Java后端调用第三方接口（HttpClient和OkHttpClient）

1.使用OkHttpClient调用第三方接口

（1）导入包

		<dependency>
            <groupId>com.squareup.okhttp3</groupId>
            <artifactId>okhttp</artifactId>
            <version>3.14.1</version>
        </dependency>

（2）实现代码入校

package com.***.util;

import okhttp3.*;

import java.io.IOException;

/**
 * http请求
 * @author zhouyaoming
 */
public class HttpClients {
    private static final OkHttpClient client = new OkHttpClient();
    private static final MediaType parse = MediaType.parse("application/json;charset=utf-8");

    /**
     * Get方法调用服务
     * @param url
     * @return
     * @throws IOException
     */
    public static String httpGet(String url) throws IOException {
        Request request = new Request.Builder()
                .url(url)
                .build();
        Response response = client.newCall(request).execute();
        return response.body().string();// 返回的是string 类型
    }

    /**
     * Post方法调用服务(json)
     * @param url
     * @param content
     * @return
     * @throws IOException
     */
    public static String httpPost4Json(String url, String content) throws IOException {
        RequestBody requestBody = RequestBody.create(parse, content);
        Request request = new Request.Builder()
                .url(url)
                .post(requestBody)
                .build();
        Response response = client.newCall(request).execute();
        return response.body().string();
    }

    /**
     * Post方法调用服务(form)
     * @param url
     * @param formBody
     * @return
     * @throws Exception
     */
    public static String httpPost4form(String url, FormBody formBody) throws Exception {
        Request request = new Request.Builder()
                .url(url)
                .post(formBody)
                .build();
        Response response = client.newCall(request).execute();
        return response.body().string();
    }
}

(3)发送请求
a.发送post请求，参数为json的格式

String result = HttpClients.httpPost4Json(url, JSONObject.fromObject(tpicRespSignDTO).toString());

b.发送post请求，参数是form的格式

FormBody body = new FormBody.Builder().add("appId", appId)
                    .add("sign", respSign)
                    .add("data", data).build();
String respStr = HttpClients.httpPost4form(url, body);

2.使用httpClient发送请求

package com.***.utils;

import lombok.extern.slf4j.Slf4j;
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.HttpClients;
import org.apache.http.util.EntityUtils;

import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;
import java.io.PrintWriter;
import java.net.URL;
import java.net.URLConnection;
import java.nio.charset.Charset;
import java.util.List;
import java.util.Map;

/**
 * 使用HttpClient发送请求
 * @author zhouyaoming
 */
@Slf4j
public class HttpClient {

    /**
     * 普通的GET请求
     *
     * @param url
     * @param param
     * @return
     */
    public static String doGet(String url, String param) {
        long startTime = System.currentTimeMillis();
        // 创建Httpclient对象
        CloseableHttpClient httpclient = HttpClients.createDefault();
        // 创建http GET请求
        HttpGet httpGet = null;
        if (null == param) {
            httpGet = new HttpGet(url);

        } else {
            httpGet = new HttpGet(url + "?" + param);

        }
        CloseableHttpResponse response = null;
        try {
            // 执行请求
            response = httpclient.execute(httpGet);
            // 判断返回状态是否为200
            if (response.getStatusLine().getStatusCode() == 200) {
                //请求体内容
                String content = EntityUtils.toString(response.getEntity(), "UTF-8");
//                System.out.println("请求时间:"+(System.currentTimeMillis()-startTime));

                return content;
            }
//            System.out.println("请求时间:"+(System.currentTimeMillis()-startTime));


        } catch (Exception e) {
            System.out.println(e.getLocalizedMessage());
        } finally {
            if (response != null) {
                try {
                    response.close();
                } catch (IOException e) {
                    e.printStackTrace();
                }
            }
            //相当于关闭浏览器
            try {
                httpclient.close();
            } catch (IOException e) {
                e.printStackTrace();
            }
        }
        return "";
    }


    /**
     * 向指定 URL 发送POST方法的请求
     *
     * @param url   发送请求的 URL
     * @param param 请求参数，请求参数应该是 name1=value1&name2=value2 的形式。
     * @return 所代表远程资源的响应结果
     */
    public static String sendPost(String url, String param) {
        PrintWriter out = null;
        BufferedReader in = null;
        String result = "";
        try {

            URL realUrl = new URL(url);
            // 打开和URL之间的连接
            URLConnection conn = realUrl.openConnection();
            // 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)");
            // 发送POST请求必须设置如下两行
            conn.setDoOutput(true);
            conn.setDoInput(true);
            // 获取URLConnection对象对应的输出流
            out = new PrintWriter(conn.getOutputStream());
            // 发送请求参数
            out.print(param);
            // flush输出流的缓冲
            out.flush();
            // 定义BufferedReader输入流来读取URL的响应
            in = new BufferedReader(
                    new InputStreamReader(conn.getInputStream()));
            String line;
            while ((line = in.readLine()) != null) {
                result += line;
            }
        } catch (Exception e) {
            System.out.println("发送 POST 请求出现异常！" + e);
            e.printStackTrace();
        }
        //使用finally块来关闭输出流、输入流
        finally {
            try {
                if (out != null) {
                    out.close();
                }
                if (in != null) {
                    in.close();
                }
            } catch (IOException ex) {
                ex.printStackTrace();
            }
        }
        return result;
    }


    /**
     * 发送post请求 json
     *
     * @param url
     * @param param
     * @return
     */
    public static String sendPostJson(String url, String param) {
        //创建client和post对象
        HttpPost post = new HttpPost(url);
        CloseableHttpClient httpclient = HttpClients.createDefault();
        //json形式
        post.addHeader("content-type", "application/json;charset=utf-8");
        post.addHeader("accept", "application/json");
        //json字符串以实体的实行放到post中
        post.setEntity(new StringEntity(param, Charset.forName("utf-8")));
        HttpResponse response = null;
        try {
            //获得response对象
            response = httpclient.execute(post);
        } catch (Exception e) {
            e.printStackTrace();
        }

        if (HttpStatus.SC_OK != response.getStatusLine().getStatusCode()) {
            System.out.println("请求返回不正确");
        }

        String result = "";
        try {
            //获得字符串形式的结果
            result = EntityUtils.toString(response.getEntity());
        } catch (Exception e) {
            e.printStackTrace();
        }
        System.out.println(result);
        return result;
    }

}