MVP+RxJava+Retrofit框架的使用及其开源项目推荐

青旅半醒 2022-06-01 07:35 131阅读 0赞

![mvp][]

前面我已经写过一篇关于Google的RxJava版MVP解读的文章，本篇就是我在此基础上进行了修改和封装，稍微变化一下，见上图。目的是让这个框架更加实用，同时简化操作，少写代码。果然程序员都是喜欢偷懒的- -

## 前言 ##

首先，阅读本篇文章前，建议你先去了解一下MVP这个设计模式。当然，也可以先看看我前面的文章^\_^ 传送门

另外，还用到了RxJava、Retrofit、Okhttp。如果你已经了解了他们的基本用法，请直接忽略这段，接着往下看~

不想看长长的文章的，可以直接看代码。代码地址已经上传到Github，[https://github.com/backkomyoung/MVP][https_github.com_backkomyoung_MVP]

## 工程结构 ##

按照惯例，先看看工程的主要结构：

![project][]

简单说一下几个主要包下的功能。首先是api包，这是存放对Retrofit进行包装的类。Base包当然是放各种Base类啦~ mvp包是将契约类Contract、Model的实现类和Presenter的实现类放一起，方便管理。其实你也可以按功能分包，个人喜好吧。ui包放一些界面的类，如Activity和Fragment。

下面正式开始~

## 契约类 ##

同样也是从Contract契约类开始说起：

我们可以看到，整体上和Google的Demo差不多，都是把View和Presenter放到Contract类里面统一管理，我这里多加了个Model接口，我不推荐在Presenter进行Model操作，本来很优雅的一件事，在Presenter进行Model操作的话，感觉就差了很多，要做一个优雅的程序员。不同的地方是Model和View接口继承了BaseModel接口和BaseView接口，Presenter变成了一个抽象类，继承于BasePresenter抽象类，传入两个泛型View、Model。为啥呢？我们接着看Base包下的三个Base类。

## Base类 ##

BaseModel：

BaseView：

BasePresenter：

BaseModel和BaseView接口里面是空的，在这里我只是为了在BasePresenter中提供一个约束。当然，如果你有其它全局的需求，可以在里面添加一些方法。重点是BasePresenter这个抽象类，传入一个View和Model，并将其用protected关键字修饰，这样，在它的子类中就可以直接对其赋值和使用了。加入CompositeSubscription变量，是为了对RxJava进行管理。unSubscribe方法对View进行null赋值和清除Rx的Subscription（订阅），防止内存泄漏。

## Presnter桥梁 ##

接下来看看这个很重要的类，作为连接Model和View的桥梁，这里又是怎么做的呢？

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    </div> </td> 
   <td style="padding:0px; vertical-align:middle; border-width:initial; border-style:none; border-color:initial"> <pre style="font-family:consolas,Menlo,&quot;PingFang SC&quot;,&quot;Microsoft YaHei&quot;,monospace; font-size:13px; padding:1px; margin-right:0px; margin-bottom:0px; margin-left:0px; line-height:1.6; color:rgb(197,200,198); word-break:break-all; background-color:rgb(29,31,33); border-width:initial; border-style:none; overflow:auto"></pre> 
    <div style="margin:0px; padding:0px"> 
     <span style="margin:0px 5px 0px 0px; padding:4px 5px 2px; background:rgb(0,102,170); color:rgb(178,148,187); word-wrap:normal">public</span>&nbsp; 
     <span style="margin:0px; padding:0px"><span style="margin:0px 5px 0px 0px; padding:4px 5px 2px; background:rgb(0,102,170); color:rgb(178,148,187); word-wrap:normal">class</span>&nbsp;<span style="margin:0px; padding:0px 10px; font-weight:700; line-height:32px; overflow:hidden; color:rgb(138,190,183)">MainPresenter</span>&nbsp;<span style="margin:0px 5px 0px 0px; padding:4px 5px 2px; background:rgb(0,102,170); color:rgb(178,148,187); word-wrap:normal">extends</span>&nbsp;<span style="margin:0px; padding:0px 10px; font-weight:700; line-height:32px; overflow:hidden; color:rgb(138,190,183)">MainContract</span>.<span style="margin:0px; padding:0px 10px; font-weight:700; line-height:32px; overflow:hidden; color:rgb(138,190,183)">Presenter</span>&nbsp;</span>{ 
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     <span style="margin:0px; padding:0px; color:rgb(129,162,190)"><span style="margin:0px 5px 0px 0px; padding:4px 5px 2px; background:rgb(0,102,170); color:rgb(178,148,187); word-wrap:normal">public</span>&nbsp;<span style="margin:0px; padding:0px 10px; font-weight:700; line-height:32px; overflow:hidden; color:rgb(138,190,183)">MainPresenter</span><span style="margin:0px; padding:0px; color:rgb(222,147,95)">(MainContract.View view)</span>&nbsp;</span>{ 
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      mView = view; 
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      mModel =&nbsp; 
     <span style="margin:0px 5px 0px 0px; padding:4px 5px 2px; background:rgb(0,102,170); color:rgb(178,148,187); word-wrap:normal">new</span>&nbsp;MainModel(); 
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      } 
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     <span style="margin:0px; padding:0px">@Override</span> 
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      Subscription subscribe = mModel.getGank() 
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      .subscribe( 
     <span style="margin:0px 5px 0px 0px; padding:4px 5px 2px; background:rgb(0,102,170); color:rgb(178,148,187); word-wrap:normal">new</span>&nbsp;Subscriber&lt;Gank&gt;() { 
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     <span style="margin:0px; padding:0px">@Override</span> 
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      mView.showDialog(); 
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      } 
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     <span style="margin:0px; padding:0px">@Override</span> 
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      mView.hideDialog(); 
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      } 
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     <span style="margin:0px; padding:0px">@Override</span> 
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     <span style="margin:0px; padding:0px; color:rgb(129,162,190)"><span style="margin:0px 5px 0px 0px; padding:4px 5px 2px; background:rgb(0,102,170); color:rgb(178,148,187); word-wrap:normal">public</span>&nbsp;<span style="margin:0px 5px 0px 0px; padding:4px 5px 2px; background:rgb(0,102,170); color:rgb(178,148,187); word-wrap:normal">void</span>&nbsp;<span style="margin:0px; padding:0px 10px; font-weight:700; line-height:32px; overflow:hidden; color:rgb(138,190,183)">onError</span><span style="margin:0px; padding:0px; color:rgb(222,147,95)">(Throwable e)</span>&nbsp;</span>{ 
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      mView.onFail(e.getMessage()); 
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      onCompleted(); 
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      } 
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     <span style="margin:0px; padding:0px">@Override</span> 
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     <span style="margin:0px; padding:0px; color:rgb(129,162,190)"><span style="margin:0px 5px 0px 0px; padding:4px 5px 2px; background:rgb(0,102,170); color:rgb(178,148,187); word-wrap:normal">public</span>&nbsp;<span style="margin:0px 5px 0px 0px; padding:4px 5px 2px; background:rgb(0,102,170); color:rgb(178,148,187); word-wrap:normal">void</span>&nbsp;<span style="margin:0px; padding:0px 10px; font-weight:700; line-height:32px; overflow:hidden; color:rgb(138,190,183)">onNext</span><span style="margin:0px; padding:0px; color:rgb(222,147,95)">(Gank gank)</span>&nbsp;</span>{ 
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      mView.onSucceed(gank); 
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      } 
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      }); 
    </div> 
    <div style="margin:0px; padding:0px"></div> 
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      addSubscribe(subscribe); 
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      } 
    </div> 
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      } 
    </div> </td> 
  </tr> 
 </tbody> 
</table>

构造方法传进一个View，并且new了一个Model对象，直接赋值给父类中的View和Model。然后下面复写的方法中调用Model中的方法，再将结果通过View中的方法传出去，这是很原始的MVP方式。最后addSubscribe添加到订阅队列中。

## Model处理数据 ##

Model分出来，而不在Presenter处理，其实也是为了简洁，当你要处理很多数据的时候，Presenter就会变得很乱了。

我这里很简单，就获取ApiService对象，然后调用API。最后compose传进我自己定义的线程切换器：

将网络请求的IO线程切换回Android的UI主线程，才能继续进行在Presenter中的操作。

## BaseActivity中的封装 ##

在前面我们可以看到BasePresenter中有两个方法，一个是添加订阅addSubscribe，另一个是unSubscribe解除订阅。我们只看到了在Presenter中使用了addSubscribe，而没有看到unSubscribe在哪使用了。因为要防止内存泄漏，所以当然要在和生命周期相关的地方进行释放资源，这个地方只有我们所说的View了，也就是Activity和Fragment中。我们先开看一下相关代码：

通过泛型确定一个Presenter的类型，然后使用抽象方法onCreatePresenter对其进行赋值，最后在onDestroy方法中进行资源的释放。继承这个BaseActivity类的Activity，就不用每次都在onDestroy进行同样的操作啦~达到简洁的目的。同理，Fragment中也是同样的，只是在生命周期的onResume和onPause中分别进行Presenter的赋值和资源的释放。这里我就不贴代码，可以上我的Github看。

## Retrofit引擎封装 ##

说到这了，就顺便说一下Retrofit吧。上面的MainModel类中用到了ApiEngine类：

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   <td style="padding:0px; vertical-align:middle; border-width:initial; border-style:none; border-color:initial"> <pre style="font-family:consolas,Menlo,&quot;PingFang SC&quot;,&quot;Microsoft YaHei&quot;,monospace; font-size:13px; padding:1px; margin-right:0px; margin-bottom:0px; margin-left:0px; line-height:1.6; color:rgb(197,200,198); word-break:break-all; background-color:rgb(29,31,33); border-width:initial; border-style:none; overflow:auto"></pre> 
    <div style="margin:0px; padding:0px"> 
     <span style="margin:0px 5px 0px 0px; padding:4px 5px 2px; background:rgb(0,102,170); color:rgb(178,148,187); word-wrap:normal">public</span>&nbsp; 
     <span style="margin:0px; padding:0px"><span style="margin:0px 5px 0px 0px; padding:4px 5px 2px; background:rgb(0,102,170); color:rgb(178,148,187); word-wrap:normal">class</span>&nbsp;<span style="margin:0px; padding:0px 10px; font-weight:700; line-height:32px; overflow:hidden; color:rgb(138,190,183)">ApiEngine</span>&nbsp;</span>{ 
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     <span style="margin:0px 5px 0px 0px; padding:4px 5px 2px; background:rgb(0,102,170); color:rgb(178,148,187); word-wrap:normal">private</span>&nbsp; 
     <span style="margin:0px 5px 0px 0px; padding:4px 5px 2px; background:rgb(0,102,170); color:rgb(178,148,187); word-wrap:normal">volatile</span>&nbsp; 
     <span style="margin:0px 5px 0px 0px; padding:4px 5px 2px; background:rgb(0,102,170); color:rgb(178,148,187); word-wrap:normal">static</span>&nbsp;ApiEngine apiEngine; 
    </div> 
    <div style="margin:0px; padding:0px"> 
     <span style="margin:0px 5px 0px 0px; padding:4px 5px 2px; background:rgb(0,102,170); color:rgb(178,148,187); word-wrap:normal">private</span>&nbsp;Retrofit retrofit; 
    </div> 
    <div style="margin:0px; padding:0px"></div> 
    <div style="margin:0px; padding:0px"> 
     <span style="margin:0px; padding:0px; color:rgb(129,162,190)"><span style="margin:0px 5px 0px 0px; padding:4px 5px 2px; background:rgb(0,102,170); color:rgb(178,148,187); word-wrap:normal">private</span>&nbsp;<span style="margin:0px; padding:0px 10px; font-weight:700; line-height:32px; overflow:hidden; color:rgb(138,190,183)">ApiEngine</span><span style="margin:0px; padding:0px; color:rgb(222,147,95)">()</span>&nbsp;</span>{ 
    </div> 
    <div style="margin:0px; padding:0px"></div> 
    <div style="margin:0px; padding:0px"> 
     <span style="margin:0px; padding:0px; color:rgb(150,152,150)">//日志拦截器</span> 
    </div> 
    <div style="margin:0px; padding:0px">
      HttpLoggingInterceptor loggingInterceptor =&nbsp; 
     <span style="margin:0px 5px 0px 0px; padding:4px 5px 2px; background:rgb(0,102,170); color:rgb(178,148,187); word-wrap:normal">new</span>&nbsp;HttpLoggingInterceptor(); 
    </div> 
    <div style="margin:0px; padding:0px">
      loggingInterceptor.setLevel(HttpLoggingInterceptor.Level.BODY); 
    </div> 
    <div style="margin:0px; padding:0px"></div> 
    <div style="margin:0px; padding:0px"> 
     <span style="margin:0px; padding:0px; color:rgb(150,152,150)">//缓存</span> 
    </div> 
    <div style="margin:0px; padding:0px"> 
     <span style="margin:0px 5px 0px 0px; padding:4px 5px 2px; background:rgb(0,102,170); color:rgb(178,148,187); word-wrap:normal">int</span>&nbsp;size =&nbsp; 
     <span style="margin:0px; padding:0px; color:rgb(181,189,104)">1024</span>&nbsp;*&nbsp; 
     <span style="margin:0px; padding:0px; color:rgb(181,189,104)">1024</span>&nbsp;*&nbsp; 
     <span style="margin:0px; padding:0px; color:rgb(181,189,104)">100</span>; 
    </div> 
    <div style="margin:0px; padding:0px">
      File cacheFile =&nbsp; 
     <span style="margin:0px 5px 0px 0px; padding:4px 5px 2px; background:rgb(0,102,170); color:rgb(178,148,187); word-wrap:normal">new</span>&nbsp;File(App.getContext().getCacheDir(),&nbsp; 
     <span style="margin:0px; padding:0px; color:rgb(181,189,104)">"OkHttpCache"</span>); 
    </div> 
    <div style="margin:0px; padding:0px">
      Cache cache =&nbsp; 
     <span style="margin:0px 5px 0px 0px; padding:4px 5px 2px; background:rgb(0,102,170); color:rgb(178,148,187); word-wrap:normal">new</span>&nbsp;Cache(cacheFile, size); 
    </div> 
    <div style="margin:0px; padding:0px"></div> 
    <div style="margin:0px; padding:0px">
      OkHttpClient client =&nbsp; 
     <span style="margin:0px 5px 0px 0px; padding:4px 5px 2px; background:rgb(0,102,170); color:rgb(178,148,187); word-wrap:normal">new</span>&nbsp;OkHttpClient.Builder() 
    </div> 
    <div style="margin:0px; padding:0px">
      .connectTimeout( 
     <span style="margin:0px; padding:0px; color:rgb(181,189,104)">12</span>, TimeUnit.SECONDS) 
    </div> 
    <div style="margin:0px; padding:0px">
      .writeTimeout( 
     <span style="margin:0px; padding:0px; color:rgb(181,189,104)">12</span>, TimeUnit.SECONDS) 
    </div> 
    <div style="margin:0px; padding:0px">
      .writeTimeout( 
     <span style="margin:0px; padding:0px; color:rgb(181,189,104)">12</span>, TimeUnit.SECONDS) 
    </div> 
    <div style="margin:0px; padding:0px">
      .addNetworkInterceptor( 
     <span style="margin:0px 5px 0px 0px; padding:4px 5px 2px; background:rgb(0,102,170); color:rgb(178,148,187); word-wrap:normal">new</span>&nbsp;NetworkInterceptor()) 
    </div> 
    <div style="margin:0px; padding:0px">
      .addInterceptor(loggingInterceptor) 
    </div> 
    <div style="margin:0px; padding:0px">
      .cache(cache) 
    </div> 
    <div style="margin:0px; padding:0px">
      .build(); 
    </div> 
    <div style="margin:0px; padding:0px"></div> 
    <div style="margin:0px; padding:0px">
      retrofit =&nbsp; 
     <span style="margin:0px 5px 0px 0px; padding:4px 5px 2px; background:rgb(0,102,170); color:rgb(178,148,187); word-wrap:normal">new</span>&nbsp;Retrofit.Builder() 
    </div> 
    <div style="margin:0px; padding:0px">
      .baseUrl(ApiService.BASE_URL) 
    </div> 
    <div style="margin:0px; padding:0px">
      .client(client) 
    </div> 
    <div style="margin:0px; padding:0px">
      .addConverterFactory(GsonConverterFactory.create()) 
    </div> 
    <div style="margin:0px; padding:0px">
      .addCallAdapterFactory(RxJavaCallAdapterFactory.create()) 
    </div> 
    <div style="margin:0px; padding:0px">
      .build(); 
    </div> 
    <div style="margin:0px; padding:0px"></div> 
    <div style="margin:0px; padding:0px">
      } 
    </div> 
    <div style="margin:0px; padding:0px"></div> 
    <div style="margin:0px; padding:0px"> 
     <span style="margin:0px; padding:0px; color:rgb(129,162,190)"><span style="margin:0px 5px 0px 0px; padding:4px 5px 2px; background:rgb(0,102,170); color:rgb(178,148,187); word-wrap:normal">public</span>&nbsp;<span style="margin:0px 5px 0px 0px; padding:4px 5px 2px; background:rgb(0,102,170); color:rgb(178,148,187); word-wrap:normal">static</span>&nbsp;ApiEngine&nbsp;<span style="margin:0px; padding:0px 10px; font-weight:700; line-height:32px; overflow:hidden; color:rgb(138,190,183)">getInstance</span><span style="margin:0px; padding:0px; color:rgb(222,147,95)">()</span>&nbsp;</span>{ 
    </div> 
    <div style="margin:0px; padding:0px"> 
     <span style="margin:0px 5px 0px 0px; padding:4px 5px 2px; background:rgb(0,102,170); color:rgb(178,148,187); word-wrap:normal">if</span>&nbsp;(apiEngine ==&nbsp; 
     <span style="margin:0px 5px 0px 0px; padding:4px 5px 2px; background:rgb(0,102,170); color:rgb(178,148,187); word-wrap:normal">null</span>) { 
    </div> 
    <div style="margin:0px; padding:0px"> 
     <span style="margin:0px 5px 0px 0px; padding:4px 5px 2px; background:rgb(0,102,170); color:rgb(178,148,187); word-wrap:normal">synchronized</span>&nbsp;(ApiEngine.class) { 
    </div> 
    <div style="margin:0px; padding:0px"> 
     <span style="margin:0px 5px 0px 0px; padding:4px 5px 2px; background:rgb(0,102,170); color:rgb(178,148,187); word-wrap:normal">if</span>&nbsp;(apiEngine ==&nbsp; 
     <span style="margin:0px 5px 0px 0px; padding:4px 5px 2px; background:rgb(0,102,170); color:rgb(178,148,187); word-wrap:normal">null</span>) { 
    </div> 
    <div style="margin:0px; padding:0px">
      apiEngine =&nbsp; 
     <span style="margin:0px 5px 0px 0px; padding:4px 5px 2px; background:rgb(0,102,170); color:rgb(178,148,187); word-wrap:normal">new</span>&nbsp;ApiEngine(); 
    </div> 
    <div style="margin:0px; padding:0px">
      } 
    </div> 
    <div style="margin:0px; padding:0px">
      } 
    </div> 
    <div style="margin:0px; padding:0px">
      } 
    </div> 
    <div style="margin:0px; padding:0px"> 
     <span style="margin:0px 5px 0px 0px; padding:4px 5px 2px; background:rgb(0,102,170); color:rgb(178,148,187); word-wrap:normal">return</span>&nbsp;apiEngine; 
    </div> 
    <div style="margin:0px; padding:0px">
      } 
    </div> 
    <div style="margin:0px; padding:0px"></div> 
    <div style="margin:0px; padding:0px"> 
     <span style="margin:0px; padding:0px; color:rgb(129,162,190)"><span style="margin:0px 5px 0px 0px; padding:4px 5px 2px; background:rgb(0,102,170); color:rgb(178,148,187); word-wrap:normal">public</span>&nbsp;ApiService&nbsp;<span style="margin:0px; padding:0px 10px; font-weight:700; line-height:32px; overflow:hidden; color:rgb(138,190,183)">getApiService</span><span style="margin:0px; padding:0px; color:rgb(222,147,95)">()</span>&nbsp;</span>{ 
    </div> 
    <div style="margin:0px; padding:0px"> 
     <span style="margin:0px 5px 0px 0px; padding:4px 5px 2px; background:rgb(0,102,170); color:rgb(178,148,187); word-wrap:normal">return</span>&nbsp;retrofit.create(ApiService.class); 
    </div> 
    <div style="margin:0px; padding:0px">
      } 
    </div> 
    <div style="margin:0px; padding:0px">
      } 
    </div> </td> 
  </tr> 
 </tbody> 
</table>

用了单例模式，在构造方法中只初始化一次Retrofit和Okhttp。双重锁的方式获取单例，然后再根据需要获取ApiService，如果你有很多个不同源的API，那就可以创建多个getXXXXApiService。

## 结语 ##

最后，来看看Demo运行效果吧：

![demo\_gif][demo_gif]

Demo数据源来自Gank.io

其实还有一个问题，就是关于错误类型的统一处理。刚开始的时候我是打算添加进去的，但是后来想想，每个项目的API都有不同的需求，有不同的错误，所以，还是留给需要的时候再封装一层错误处理吧。如果要统一处理错误，自定义一个Subscriber，在里面的onError方法处理即可。

推荐MVP开源项目:

[MVP做一款阅读类的app][MVP_app]

[MVP新闻阅读app][MVP_app 1]

[MVPArms][]

[mvp]: http://ofp4swv4i.bkt.clouddn.com/mvp-rxjava-retrofit.png
[https_github.com_backkomyoung_MVP]: https://github.com/backkomyoung/MVP
[project]: http://ofp4swv4i.bkt.clouddn.com/mvp-rxjava-retrofit-package.png
[demo_gif]: http://ofp4swv4i.bkt.clouddn.com/mvp-rxjava-retrofit-gif.gif
[MVP_app]: https://www.jianshu.com/p/be0f4a4863ae
[MVP_app 1]: https://github.com/jaydenxiao2016/AndroidFire
[MVPArms]: https://github.com/JessYanCoding/MVPArms/blob/master/MVPArms.md