简易版LiveData-->实现MVVM
作者:互联网
遵循LiveData原理,摒弃其中的复杂逻辑,只取LiveData的响应更新能力,做一套简易版本的实现。
一、简易的ViewModel
package com.example.jetpacktest;
public class ViewModel {
public String name;
public int count;
}
二、简易的LiveData实现--命名为:ObserableAny
package com.example.jetpacktest;
import android.util.Log;
//如无需生命周期,可不引用androidx组件。这样就剩余纯响应式监听数据的逻辑
import androidx.lifecycle.Lifecycle;
import androidx.lifecycle.LifecycleObserver;
import androidx.lifecycle.LifecycleOwner;
import androidx.lifecycle.OnLifecycleEvent;
public class ObserableAny<T> implements LifecycleObserver {
private static final String TAG = "ObserableAny";
//观察者
private Observer<T> observer;
//生命周期
private LifecycleOwner lifecycleOwner;
//数据
private T value;
public void setObserver(LifecycleOwner lifecycleOwner, Observer<T> observer) {
this.observer = observer;
this.lifecycleOwner = lifecycleOwner;
this.lifecycleOwner.getLifecycle().addObserver(this);
}
public void setObserver(Observer<T> observer) {
this.observer = observer;
}
//setValue时触发更新
public void setValue(T t) {
value = t;
if (observer != null) {
observer.update(t);
}
}
public T getValue() {
return value;
}
public interface Observer<T> {
void update(T t);
}
/*** 无需生命周期的时候,可去除以下代码 ***/
@OnLifecycleEvent(Lifecycle.Event.ON_RESUME)
void onResume() {
Log.e(TAG, "OnLifecycleEvent onResume");
}
@OnLifecycleEvent(Lifecycle.Event.ON_DESTROY)
void onDestroy() {
Log.e(TAG, "OnLifecycleEvent onDestroy");
if(lifecycleOwner != null){
lifecycleOwner.getLifecycle().removeObserver(this);
lifecycleOwner = null;
}
if(observer != null){
observer = null;
}
}
}
三、简易实用
package com.example.jetpacktest;
import androidx.appcompat.app.AppCompatActivity;
import android.os.Bundle;
import android.view.View;
import android.widget.Toast;
public class MainActivity extends AppCompatActivity {
private ObserableAny<ViewModel> obserableAny;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
obserableAny = new ObserableAny<>();
obserableAny.setObserver(this,new ObserableAny.Observer<ViewModel>() {
@Override
public void update(ViewModel viewModel) {
Toast.makeText(MainActivity.this, buildDisplay(viewModel), Toast.LENGTH_SHORT).show();
}
});
}
public void test(View view) {
ViewModel viewModel = new ViewModel();
viewModel.name = "张三";
viewModel.count = 1;
obserableAny.setValue(viewModel);
}
private String buildDisplay(ViewModel viewModel){
return viewModel.name + " " + viewModel.count;
}
public void test1(View view) {
ViewModel viewModel = new ViewModel();
viewModel.name = "李四";
viewModel.count = 2;
obserableAny.setValue(viewModel);
}
}
标签:MVVM,observer,lifecycleOwner,--,void,viewModel,简易版,import,public 来源: https://blog.csdn.net/yangzhaomuma/article/details/121562115