okhttp使用备忘录

前言

OkHttp是目前使用最广泛的移动端网络底层库。在Volley、Retrofit等知名上层网络库中,都可以看到它的身影。即使在高版本的Android系统中的URLConnection中也可以看到它的身影。�

因为,各大网络库对OkHttp进行了封装。我们虽然使用方便,却不免失去了一定的灵活性。如果OkHttp拥有的功能,上层库却没有封装,我们在使用时,就会比较麻烦。因此,我们在这里尝试直接使用OkHttp,看看未经封装的OkHttp如何使用。

Request

OkHttp将请求封装在了Request类中。我们大致看看Request的成员:

public final class Request{
    private final HttpUrl url;
    private final String method;
    private final Headers headers;
    private final RequestBody body;
    private final Object tag;
}

其中HttpUrl类代表请求地址, String method代表请求方法, Headers代表请求头, RequestBody代表请求体. Object tag是用来取消http请求的标志, 这个我们先不管.

我们在使用OkHttp时,我们可以用Request提供的Builder生成我们想要的Request。

final Request request = new Request.Builder().url("https://github.com/").build();

完成Request的创建后,我们可以调用:

final Request request = new Request.Builder().url("https://github.com/").build();
Response response = client.newCall(request).execute();

Request被调用的方式,我们可以发现,这是一个同步网络请求。请求完成后,会直接返回Response给我们。下面,我们就来看看Response的结构。

Response

public final class Response{
  private final Request request;
  private final Protocol protocol;
  private final int code;
  private final String message;
  private final HandShake handShake;
  private final Headers headers;
  private final ResponseBody body;
  private Response networkResponse;
  private Response cacheResponse;
  private final Response priorResponse;
}

可以看到Response类里面有Protocol代表请求协议, int code代表响应码, String message代表描述信息, Headers代表响应头, ResponseBody代表响应体. 当然除此之外, 还有Request代表持有的请求, Handshake代表SSL/TLS握手协议验证时的信息, 这些额外信息我们暂时不问.

介绍完RequestResponse两个重要的类,下面我们可看看,OkHttp的各种请求的调用方法。

GET请求

同步GET

同步GET的意思是一直等待http请求, 直到返回了响应. 在这之间会阻塞进程, 所以通过get不能在Android的主线程中执行, 否则会报错。

private final OkHttpClient client = new OkHttpClient();

public void run() throw Exception{
  Request request = new Request.Builder()
        .url("https://github.com/")
        .build();

  Response response = client.newCall(request).execute();      
}

异步GET

异步GET的意思是OkHttp会帮我们另外开启后台线程发送http请求,开启后台线程后,不再阻碍当前线程的执行。当http请求完成后,会以回调的方式,将请求结果返回到当前线程。

private final OkHttpClient client = new OkHttpClient();

public void run() throw Exception{
  Request request = new Request.Builder()
        .url("https://github.com/")
        .build();

  Response response = client.newCall(request).enqueue(new Callback(){

    @Override
    public void onResponse(Response response) throw IOException{

    }

    @Override
    public void onFailure(Request request , Throwable throwable){

    }
  });      
}

POST请求

在上面的GET请求的介绍中,我们已经分别介绍了同步请求和异常请求。在POST请求的介绍中,我们不再以同步和异步进行分类,只介绍同步情况,而把精力集中在,POST上传的内容形式的分类上。

POST提交String

private final OkHttpClient client = new OkHttpClient();

public void run() throw Exception{

  String uploadInfo = "Need to Upload!";

  Request request = new Request.Builder()
        .url("https://github.com/")
        .post(RequestBody.create("text/x-markdown; charset=utf-8" , uploadInfo))
        .build();

  Response response = client.newCall(request).execute();      
}

POST提交文件

private final OkHttpClient client = new OkHttpClient();

public void run() throw Exception{

  File file = new File("README.md");

  Request request = new Request.Builder()
        .url("https://github.com/")
        .post(RequestBody.create("text/x-markdown; charset=utf-8" , file))
        .build();

  Response response = client.newCall(request).execute();      
}

POST提交表单

private final OkHttpClient client = new OkHttpClient();

public void run() throw Exception{

  RequestBody formBody = new formBody.Builder()
      .add("user" , "oldFrog")
      .build();

  Request request = new Request.Builder()
        .url("https://github.com/")
        .post(formBody)
        .build();

  Response response = client.newCall(request).execute();      
}

POST提交分块请求

private final OkHttpClient client = new OkHttpClient();

public void run() throw Exception{

  RequestBody requestBody = new MultipartBody.Builder()
      .setType(MultipartBody.FORM)
      .addFormDataPart("user" , "oldFrog")
      .addFormDataPart("image" , "logo.png" , RequestBody.create(MEDIA_TYPE_PNG, new File("local_logo.png")))    
      .build();

  Request request = new Request.Builder()
        .url("https://github.com/")
        .post(requestBody)
        .build();

  Response response = client.newCall(request).execute();      
}

POST提交Stream

private static final MediaType MEDIA_TYPE_PLAINTEXT = MediaType
    .parse("text/plain; charset=utf-8");
  private final OkHttpClient client = new OkHttpClient();
 
  @Test
  public void testPostStream() throws Exception {
 
    RequestBody requestBody = new RequestBody() {
      @Override
      public MediaType contentType() {
        return MEDIA_TYPE_PLAINTEXT;
      }
 
      @Override
      public void writeTo(BufferedSink sink) throws IOException {
 
        File file = new File("src/test/resources/Lorem Ipsum.txt");
        try (BufferedReader br = new BufferedReader(new FileReader(file))) {
          String line;
          while ((line = br.readLine()) != null) {
            sink.writeUtf8(line);
          }
        }
      }
 
    };
 
    Request request = new Request.Builder()
      .url("http://httpbin.org/post")
      .post(requestBody)
      .build();
 
    Response response = client.newCall(request).execute();
   }

至此,就介绍了okhttp的基本使用。后面会开始分析okhttp的源码,以深入其进阶使用。
如有问题,欢迎指正。

你可能感兴趣的:(okhttp使用备忘录)