【自学Android】使用DataBinding,ViewModel,LiveData完成点赞小功能

使用DataBinding,ViewModel,LiveData完成点赞小功能

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1.build.gradle

apply plugin: 'com.android.application'android {    compileSdkVersion 28    defaultConfig {        applicationId "com.example.clickzan"        minSdkVersion 19        targetSdkVersion 28        versionCode 1        versionName "1.0"        testInstrumentationRunner "androidx.test.runner.AndroidJUnitRunner"        android.defaultConfig.vectorDrawables.useSupportLibrary = true        dataBinding {            enabled true        }    }    buildTypes {        release {            minifyEnabled false            proguardFiles getDefaultProguardFile('proguard-android-optimize.txt'), 'proguard-rules.pro'        }    }}dependencies {    implementation fileTree(dir: 'libs', include: ['*.jar'])    implementation 'androidx.appcompat:appcompat:1.0.2'    implementation 'androidx.constraintlayout:constraintlayout:1.1.3'    testImplementation 'junit:junit:4.12'    androidTestImplementation 'androidx.test:runner:1.2.0'    androidTestImplementation 'androidx.test.espresso:espresso-core:3.2.0'    implementation 'androidx.lifecycle:lifecycle-extensions:2.0.0'}

2.MyViewModel.java

package com.example.clickzan;import androidx.lifecycle.MutableLiveData;import androidx.lifecycle.ViewModel;public class MyViewModel extends ViewModel {    private MutableLiveData<Integer> mutableLiveData;    public MutableLiveData<Integer> getMutableLiveData() {        if (mutableLiveData==null) {            mutableLiveData = new MutableLiveData<>();            mutableLiveData.setValue(0);        }        return mutableLiveData;    }    public void addCount(){        mutableLiveData.setValue(mutableLiveData.getValue()+1);    }}

3.activity_main.xml

<?xml version="1.0" encoding="utf-8"?><layout xmlns:android="http://schemas.android.com/apk/res/android"    xmlns:app="http://schemas.android.com/apk/res-auto"    xmlns:tools="http://schemas.android.com/tools">    <data>        <variable            name="data"            type="com.example.clickzan.MyViewModel" />    data>    <androidx.constraintlayout.widget.ConstraintLayout        android:layout_width="match_parent"        android:layout_height="match_parent"        tools:context=".MainActivity">        <TextView            android:id="@+id/textView"            android:layout_width="wrap_content"            android:layout_height="wrap_content"            android:layout_marginStart="8dp"            android:layout_marginEnd="8dp"            android:layout_marginBottom="8dp"            android:text="@{String.valueOf(data.mutableLiveData)}"            android:textSize="36sp"            app:layout_constraintBottom_toBottomOf="parent"            app:layout_constraintEnd_toEndOf="parent"            app:layout_constraintHorizontal_bias="0.498"            app:layout_constraintStart_toStartOf="parent"            app:layout_constraintTop_toTopOf="parent"            app:layout_constraintVertical_bias="0.149" />        <ImageView            android:id="@+id/imageView"            android:layout_width="wrap_content"            android:layout_height="wrap_content"            android:layout_marginStart="8dp"            android:layout_marginTop="8dp"            android:layout_marginEnd="8dp"            android:layout_marginBottom="8dp"            android:contentDescription="@string/img_button_msg"            app:layout_constraintBottom_toBottomOf="parent"            app:layout_constraintEnd_toEndOf="parent"            app:layout_constraintHorizontal_bias="0.498"            app:layout_constraintStart_toStartOf="parent"            app:layout_constraintTop_toTopOf="parent"            app:layout_constraintVertical_bias="0.353"            app:srcCompat="@drawable/ic_thumb_up_black_24dp"            android:onClick="@{()->data.addCount()}"/>    androidx.constraintlayout.widget.ConstraintLayout>layout>

4.MainActivity.java

package com.example.clickzan;import androidx.appcompat.app.AppCompatActivity;import androidx.databinding.DataBindingUtil;import androidx.lifecycle.ViewModelProviders;import android.os.Bundle;import com.example.clickzan.databinding.ActivityMainBinding;public class MainActivity extends AppCompatActivity {    MyViewModel myViewModel;    ActivityMainBinding activityMainBinding;    @Override    protected void onCreate(Bundle savedInstanceState) {        super.onCreate(savedInstanceState);        activityMainBinding = DataBindingUtil.setContentView(this,R.layout.activity_main);        myViewModel = ViewModelProviders.of(this).get(MyViewModel.class);        activityMainBinding.setData(myViewModel);        activityMainBinding.setLifecycleOwner(this);    }}

5.效果图

功能：点赞数累加

使用DataBinding,ViewModel,LiveData完成点赞小功能

1.build.gradle

2.MyViewModel.java

3.activity_main.xml

4.MainActivity.java

5.效果图

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