Retrofit(四)--Platform Retrofit(四)--Platform

移步Retrofit--网络通讯框架 Platform的工作

根据不同平台初始化不同平台的对应继承子类，此处就是Android类
Android类可以返回一个回调回UI线程的执行器
Android类可以返回网络请求适配器工厂ExecutorCallAdapterFactory

源码分析
1. 通过Retrofit内的调用进入Platform

public Builder() { this(Platform.get()); }

class Platform { private static final Platform PLATFORM = findPlatform(); static Platform get() { return PLATFORM; } ... }

通过上面代码可以看出将要进入findPlatform()方法

private static Platform findPlatform() { try { //为Android平台，所以会生成Android类 Class.forName("android.os.Build"); if (Build.VERSION.SDK_INT != 0) { return new Android(); } } catch (ClassNotFoundException ignored) { } try { Class.forName("java.util.Optional"); return new Java8(); } catch (ClassNotFoundException ignored) { } return new Platform(); }

【Retrofit(四)--Platform】接下来看Android类
2. Android类

static class Android extends Platform { @Override public Executor defaultCallbackExecutor() { return new MainThreadExecutor(); }@Override CallAdapter.Factory defaultCallAdapterFactory(@Nullable Executor callbackExecutor) { if (callbackExecutor == null) throw new AssertionError(); return new ExecutorCallAdapterFactory(callbackExecutor); }static class MainThreadExecutor implements Executor { private final Handler handler = new Handler(Looper.getMainLooper()); @Override public void execute(Runnable r) { handler.post(r); } } }

这里面有两个方法，