【Java工具类】OkHttp工具类

		<dependency>
            <groupId>com.squareup.okhttp3groupId>
            <artifactId>okhttpartifactId>
            <version>4.8.1version>
        dependency>
        <dependency>
            <groupId>com.alibabagroupId>
            <artifactId>fastjsonartifactId>
            <version>1.2.83version>
        dependency>

package com.frcoder;

import com.alibaba.fastjson.JSON;
import okhttp3.Call;
import okhttp3.Callback;
import okhttp3.FormBody;
import okhttp3.MediaType;
import okhttp3.OkHttpClient;
import okhttp3.Request;
import okhttp3.RequestBody;
import okhttp3.Response;

import javax.net.ssl.SSLContext;
import javax.net.ssl.SSLSocketFactory;
import javax.net.ssl.TrustManager;
import javax.net.ssl.X509TrustManager;
import java.io.IOException;
import java.net.URLEncoder;
import java.security.SecureRandom;
import java.security.cert.X509Certificate;
import java.util.LinkedHashMap;
import java.util.Map;
import java.util.concurrent.Semaphore;
import java.util.concurrent.TimeUnit;

public class OkHttpUtils {
    private static volatile OkHttpClient okHttpClient = null;
    private static volatile Semaphore semaphore = null;
    private Map<String, String> headerMap;
    private Map<String, String> paramMap;
    private Map<String, String> formMap;
    private Object body;
    private String url;
    private Request.Builder request;

    /**
     * 初始化okHttpClient，并且允许https访问
     */
    private OkHttpUtils() {
        if (okHttpClient == null) {
            synchronized (OkHttpUtils.class) {
                if (okHttpClient == null) {
                    TrustManager[] trustManagers = buildTrustManagers();
                    okHttpClient = new OkHttpClient.Builder()
                            .connectTimeout(15, TimeUnit.SECONDS)
                            .writeTimeout(20, TimeUnit.SECONDS)
                            .readTimeout(20, TimeUnit.SECONDS)
                            .sslSocketFactory(createSSLSocketFactory(trustManagers), (X509TrustManager) trustManagers[0])
                            .hostnameVerifier((hostName, session) -> true)
                            .retryOnConnectionFailure(true)
                            .build();
                    addHeader("User-Agent", "Mozilla/5.0 (Macintosh; Intel Mac OS X 10_12_6) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/63.0.3239.132 Safari/537.36");
                }
            }
        }
    }

    /**
     * 用于异步请求时，控制访问线程数，返回结果
     */
    private static Semaphore getSemaphoreInstance() {
        // 只能1个线程同时访问
        synchronized (OkHttpUtils.class) {
            if (semaphore == null) {
                semaphore = new Semaphore(0);
            }
        }
        return semaphore;
    }

    /**
     * 创建OkHttpUtils
     */
    public static OkHttpUtils builder() {
        return new OkHttpUtils();
    }

    /**
     * 添加url
     */
    public OkHttpUtils url(String url) {
        this.url = url;
        return this;
    }

    /**
     * 添加body
     */
    public OkHttpUtils body(Object body) {
        this.body = body;
        return this;
    }

    /**
     * 添加参数
     */
    public OkHttpUtils addParam(String key, String value) {
        if (paramMap == null) {
            paramMap = new LinkedHashMap<>(16);
        }
        paramMap.put(key, value);
        return this;
    }

    /**
     * 添加参数
     */
    public OkHttpUtils addFormParam(String key, String value) {
        if (formMap == null) {
            formMap = new LinkedHashMap<>(16);
        }
        formMap.put(key, value);
        return this;
    }

    /**
     * 添加请求头
     */
    public OkHttpUtils addHeader(String key, String value) {
        if (headerMap == null) {
            headerMap = new LinkedHashMap<>(16);
        }
        headerMap.put(key, value);
        return this;
    }

    /**
     * 初始化get方法
     */
    public OkHttpUtils get() {
        request = new Request.Builder().get();
        StringBuilder urlBuilder = new StringBuilder(url);
        if (paramMap != null) {
            urlBuilder.append("?");
            try {
                for (Map.Entry<String, String> entry : paramMap.entrySet()) {
                    urlBuilder.append(URLEncoder.encode(entry.getKey(), "utf-8")).
                            append("=").
                            append(URLEncoder.encode(entry.getValue(), "utf-8")).
                            append("&");
                }
            } catch (Exception e) {
                e.printStackTrace();
            }
            urlBuilder.deleteCharAt(urlBuilder.length() - 1);
        }
        request.url(urlBuilder.toString());
        return this;
    }

    /**
     * 初始化post方法
     */
    public OkHttpUtils post() {
        RequestBody requestBody = null;
        StringBuilder urlBuilder = new StringBuilder(url);
        if (paramMap != null) {
            urlBuilder.append("?");
            try {
                for (Map.Entry<String, String> entry : paramMap.entrySet()) {
                    urlBuilder.append(URLEncoder.encode(entry.getKey(), "utf-8")).
                            append("=").
                            append(URLEncoder.encode(entry.getValue(), "utf-8")).
                            append("&");
                }
            } catch (Exception e) {
                e.printStackTrace();
            }
            urlBuilder.deleteCharAt(urlBuilder.length() - 1);
        }
        if (formMap != null) {
            FormBody.Builder formBody = new FormBody.Builder();
            if (formMap != null) {
                formMap.forEach(formBody::add);
            }
            requestBody = formBody.build();
        }
        if (requestBody == null) {
            if (body == null) {
                body = new Object();
            }
            String json = JSON.toJSONString(body);
            requestBody = RequestBody.create(MediaType.parse("application/json; charset=utf-8"), json);
        }
        request = new Request.Builder().post(requestBody).url(urlBuilder.toString());
        return this;
    }

    /**
     * 同步请求
     */
    public String sync() {
        setHeader(request);
        try {
            Request req = request.build();
            System.out.println(req);
            System.out.println(JSON.toJSONString(req.body()));
            Response response = okHttpClient.newCall(req).execute();
            assert response.body() != null;
            String resp = response.body().string();
            return resp;
        } catch (IOException e) {
            e.printStackTrace();
            return "请求失败：" + e.getMessage();
        }
    }

    /**
     * 异步请求，有返回值
     */
    public String async() {
        StringBuilder buffer = new StringBuilder("");
        setHeader(request);
        Request req = request.build();
        okHttpClient.newCall(req).enqueue(new Callback() {
            @Override
            public void onFailure(Call call, IOException e) {
                buffer.append("请求出错：").append(e.getMessage());
            }

            @Override
            public void onResponse(Call call, Response response) throws IOException {
                assert response.body() != null;
                buffer.append(response.body().string());
                getSemaphoreInstance().release();
            }
        });
        try {
            getSemaphoreInstance().acquire();
        } catch (InterruptedException e) {
            e.printStackTrace();
        }
        String resp = buffer.toString();
        return resp;
    }

    /**
     * 异步请求，带有接口回调
     */
    public void async(ICallBack callBack) {
        setHeader(request);
        Request req = request.build();
        System.out.println(JSON.toJSONString(req));
        okHttpClient.newCall(req).enqueue(new Callback() {
            @Override
            public void onFailure(Call call, IOException e) {
                callBack.onFailure(call, e.getMessage());
            }

            @Override
            public void onResponse(Call call, Response response) throws IOException {
                assert response.body() != null;
                callBack.onSuccessful(call, response.body().string());
            }
        });
    }

    /**
     * 为request添加请求头
     */
    private void setHeader(Request.Builder request) {
        if (headerMap != null) {
            try {
                for (Map.Entry<String, String> entry : headerMap.entrySet()) {
                    request.addHeader(entry.getKey(), entry.getValue());
                }
            } catch (Exception e) {
                e.printStackTrace();
            }
        }
    }


    /**
     * 生成安全套接字工厂，用于https请求的证书跳过
     */
    private static SSLSocketFactory createSSLSocketFactory(TrustManager[] trustAllCerts) {
        SSLSocketFactory ssfFactory = null;
        try {
            SSLContext sc = SSLContext.getInstance("SSL");
            sc.init(null, trustAllCerts, new SecureRandom());
            ssfFactory = sc.getSocketFactory();
        } catch (Exception e) {
            e.printStackTrace();
        }
        return ssfFactory;
    }

    private static TrustManager[] buildTrustManagers() {
        return new TrustManager[]{
                new X509TrustManager() {
                    @Override
                    public void checkClientTrusted(X509Certificate[] chain, String authType) {
                    }

                    @Override
                    public void checkServerTrusted(X509Certificate[] chain, String authType) {
                    }

                    @Override
                    public X509Certificate[] getAcceptedIssuers() {
                        return new X509Certificate[]{};
                    }
                }
        };
    }

    /**
     * 自定义一个接口回调
     */
    public interface ICallBack {

        void onSuccessful(Call call, String data);

        void onFailure(Call call, String errorMsg);

    }


    public static void main(String[] args) {
        // get请求，方法顺序按照这种方式，切记选择post/get一定要放在倒数第二，同步或者异步倒数第一，才会正确执行
        OkHttpUtils.builder().url("http://baidu.com")
                .addHeader("Content-Type", "application/json; charset=utf-8")
                // 有参数的话添加参数，可多个
                .addParam("param1", "a")
                .addParam("param2", "b")
                // 也可以添加多个
                .get()
                // 可选择是同步请求还是异步请求
                //.async();
                .sync();
    }
}