call.enqueue(new Callback<HistoryBean>() {
      @Override
      public void onResponse(Call<HistoryBean> call, Response<HistoryBean> response) {
        HistoryBean hb = response.body();
        if(hb == null) return;
        showText.append(hb.isError() + "");
        for(HistoryBean.ResultsBean rb : hb.getResults()){
          showText.append(rb.getTitle() + "/n");
        }
      }
      @Override
      public void onFailure(Call<HistoryBean> call, Throwable t) {
      }
    });

public interface CallBack {
  void eat();
}

public class Son implements CallBack{
  private Mom mom;
  //A类持有对B类的引用
  public void setMom(Mom mom){
    this.mom = mom;
  }
  @Override
  public void eat() {
    System.out.println("我来吃饭了");
  }
  public void askMom(){
    //通过B类的引用调用含有接口参数的方法。
     System.out.println("饭做了吗？");
    System.out.println("没做好，我玩游戏了");
    new Thread(() -> mom.doCook(Son.this)).start();
    System.out.println("玩游戏了中......");
  }
}

public class Mom {
  //在含有接口参数的方法中利用接口参数调用回调方法
  public void doCook(CallBack callBack){
    new Thread(new Runnable() {
      @Override
      public void run() {
        try {
          System.out.println("做饭中......");
          Thread.sleep(5000);
          callBack.eat();
        } catch (InterruptedException e) {
          e.printStackTrace();
        }
      }
    }).start();
  }
}

public class Test {
  public static void main(String[] args) {
    Mom mom = new Mom();
    Son son = new Son();
    son.setMom(mom);
    son.askMom();
  }
}

public class Son implements CallBack{
  public Mom mom;
  public Son(Mom mom){
    this.mom = mom;
  }
  public void askMom(){
    System.out.println("饭做了吗？");
    System.out.println("没做好，我玩游戏了");
    new Thread(() -> mom.doCook(Son.this)).start();
    System.out.println("玩游戏了中......");
  }
  @Override
  public void eat() {
    System.out.println("好了，我来吃饭了");
  }
}

public class CallBackTest {
  public static void main(String[] args) {
    Mom mom = new Mom();
    new Thread(()-> mom.doCook(() -> System.out.println("吃饭了......"))).start();
  }
}

button.setOnClickListener(new View.OnClickListener() {
    @Override
    public void onClick(View v) {
       Log.i("button","被点击");
    }
});

call.enqueue(new Callback<HistoryBean>() {
      @Override
      public void onResponse(Call<HistoryBean> call, Response<HistoryBean> response) {
        HistoryBean hb = response.body();
        if(hb == null) return;
        showText.append(hb.isError() + "");
        for(HistoryBean.ResultsBean rb : hb.getResults()){
          showText.append(rb.getTitle() + "/n");
        }
      }
      @Override
      public void onFailure(Call<HistoryBean> call, Throwable t) {
      }
    });

public class Client{
  public Server server;
  public String request;
  //链接Server，得到Server引用。
  public Client connect(Server server){
    this.server = server;
    return this;
  }
  //Client，设置request
  public Client setRequest(String request){
    this.request = request;
    return this;
  }
  //异步发送请求的方法，lamdba表达式。
  public void enqueue(Server.CallBack callBack){
    new Thread(()->server.setCallBack(request,callBack)).start();
  }
}

public class Server {
  public String response = "这是一个html";
  //注册回调接口的方法，把数据通过参数传给回调接口
  public void setCallBack(String request,CallBack callBack){
    System.out.println("已经收到request，正在计算当中......");
    new Thread(() -> {
      try {
        Thread.sleep(5000);
        callBack.onResponse(request + response);
      } catch (InterruptedException e) {
        e.printStackTrace();
        callBack.onFail(e);
      }
    }).start();
  }
  //在拥有数据的那个类里面写一个接口
  public interface CallBack{
    void onResponse(String response);
    void onFail(Throwable throwable);
  }
}

public class CallBackTest {
  public static void main(String[] args) {
    Client client = new Client();
    client.connect(new Server()).setRequest("这个文件是什么？").enqueue(new Server.CallBack() {
      @Override
      public void onResponse(String response) {
        System.out.println(response);
      }
      @Override
      public void onFail(Throwable throwable) {
        System.out.println(throwable.getMessage());
      }
    });
  }
}

已经收到request，正在计算当中......
这个文件是什么？这是一个html