调用别人的接口的几种方法

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；

2. 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，直接上代码：

import java.io.*;
import java.net.HttpURLConnection;
import java.net.MalformedURLException;
import java.net.URL;

/**
 * @Author: Yang JianQiu
 * @Date: 2019/4/26 11:34
 * jdk类HttpURLConnection调用第三方http接口
 *
 * 通常分get和post两种方式
 *
 * 参考资料：
 * http://www.cnblogs.com/angusbao/p/7727649.html
 */
public class HttpUrlConnectionToInterface {

    /**
     * 以post或get方式调用对方接口方法，
     * @param pathUrl
     */
    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", "*/*");
            conn.setRequestProperty("connection", "Keep-Alive");
            conn.setRequestProperty("user-agent", "Mozilla/4.0 (compatible; MSIE 6.0; Windows NT 5.1; SV1)");
            conn.setRequestProperty("Content-Type", "application/json;charset=utf-8");

            //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
            conn.setDoOutput(true);
            conn.setDoInput(true);

            /**
             * 下面的三句代码，就是调用第三方http接口
             */
            //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();

            /**
             * 下面的代码相当于，获取调用第三方http接口后返回的结果
             */
            //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) {
        /**
         *手机信息查询接口：http://tcc.taobao.com/cc/json/mobile_tel_segment.htm?tel=手机号
　　　　 *　　　　　　http://api.showji.com/Locating/www.showji.com.aspx?m=手机号&output=json&callback=querycallback
         */
        doPostOrGet("https://tcc.taobao.com/cc/json/mobile_tel_segment.htm?tel=13026194071", "");
    }
}

2.2 通过apache common封装好的HttpClient
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。
导入如下jar包：

  <!--HttpClient-->
        <dependency>
            <groupId>commons-httpclient</groupId>
            <artifactId>commons-httpclient</artifactId>
            <version>3.1</version>
        </dependency>

代码如下：

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;

/**
 * @Author: Yang JianQiu
 * @Date: 2019/4/28 11:07
 *
 * HttpClient模拟get、post请求并发送请求参数（json等）
 * 【参考资料】
 * https://javasam.iteye.com/blog/2117845
 * https://blog.csdn.net/qq_28379809/article/details/82898792
 */
public class HttpClientToInterface {

    /**
     * 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=utf-8");
        //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) {
        doGet("http://tcc.taobao.com/cc/json/mobile_tel_segment.htm?tel=13026194071", "UTF-8");
        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");
        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>
        <dependency>
            <groupId>com.alibaba</groupId>
            <artifactId>fastjson</artifactId>
            <version>1.2.28</version>
        </dependency>

代码如下：

import com.alibaba.fastjson.JSONObject;
import org.apache.http.HttpResponse;
import org.apache.http.HttpStatus;
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;

/**
 * @Author: Yang JianQiu
 * @Date: 2019/4/26 11:41
 * Apache封装好的CloseableHttpClient
 * 【参考资料】
 *  https://www.cnblogs.com/siv8/p/6222709.html
 *  https://blog.csdn.net/qq_35860138/article/details/82967727
 */
public class CloseableHttpClientToInterface {

    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
     * @return
     */
    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;
    }

    /**
     * 以post方式调用第三方接口
     * @param url
     * @param json
     * @return
     */
    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;
    }

    /**
     * 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");

        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;
    }

    /**
     * 测试
     */
    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");
    }

}

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：目前标红的为常用的

首先导入springboot的web包

复制代码

<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: Yang JianQiu
 * @Date: 2019/4/28 14:01
 */
@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: Yang JianQiu
 * @Date: 2019/4/28 14:13
 *
 * 【参考资料】
 * https://blog.csdn.net/qq_15452971/article/details/79416469
 * https://blog.csdn.net/weixin_40461281/article/details/83540604
 */
@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;
    }
}