面试被问：HTTP客户端连接，选择HttpClient还是OkHttp？

田维常

发布于 2020-02-24 12:55:18

8.5K0

发布于 2020-02-24 12:55:18

文章被收录于专栏：Java后端技术栈cwnait Java后端技术栈cwnaitJava后端技术栈cwnait

作者：何甜甜在吗 juejin.im/post/5e156c80f265da5d3c6de72a

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

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);  //addPart上传文件
    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);  //设置超时时间
    //测试连接的取消

    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 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());
}

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);
    //请求参数
    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) //post请求
           .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)  //默认为GET请求，可以不写
            .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);
  //请求参数
  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();
    //测试连接的取消
    while (true) {
         //1分钟获取不到结果就取消请求
        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
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

 <!---文件上传-->
 <dependency>
     <groupId>org.apache.httpcomponents</groupId>
     <artifactId>httpmime</artifactId>
     <version>4.5.3</version>
 </dependency>
 <!--异步请求-->
 <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);  //设置超时时间

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)//设置连接超时时间
        .readTimeout(60, TimeUnit.SECONDS)//设置读取超时时间
        .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