根据技术选型总结常见的三种方式发送http请求，本问介绍框架中常用的HttpClient和OkHttp方式，其他两种如下链接
java原生发送http请求_程序三两行的博客-CSDN博客
springboot中使用restTemplate发送http请求
一、httpclient
1、直接使用apache的HttpClient开发
使用方便，但依赖于第三方jar包，相关maven依赖如下：
<!-- https://mvnrepository.com/artifact/commons-httpclient/commons-httpclient --> <dependency> <groupId>commons-httpclient</groupId> <artifactId>commons-httpclient</artifactId> <version>3.1</version> </dependency
简单测试
package httpClient; import java.io.IOException; import org.apache.commons.httpclient.HttpClient; import org.apache.commons.httpclient.HttpException; import org.apache.commons.httpclient.methods.GetMethod; import org.apache.commons.httpclient.methods.PostMethod; import org.apache.commons.httpclient.params.HttpMethodParams; public class HttpClientHelper { public static String sendPost(String urlParam) throws HttpException, IOException { // 创建httpClient实例对象 HttpClient httpClient = new HttpClient(); // 设置httpClient连接主机服务器超时时间：15000毫秒 httpClient.getHttpConnectionManager().getParams().setConnectionTimeout(15000); // 创建post请求方法实例对象 PostMethod postMethod = new PostMethod(urlParam); // 设置post请求超时时间 postMethod.getParams().setParameter(HttpMethodParams.SO_TIMEOUT, 60000); postMethod.addRequestHeader("Content-Type", "application/json"); httpClient.executeMethod(postMethod); String result = postMethod.getResponseBodyAsString(); postMethod.releaseConnection(); return result; } public static String sendGet(String urlParam) throws HttpException, IOException { // 创建httpClient实例对象 HttpClient httpClient = new HttpClient(); // 设置httpClient连接主机服务器超时时间：15000毫秒 httpClient.getHttpConnectionManager().getParams().setConnectionTimeout(15000); // 创建GET请求方法实例对象 GetMethod getMethod = new GetMethod(urlParam); // 设置post请求超时时间 getMethod.getParams().setParameter(HttpMethodParams.SO_TIMEOUT, 60000); getMethod.addRequestHeader("Content-Type", "application/json"); httpClient.executeMethod(getMethod); String result = getMethod.getResponseBodyAsString(); getMethod.releaseConnection(); return result; } public static void main(String[] args) throws HttpException, IOException { String url ="http://int.dpool.sina.com.cn/iplookup/iplookup.php?ip=120.79.75.96"; System.out.println(sendPost(url)); System.out.println(sendGet(url)); } }
比较全的工具类
导入jar
<dependency> <groupId>com.alibaba</groupId> <artifactId>fastjson</artifactId> <version>1.2.32</version> </dependency>
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; 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、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。
<!--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>
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; 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"); } }
二、okhttp
引入依赖
<dependency> <groupId>com.squareup.okhttp3</groupId> <artifactId>okhttp</artifactId> <version>3.10.0</version> </dependency>
参考文章
HTTP连接客户端，选 HttpClient 还是 OkHttp ？_Java技术头条的博客-CSDN博客
