ym——Android开发MVP模式（解决了View和Model的耦合）

ProgressBar控件和TextView控件，我们判断它是否有网络连接，如果有的话就隐藏  ProgressBar和跳转到MainActivity如果没有网络的话则显示ProgressBar和TextView，TextView则提示用户No internet。就这么简单的一个需求，我们看看如何用MVP模式做这个需求

首先我们看下M层是如何接口写的

<span style="font-size:18px;">package com.manning.androidhacks.hack020.presenter.model;

public interface IConnectionStatus {
  boolean isOnline();
}
</span>

<span style="font-size:18px;">package com.manning.androidhacks.hack020.presenter.model.impl;

import com.manning.androidhacks.hack020.presenter.model.IConnectionStatus;

public class ConnectionStatus implements IConnectionStatus {

  @Override
  public boolean isOnline() {
    // TODO: Here we should place the code to check the connectivity.
    return true;
  }

}</span>

<span style="font-size:18px;">package com.manning.androidhacks.hack020.view;

public interface ISplashView {

  void showProgress();
  void hideProgress();
  void showNoInetErrorMsg();
  void moveToMainView();
}
</span>

<span style="font-size:18px;">package com.manning.androidhacks.hack020.view.impl;

import android.app.Activity;
import android.content.Intent;
import android.os.Bundle;
import android.view.View;
import android.widget.ProgressBar;
import android.widget.TextView;

import com.manning.androidhacks.hack020.R;
import com.manning.androidhacks.hack020.presenter.SplashPresenter;
import com.manning.androidhacks.hack020.view.ISplashView;

public class SplashActivity extends Activity implements ISplashView {

  private TextView mTextView;
  private ProgressBar mProgressBar;
  private SplashPresenter mPresenter = new SplashPresenter();

  @Override
  public void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.splash);

    mPresenter.setView(this);

    mTextView = (TextView) findViewById(R.id.splash_text);
    mProgressBar = (ProgressBar) findViewById(R.id.splash_progress_bar);
  }

  @Override
  protected void onResume() {
    super.onResume();
    mPresenter.didFinishLoading();
  }

  public void showProgress() {
    mProgressBar.setVisibility(View.VISIBLE);
  }

  public void hideProgress() {
    mProgressBar.setVisibility(View.INVISIBLE);
  }

  public void showNoInetErrorMsg() {
    mTextView.setText("No internet");
  }

  @Override
  public void moveToMainView() {
    startActivity(new Intent(this, MainActivity.class));
  }
}</span>

最后我们来看看P层是如何控制他们的逻辑的：

<span style="font-size:18px;">package com.manning.androidhacks.hack020.view.impl;

import android.app.Activity;
import android.content.Intent;
import android.os.Bundle;
import android.view.View;
import android.widget.ProgressBar;
import android.widget.TextView;

import com.manning.androidhacks.hack020.R;
import com.manning.androidhacks.hack020.presenter.SplashPresenter;
import com.manning.androidhacks.hack020.view.ISplashView;

public class SplashActivity extends Activity implements ISplashView {

  private TextView mTextView;
  private ProgressBar mProgressBar;
  private SplashPresenter mPresenter = new SplashPresenter();

  @Override
  public void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.splash);

    mPresenter.setView(this);

    mTextView = (TextView) findViewById(R.id.splash_text);
    mProgressBar = (ProgressBar) findViewById(R.id.splash_progress_bar);
  }

  @Override
  protected void onResume() {
    super.onResume();
    mPresenter.didFinishLoading();
  }

  public void showProgress() {
    mProgressBar.setVisibility(View.VISIBLE);
  }

  public void hideProgress() {
    mProgressBar.setVisibility(View.INVISIBLE);
  }

  public void showNoInetErrorMsg() {
    mTextView.setText("No internet");
  }

  @Override
  public void moveToMainView() {
    startActivity(new Intent(this, MainActivity.class));
  }
}</span>