一. 前言
你是否遇到過(guò)Activity/Fragment中成百上千行代碼,完全無(wú)法維護(hù),看著頭疼?
你是否遇到過(guò)因后臺(tái)接口還未寫而你不能先寫代碼邏輯的情況?
你是否遇到過(guò)用MVC架構(gòu)寫的項(xiàng)目進(jìn)行單元測(cè)試時(shí)的深深無(wú)奈?
如果你現(xiàn)在還是用MVC架構(gòu)模式在寫項(xiàng)目,請(qǐng)先轉(zhuǎn)到MVP模式!
二. MVC架構(gòu)
MVC架構(gòu)模式最初生根于服務(wù)器端的Web開發(fā)，后來(lái)漸漸能夠勝任客戶端Web開發(fā)，再后來(lái)因Android項(xiàng)目由XML和Activity/Fragment組成,慢慢的Android開發(fā)者開始使用類似MVC的架構(gòu)模式開發(fā)應(yīng)用.
M層:模型層(model),主要是實(shí)體類,數(shù)據(jù)庫(kù),網(wǎng)絡(luò)等存在的層面,model將新的數(shù)據(jù)發(fā)送到view層,用戶得到數(shù)據(jù)響應(yīng).
V層:視圖層(view),一般指XML為代表的視圖界面.顯示來(lái)源于model層的數(shù)據(jù).用戶的點(diǎn)擊操作等事件從view層傳遞到controller層.
C層:控制層(controller),一般以Activity/Fragment為代表.C層主要是連接V層和M層的,C層收到V層發(fā)送過(guò)來(lái)的事件請(qǐng)求,從M層獲取數(shù)據(jù),展示給V層.
從上圖可以看出M層和V層有連接關(guān)系,而Activity有時(shí)候既充當(dāng)了控制層又充當(dāng)了視圖層,導(dǎo)致項(xiàng)目維護(hù)比較麻煩.
1. MVC架構(gòu)優(yōu)缺點(diǎn)
A. 缺點(diǎn)
M層和V層有連接關(guān)系,沒(méi)有解耦,導(dǎo)致維護(hù)困難.
Activity/Fragment中的代碼過(guò)多,難以維護(hù).
Activity中有很多關(guān)于視圖UI的顯示代碼，因此View視圖和Activity控制器并不是完全分離的，當(dāng)Activity類業(yè)務(wù)過(guò)多的時(shí)候，會(huì)變得難以管理和維護(hù).尤其是當(dāng)UI的狀態(tài)數(shù)據(jù)，跟持久化的數(shù)據(jù)混雜在一起，變得極為混亂.
B. 優(yōu)點(diǎn)
控制層和View層都在Activity中進(jìn)行操作，數(shù)據(jù)操作方便.
模塊職責(zé)劃分明確.主要?jiǎng)澐謱覯,V,C三個(gè)模塊.
三. MVP架構(gòu)
MVP,即是Model,View,Presenter架構(gòu)模式.看起來(lái)類似MVC,其實(shí)不然.從上圖能看到Model層和View層沒(méi)有相連接,完全解耦.
用戶觸碰界面觸發(fā)事件,View層把事件通知Presenter層,Presenter層通知Model層處理這個(gè)事件,Model層處理后把結(jié)果發(fā)送到Presenter層,Presenter層再通知View層,最后View層做出改變.這是一整套流程.
M層:模型層(Model),此層和MVC中的M層作用類似.
V層:視圖層(View),在MVC中V層只包含XML文件,而MVP中V層包含XML,Activity和Fragment三者.理論上V層不涉及任何邏輯,只負(fù)責(zé)界面的改變,盡量把邏輯處理放到M層.
P層:通知層(Presenter),P層的主要作用就是連接V層和M層,起到一個(gè)通知傳遞數(shù)據(jù)的作用.
1. MVP架構(gòu)優(yōu)缺點(diǎn)
A. 缺點(diǎn)
MVP中接口過(guò)多.
每一個(gè)功能,相比于MVC要多寫好幾個(gè)文件.
如果某一個(gè)界面中需要請(qǐng)求多個(gè)服務(wù)器接口,這個(gè)界面文件中會(huì)實(shí)現(xiàn)很多的回調(diào)接口,導(dǎo)致代碼繁雜.
如果更改了數(shù)據(jù)源和請(qǐng)求中參數(shù),會(huì)導(dǎo)致更多的代碼修改.
額外的代碼復(fù)雜度及學(xué)習(xí)成本.
B. 優(yōu)點(diǎn)
模塊職責(zé)劃分明顯,層次清晰,接口功能清晰.
Model層和View層分離,解耦.修改View而不影響Model.
功能復(fù)用度高,方便.一個(gè)Presenter可以復(fù)用于多個(gè)View,而不用更改Presenter的邏輯.
有利于測(cè)試驅(qū)動(dòng)開發(fā),以前的Android開發(fā)是難以進(jìn)行單元測(cè)試.
如果后臺(tái)接口還未寫好,但已知返回?cái)?shù)據(jù)類型的情況下,完全可以寫出此接口完整的功能.
四. MVP架構(gòu)實(shí)戰(zhàn)(真槍實(shí)彈)
1. MVP三層代碼簡(jiǎn)單書寫
接下來(lái)筆者從簡(jiǎn)到繁,一點(diǎn)一點(diǎn)的堆砌MVP的整個(gè)架構(gòu).先看一下XML布局,布局中一個(gè)Button按鈕和一個(gè)TextView控件,用戶點(diǎn)擊按鈕后,Presenter層通知Model層請(qǐng)求處理網(wǎng)絡(luò)數(shù)據(jù),處理后Model層把結(jié)果數(shù)據(jù)發(fā)送給Presenter層,Presenter層再通知View層,然后View層改變TextView顯示的內(nèi)容.
<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:layout_gravity="center"
android:gravity="center"
android:orientation="vertical"
tools:context=".view.SingleInterfaceActivity">
<Button
android:id="@+id/button"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="點(diǎn)擊" />
<TextView
android:id="@+id/textView"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_marginTop="100px"
android:text="請(qǐng)點(diǎn)擊上方按鈕獲取數(shù)據(jù)" />
</LinearLayout>
接下來(lái)是Activity代碼,里面就是獲取Button和TextView控件,然后對(duì)Button做監(jiān)聽,先簡(jiǎn)單的這樣寫,一會(huì)慢慢的增加代碼.
public class SingleInterfaceActivity extends AppCompatActivity {
private Button button;
private TextView textView;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_single_interface);
button = findViewById(R.id.button);
textView = findViewById(R.id.textView);
button.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
}
});
}
}
下面是Model層代碼.本次網(wǎng)絡(luò)請(qǐng)求用的是wanandroid網(wǎng)站的開放api,其中的文章首頁(yè)列表接口.SingleInterfaceModel文件里面有一個(gè)方法getData,第一個(gè)參數(shù)curPage意思是獲取第幾頁(yè)的數(shù)據(jù),第二個(gè)參數(shù)callback是Model層通知Presenter層的回調(diào).
public class SingleInterfaceModel {
public void getData(int curPage, final Callback callback) {
NetUtils.getRetrofit()
.create(Api.class)
.getData(curPage)
.subscribeOn(Schedulers.io())
.observeOn(AndroidSchedulers.mainThread())
.subscribe(new Subscriber<ArticleListBean>() {
@Override
public void onCompleted() {
LP.w("completed");
}
@Override
public void onError(Throwable e) {
callback.onFail("出現(xiàn)錯(cuò)誤");
}
@Override
public void onNext(ArticleListBean bean) {
if (null == bean) {
callback.onFail("出現(xiàn)錯(cuò)誤");
} else if (bean.errorCode != 0) {
callback.onFail(bean.errorMsg);
} else {
callback.onSuccess(bean);
}
}
});
}
}
Callback文件內(nèi)容如下.里面一個(gè)成功一個(gè)失敗的回調(diào)接口,參數(shù)全是泛型,為啥使用泛型筆者就不用說(shuō)了吧.
public interface Callback<K, V> {
void onSuccess(K data);
void onFail(V data);
}
再接下來(lái)是Presenter層的代碼.SingleInterfacePresenter類構(gòu)造函數(shù)中直接new了一個(gè)Model層對(duì)象,用于Presenter層對(duì)Model層的調(diào)用.然后SingleInterfacePresenter類的方法getData用于與Model的互相連接.
public class SingleInterfacePresenter {
private final SingleInterfaceModel singleInterfaceModel;
public SingleInterfacePresenter() {
this.singleInterfaceModel = new SingleInterfaceModel();
}
public void getData(int curPage) {
singleInterfaceModel.getData(curPage, new Callback<ArticleListBean, String>() {
@Override
public void onSuccess(ArticleListBean loginResultBean) {
//如果Model層請(qǐng)求數(shù)據(jù)成功,則此處應(yīng)執(zhí)行通知View層的代碼
}
@Override
public void onFail(String errorMsg) {
//如果Model層請(qǐng)求數(shù)據(jù)失敗,則此處應(yīng)執(zhí)行通知View層的代碼
}
});
}
}
至此,MVP三層簡(jiǎn)單的部分代碼算是完成.那么怎樣進(jìn)行整個(gè)流程的相互調(diào)用呢.我們把剛開始的SingleInterfaceActivity代碼改一下,讓SingleInterfaceActivity持有Presenter層的對(duì)象,這樣View層就可以調(diào)用Presenter層了.修改后代碼如下.
public class SingleInterfaceActivity extends AppCompatActivity {
private Button button;
private TextView textView;
private SingleInterfacePresenter singleInterfacePresenter;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_single_interface);
button = findViewById(R.id.button);
textView = findViewById(R.id.textView);
singleInterfacePresenter = new SingleInterfacePresenter();
button.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
singleInterfacePresenter.getData(0);
}
});
}
}
從以上所有代碼可以看出,當(dāng)用戶點(diǎn)擊按鈕后,View層按鈕的監(jiān)聽事件執(zhí)行調(diào)用了Presenter層對(duì)象的getData方法,此時(shí),Presenter層對(duì)象的getData方法調(diào)用了Model層對(duì)象的getData方法,Model層對(duì)象的getData方法中執(zhí)行了網(wǎng)絡(luò)請(qǐng)求和邏輯處理,把成功或失敗的結(jié)果通過(guò)Callback接口回調(diào)給了Presenter層,然后Presenter層再通知View層改變界面.但此時(shí)SingleInterfacePresenter類中收到Model層的結(jié)果后無(wú)法通知View層,因?yàn)镾ingleInterfacePresenter未持有View層的對(duì)象.如下代碼的注釋中有說(shuō)明.(如果此時(shí)點(diǎn)擊按鈕,下方代碼LP.w()處會(huì)打印出網(wǎng)絡(luò)請(qǐng)求成功的log)
public class SingleInterfacePresenter {
private final SingleInterfaceModel singleInterfaceModel;
public SingleInterfacePresenter() {
this.singleInterfaceModel = new SingleInterfaceModel();
}
public void getData(int curPage) {
singleInterfaceModel.getData(curPage, new Callback<ArticleListBean, String>() {
@Override
public void onSuccess(ArticleListBean loginResultBean) {
//如果Model層請(qǐng)求數(shù)據(jù)成功,則此處應(yīng)執(zhí)行通知View層的代碼
//LP.w()是一個(gè)簡(jiǎn)單的log打印
LP.w(loginResultBean.toString());
}
@Override
public void onFail(String errorMsg) {
//如果Model層請(qǐng)求數(shù)據(jù)失敗,則此處應(yīng)執(zhí)行通知View層的代碼
}
});
}
}
代碼寫到這里,筆者先把這些代碼提交到github(https://github.com/serge66/MVPDemo),github上會(huì)有一次提交記錄,如果想看此時(shí)的代碼,可以根據(jù)提交記錄"第一次修改"克隆此時(shí)的代碼.
2. P層V層溝通橋梁
現(xiàn)在P層未持有V層對(duì)象,不能通知V層改變界面,那么就繼續(xù)演變MVP架構(gòu).
在MVP架構(gòu)中,我們要為每個(gè)Activity/Fragment寫一個(gè)接口,這個(gè)接口需要讓Presenter層持有,P層通過(guò)這個(gè)接口去通知V層更改界面.接口中包含了成功和失敗的回調(diào),這個(gè)接口Activity/Fragment要去實(shí)現(xiàn),最終P層才能通知V層.
public interface SingleInterfaceIView {
void showArticleSuccess(ArticleListBean bean);
void showArticleFail(String errorMsg);
}
一個(gè)完整的項(xiàng)目以后肯定會(huì)有許多功能界面,那么我們應(yīng)該抽出一個(gè)IView公共接口,讓所有的Activity/Fragment都間接實(shí)現(xiàn)它.IVew公共接口是用于給View層的接口繼承的,注意,不是View本身繼承.因?yàn)樗x的是接口的規(guī)范, 而其他接口才是定義的類的規(guī)范(這句話請(qǐng)仔細(xì)理解).
/**
* @Description: 公共接口 是用于給View的接口繼承的，注意，不是View本身繼承。
* 因?yàn)樗x的是接口的規(guī)范， 而其他接口才是定義的類的規(guī)范
* @Author: lishengjiejob@163.com
* @Time: 2018/11/22 17:26
*/
public interface IView {
}
這個(gè)接口中可以寫一些所有Activigy/Fragment共用的方法,我們把SingleInterfaceIView繼承IView接口.
public interface SingleInterfaceIView extends IView {
void showArticleSuccess(ArticleListBean bean);
void showArticleFail(String errorMsg);
}
同理Model層和Presenter層也是如此.
public interface IModel {
}
public interface IPresenter {
}
現(xiàn)在項(xiàng)目中Model層是一個(gè)SingleInterfaceModel類,這個(gè)類對(duì)象被P層持有,對(duì)于面向?qū)ο笤O(shè)計(jì)來(lái)講,利用接口達(dá)到解耦目的已經(jīng)人盡皆知,那我們就要對(duì)SingleInterfaceModel類再寫一個(gè)可繼承的接口.代碼如下.
public interface ISingleInterfaceModel extends IModel {
void getData(int curPage, final Callback callback);
}
如此,SingleInterfaceModel類的修改如下.
public class SingleInterfaceModel implements ISingleInterfaceModel {
@Override
public void getData(int curPage, final Callback callback) {
NetUtils.getRetrofit()
.create(Api.class)
.getData(curPage)
.subscribeOn(Schedulers.io())
.observeOn(AndroidSchedulers.mainThread())
.subscribe(new Subscriber<ArticleListBean>() {
@Override
public void onCompleted() {
LP.w("completed");
}
@Override
public void onError(Throwable e) {
callback.onFail("出現(xiàn)錯(cuò)誤");
}
@Override
public void onNext(ArticleListBean bean) {
if (null == bean) {
callback.onFail("出現(xiàn)錯(cuò)誤");
} else if (bean.errorCode != 0) {
callback.onFail(bean.errorMsg);
} else {
callback.onSuccess(bean);
}
}
});
}
}
同理,View層持有P層對(duì)象,我們也需要對(duì)P層進(jìn)行改造.但是下面的代碼卻沒(méi)有像ISingleInterfaceModel接口繼承IModel一樣繼承IPresenter,這點(diǎn)需要注意,筆者把IPresenter的繼承放在了其他處,后面會(huì)講解.
public interface ISingleInterfacePresenter {
void getData(int curPage);
}
然后SingleInterfacePresenter類的修改如下:
public class SingleInterfacePresenter implements ISingleInterfacePresenter {
private final ISingleInterfaceModel singleInterfaceModel;
public SingleInterfacePresenter() {
this.singleInterfaceModel = new SingleInterfaceModel();
}
@Override
public void getData(int curPage) {
singleInterfaceModel.getData(curPage, new Callback<ArticleListBean, String>() {
@Override
public void onSuccess(ArticleListBean loginResultBean) {
//如果Model層請(qǐng)求數(shù)據(jù)成功,則此處應(yīng)執(zhí)行通知View層的代碼
//LP.w()是一個(gè)簡(jiǎn)單的log打印
LP.w(loginResultBean.toString());
}
@Override
public void onFail(String errorMsg) {
//如果Model層請(qǐng)求數(shù)據(jù)失敗,則此處應(yīng)執(zhí)行通知View層的代碼
LP.w(errorMsg);
}
});
}
}
3. 生命周期適配
至此,MVP三層每層的接口都寫好了.但是P層連接V層的橋梁還沒(méi)有搭建好,這個(gè)慢慢來(lái),一個(gè)好的高樓大廈都是一步一步建造的.上面IPresenter接口我們沒(méi)有讓其他類繼承,接下來(lái)就講下這個(gè).P層和V層相連接,V層的生命周期也要適配到P層,P層的每個(gè)功能都要適配生命周期,這里可以把生命周期的適配放在IPresenter接口中.P層持有V層對(duì)象,這里把它放到泛型中.代碼如下.
public interface IPresenter<T extends IView> {
/**
* 依附生命view
*
* @param view
*/
void attachView(T view);
/**
* 分離View
*/
void detachView();
/**
* 判斷View是否已經(jīng)銷毀
*
* @return
*/
boolean isViewAttached();
}
這個(gè)IPresenter接口需要所有的P層實(shí)現(xiàn)類繼承,對(duì)于生命周期這部分功能都是通用的,那么就可以抽出來(lái)一個(gè)抽象基類BasePresenter,去實(shí)現(xiàn)IPresenter的接口.
public abstract class BasePresenter<T extends IView> implements IPresenter<T> {
protected T mView;
@Override
public void attachView(T view) {
mView = view;
}
@Override
public void detachView() {
mView = null;
}
@Override
public boolean isViewAttached() {
return mView != null;
}
}
此時(shí),SingleInterfacePresenter類的代碼修改如下.泛型中的SingleInterfaceIView可以理解成對(duì)應(yīng)的Activity,P層此時(shí)完成了對(duì)V層的通信.
public class SingleInterfacePresenter extends BasePresenter<SingleInterfaceIView> implements ISingleInterfacePresenter {
private final ISingleInterfaceModel singleInterfaceModel;
public SingleInterfacePresenter() {
this.singleInterfaceModel = new SingleInterfaceModel();
}
@Override
public void getData(int curPage) {
singleInterfaceModel.getData(curPage, new Callback<ArticleListBean, String>() {
@Override
public void onSuccess(ArticleListBean loginResultBean) {
//如果Model層請(qǐng)求數(shù)據(jù)成功,則此處應(yīng)執(zhí)行通知View層的代碼
//LP.w()是一個(gè)簡(jiǎn)單的log打印
LP.w(loginResultBean.toString());
if (isViewAttached()) {
mView.showArticleSuccess(loginResultBean);
}
}
@Override
public void onFail(String errorMsg) {
//如果Model層請(qǐng)求數(shù)據(jù)失敗,則此處應(yīng)執(zhí)行通知View層的代碼
LP.w(errorMsg);
if (isViewAttached()) {
mView.showArticleFail(errorMsg);
}
}
});
}
}
此時(shí),P層和V層的連接橋梁已經(jīng)搭建,但還未搭建完成,我們需要寫個(gè)BaseMVPActvity讓所有的Activity繼承,統(tǒng)一處理Activity相同邏輯.在BaseMVPActvity中使用IPresenter的泛型,因?yàn)槊總€(gè)Activity中需要持有P層對(duì)象,這里把P層對(duì)象抽出來(lái)也放在BaseMVPActvity中.同時(shí)BaseMVPActvity中也需要繼承IView,用于P層對(duì)V層的生命周期中.代碼如下.
public abstract class BaseMVPActivity<T extends IPresenter> extends AppCompatActivity implements IView {
protected T mPresenter;
@Override
protected void onCreate(@Nullable Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
initPresenter();
init();
}
protected void initPresenter() {
mPresenter = createPresenter();
//綁定生命周期
if (mPresenter != null) {
mPresenter.attachView(this);
}
}
@Override
protected void onDestroy() {
if (mPresenter != null) {
mPresenter.detachView();
}
super.onDestroy();
}
/**
* 創(chuàng)建一個(gè)Presenter
*
* @return
*/
protected abstract T createPresenter();
protected abstract void init();
}
接下來(lái)讓SingleInterfaceActivity實(shí)現(xiàn)這個(gè)BaseMVPActivity.
public class SingleInterfaceActivity extends BaseMVPActivity<SingleInterfacePresenter> implements SingleInterfaceIView {
private Button button;
private TextView textView;
@Override
protected void init() {
setContentView(R.layout.activity_single_interface);
button = findViewById(R.id.button);
textView = findViewById(R.id.textView);
button.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
mPresenter.getData(0);
}
});
}
@Override
protected SingleInterfacePresenter createPresenter() {
return new SingleInterfacePresenter();
}
@Override
public void showArticleSuccess(ArticleListBean bean) {
textView.setText(bean.data.datas.get(0).title);
}
@Override
public void showArticleFail(String errorMsg) {
Toast.makeText(this, errorMsg, Toast.LENGTH_SHORT).show();
}
}
到此,MVP架構(gòu)的整個(gè)簡(jiǎn)易流程完成.
代碼寫到這里,筆者先把這些代碼提交到github(https://github.com/serge66/MVPDemo),github上會(huì)有一次提交記錄,如果想看此時(shí)的代碼,可以根據(jù)提交記錄"第二次修改"克隆此時(shí)的代碼.
4. 優(yōu)化MVP架構(gòu)
上面是MVP的目錄,從目錄中我們可以看到一個(gè)功能點(diǎn)(網(wǎng)絡(luò)請(qǐng)求)MVP三層各有兩個(gè)文件需要寫,相對(duì)于MVC來(lái)說(shuō)寫起來(lái)確實(shí)麻煩,這也是一些人不愿意寫MVP,寧愿用MVC的原因.
這里我們可以對(duì)此優(yōu)化一下.MVP架構(gòu)中有個(gè)Contract的概念,Contract有統(tǒng)一管理接口的作用,目的是為了統(tǒng)一管理一個(gè)頁(yè)面的View和Presenter接口,用Contract可以減少部分文件的創(chuàng)建,比如P層和V層的接口文件.
那我們就把P層的ISingleInterfacePresenter接口和V層的SingleInterfaceIView接口文件刪除掉,放入SingleInterfaceContract文件中.代碼如下.
public interface SingleInterfaceContract {
interface View extends IView {
void showArticleSuccess(ArticleListBean bean);
void showArticleFail(String errorMsg);
}
interface Presenter {
void getData(int curPage);
}
}
此時(shí),SingleInterfacePresenter和SingleInterfaceActivity的代碼修改如下.
public class SingleInterfacePresenter extends BasePresenter<SingleInterfaceContract.View>
implements SingleInterfaceContract.Presenter {
private final ISingleInterfaceModel singleInterfaceModel;
public SingleInterfacePresenter() {
this.singleInterfaceModel = new SingleInterfaceModel();
}
@Override
public void getData(int curPage) {
singleInterfaceModel.getData(curPage, new Callback<ArticleListBean, String>() {
@Override
public void onSuccess(ArticleListBean loginResultBean) {
//如果Model層請(qǐng)求數(shù)據(jù)成功,則此處應(yīng)執(zhí)行通知View層的代碼
//LP.w()是一個(gè)簡(jiǎn)單的log打印
LP.w(loginResultBean.toString());
if (isViewAttached()) {
mView.showArticleSuccess(loginResultBean);
}
}
@Override
public void onFail(String errorMsg) {
//如果Model層請(qǐng)求數(shù)據(jù)失敗,則此處應(yīng)執(zhí)行通知View層的代碼
LP.w(errorMsg);
if (isViewAttached()) {
mView.showArticleFail(errorMsg);
}
}
});
}
}
public class SingleInterfaceActivity extends BaseMVPActivity<SingleInterfacePresenter>
implements SingleInterfaceContract.View {
private Button button;
private TextView textView;
@Override
protected void init() {
setContentView(R.layout.activity_single_interface);
button = findViewById(R.id.button);
textView = findViewById(R.id.textView);
button.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
mPresenter.getData(0);
}
});
}
@Override
protected SingleInterfacePresenter createPresenter() {
return new SingleInterfacePresenter();
}
@Override
public void showArticleSuccess(ArticleListBean bean) {
textView.setText(bean.data.datas.get(0).title);
}
@Override
public void showArticleFail(String errorMsg) {
Toast.makeText(this, errorMsg, Toast.LENGTH_SHORT).show();
}
}
代碼寫到這里,筆者先把這些代碼提交到github(https://github.com/serge66/MVPDemo),github上會(huì)有一次提交記錄,如果想看此時(shí)的代碼,可以根據(jù)提交記錄"第三次修改"克隆此時(shí)的代碼.
5. 單頁(yè)面多網(wǎng)絡(luò)請(qǐng)求
上面的MVP封裝只適用于單頁(yè)面一個(gè)網(wǎng)絡(luò)請(qǐng)求的情況,當(dāng)一個(gè)界面有兩個(gè)網(wǎng)絡(luò)請(qǐng)求時(shí),此封裝已不適合.為此,我們?cè)俅涡陆ㄒ粋€(gè)MultipleInterfaceActivity來(lái)進(jìn)行說(shuō)明.XML中布局是兩個(gè)按鈕兩個(gè)Textview,點(diǎn)擊則可以進(jìn)行網(wǎng)絡(luò)請(qǐng)求.
<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:layout_gravity="center"
android:gravity="center"
android:orientation="vertical"
tools:context=".view.MultipleInterfaceActivity">
<Button
android:id="@+id/button"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="點(diǎn)擊" />
<TextView
android:id="@+id/textView"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_marginTop="50px"
android:text="請(qǐng)點(diǎn)擊上方按鈕獲取數(shù)據(jù)" />
<Button
android:id="@+id/btn"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_marginTop="100px"
android:text="點(diǎn)擊" />
<TextView
android:id="@+id/tv"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_marginTop="50px"
android:text="請(qǐng)點(diǎn)擊上方按鈕獲取數(shù)據(jù)" />
</LinearLayout>
MultipleInterfaceActivity類代碼暫時(shí)如下.
public class MultipleInterfaceActivity extends BaseMVPActivity {
private Button button;
private TextView textView;
private Button btn;
private TextView tv;
@Override
protected void init() {
setContentView(R.layout.activity_multiple_interface);
button = findViewById(R.id.button);
textView = findViewById(R.id.textView);
button.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
}
});
btn = findViewById(R.id.btn);
tv = findViewById(R.id.tv);
btn.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
}
});
}
@Override
protected IPresenter createPresenter() {
return null;
}
}
此時(shí)我們可以想下,當(dāng)一個(gè)頁(yè)面中有多個(gè)網(wǎng)絡(luò)請(qǐng)求時(shí),Activity所繼承的BaseMVPActivity的泛型中要寫多個(gè)參數(shù),那有沒(méi)有上面代碼的框架不變的情況下實(shí)現(xiàn)這個(gè)需求呢?答案必須有的.我們可以把多個(gè)網(wǎng)絡(luò)請(qǐng)求的功能當(dāng)做一個(gè)網(wǎng)絡(luò)請(qǐng)求來(lái)看待,封裝成一個(gè)MultiplePresenter,其繼承至BasePresenter實(shí)現(xiàn)生命周期的適配.此MultiplePresenter類的作用就是容納多個(gè)Presenter,連接同一個(gè)View.代碼如下.
public class MultiplePresenter<T extends IView> extends BasePresenter<T> {
private T mView;
private List<IPresenter> presenters = new ArrayList<>();
@SafeVarargs
public final <K extends IPresenter<T>> void addPresenter(K... addPresenter) {
for (K ap : addPresenter) {
ap.attachView(mView);
presenters.add(ap);
}
}
public MultiplePresenter(T mView) {
this.mView = mView;
}
@Override
public void detachView() {
for (IPresenter presenter : presenters) {
presenter.detachView();
}
}
}
因MultiplePresenter類中需要有多個(gè)網(wǎng)絡(luò)請(qǐng)求,現(xiàn)在舉例說(shuō)明時(shí),暫時(shí)用兩個(gè)網(wǎng)絡(luò)請(qǐng)求接口.MultipleInterfaceActivity類中代碼改造如下.
public class MultipleInterfaceActivity extends BaseMVPActivity<MultiplePresenter>
implements SingleInterfaceContract.View, MultipleInterfaceContract.View {
private Button button;
private TextView textView;
private Button btn;
private TextView tv;
private SingleInterfacePresenter singleInterfacePresenter;
private MultipleInterfacePresenter multipleInterfacePresenter;
@Override
protected void init() {
setContentView(R.layout.activity_multiple_interface);
button = findViewById(R.id.button);
textView = findViewById(R.id.textView);
button.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
singleInterfacePresenter.getData(0);
}
});
btn = findViewById(R.id.btn);
tv = findViewById(R.id.tv);
btn.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
multipleInterfacePresenter.getBanner();
}
});
}
@Override
protected MultiplePresenter createPresenter() {
MultiplePresenter multiplePresenter = new MultiplePresenter(this);
singleInterfacePresenter = new SingleInterfacePresenter();
multipleInterfacePresenter = new MultipleInterfacePresenter();
multiplePresenter.addPresenter(singleInterfacePresenter);
multiplePresenter.addPresenter(multipleInterfacePresenter);
return multiplePresenter;
}
@Override
public void showArticleSuccess(ArticleListBean bean) {
textView.setText(bean.data.datas.get(0).title);
}
@Override
public void showArticleFail(String errorMsg) {
Toast.makeText(this, errorMsg, Toast.LENGTH_SHORT).show();
}
@Override
public void showMultipleSuccess(BannerBean bean) {
tv.setText(bean.data.get(0).title);
}
@Override
public void showMultipleFail(String errorMsg) {
Toast.makeText(this, errorMsg, Toast.LENGTH_SHORT).show();
}
}
寫到這里,MVP框架基本算是完成.如果想再次優(yōu)化,其實(shí)還是有可優(yōu)化的地方,比如當(dāng)View銷毀時(shí),現(xiàn)在只是讓P層中的View對(duì)象置為null,并沒(méi)有繼續(xù)對(duì)M層通知.如果View銷毀時(shí),M層還在請(qǐng)求網(wǎng)絡(luò)中呢,可以為此再加入一個(gè)取消網(wǎng)絡(luò)請(qǐng)求的通用功能.這里只是舉一個(gè)例子,每個(gè)人對(duì)MVP的理解不一樣,而MVP架構(gòu)也并不是一成不變,適合自己項(xiàng)目的才是最好的.
6. 完整項(xiàng)目地址
完整項(xiàng)目已提交到github(https://github.com/serge66/MVPDemo),若需要敬請(qǐng)查看.
五. 參考資料
一步步帶你精通MVP
從0到1搭建MVP框架
Presenter層如何高度的復(fù)用
六. 后續(xù)
<<MVVM架構(gòu)從入門到精通-真槍實(shí)彈>> 敬請(qǐng)期待~~~
原創(chuàng)文章，來(lái)自于Vitamio(http://blog.csdn.net/vitamio)，轉(zhuǎn)載請(qǐng)注明出處。
