OkHttp3使用教程，实现get、post请求发送，自动重试，打印响应日志。

一、创建线程安全的okhttp单例

import service.NetworkIntercepter;
import service.RetryIntercepter;
import okhttp3.*;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

import java.io.IOException;
import java.util.HashMap;
import java.util.Map;
import java.util.concurrent.TimeUnit;

public class HttpUtils {
    private static final Logger LOGGER = LoggerFactory.getLogger(HttpUtils.class);
    private static final int CONNECTION_TIME_OUT = 2000;//连接超时时间
    private static final int SOCKET_TIME_OUT = 2000;//读写超时时间
    private static final int MAX_IDLE_CONNECTIONS = 30;// 空闲连接数
    private static final long KEEP_ALLIVE_TIME = 60000L;//保持连接时间

    private OkHttpClient okHttpClient;
    private volatile static HttpUtils httpUtils;

    public static HttpUtils getInstance(){
        if(httpUtils == null){
            synchronized (HttpUtils.class){
                if(httpUtils == null){
                    httpUtils = new HttpUtils();
                }
            }
        }
        return httpUtils;

    }
    public HttpUtils(){
        ConnectionPool connectionPool = new ConnectionPool(MAX_IDLE_CONNECTIONS,KEEP_ALLIVE_TIME,TimeUnit.MILLISECONDS);
        this.okHttpClient = new OkHttpClient()
                .newBuilder()
                .readTimeout(SOCKET_TIME_OUT, TimeUnit.MILLISECONDS)
                .writeTimeout(SOCKET_TIME_OUT, TimeUnit.MILLISECONDS)
                .connectionPool(connectionPool)
                .retryOnConnectionFailure(false) //自动重连设置为false
                .connectTimeout(CONNECTION_TIME_OUT,TimeUnit.MILLISECONDS)
                .addInterceptor(new RetryIntercepter(2)) //重试拦截器2次
                .addNetworkInterceptor(new NetworkIntercepter()) //网络拦截器，统一打印日志
                .build();
    }
}

重试拦截器：

 import okhttp3.Interceptor;

 import okhttp3.Request;

 import okhttp3.Response;

 import java.io.IOException;

 public class RetryIntercepter implements Interceptor{

     public int maxRetryCount;

     private int count = 0;

     public RetryIntercepter(int maxRetryCount) {

         this.maxRetryCount = maxRetryCount;

     }

     @Override

     public Response intercept(Chain chain) throws IOException {

         return retry(chain);

     }

     public Response retry(Chain chain){

         Response response = null;

         Request request = chain.request();

         try {

             response = chain.proceed(request);

             while (!response.isSuccessful() && count < maxRetryCount) {

                 count++;

                 response = retry(chain);

             }

         }

         catch (Exception e){

             while (count < maxRetryCount){

                 count++;

                 response = retry(chain);

             }

         }

         return response;

     }

 }

注意：两处while是因为如果请求中出现异常，也能进行重试，比如超时，后面会有例子。

网络拦截器，打印请求、响应时间、响应状态码，响应内容

 import okhttp3.*;

 import okio.Buffer;

 import org.slf4j.Logger;

 import org.slf4j.LoggerFactory;

 import java.io.IOException;

 import java.nio.charset.Charset;

 public class NetworkIntercepter implements Interceptor{

     private static Logger LOGGER = LoggerFactory.getLogger(NetworkIntercepter.class);

     @Override

     public Response intercept(Interceptor.Chain chain) {

         long start = System.currentTimeMillis();

         Response response=null;

         String responseBody = null;

         String responseCode = null;

         String url = null;

         String requestBody = null;

         try {

             Request request = chain.request();

             url = request.url().toString();

             requestBody = getRequestBody(request);

             response = chain.proceed(request);

             responseBody = response.body().string();

             responseCode = String.valueOf(response.code());

             MediaType mediaType = response.body().contentType();

             response = response.newBuilder().body(ResponseBody.create(mediaType,responseBody)).build();

         }

         catch (Exception e){

             LOGGER.error(e.getMessage());

         }

         finally {

             long end = System.currentTimeMillis();

             String duration = String.valueOf(end - start);

             LOGGER.info("responseTime= {}, requestUrl= {}, params={}, responseCode= {}, result= {}",

                         duration, url,requestBody,responseCode,responseBody);

         }

         return response;

     }

     private String getRequestBody(Request request) {

         String requestContent = "";

         if (request == null) {

             return requestContent;

         }

         RequestBody requestBody = request.body();

         if (requestBody == null) {

             return requestContent;

         }

         try {

             Buffer buffer = new Buffer();

             requestBody.writeTo(buffer);

             Charset charset = Charset.forName("utf-8");

             requestContent = buffer.readString(charset);

         } catch (IOException e) {

             e.printStackTrace();

         }

         return requestContent;

     }

 }

二、GET请求

1、带参数的get请求

 /*

     * 发送待url参数的get

     */

     public String get(String url,Map<String,String> pathParams){

         HttpUrl.Builder builder = HttpUrl.parse(url).newBuilder();

         for(String key:pathParams.keySet()){

             builder.addQueryParameter(key,pathParams.get(key) );

         }

         Request request = new Request.Builder()

                 .url(builder.build().toString())

                 .build();

         return execute(request);

     }

 private String execute(Request request){

         String responseBody=null;

         try {

             Response response = okHttpClient.newCall(request).execute();

             responseBody = response.body().string();

         } catch (IOException |NullPointerException e) {

             e.printStackTrace();

         }

         return responseBody;

     }

测试:

String url = "http://localhost:8080/test/12346/query";
Map<String,String> params = new HashMap<>();
params.put("aaa","111");
params.put("bbb","222");
HttpUtils httpUtils = HttpUtils.getInstance();
httpUtils.get(url,params);

打印日志如下：
[main][2019-09-21 10:19:02.072] [INFO] [NetworkIntercepter.intercept:40] responseTime= 62, requestUrl= http://localhost:8080/test/12346/query?aaa=111&bbb=222, params=, responseCode= 200, result= {"result_code":"success","data":{"aaa":"111"},"path":"/test/12346/query"}

2、不带参数的get请求

测试：

String url = "http://localhost:8080/test/12346/query?ccc=1&ddd=2";
HttpUtils httpUtils = HttpUtils.getInstance();
httpUtils.get(url);

打印日志如下：
[main][2019-09-21 10:25:46.943] [INFO] [NetworkIntercepter.intercept:38] responseTime= 11, requestUrl= http://localhost:8080/test/12346/query?ccc=1&ddd=2, params=, responseCode= 200, result= {"result_code":"success","data":{"aaa":"111"},"path":"/test/12346/query"}

三、POST请求

1、post发送带url参数的json

 /*

     * post发送带url参数的json

     */

     public String post(String url, Map<String,String> pathParams, String body){

         RequestBody requestBody = RequestBody.

                 create(MediaType.parse("application/json;charset=utf-8"), body);

         HttpUrl.Builder builder = HttpUrl.parse(url).newBuilder();

         for(String key:pathParams.keySet()){

             builder.addQueryParameter(key,pathParams.get(key) );

         }

         Request request = new Request.Builder()

                 .post(requestBody)

                 .url(builder.build().toString())

                 .build();

         return execute(request);

     }

　测试：

Gson gson = new Gson();
String url = "http://localhost:8080/test/12346/query";
Map<String,String> params = new HashMap<>();
params.put("aaa","111");
params.put("bbb","222");

Map<String,Object> bodyMap = new HashMap<>();
bodyMap.put("name","zhangsan");
bodyMap.put("age",15);
HttpUtils httpUtils = HttpUtils.getInstance();
httpUtils.post(url,params,gson.toJson(bodyMap));

打印日志
[main][2019-09-21 10:37:04.577] [INFO] [NetworkIntercepter.intercept:38] responseTime= 304, requestUrl= http://localhost:8080/test/12346/query?aaa=111&bbb=222, params={"name":"zhangsan","age":15}, responseCode= 200, result= {"result_code":"success","data":{"aaa":"111"},"path":"/test/12346/query"}　　　　

2、post发送json

 /*

     * post发送json

     */

     public String post(String url,String body){

         Map<String,String> pathParams = new HashMap<>();

         return post(url,pathParams ,body );

     }

测试：

Gson gson = new Gson();
String url = "http://localhost:8080/test/12346/query";
Map<String,Object> bodyMap = new HashMap<>();
bodyMap.put("name","zhangsan");
bodyMap.put("age",15);
HttpUtils httpUtils = HttpUtils.getInstance();
httpUtils.post(url,gson.toJson(bodyMap));

打印日志：

[main][2019-09-21 10:44:00.835] [INFO] [NetworkIntercepter.intercept:38] responseTime= 17, requestUrl= http://localhost:8080/test/12346/query, params={"name":"zhangsan","age":15}, responseCode= 200, result= {"result_code":"success","data":{"aaa":"111"},"path":"/test/12346/query"}

3、post发送表单

  /*

     * post发送表单

     */

     public String post(String url, Map<String,String> pathParams){

         FormBody.Builder formBodyBuilder = new FormBody.Builder();

         HttpUrl.Builder builder = HttpUrl.parse(url).newBuilder();

         for(String key:pathParams.keySet()){

             formBodyBuilder.add(key,pathParams.get(key) );

         }

         RequestBody requestBody = formBodyBuilder.build();

         Request request = new Request.Builder()

                 .post(requestBody)

                 .url(builder.build().toString())

                 .build();

         return execute(request);

     }

测试：

String url = "http://localhost:8080/test/12346/query";
Map<String,String> params = new HashMap<>();
params.put("aaa","111");
params.put("bbb","222");
HttpUtils httpUtils = HttpUtils.getInstance();
httpUtils.post(url,params);

打印日志：
[main][2019-09-21 10:49:54.136] [INFO] [NetworkIntercepter.intercept:38] responseTime= 21, requestUrl= http://localhost:8080/test/12346/query, params=aaa=111&bbb=222, responseCode= 200, result= {"result_code":"success","data":{"aaa":"111"},"path":"/test/12346/query"}

四、网络拦截器

1、404重试

测试：

String url = "http://localhost:8080/test/12346/query2";
Map<String,String> params = new HashMap<>();
params.put("aaa","111");
params.put("bbb","222");
HttpUtils httpUtils = HttpUtils.getInstance();
httpUtils.post(url,params);

日志打印：

[main][2019-09-21 10:56:20.495] [INFO] [NetworkIntercepter.intercept:38] responseTime= 26, requestUrl= http://localhost:8080/test/12346/query2, params=aaa=111&bbb=222, responseCode= 404, result= {"timestamp":1569034580,"status":404,"error":"Not Found","message":"Not Found","path":"/test/12346/query2"}
[main][2019-09-21 10:56:20.506] [INFO] [NetworkIntercepter.intercept:38] responseTime= 4, requestUrl= http://localhost:8080/test/12346/query2, params=aaa=111&bbb=222, responseCode= 404, result= {"timestamp":1569034580,"status":404,"error":"Not Found","message":"Not Found","path":"/test/12346/query2"}
[main][2019-09-21 10:56:20.512] [INFO] [NetworkIntercepter.intercept:38] responseTime= 4, requestUrl= http://localhost:8080/test/12346/query2, params=aaa=111&bbb=222, responseCode= 404, result= {"timestamp":1569034580,"status":404,"error":"Not Found","message":"Not Found","path":"/test/12346/query2"

重试了2次，共请求3次

2、超时重试

日志打印：

[main][2019-09-21 10:59:30.086] [ERROR] [NetworkIntercepter.intercept:33] timeout
[main][2019-09-21 10:59:30.092] [INFO] [NetworkIntercepter.intercept:38] responseTime= 2009, requestUrl= http://localhost:8080/test/12346/query, params=aaa=111&bbb=222, responseCode= null, result= null
[main][2019-09-21 10:59:32.097] [ERROR] [NetworkIntercepter.intercept:33] timeout
[main][2019-09-21 10:59:32.097] [INFO] [NetworkIntercepter.intercept:38] responseTime= 2004, requestUrl= http://localhost:8080/test/12346/query, params=aaa=111&bbb=222, responseCode= null, result= null
[main][2019-09-21 10:59:34.101] [ERROR] [NetworkIntercepter.intercept:33] timeout
[main][2019-09-21 10:59:34.101] [INFO] [NetworkIntercepter.intercept:38] responseTime= 2002, requestUrl= http://localhost:8080/test/12346/query, params=aaa=111&bbb=222, responseCode= null, result= null