什么是MVP陌凳，為什么要用MVP配椭？
網(wǎng)上介紹MVP的很多，百度一下你就知道游桩，至于為什么要用MVP牲迫，當(dāng)然是由于它的優(yōu)勢了：
1.代碼簡潔
此處的簡潔是邏輯的簡潔，而不是代碼本身 舉個栗子
image
比如購物車界面借卧，有很多請求網(wǎng)絡(luò)的地方：獲取購物車商品列表盹憎、購物車商品的刪除、購物車商品的購買等等铐刘， 這么多網(wǎng)絡(luò)請求陪每，如果都寫在一個Activity，而且還有大量邏輯判斷镰吵，那這個Activity的行數(shù)~ 看著就讓人頭痛檩禾， 即便寫了注釋，維護起來也是比較麻煩的
2.降低耦合疤祭，方便維護
MVP的使用盼产，使Activity中的網(wǎng)絡(luò)請求剝離出來 成為model、presenter勺馆，model只負責(zé)網(wǎng)絡(luò)的請求戏售、pesenter負責(zé)處理請求網(wǎng)絡(luò)后的數(shù)據(jù)處理：加載中 成功 or 失敗 取消加載；最后View進行界面的展示
整體的mvp結(jié)構(gòu)圖
image.png
Start：介紹一下BaseMvpActivity
MVP的Activity基類：純粹的 MVP 包裝草穆，不要增加任何View層基礎(chǔ)功能 如果要添加基類功能灌灾，建議寫一個所有activity的基類添加
public abstract class BaseMvpActivity<P extends IPresenter> extends Activity implements BaseView {
protected P mPresenter;
protected abstract P createPresenter();
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
mPresenter = createPresenter();
if (mPresenter == null) {
throw new NullPointerException("Presenter is null! Do you return null in createPresenter()?");
}
mPresenter.onMvpAttachView(this, savedInstanceState);
}
@Override
protected void onStart() {
super.onStart();
if (mPresenter != null) {
mPresenter.onMvpStart();
}
}
@Override
protected void onResume() {
super.onResume();
if (mPresenter != null) {
mPresenter.onMvpResume();
}
}
@Override
protected void onPause() {
super.onPause();
if (mPresenter != null) {
mPresenter.onMvpPause();
}
}
@Override
protected void onStop() {
super.onStop();
if (mPresenter != null) {
mPresenter.onMvpStop();
}
}
@Override
protected void onSaveInstanceState(Bundle outState) {
super.onSaveInstanceState(outState);
if (mPresenter != null) {
mPresenter.onMvpSaveInstanceState(outState);
}
}
@Override
protected void onDestroy() {
super.onDestroy();
if (mPresenter != null) {
mPresenter.onMvpDetachView(false);
mPresenter.onMvpDestroy();
}
}
}
在這里有人會覺得生命周期怎么會出現(xiàn)onMvpStart 或者onMvpResume等等
下面來解釋一下MVP的生命周期：
就是為了定義P層生命周期與 V層同步
public interface IPresenter<V extends BaseView> {
void onMvpAttachView(V view, Bundle savedInstanceState);
void onMvpStart();
void onMvpResume();
void onMvpPause();
void onMvpStop();
void onMvpSaveInstanceState(Bundle savedInstanceState);
void onMvpDetachView(boolean retainInstance);
void onMvpDestroy();
}
接下來 我們會用到WeakReference類從字面上了解 他的意思是弱引用
關(guān)于 弱引用，強引用续挟、軟引用紧卒、虛引用，可以參考
https://www.cnblogs.com/gudi/p/6403953.html
public class BasePresenter<V extends BaseView> implements IPresenter<V> {
private WeakReference<V> viewRef;
protected V getView() {
return viewRef.get();
}
protected boolean isViewAttached() {
return viewRef != null && viewRef.get() != null;
}
private void attach(V view, Bundle savedInstanceState) {
viewRef = new WeakReference<V>(view);
}
@Override
public void onMvpAttachView(V view, Bundle savedInstanceState) {
attach(view, savedInstanceState);
}
@Override
public void onMvpStart() {
}
@Override
public void onMvpResume() {
}
@Override
public void onMvpPause() {
}
@Override
public void onMvpStop() {
}
@Override
public void onMvpSaveInstanceState(Bundle savedInstanceState) {
}
private void _detach(boolean retainInstance) {
if (viewRef != null) {
viewRef.clear();
viewRef = null;
}
}
@Override
public void onMvpDetachView(boolean retainInstance) {
_detach(retainInstance);
}
@Override
public void onMvpDestroy() {
}
}
接下來就是 view和model綁定處理數(shù)據(jù)
public class MainPresenterImpl extends BasePresenter<MainContract.IMainView> implements MainContract.IMainPresenter {
private LoginMobel mMobel;
public MainPresenterImpl() {
mMobel = new LoginMobel();
}
@Override
public void main(String username, String password, String token) {
//先進行非空判斷
if (isViewAttached()) {
handleLogin(getView(), username, password, token);
}
}
@Override
public void login(String username, String password, String token) {
//先進行非空判斷
if (isViewAttached()) {
Login(getView(), username, password, token);
}
}
private void Login(final MainContract.IMainView view, String username, String password, String token) {
mMobel.login(username, password, token, new StringCallbackAdapter() {
@Override
public void onError(Call call, Exception e, int id) {
super.onError(call, e, id);
view.loginSuccess();
}
@Override
public void onResponse(String response, int id) {
super.onResponse(response, id);
view.loginFailed(response);
}
});
}
private void handleLogin(final MainContract.IMainView view, String username, String password, String token) {
mMobel.login(username, password, token, new StringCallbackAdapter() {
@Override
public void onError(Call call, Exception e, int id) {
super.onError(call, e, id);
view.mainSuccess();
}
@Override
public void onResponse(String response, int id) {
super.onResponse(response, id);
view.mainFailed(response);
}
});
}
}
使用
public class MainActivity extends BaseMvpActivity<MainContract.IMainPresenter> implements MainContract.IMainView {
@Override
protected MainContract.IMainPresenter createPresenter() {
return new MainPresenterImpl();
}
mPresenter.main(username, password, token);
@Override
public void mainSuccess() {
Toast.makeText(this, "mainSuccess", Toast.LENGTH_SHORT).show();
}
@Override
public void mainFailed(String msg) {
Toast.makeText(this, "mainFailed", Toast.LENGTH_SHORT).show();
}
時間有限诗祸，暫時就先這樣跑芳，具體可下載Demo查看 ↓
本Demo：https://gitee.com/oubajunping/androidzhimvprumen
MVP快速生成類的插件： https://github.com/githubwing/MVPHelper
