HTTP客户端连接，选择HttpClient还是OkHttp？-优快云博客

何甜甜在吗
https://www.jianshu.com/p/68c30beca612

代码示例：https://github.com/TiantianUpup/http-call

写在前面

为什么会写这篇文章，起因于和朋友的聊天

这又触及到我的知识盲区了，首先来一波面向百度学习，直接根据关键字 httpclient 和 okhttp 的区别、性能比较进行搜索，没有找到想要的答案，于是就去 overstackflow 上看看是不是有人问过这个问题，果然不会让你失望的

所以从使用、性能、超时配置方面进行比较

使用

HttpClient 和 OkHttp 一般用于调用其它服务，一般服务暴露出来的接口都为 http，http 常用请求类型就为 GET、PUT、POST 和 DELETE，因此主要介绍这些请求类型的调用

精选：2020年最新的常问企业面试题大全以及答案

HttpClient 使用介绍

使用 HttpClient 发送请求主要分为一下几步骤：

创建 CloseableHttpClient 对象或 CloseableHttpAsyncClient 对象，前者同步，后者为异步
创建 Http 请求对象
调用 execute 方法执行请求，如果是异步请求在执行之前需调用 start 方法

创建连接：

CloseableHttpClient httpClient = HttpClientBuilder.create().build();

该连接为同步连接

GET 请求：

@Test
public void testGet() throws IOException {
    String api = "/api/files/1";
    String url = String.format("%s%s", BASE_URL, api);
    HttpGet httpGet = new HttpGet(url);
    CloseableHttpResponse response = httpClient.execute(httpGet);
    System.out.println(EntityUtils.toString(response.getEntity()));
}

使用 HttpGet 表示该连接为 GET 请求，HttpClient 调用 execute 方法发送 GET 请求

PUT 请求：

@Test
public void testPut() throws IOException {
    String api = "/api/user";
    String url = String.format("%s%s", BASE_URL, api);
    HttpPut httpPut = new HttpPut(url);
    UserVO userVO = UserVO.builder().name("h2t").id(16L).build();
    httpPut.setHeader("Content-Type", "application/json;charset=utf8");
    httpPut.setEntity(new StringEntity(JSONObject.toJSONString(userVO), "UTF-8"));
    CloseableHttpResponse response = httpClient.execute(httpPut);
    System.out.println(EntityUtils.toString(response.getEntity()));
}

POST 请求：

添加对象

    @Test
    public void testPost() throws IOException {
        String api = "/api/user";
        String url = String.format("%s%s", BASE_URL, api);
        HttpPost httpPost = new HttpPost(url);
        UserVO userVO = UserVO.builder().name("h2t2").build();
        httpPost.setHeader("Content-Type", "application/json;charset=utf8");
        httpPost.setEntity(new StringEntity(JSONObject.toJSONString(userVO), "UTF-8"));
        CloseableHttpResponse response = httpClient.execute(httpPost);
        System.out.println(EntityUtils.toString(response.getEntity()));
    }

该请求是一个创建对象的请求，需要传入一个 json 字符串

上传文件

    @Test
    public void testUpload1() throws IOException {
        String api = "/api/files/1";
        String url = String.format("%s%s", BASE_URL, api);
        HttpPost httpPost = new HttpPost(url);
        File file = new File("C:/Users/hetiantian/Desktop/学习/docker_practice.pdf");
        FileBody fileBody = new FileBody(file);
        MultipartEntityBuilder builder = MultipartEntityBuilder.create();
        builder.setMode(HttpMultipartMode.BROWSER_COMPATIBLE);
        builder.addPart("file", fileBody);  
        HttpEntity entity = builder.build();
        httpPost.setEntity(entity);
        CloseableHttpResponse response = httpClient.execute(httpPost);
        System.out.println(EntityUtils.toString(response.getEntity()));
    }

通过 addPart 上传文件

DELETE 请求：

@Test
public void testDelete() throws IOException {
    String api = "/api/user/12";
    String url = String.format("%s%s", BASE_URL, api);
    HttpDelete httpDelete = new HttpDelete(url);
    CloseableHttpResponse response = httpClient.execute(httpDelete);
    System.out.println(EntityUtils.toString(response.getEntity()));
}

请求的取消：

@Test
public void testCancel() throws IOException {
    String api = "/api/files/1";
    String url = String.format("%s%s", BASE_URL, api);
    HttpGet httpGet = new HttpGet(url);
    httpGet.setConfig(requestConfig);  
    long begin = System.currentTimeMillis();
    CloseableHttpResponse response = httpClient.execute(httpGet);
    while (true) {
        if (System.currentTimeMillis() - begin > 1000) {
          httpGet.abort();
          System.out.println("task canceled");
          break;
      }
    }
    System.out.println(EntityUtils.toString(response.getEntity()));
}

调用 abort 方法取消请求
执行结果：

task canceled
cost 8098 msc
Disconnected from the target VM, address: '127.0.0.1:60549', transport: 'socket'
java.net.SocketException: socket closed...【省略】

OkHttp 使用

使用 OkHttp 发送请求主要分为一下几步骤：

创建 OkHttpClient 对象
创建 Request 对象
将 Request 对象封装为 Call
通过 Call 来执行同步或异步请求，调用 execute 方法同步执行，调用 enqueue 方法异步执行

创建连接：

private OkHttpClient client = new OkHttpClient();

GET 请求：

@Test
public void testGet() throws IOException {
    String api = "/api/files/1";
    String url = String.format("%s%s", BASE_URL, api);
    Request request = new Request.Builder()
            .url(url)
            .get() 
            .build();
    final Call call = client.newCall(request);
    Response response = call.execute();
    System.out.println(response.body().string());
}

PUT 请求：

@Test
public void testPut() throws IOException {
    String api = "/api/user";
    String url = String.format("%s%s", BASE_URL, api);
    UserVO userVO = UserVO.builder().name("h2t").id(11L).build();
    RequestBody requestBody = RequestBody.create(MediaType.parse("application/json; charset=utf-8"),
    JSONObject.toJSONString(userVO));
    Request request = new Request.Builder()
            .url(url)
            .put(requestBody)
            .build();
    final Call call = client.newCall(request);
    Response response = call.execute();
    System.out.println(response.body().string());
}

POST 请求：

添加对象

    @Test
    public void testPost() throws IOException {
        String api = "/api/user";
        String url = String.format("%s%s", BASE_URL, api);
        JSONObject json = new JSONObject();
        json.put("name", "hetiantian");
        RequestBody requestBody = RequestBody.create(MediaType.parse("application/json; charset=utf-8"),     String.valueOf(json));
        Request request = new Request.Builder()
                .url(url)
                .post(requestBody) 
               .build();
        final Call call = client.newCall(request);
        Response response = call.execute();
        System.out.println(response.body().string());
    }

上传文件

    @Test
    public void testUpload() throws IOException {
        String api = "/api/files/1";
        String url = String.format("%s%s", BASE_URL, api);
        RequestBody requestBody = new MultipartBody.Builder()
                .setType(MultipartBody.FORM)
                .addFormDataPart("file", "docker_practice.pdf",
                        RequestBody.create(MediaType.parse("multipart/form-data"),
                                new File("C:/Users/hetiantian/Desktop/学习/docker_practice.pdf")))
                .build();
        Request request = new Request.Builder()
                .url(url)
                .post(requestBody)  
                .build();
        final Call call = client.newCall(request);
        Response response = call.execute();
        System.out.println(response.body().string());
    }

通过 addFormDataPart 方法模拟表单方式上传文件

DELETE 请求：

@Test
public void testDelete() throws IOException {
  String url = String.format("%s%s", BASE_URL, api);
  Request request = new Request.Builder()
          .url(url)
          .delete()
          .build();
  final Call call = client.newCall(request);
  Response response = call.execute();
  System.out.println(response.body().string());
}

请求的取消：

@Test
public void testCancelSysnc() throws IOException {
    String api = "/api/files/1";
    String url = String.format("%s%s", BASE_URL, api);
    Request request = new Request.Builder()
            .url(url)
            .get()  
            .build();
    final Call call = client.newCall(request);
    Response response = call.execute();
    long start = System.currentTimeMillis();
    while (true) {
        if (System.currentTimeMillis() - start > 1000) {
            call.cancel();
            System.out.println("task canceled");
            break;
        }
    }
    System.out.println(response.body().string());
}

调用 cancel 方法进行取消
测试结果：

task canceled
cost 9110 msc
java.net.SocketException: socket closed...【省略】

小结

OkHttp 使用 build 模式创建对象来的更简洁一些，并且使用. post/.delete/.put/.get 方法表示请求类型，不需要像 HttpClient 创建 HttpGet、HttpPost 等这些方法来创建请求类型

精选：2020年最新的常问企业面试题大全以及答案

依赖包上，如果 HttpClient 需要发送异步请求、实现文件上传，需要额外的引入异步请求依赖

     <dependency>
         <groupId>org.apache.httpcomponents</groupId>
         <artifactId>httpmime</artifactId>
         <version>4.5.3</version>
     </dependency>
     <dependency>
         <groupId>org.apache.httpcomponents</groupId>
         <artifactId>httpasyncclient</artifactId>
         <version>4.5.3</version>
    </dependency>

请求的取消，HttpClient 使用 abort 方法，OkHttp 使用 cancel 方法，都挺简单的，如果使用的是异步 client，则在抛出异常时调用取消请求的方法即可

超时设置

HttpClient 超时设置：
在 HttpClient4.3 + 版本以上，超时设置通过 RequestConfig 进行设置

private CloseableHttpClient httpClient = HttpClientBuilder.create().build();
private RequestConfig requestConfig =  RequestConfig.custom()
        .setSocketTimeout(60 * 1000)
        .setConnectTimeout(60 * 1000).build();
String api = "/api/files/1";
String url = String.format("%s%s", BASE_URL, api);
HttpGet httpGet = new HttpGet(url);
httpGet.setConfig(requestConfig);

超时时间是设置在请求类型 HttpGet 上，而不是 HttpClient 上

OkHttp 超时设置：
直接在 OkHttp 上进行设置

private OkHttpClient client = new OkHttpClient.Builder()
        .connectTimeout(60, TimeUnit.SECONDS)
        .readTimeout(60, TimeUnit.SECONDS)
        .build();

小结：
如果 client 是单例模式，HttpClient 在设置超时方面来的更灵活，针对不同请求类型设置不同的超时时间，OkHttp 一旦设置了超时时间，所有请求类型的超时时间也就确定