java实现调用http请求的几种常见方式

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；

Java调用第三方http接口的方式

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

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);
   }
}

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>
 
<!--fastjson-->
<dependency>
    <groupId>com.alibaba</groupId>
    <artifactId>fastjson</artifactId>
    <version>1.2.32</version>
</dependency>

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));
    }
}

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>

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");
    }
}

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");
        }
    }
 
}