OkHttp源码分析 初识结构篇(一)

public class GetExample {
    //构建一个 OkHttpClient的实例
  OkHttpClient client = new OkHttpClient();

  String run(String url) throws IOException {
      //构建一个 request 网络请求，传入定义的url
    Request request = new Request.Builder()
        .url(url)
        .build();
    //传入client，调用excute进行执行获取到用户需要的响应
    try (Response response = client.newCall(request).execute()) {
      return response.body().string();
    }
  }
}

//定义MediaType 
public static final MediaType JSON
    = MediaType.get("application/json; charset=utf-8");
//初始化 OKhttpClient
OkHttpClient client = new OkHttpClient();

String post(String url, String json) throws IOException {
  //针对requestBody进行初始化
  RequestBody body = RequestBody.create(JSON, json);
  //传入对应的url和body，构建
  Request request = new Request.Builder()
      .url(url)
      .post(body)
      .build();
      Call call = client.newCall(request);
  try (Response response = call.execute()) {
    return response.body().string();
  }
}

class LoggingInterceptor implements Interceptor {
  @Override public Response intercept(Interceptor.Chain chain) throws IOException {
      //获取拦截器链中的request
    Request request = chain.request();
    //记录 request相关信息
    long t1 = System.nanoTime();
    logger.info(String.format("Sending request %s on %s%n%s",
        request.url(), chain.connection(), request.headers()));

    Response response = chain.proceed(request);

    long t2 = System.nanoTime();
    logger.info(String.format("Received response for %s in %.1fms%n%s",
        response.request().url(), (t2 - t1) / 1e6d, response.headers()));

    return response;
  }
}

OkHttpClient client = new OkHttpClient.Builder()
//添加了上文的日志拦截器 (应用级别拦截器)
    .addInterceptor(new LoggingInterceptor())
    .build();
//添加url以及header
Request request = new Request.Builder()
    .url("http://www.publicobject.com/helloworld.txt")
    .header("User-Agent", "OkHttp Example")
    .build();

Response response = client.newCall(request).execute();
response.body().close();

OkHttpClient client = new OkHttpClient.Builder()
//添加了上文的日志拦截器 (网络级别拦截器)
    .addNetworkInterceptor(new LoggingInterceptor())
    .build();

Request request = new Request.Builder()
    .url("http://www.publicobject.com/helloworld.txt")
    .header("User-Agent", "OkHttp Example")
    .build();

Response response = client.newCall(request).execute();
response.body().close();

//定义client
OkHttpClient client = new OkHttpClient.Builder()
//添加用户的拦截器
    .addInterceptor(new LoggingInterceptor())
    .addNetworkInterceptor(new LoggingInterceptor())
    .build();
    //开始执行网络请求
 try (Response response = client.newCall(request).execute()) {
    return response.body().string();
  }

 @Override public Response execute() throws IOException {
    synchronized (this) {
        //暂时忽略部分
      //执行响应链
      return getResponseWithInterceptorChain();
        //暂时忽略部分  
  }

 Response getResponseWithInterceptorChain() throws IOException {
    // Build a full stack of interceptors.
    List<Interceptor> interceptors = new ArrayList<>();
    //重试之前添加的拦截器，由于 重试层将网络请求全部处理完毕后，才返回；所以是无感知的，用户的拦截器只会得到一个结果
    interceptors.addAll(client.interceptors());
    //重试重定向拦截器
    interceptors.add(new RetryAndFollowUpInterceptor(client));
    //给request添加网络请求必须的header,处理request的response的压缩和解压缩
    interceptors.add(new BridgeInterceptor(client.cookieJar()));
    //处理网路的缓存的部分
    interceptors.add(new CacheInterceptor(client.internalCache()));
    //创建或者从连接池中找到合适的安全的连接
    interceptors.add(new ConnectInterceptor(client));
    if (!forWebSocket) {
    	//网络层的拦截器，由于在重试层之下；所以，每次的重试重定向都会有感知，并且所以此时用户添加的 网络级别的 拦截器 就会调用多次
      interceptors.addAll(client.networkInterceptors());
    }
    //执行实际的io流，request和resopnse的接收
    interceptors.add(new CallServerInterceptor(forWebSocket));
    //定义 串联拦截的链对象，将拦截器串联起来
    Interceptor.Chain chain = new RealInterceptorChain(interceptors, transmitter, null, 0,
        originalRequest, this, client.connectTimeoutMillis(),
        client.readTimeoutMillis(), client.writeTimeoutMillis());

      //忽略
    try {
    	//依次执行拦截器
      Response response = chain.proceed(originalRequest);
      //忽略
      return response;
    } catch (IOException e) {
     //忽略
    } finally {
      //忽略
    
    }
  } 

OkHttpClient client = new OkHttpClient.Builder()
//添加用户的拦截器
    .addInterceptor(new LoggingInterceptor())
    .addNetworkInterceptor(new LoggingInterceptor())
    .build();

public class OkHttpClient implements Cloneable, Call.Factory, WebSocket.Factory {
    final List<Interceptor> interceptors;
  final List<Interceptor> networkInterceptors;
}

OkHttpClient client = new OkHttpClient.Builder()
    //添加了明文的日志拦截器
    .addInterceptor(new ClearTextLoggingInterceptor())
    //添加了加解密
    .addInterceptor(new CodecInterceptor())
    //添加了密文的日志拦截器
    .addInterceptor(new EncrypteLoggingInterceptor())
    .build();

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

    interceptors.addAll(client.interceptors());
    interceptors.add(new RetryAndFollowUpInterceptor(client));
    interceptors.add(new BridgeInterceptor(client.cookieJar()));
    interceptors.add(new CacheInterceptor(client.internalCache()));
    interceptors.add(new ConnectInterceptor(client));
    interceptors.addAll(client.networkInterceptors());    
    interceptors.add(new CallServerInterceptor(forWebSocket));

class SomeInterceptor implements Interceptor {
  @Override public Response intercept(Interceptor.Chain chain) throws IOException {
    Request request = chain.request();
    //调用此行代码去链式调用下一个拦截器
    Response response = chain.proceed(request);
    return response;
  }

class MockInterceptor implements Interceptor {
  @Override public Response intercept(Interceptor.Chain chain) throws IOException {
    Request request = chain.request();
    //判断是否需要mock
    if(isNeedMock(request)){
      //读取原始request构建对应的MOCK server的request
      Request mockRequest = buildMockRequest(request);
      //访问mockServer
      return MockServer(mockRequest);
    }
    //调用此行代码去链式调用下一个拦截器
    Response response = chain.proceed(request);
    return response;
  }

  private boolean isNeedMock(){
    /*此方法主要是用来控制哪些request走假数据，哪些request走真实数据，方便开发自己切换;读者可以根据自己需求自行设计，笔者此处仅提供一个思路*/
  }

  private Request buildMockRequest( Request request){
    /*该方法的主要作用在于我们要把真实的request替换成访问我们自行搭建的mock server平台的请求，一般是替换掉请求的baseUrl部分（即ip地址部分）；其他的替换根据读者选用的mock平台自行决定
    */
  }
  /**
  *这一部分的就非常简单了，发送一个网络请求给 mockServer把mockServer的response返回用户
  **/ 
  private Response MockServer(Request request) throw Exeption{
      return client.newCall(request).execute());
  }