、然后在Service类（RestTemplateToInterface ）中注入使用
import com.alibaba.fastjson.JSONObject;import com.swordfall.model.User;import org.springframework.beans.factory.annotation.Autowired;import org.springframework.http.*;import org.springframework.stereotype.Service;import org.springframework.web.client.RestTemplate; @Servicepublic class RestTemplateToInterface { @Autowired private RestTemplate restTemplate; public User doGetWith1(String url){ ResponseEntity responseEntity = restTemplate.getForEntity(url, User.class); User user = responseEntity.getBody(); return user; } public User doGetWith2(String url){ User user = restTemplate.getForObject(url, User.class); return user; } public String doPostWith1(String url){ User user = new User("小白", 20); ResponseEntity responseEntity = restTemplate.postForEntity(url, user, String.class); String body = responseEntity.getBody(); return body; } public String doPostWith2(String url){ User user = new User("小白", 20); String body = restTemplate.postForObject(url, user, String.class); return body; } public String doExchange(String url, Integer age, String name){ //header参数 HttpHeaders headers = new HttpHeaders(); String token = "asdfaf2322"; headers.add("authorization", token); headers.setContentType(MediaType.APPLICATION_JSON); //放入body中的json参数 JSONObject obj = new JSONObject(); obj.put("age", age); obj.put("name", name); //组装 HttpEntity request = new HttpEntity<>(obj, headers); ResponseEntity responseEntity = restTemplate.exchange(url, HttpMethod.POST, request, String.class); String body = responseEntity.getBody(); return body; }} 二、通过JDK网络类Java.net.HttpURLConnection
比较原始的一种调用做法，这里把get请求和post请求都统一放在一个方法里面
import java.io.*;import java.net.HttpURLConnection;import java.net.MalformedURLException;import java.net.URL;public class HttpUrlConnectionToInterface { public static void doPostOrGet(String pathUrl, String data){ OutputStreamWriter out = null; BufferedReader br = null; String result = ""; try { URL url = new URL(pathUrl); //打开和url之间的连接 HttpURLConnection conn = (HttpURLConnection) url.openConnection(); //请求方式 conn.setRequestMethod("POST"); //conn.setRequestMethod("GET"); //设置通用的请求属性 conn.setRequestProperty("accept", "* //获取URLConnection对象对应的输出流 out = new OutputStreamWriter(conn.getOutputStream(), "UTF-8"); //发送请求参数即数据 out.write(data); //flush输出流的缓冲 out.flush(); //获取URLConnection对象对应的输入流 InputStream is = conn.getInputStream(); //构造一个字符流缓存 br = new BufferedReader(new InputStreamReader(is)); String str = ""; while ((str = br.readLine()) != null){ result += str; } System.out.println(result); //关闭流 is.close(); //断开连接，disconnect是在底层tcp socket链接空闲时才切断，如果正在被其他线程使用就不切断。 conn.disconnect(); } catch (Exception e) { e.printStackTrace(); }finally { try { if (out != null){ out.close(); } if (br != null){ br.close(); } } catch (IOException e) { e.printStackTrace(); } } } public static void main(String[] args) { doPostOrGet("https://tcc.taobao.com/cc/json/mobile_tel_segment.htm?tel=13026194071", ""); }}三、 通过apache common封装好的HttpClient
（1）httpClient的get或post请求方式步骤
- 生成一个HttpClient对象并设置相应的参数；
- 生成一个GetMethod对象或PostMethod并设置响应的参数；
- 用HttpClient生成的对象来执行GetMethod生成的Get方法；
- 处理响应状态码；
- 若响应正常，处理HTTP响应内容；
- 释放连接。
（2）导入如下jar包
commons-httpclient commons-httpclient 3.1 import com.alibaba.fastjson.JSONObject;import org.apache.commons.httpclient.*;import org.apache.commons.httpclient.methods.GetMethod;import org.apache.commons.httpclient.methods.PostMethod;import org.apache.commons.httpclient.params.HttpMethodParams; import java.io.IOException;import java.io.InputStream;public class HttpClientToInterface { public static String doGet(String url, String charset){ HttpClient httpClient = new HttpClient(); //设置Http连接超时为5秒 httpClient.getHttpConnectionManager().getParams().setConnectionTimeout(5000); GetMethod getMethod = new GetMethod(url); //设置get请求超时为5秒 getMethod.getParams().setParameter(HttpMethodParams.SO_TIMEOUT, 5000); //设置请求重试处理，用的是默认的重试处理：请求三次 getMethod.getParams().setParameter(HttpMethodParams.RETRY_HANDLER, new DefaultHttpMethodRetryHandler()); String response = ""; try { int statusCode = httpClient.executeMethod(getMethod); if (statusCode != HttpStatus.SC_OK){ System.err.println("请求出错：" + getMethod.getStatusLine()); } //HTTP响应头部信息，这里简单打印 Header[] headers = getMethod.getResponseHeaders(); for (Header h: headers){ System.out.println(h.getName() + "---------------" + h.getValue()); } //读取HTTP响应内容，这里简单打印网页内容 //读取为字节数组 byte[] responseBody = getMethod.getResponseBody(); response = new String(responseBody, charset); System.out.println("-----------response:" + response); //读取为InputStream，在网页内容数据量大时候推荐使用 //InputStream response = getMethod.getResponseBodyAsStream(); } catch (HttpException e) { //发生致命的异常，可能是协议不对或者返回的内容有问题 System.out.println("请检查输入的URL!"); e.printStackTrace(); } catch (IOException e){ //发生网络异常 System.out.println("发生网络异常!"); }finally { getMethod.releaseConnection(); } return response; } public static String doPost(String url, JSONObject json){ HttpClient httpClient = new HttpClient(); PostMethod postMethod = new PostMethod(url); postMethod.addRequestHeader("accept", "* public static String doGet(String url, String token){ //创建HttpClient对象 CloseableHttpClient httpClient = HttpClientBuilder.create().build(); HttpGet get = new HttpGet(url); try { if (tokenString != null && !tokenString.equals("")){ tokenString = getToken(); } //api_gateway_auth_token自定义header头，用于token验证使用 get.addHeader("api_gateway_auth_token", tokenString); get.addHeader("User-Agent", "Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/58.0.3029.81 Safari/537.36"); HttpResponse response = httpClient.execute(get); if (response.getStatusLine().getStatusCode() == HttpStatus.SC_OK){ //返回json格式 String res = EntityUtils.toString(response.getEntity()); return res; } } catch (IOException e) { e.printStackTrace(); } return null; } public static String doPost(String url, JSONObject json){ try { if (httpClient == null){ httpClient = HttpClientBuilder.create().build(); } HttpPost post = new HttpPost(url); if (tokenString != null && !tokenString.equals("")){ tokenString = getToken(); } //api_gateway_auth_token自定义header头，用于token验证使用 post.addHeader("api_gateway_auth_token", tokenString); post.addHeader("User-Agent", "Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/58.0.3029.81 Safari/537.36"); StringEntity s = new StringEntity(json.toString()); s.setContentEncoding("UTF-8"); //发送json数据需要设置contentType s.setContentType("application/x-www-form-urlencoded"); //设置请求参数 post.setEntity(s); HttpResponse response = httpClient.execute(post); if (response.getStatusLine().getStatusCode() == HttpStatus.SC_OK){ //返回json格式 String res = EntityUtils.toString(response.getEntity()); return res; } } catch (Exception e) { e.printStackTrace(); }finally { if (httpClient != null){ try { httpClient.close(); } catch (IOException e) { e.printStackTrace(); } } } return null; } public static String getToken(){ String token = ""; JSONObject object = new JSONObject(); object.put("appid", "appid"); object.put("secretkey", "secretkey"); try { if (httpClient == null){ httpClient = HttpClientBuilder.create().build(); } HttpPost post = new HttpPost("http://localhost/login"); post.addHeader("User-Agent", "Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/58.0.3029.81 Safari/537.36"); StringEntity s = new StringEntity(object.toString()); s.setContentEncoding("UTF-8"); //发送json数据需要设置contentType s.setContentType("application/x-www-form-urlencoded"); //设置请求参数 post.setEntity(s); HttpResponse response = httpClient.execute(post); //这里可以把返回的结果按照自定义的返回数据结果，把string转换成自定义类 //ResultTokenBO result = JSONObject.parseObject(response, ResultTokenBO.class); //把response转为jsonObject JSONObject result = JSONObject.parseObject(response); if (result.containsKey("token")){ token = result.getString("token"); } } catch (Exception e) { e.printStackTrace(); } return token; } public static void test(String telephone){ JSONObject object = new JSONObject(); object.put("telephone", telephone); try { //首先获取token tokenString = getToken(); String response = doPost("http://localhost/searchUrl", object); //如果返回的结果是list形式的，需要使用JSONObject.parseArray转换 //List list = JSONObject.parseArray(response, Result.class); System.out.println(response); } catch (Exception e) { e.printStackTrace(); } } public static void main(String[] args) { test("12345678910"); } } public static void doPost(String url, String name, String pwd, String phone, String content) {// 创建默认的httpClient实例.CloseableHttpClient httpclient = HttpClients.createDefault();// 创建httppostHttpPost httppost = new HttpPost(url);// 创建参数队列List formparams = new ArrayList();formparams.add(new BasicNameValuePair("account", name));formparams.add(new BasicNameValuePair("passwd", pwd));formparams.add(new BasicNameValuePair("phone", phone));formparams.add(new BasicNameValuePair("content", content));UrlEncodedFormEntity uefEntity;try {uefEntity = new UrlEncodedFormEntity(formparams, "UTF-8");httppost.setEntity(uefEntity);System.out.println("executing request " + httppost.getURI());CloseableHttpResponse response = httpclient.execute(httppost);try {HttpEntity entity = response.getEntity();if (entity != null) {System.out.println("Response content: " + EntityUtils.toString(entity, "UTF-8"));}} finally {response.close();}} catch (Exception e) {e.printStackTrace();} finally {// 关闭连接,释放资源try {httpclient.close();} catch (IOException e) {e.printStackTrace();}}} 来源地址：https://blog.csdn.net/qq_43842093/article/details/129292201
