之前用的是 HttpClient ，发现好难用！
后来发现 OkHttp3 这个请求工具挺好用的！
目前只封装了 get、post 、以及文件流上传

        <!-- https://mvnrepository.com/artifact/com.squareup.okhttp3/okhttp -->
        <dependency>
            <groupId>com.squareup.okhttp3</groupId>
            <artifactId>okhttp</artifactId>
            <version>4.2.2</version>
        </dependency>

        <!-- https://mvnrepository.com/artifact/com.google.guava/guava -->
        <dependency>
            <groupId>com.google.guava</groupId>
            <artifactId>guava</artifactId>
            <version>28.1-jre</version>
        </dependency>
        <!-- https://mvnrepository.com/artifact/org.apache.commons/commons-lang3 -->
        <dependency>
            <groupId>org.apache.commons</groupId>
            <artifactId>commons-lang3</artifactId>
            <version>3.9</version>
        </dependency>

        <!-- https://mvnrepository.com/artifact/com.alibaba/fastjson -->
        <dependency>
            <groupId>com.alibaba</groupId>
            <artifactId>fastjson</artifactId>
            <version>1.2.62</version>
        </dependency>

更新日志：

2019/11/21 新增 JSON格式数据请求

import com.alibaba.fastjson.JSONObject;
import com.google.common.collect.Maps;
import okhttp3.*;
import org.apache.commons.lang3.StringUtils;

import java.io.*;
import java.util.Iterator;
import java.util.Map;

/**
 * 封装请求
 * @author weiximei
 */
public class OkHttpRequestUtils {

    /**
     * 定义请求客户端
     */
    private static OkHttpClient client = new OkHttpClient();

    /**
     * get 请求
     * @param url 请求URL
     * @return
     * @throws Exception
     */
    public static String doGet(String url) throws Exception {
        return doGet(url, Maps.newHashMap());
    }


    /**
     * get 请求
     * @param url 请求URL
     * @param query 携带参数参数
     * @return
     * @throws Exception
     */
    public static String doGet(String url, Map<String, Object> query) throws Exception {

        return doGet(url, Maps.newHashMap(), query);
    }

    /**
     * get 请求
     * @param url url
     * @param header 请求头参数
     * @param query 参数
     * @return
     */
    public static String doGet(String url, Map<String, Object> header, Map<String, Object> query) throws Exception {

        // 创建一个请求 Builder
        Request.Builder builder = new Request.Builder();
        // 创建一个 request
        Request request = builder.url(url).build();

        // 创建一个 HttpUrl.Builder
        HttpUrl.Builder urlBuilder = request.url().newBuilder();
        // 创建一个 Headers.Builder
        Headers.Builder headerBuilder = request.headers().newBuilder();

        // 装载请求头参数
        Iterator<Map.Entry<String, Object>> headerIterator = header.entrySet().iterator();
        headerIterator.forEachRemaining(e -> {
            headerBuilder.add(e.getKey(), (String) e.getValue());
        });

        // 装载请求的参数
        Iterator<Map.Entry<String, Object>> queryIterator = query.entrySet().iterator();
        queryIterator.forEachRemaining(e -> {
            urlBuilder.addQueryParameter(e.getKey(), (String) e.getValue());
        });

        // 设置自定义的 builder
        // 因为 get 请求的参数，是在 URL 后面追加  http://xxxx:8080/user?name=xxxx?sex=1
        builder.url(urlBuilder.build()).headers(headerBuilder.build());

        try (Response execute = client.newCall(builder.build()).execute()) {
            return execute.body().string();
        }
    }

    /**
     * post 请求， 请求参数 并且 携带文件上传
     * @param url
     * @param header
     * @param parameter
     * @param file 文件
     * @param fileFormName 远程接口接收 file 的参数
     * @return
     * @throws Exception
     */
    public static String doPost(String url, Map<String, Object> header, Map<String, Object> parameter, File file, String fileFormName) throws Exception {

        // 创建一个请求 Builder
        Request.Builder builder = new Request.Builder();
        // 创建一个 request
        Request request = builder.url(url).build();

        // 创建一个 Headers.Builder
        Headers.Builder headerBuilder = request.headers().newBuilder();

        // 装载请求头参数
        Iterator<Map.Entry<String, Object>> headerIterator = header.entrySet().iterator();
        headerIterator.forEachRemaining(e -> {
            headerBuilder.add(e.getKey(), (String) e.getValue());
        });

        // 或者 FormBody.create 方式，只适用于接口只接收文件流的情况
        // RequestBody requestBody = FormBody.create(MediaType.parse("application/octet-stream"), file);
        MultipartBody.Builder requestBuilder = new MultipartBody.Builder();

        // 状态请求参数
        Iterator<Map.Entry<String, Object>> queryIterator = parameter.entrySet().iterator();
        queryIterator.forEachRemaining(e -> {
            requestBuilder.addFormDataPart(e.getKey(), (String) e.getValue());
        });

        if (null != file) {
            // application/octet-stream
            requestBuilder.addFormDataPart(StringUtils.isNotBlank(fileFormName) ? fileFormName : "file", file.getName(), RequestBody.create(file, MediaType.parse("application/octet-stream")));
        }

        // 设置自定义的 builder
        builder.headers(headerBuilder.build()).post(requestBuilder.build());

        // 然后再 build 一下
        try (Response execute = client.newCall(builder.build()).execute()) {
            return execute.body().string();
        }
    }

    /**
     * post 请求， 请求参数 并且 携带文件上传二进制流
     * @param url
     * @param header
     * @param parameter
     * @param fileName 文件名
     * @param fileByte 文件的二进制流
     * @param fileFormName 远程接口接收 file 的参数
     * @return
     * @throws Exception
     */
    public static String doPost(String url, Map<String, Object> header, Map<String, Object> parameter, String fileName, byte [] fileByte, String fileFormName) throws Exception {
        // 创建一个请求 Builder
        Request.Builder builder = new Request.Builder();
        // 创建一个 request
        Request request = builder.url(url).build();

        // 创建一个 Headers.Builder
        Headers.Builder headerBuilder = request.headers().newBuilder();

        // 装载请求头参数
        Iterator<Map.Entry<String, Object>> headerIterator = header.entrySet().iterator();
        headerIterator.forEachRemaining(e -> {
            headerBuilder.add(e.getKey(), (String) e.getValue());
        });

        MultipartBody.Builder requestBuilder = new MultipartBody.Builder();

        // 状态请求参数
        Iterator<Map.Entry<String, Object>> queryIterator = parameter.entrySet().iterator();
        queryIterator.forEachRemaining(e -> {
            requestBuilder.addFormDataPart(e.getKey(), (String) e.getValue());
        });

        if (fileByte.length > 0) {
            // application/octet-stream
            requestBuilder.addFormDataPart(StringUtils.isNotBlank(fileFormName) ? fileFormName : "file", fileName, RequestBody.create(fileByte, MediaType.parse("application/octet-stream")));
        }

        // 设置自定义的 builder
        builder.headers(headerBuilder.build()).post(requestBuilder.build());

        try (Response execute = client.newCall(builder.build()).execute()) {
            return execute.body().string();
        }
    }


    /**
     * post 请求  携带文件上传
     * @param url
     * @param file
     * @return
     * @throws Exception
     */
    public static String doPost(String url, File file, String fileFormName) throws Exception {
        return doPost(url, Maps.newHashMap(), Maps.newHashMap(), file, fileFormName);
    }

    /**
     * post 请求
     * @param url
     * @param header 请求头
     * @param parameter 参数
     * @return
     * @throws Exception
     */
    public static String doPost(String url, Map<String, Object> header, Map<String, Object> parameter) throws Exception {
        return doPost(url, header, parameter, null, null);
    }

    /**
     * post 请求
     * @param url
     * @param parameter 参数
     * @return
     * @throws Exception
     */
    public static String doPost(String url, Map<String, Object> parameter) throws Exception {
        return doPost(url, Maps.newHashMap(), parameter, null, null);
    }

    /**
     * JSON数据格式请求
     * @param url
     * @param header
     * @param json
     * @return
     */
    private static String json(String url, Map<String, Object> header,String json) throws IOException {
        // 创建一个请求 Builder
        Request.Builder builder = new Request.Builder();
        // 创建一个 request
        Request request = builder.url(url).build();

        // 创建一个 Headers.Builder
        Headers.Builder headerBuilder = request.headers().newBuilder();

        // 装载请求头参数
        Iterator<Map.Entry<String, Object>> headerIterator = header.entrySet().iterator();
        headerIterator.forEachRemaining(e -> {
            headerBuilder.add(e.getKey(), (String) e.getValue());
        });

        // application/octet-stream
        RequestBody requestBody = FormBody.create(json, MediaType.parse("application/json"));

        // 设置自定义的 builder
        builder.headers(headerBuilder.build()).post(requestBody);

        try (Response execute = client.newCall(builder.build()).execute()) {
            return execute.body().string();
        }
    }

    /**
     * post请求  参数JSON格式
     * @param url
     * @param header 请求头
     * @param json JSON数据
     * @return
     * @throws IOException
     */
    public static String doPost(String url, Map<String, Object> header,String json) throws IOException {
        return json(url, header, json);
    }

    /**
     * post请求  参数JSON格式
     * @param url
     * @param json JSON数据
     * @return
     * @throws IOException
     */
    public static String doPost(String url,String json) throws IOException {
        return json(url, Maps.newHashMap(), json);
    }

现在写个 main 方法测试

    public static void main(String[] args) throws Exception {
        /**
         * JSON 数据请求
         */
        Map<String, Object> headerMap = Maps.newHashMap();
        headerMap.put("app_key","xxx999");
        headerMap.put("sign","xxxxxx212bc7c939bb");

        Map<String, Object> dataMap = Maps.newHashMap();
        dataMap.put("appKey", "xxx999");
        dataMap.put("shipId","xxx000668888");

        Map<String, Object> jsonMap = Maps.newHashMap();
        jsonMap.put("action", "xxxlogistics.querylst");
        jsonMap.put("data", dataMap);

        // JSON 字符串
        System.out.println(OkHttpRequestUtils.doPost("http://localhost:8080/openapi-api", headerMap, JSONObject.toJSONString(jsonMap)));


        /**
         * 上传文件
         */
        byte [] fileByte = null;

        File file = new File("file-read-4182.jpg");
        FileInputStream fileInputStream = new FileInputStream(file);

        ByteArrayOutputStream bos = new ByteArrayOutputStream();
        byte[] b = new byte[1024];
        int n;
        while ((n = fileInputStream.read(b)) != -1)
        {
            bos.write(b, 0, n);
        }
        fileInputStream.close();
        bos.close();
        fileByte = bos.toByteArray();


        Map<String, Object> queryMap = Maps.newHashMap();
        queryMap.put("pageNum","2");
        queryMap.put("pageSize","50");
        System.out.println(OkHttpRequestUtils.doPost("http://localhost:8566/uploadImage" , Maps.newHashMap(), Maps.newHashMap(),file.getName(), fileByte, "uploadFile"));


    }