简易版LiveData-->实现MVVM
Posted 战国剑
tags:
篇首语:本文由小常识网(cha138.com)小编为大家整理,主要介绍了简易版LiveData-->实现MVVM相关的知识,希望对你有一定的参考价值。
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);
以上是关于简易版LiveData-->实现MVVM的主要内容,如果未能解决你的问题,请参考以下文章
Android MVVM系列:LiveData的简单使用java版
Android简易音乐重构MVVM Java版-新增推荐菜单及侧边栏展示