java实现调用http请求的几种常见方式
一、概述
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）。
在Java项目中调用第三方接口的方式有：
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；
二、 Java调用第三方http接口的方式
2.1、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。
实现过程：
GET: 1、创建远程连接 2、设置连接方式（get、post、put。。。） 3、设置连接超时时间 4、设置响应读取时间 5、发起请求 6、获取请求数据 7、关闭连接 POST: 1、创建远程连接 2、设置连接方式（get、post、put。。。） 3、设置连接超时时间 4、设置响应读取时间 5、当向远程服务器传送数据/写数据时，需要设置为true（setDoOutput） 6、当前向远程服务读取数据时，设置为true，该参数可有可无（setDoInput） 7、设置传入参数的格式:（setRequestProperty） 8、设置鉴权信息：Authorization:（setRequestProperty） 9、设置参数 10、发起请求 11、获取请求数据 12、关闭连接
直接上代码:
package com.xxxx.util.common.httpConnectionUtil; import org.springframework.lang.Nullable; import java.io.*; import java.net.HttpURLConnection; import java.net.MalformedURLException; import java.net.URL; import java.net.URLConnection; /** * @author riemann * @date 2019/05/24 23:42 */ public class HttpURLConnectionUtil { /** * Http get请求 * @param httpUrl 连接 * @return 响应数据 */ public static String doGet(String httpUrl){ //链接 HttpURLConnection connection = null; InputStream is = null; BufferedReader br = null; StringBuffer result = new StringBuffer(); try { //创建连接 URL url = new URL(httpUrl); connection = (HttpURLConnection) url.openConnection(); //设置请求方式 connection.setRequestMethod("GET"); //设置连接超时时间 connection.setReadTimeout(15000); //开始连接 connection.connect(); //获取响应数据 if (connection.getResponseCode() == 200) { //获取返回的数据 is = connection.getInputStream(); if (null != is) { br = new BufferedReader(new InputStreamReader(is, "UTF-8")); String temp = null; while (null != (temp = br.readLine())) { result.append(temp); } } } } catch (IOException e) { e.printStackTrace(); } finally { if (null != br) { try { br.close(); } catch (IOException e) { e.printStackTrace(); } } if (null != is) { try { is.close(); } catch (IOException e) { e.printStackTrace(); } } //关闭远程连接 connection.disconnect(); } return result.toString(); } /** * Http post请求 * @param httpUrl 连接 * @param param 参数 * @return */ public static String doPost(String httpUrl, @Nullable String param) { StringBuffer result = new StringBuffer(); //连接 HttpURLConnection connection = null; OutputStream os = null; InputStream is = null; BufferedReader br = null; try { //创建连接对象 URL url = new URL(httpUrl); //创建连接 connection = (HttpURLConnection) url.openConnection(); //设置请求方法 connection.setRequestMethod("POST"); //设置连接超时时间 connection.setConnectTimeout(15000); //设置读取超时时间 connection.setReadTimeout(15000); //DoOutput设置是否向httpUrlConnection输出，DoInput设置是否从httpUrlConnection读入，此外发送post请求必须设置这两个 //设置是否可读取 connection.setDoOutput(true); connection.setDoInput(true); //设置通用的请求属性 connection.setRequestProperty("accept", "*/*"); connection.setRequestProperty("connection", "Keep-Alive"); connection.setRequestProperty("user-agent", "Mozilla/4.0 (compatible; MSIE 6.0; Windows NT 5.1; SV1)"); connection.setRequestProperty("Content-Type", "application/json;charset=utf-8"); //拼装参数 if (null != param && param.equals("")) { //设置参数 os = connection.getOutputStream(); //拼装参数 os.write(param.getBytes("UTF-8")); } //设置权限 //设置请求头等 //开启连接 //connection.connect(); //读取响应 if (connection.getResponseCode() == 200) { is = connection.getInputStream(); if (null != is) { br = new BufferedReader(new InputStreamReader(is, "GBK")); String temp = null; while (null != (temp = br.readLine())) { result.append(temp); result.append("\r\n"); } } } } catch (MalformedURLException e) { e.printStackTrace(); } catch (IOException e) { e.printStackTrace(); } finally { //关闭连接 if(br!=null){ try { br.close(); } catch (IOException e) { e.printStackTrace(); } } if(os!=null){ try { os.close(); } catch (IOException e) { e.printStackTrace(); } } if(is!=null){ try { is.close(); } catch (IOException e) { e.printStackTrace(); } } //关闭连接 connection.disconnect(); } return result.toString(); } public static void main(String[] args) { String message = doPost("https://tcc.taobao.com/cc/json/mobile_tel_segment.htm?tel=13026194071", ""); System.out.println(message); } }
2.2 通过apache common封装好的HttpClient
httpClient的get或post请求方式步骤：
1.生成一个HttpClient对象并设置相应的参数； 2.生成一个GetMethod对象或PostMethod并设置响应的参数； 3.用HttpClient生成的对象来执行GetMethod生成的Get方法； 4.处理响应状态码； 5.若响应正常，处理HTTP响应内容； 6.释放连接。
导入如下jar包：
<!--HttpClient--> <dependency> <groupId>commons-httpclient</groupId> <artifactId>commons-httpclient</artifactId> <version>3.1</version> </dependency> <!--fastjson--> <dependency> <groupId>com.alibaba</groupId> <artifactId>fastjson</artifactId> <version>1.2.32</version> </dependency>
代码如下：
package com.riemann.springbootdemo.util.common.httpConnectionUtil; 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; /** * @author riemann * @date 2019/05/25 0:58 */ public class HttpClientUtil { /** * httpClient的get请求方式 * 使用GetMethod来访问一个URL对应的网页实现步骤： * 1.生成一个HttpClient对象并设置相应的参数； * 2.生成一个GetMethod对象并设置响应的参数； * 3.用HttpClient生成的对象来执行GetMethod生成的Get方法； * 4.处理响应状态码； * 5.若响应正常，处理HTTP响应内容； * 6.释放连接。 * @param url * @param charset * @return */ public static String doGet(String url, String charset) { //1.生成HttpClient对象并设置参数 HttpClient httpClient = new HttpClient(); //设置Http连接超时为5秒 httpClient.getHttpConnectionManager().getParams().setConnectionTimeout(5000); //2.生成GetMethod对象并设置参数 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 = ""; //3.执行HTTP GET 请求 try { int statusCode = httpClient.executeMethod(getMethod); //4.判断访问的状态码 if (statusCode != HttpStatus.SC_OK) { System.err.println("请求出错：" + getMethod.getStatusLine()); } //5.处理HTTP响应内容 //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 { //6.释放连接 getMethod.releaseConnection(); } return response; } /** * post请求 * @param url * @param json * @return */ public static String doPost(String url, JSONObject json){ HttpClient httpClient = new HttpClient(); PostMethod postMethod = new PostMethod(url); postMethod.addRequestHeader("accept", "*/*"); postMethod.addRequestHeader("connection", "Keep-Alive"); //设置json格式传送 postMethod.addRequestHeader("Content-Type", "application/json;charset=GBK"); //必须设置下面这个Header postMethod.addRequestHeader("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"); //添加请求参数 postMethod.addParameter("commentId", json.getString("commentId")); String res = ""; try { int code = httpClient.executeMethod(postMethod); if (code == 200){ res = postMethod.getResponseBodyAsString(); System.out.println(res); } } catch (IOException e) { e.printStackTrace(); } return res; } public static void main(String[] args) { System.out.println(doGet("http://tcc.taobao.com/cc/json/mobile_tel_segment.htm?tel=13026194071", "GBK")); System.out.println("-----------分割线------------"); System.out.println("-----------分割线------------"); System.out.println("-----------分割线------------"); JSONObject jsonObject = new JSONObject(); jsonObject.put("commentId", "13026194071"); System.out.println(doPost("http://tcc.taobao.com/cc/json/mobile_tel_segment.htm?tel=13026194071", jsonObject)); } }
2.3 通过Apache封装好的CloseableHttpClient
CloseableHttpClient是在HttpClient的基础上修改更新而来的，这里还涉及到请求头token的设置（请求验证），利用fastjson转换请求或返回结果字符串为json格式，当然上面两种方式也是可以设置请求头token、json的，这里只在下面说明。
导入如下jar包：
<!--CloseableHttpClient-->
<dependency>
<groupId>org.apache.httpcomponents</groupId>
<artifactId>httpclient</artifactId>
<version>4.5.2</version>
</dependency>
<!--fastjson-->
<dependency>
<groupId>com.alibaba</groupId>
<artifactId>fastjson</artifactId>
<version>1.2.32</version>
</dependency>
代码如下：
package com.riemann.springbootdemo.util.common.httpConnectionUtil; import com.alibaba.fastjson.JSONObject; import org.apache.http.HttpResponse; import org.apache.http.HttpStatus; 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.entity.StringEntity; import org.apache.http.impl.client.CloseableHttpClient; import org.apache.http.impl.client.HttpClientBuilder; import org.apache.http.util.EntityUtils; import java.io.IOException; import java.io.UnsupportedEncodingException; /** * @author riemann * @date 2019/05/25 1:35 */ public class CloseableHttpClientUtil { private static String tokenString = ""; private static String AUTH_TOKEN_EXPIRED = "AUTH_TOKEN_EXPIRED"; private static CloseableHttpClient httpClient = null; /** * 以get方式调用第三方接口 * @param url * @param token * @return */ public static String doGet(String url, String token) { //创建HttpClient对象 CloseableHttpClient httpClient = HttpClientBuilder.create().build(); HttpGet httpGet = new HttpGet(url); if (null != tokenString && !tokenString.equals("")) { tokenString = getToken(); } //api_gateway_auth_token自定义header头，用于token验证使用 httpGet.addHeader("api_gateway_auth_token",tokenString); httpGet.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"); try { HttpResponse response = httpClient.execute(httpGet); 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; } /** * 以post方式调用第三方接口 * @param url * @param json * @return */ public static String doPost(String url, JSONObject json) { if (null == httpClient) { httpClient = HttpClientBuilder.create().build(); } HttpPost httpPost = new HttpPost(url); if (null != tokenString && tokenString.equals("")) { tokenString = getToken(); } //api_gateway_auth_token自定义header头，用于token验证使用 httpPost.addHeader("api_gateway_auth_token", tokenString); httpPost.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"); try { StringEntity se = new StringEntity(json.toString()); se.setContentEncoding("UTF-8"); //发送json数据需要设置contentType se.setContentType("application/x-www-form-urlencoded"); //设置请求参数 httpPost.setEntity(se); HttpResponse response = httpClient.execute(httpPost); 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(); } finally { if (httpClient != null){ try { httpClient.close(); } catch (IOException e) { e.printStackTrace(); } } } return null; } /** * 获取第三方接口的token */ public static String getToken() { String token = ""; JSONObject object = new JSONObject(); object.put("appid", "appid"); object.put("secretkey", "secretkey"); if (null == httpClient) { httpClient = HttpClientBuilder.create().build(); } HttpPost httpPost = new HttpPost("http://localhost/login"); httpPost.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"); try { StringEntity se = new StringEntity(object.toString()); se.setContentEncoding("UTF-8"); //发送json数据需要设置contentType se.setContentType("application/x-www-form-urlencoded"); //设置请求参数 httpPost.setEntity(se); HttpResponse response = httpClient.execute(httpPost); //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) JSONObject.parseObject(String.valueOf(response)); if (result.containsKey("token")) { token = result.getString("token"); } } catch (IOException e) { e.printStackTrace(); } return token; } /** * 测试 */ public static void test(String telephone) { JSONObject object = new JSONObject(); object.put("telephone", telephone); //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<Result> list = JSONObject.parseArray(response, Result.class); System.out.println(response); } public static void main(String[] args) { test("12345678910"); } }
2.4 通过SpringBoot-RestTemplate
springBoot-RestTemple是上面三种方式的集大成者，代码编写更加简单，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
注意：目前标粗的为常用的
首先导入springboot的web包
<parent>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-parent</artifactId>
<version>2.0.4.RELEASE</version>
</parent>
<dependencies>
<!--CloseableHttpClient-->
<dependency>
<groupId>org.apache.httpcomponents</groupId>
<artifactId>httpclient</artifactId>
<version>4.5.2</version>
</dependency>
<!--spring restTemplate-->
<!-- @ConfigurationProperties annotation processing (metadata for IDEs)
生成spring-configuration-metadata.json类，需要引入此类-->
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-configuration-processor</artifactId>
<optional>true</optional>
</dependency>
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-aop</artifactId>
</dependency>
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-web</artifactId>
<exclusions>
<exclusion>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-tomcat</artifactId>
</exclusion>
</exclusions>
</dependency>
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-jetty</artifactId>
</dependency>
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-test</artifactId>
<scope>test</scope>
</dependency>
</dependencies>
在启动类同包下创建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; /** * @author riemann * @date 2019/05/25 2:16 */ @Configuration public 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; } }
然后在Service类（RestTemplateToInterface ）中注入使用
具体代码如下：
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; /** * @author riemann * @date 2019/05/25 2:20 */ @Service public class RestTemplateToInterface { @Autowired private RestTemplate restTemplate; /** * 以get方式请求第三方http接口 getForEntity * @param url * @return */ public User doGetWith1(String url){ ResponseEntity<User> responseEntity = restTemplate.getForEntity(url, User.class); User user = responseEntity.getBody(); return user; } /** * 以get方式请求第三方http接口 getForObject * 返回值返回的是响应体，省去了我们再去getBody() * @param url * @return */ public User doGetWith2(String url){ User user = restTemplate.getForObject(url, User.class); return user; } /** * 以post方式请求第三方http接口 postForEntity * @param url * @return */ public String doPostWith1(String url){ User user = new User("小白", 20); ResponseEntity<String> responseEntity = restTemplate.postForEntity(url, user, String.class); String body = responseEntity.getBody(); return body; } /** * 以post方式请求第三方http接口 postForEntity * @param url * @return */ public String doPostWith2(String url){ User user = new User("小白", 20); String body = restTemplate.postForObject(url, user, String.class); return body; } /** * exchange * @return */ 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<JSONObject> request = new HttpEntity<>(obj, headers); ResponseEntity<String> responseEntity = restTemplate.exchange(url, HttpMethod.POST, request, String.class); String body = responseEntity.getBody(); return body; } }
2.5 通过okhttp
应大家的响应，okhttp 现在也是蛮流行的，基于手机端很火，这里分享一下OkHttpClient客户端，业务代码get、post请求直接调用就好哈。
pom文件引入依赖包
<dependency>
<groupId>com.squareup.okhttp3</groupId>
<artifactId>okhttp</artifactId>
<version>3.10.0</version>
</dependency>
@Slf4j public class OkHttpClient { private static final MediaType JSON = MediaType.parse("application/json; charset=utf-8"); private volatile static okhttp3.OkHttpClient client; private static final int MAX_IDLE_CONNECTION = Integer .parseInt(ConfigManager.get("httpclient.max_idle_connection")); private static final long KEEP_ALIVE_DURATION = Long .parseLong(ConfigManager.get("httpclient.keep_alive_duration")); private static final long CONNECT_TIMEOUT = Long.parseLong(ConfigManager.get("httpclient.connectTimeout")); private static final long READ_TIMEOUT = Long.parseLong(ConfigManager.get("httpclient. ")); /** * 单例模式(双重检查模式) 获取类实例 * * @return client */ private static okhttp3.OkHttpClient getInstance() { if (client == null) { synchronized (okhttp3.OkHttpClient.class) { if (client == null) { client = new okhttp3.OkHttpClient.Builder() .connectTimeout(CONNECT_TIMEOUT, TimeUnit.SECONDS) .readTimeout(READ_TIMEOUT, TimeUnit.SECONDS) .connectionPool(new ConnectionPool(MAX_IDLE_CONNECTION, KEEP_ALIVE_DURATION, TimeUnit.MINUTES)) .build(); } } } return client; } public static String syncPost(String url, String json) throws IOException { RequestBody body = RequestBody.create(JSON, json); Request request = new Request.Builder() .url(url) .post(body) .build(); try { Response response = OkHttpClient.getInstance().newCall(request).execute(); if (response.isSuccessful()) { String result = response.body().string(); log.info("syncPost response = {}, responseBody= {}", response, result); return result; } String result = response.body().string(); log.info("syncPost response = {}, responseBody= {}", response, result); throw new IOException("三方接口返回http状态码为" + response.code()); } catch (Exception e) { log.error("syncPost() url:{} have a ecxeption {}", url, e); throw new RuntimeException("syncPost() have a ecxeption {}" + e.getMessage()); } } public static String syncGet(String url, Map<String, Object> headParamsMap) throws IOException { Request request; final Request.Builder builder = new Request.Builder().url(url); try { if (!CollectionUtils.isEmpty(headParamsMap)) { final Iterator<Map.Entry<String, Object>> iterator = headParamsMap.entrySet() .iterator(); while (iterator.hasNext()) { final Map.Entry<String, Object> entry = iterator.next(); builder.addHeader(entry.getKey(), (String) entry.getValue()); } } request = builder.build(); Response response = OkHttpClient.getInstance().newCall(request).execute(); String result = response.body().string(); log.info("syncGet response = {},responseBody= {}", response, result); if (!response.isSuccessful()) { throw new IOException("三方接口返回http状态码为" + response.code()); } return result; } catch (Exception e) { log.error("remote interface url:{} have a ecxeption {}", url, e); throw new RuntimeException("三方接口返回异常"); } } }
