簡介

OkHttp是一款適用于Android和Java應(yīng)用程序的HTTP&HTTP2客戶端。它有如下特性：

• 支持http2，對一臺機(jī)器的所有請求共享同一個socket
• 內(nèi)置連接池，支持連接復(fù)用，減少延遲
• 支持透明的gzip壓縮響應(yīng)體
• 通過緩存避免重復(fù)的請求
• 請求失敗時自動重試主機(jī)的其他ip，自動重定向
• 好用的API

引入

以Java為例，通常使用Maven構(gòu)建方式，在pom文件中加入依賴。

<dependency>
    <groupId>com.squareup.okhttp3</groupId>
    <artifactId>okhttp</artifactId>
    <version>3.9.1</version>
</dependency>

get請求

1. 先實(shí)例化okhttp，構(gòu)建一個request，由于get是默認(rèn)方式，所以設(shè)置一個url地址就可以了，也可以通過Request.Builder設(shè)置更多的參數(shù)。
2. 然后通過client創(chuàng)建一個call對象并發(fā)送請求。
3. 通過response.body().string()獲取返回的字符串。這個body()其實(shí)就是ResponseBody對象。

OkHttpClient client = new OkHttpClient();

Request request = new Request.Builder()
    .url(url)
    .build();

Response response = client.newCall(request).execute();
String responseBody = response.body().string();

post請求

1. 提交字符串

OkHttpClient client = new OkHttpClient();

MediaType mediaType = MediaType.parse("text/plain; charset=utf-8");
String str = "abcd";
RequestBody body = RequestBody.create(mediaType, str);

Request request = new Request.Builder()
    .url(url)
    .post(body)
    .build();

Response response = client.newCall(request).execute();
String responseBody = response.body().string();

2. 提交json

OkHttpClient client = new OkHttpClient();

MediaType mediaType = MediaType.parse("application/json; charset=utf-8");
String json = "{'name':'kmt','sex':'man'}";
RequestBody body = RequestBody.create(mediaType, json);

Request request = new Request.Builder()
    .url(url)
    .post(body)
    .build();
    
Response response = client.newCall(request).execute();
String responseBody = response.body().string();

3. 提交form表單

OkHttpClient client = new OkHttpClient();

RequestBody body = new FormBody.Builder()
    .add("name", "kmt")
    .add("sex", "man")
    .build();
    
Request request = new Request.Builder()
    .url(url)
    .post(body)
    .build();

Response response = client.newCall(request).execute();
String responseBody = response.body().string();

4. 上傳文件

OkHttpClient client = new OkHttpClient();

MediaType mediaType = MediaType.parse("image/png");
File file = new File("/file/test.png");
RequestBody body = RequestBody.create(mediaType, file);

Request request = new Request.Builder()
    .url(url)
    .post(body)
    .build();

Response response = client.newCall(request).execute();
String responseBody = response.body().string();

5. 提交分塊請求

OkHttpClient client = new OkHttpClient();

MediaType mediaType = MediaType.parse("image/png");
File file = new File("/file/test.png");
RequestBody fileBody = RequestBody.create(mediaType, file);

RequestBody requestBody = new MultipartBody.Builder()
    .setType(MultipartBody.FORM)
    .addFormDataPart("file", "test_img", fileBody)
    .addFormDataPart("name", "kmt")
    .build();

Request request = new Request.Builder()
    .url(url)
    .post(requestBody)
    .build();

Response response = client.newCall(request).execute();
String responseBody = response.body().string();

其他

1. 設(shè)置超時時間

OkHttpClient client = new OkHttpClient.Builder()
    .connectTimeout(10, TimeUnit.SECONDS)
    .readTimeout(10,TimeUnit.SECONDS)
    .writeTimeout(10,TimeUnit.SECONDS)
    .build();

2. 添加請求頭

Request request = new Request.Builder()
    .url(url)
    .addHeader("authorization", authorization)
    .addHeader("content-type", "application/x-www-form-urlencoded")
    .addHeader("cache-control", "no-cache")
    .post(body)
    .build();

3. 異步

client.newCall(request).execute()是同步的，client.newCall(request).enqueue()是異步的。onFailure是請求失敗執(zhí)行的方法，onResponse是請求成功執(zhí)行的方法。

client.newCall(request).enqueue(new Callback() {
    @Override
    public void onFailure(Call call, IOException e) {
        e.printStackTrace();
    }

    @Override
    public void onResponse(Call call, Response response) throws IOException {
        String responseBody = response.body().string();
    }
});