Android学习进度三
由昨天学习的 ViewModel 以及今天早上学习的 LiveData 和 DataBinding 的相关知识，开发过程中 Controller 类代码变得十分精简。以此为基础，我开发了一款十分简单的篮球比赛计分器，将以前所学的知识串联了起来，作为一次复习参考。
完成实例图：
用户可以点击加分按键进行统分，可以进行一次撤销，也可以重置比分。
附上代码
bulid.gradle
apply plugin: 'com.android.application' android { compileSdkVersion 29 buildToolsVersion "29.0.2" defaultConfig { applicationId "com.example.score" minSdkVersion 19 targetSdkVersion 29 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:1.1.0' implementation 'androidx.constraintlayout:constraintlayout:1.1.3' testImplementation 'junit:junit:4.12' androidTestImplementation 'androidx.test.ext:junit:1.1.1' androidTestImplementation 'androidx.test.espresso:espresso-core:3.2.0' implementation 'androidx.lifecycle:lifecycle-extensions:2.1.0' }
MyViewModel.java
package com.example.score; import androidx.lifecycle.MutableLiveData; import androidx.lifecycle.ViewModel; public class MyViewModel extends ViewModel { private MutableLiveData<Integer> aTeamScore; private MutableLiveData<Integer> bTeamScore; private int aBack,bBack; public MutableLiveData<Integer> getaTeamScore() { if (aTeamScore == null) { aTeamScore = new MutableLiveData<>(); aTeamScore.setValue(0); } return aTeamScore; } public MutableLiveData<Integer> getbTeamScore() { if (bTeamScore == null) { bTeamScore = new MutableLiveData<>(); bTeamScore.setValue(0); } return bTeamScore; } public void aTeamAdd(int p) { aBack = aTeamScore.getValue(); bBack = bTeamScore.getValue(); aTeamScore.setValue(aTeamScore.getValue() + p); } public void bTeamAdd(int p) { aBack = aTeamScore.getValue(); bBack = bTeamScore.getValue(); bTeamScore.setValue(bTeamScore.getValue() + p); } public void reset() { aBack = aTeamScore.getValue(); bBack = bTeamScore.getValue(); aTeamScore.setValue(0); bTeamScore.setValue(0); } public void undo() { aTeamScore.setValue(aBack); bTeamScore.setValue(bBack); } }
MainActivity.java
package com.example.score; import androidx.appcompat.app.AppCompatActivity; import androidx.databinding.DataBindingUtil; import androidx.lifecycle.ViewModelProvider; import androidx.lifecycle.ViewModelProviders; import android.os.Bundle; import com.example.score.databinding.ActivityMainBinding; public class MainActivity extends AppCompatActivity { MyViewModel myViewModel; ActivityMainBinding binding; @Override protected void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); binding = DataBindingUtil.setContentView(this,R.layout.activity_main); myViewModel = ViewModelProviders.of(this).get(MyViewModel.class); binding.setData(myViewModel); binding.setLifecycleOwner(this); } }
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.score.MyViewModel" /> </data> <androidx.constraintlayout.widget.ConstraintLayout android:layout_width="match_parent" android:layout_height="match_parent" tools:context=".MainActivity"> <androidx.constraintlayout.widget.Guideline android:id="@+id/guideline6" android:layout_width="wrap_content" android:layout_height="wrap_content" android:orientation="horizontal" app:layout_constraintGuide_percent="0.8" /> <androidx.constraintlayout.widget.Guideline android:id="@+id/guideline7" android:layout_width="wrap_content" android:layout_height="wrap_content" android:orientation="horizontal" app:layout_constraintGuide_percent="0.05" /> <androidx.constraintlayout.widget.Guideline android:id="@+id/guideline4" android:layout_width="wrap_content" android:layout_height="wrap_content" android:orientation="horizontal" app:layout_constraintGuide_percent="0.35" /> <androidx.constraintlayout.widget.Guideline android:id="@+id/guideline5" android:layout_width="wrap_content" android:layout_height="wrap_content" android:orientation="horizontal" app:layout_constraintGuide_percent="0.65" /> <androidx.constraintlayout.widget.Guideline android:id="@+id/guideline" android:layout_width="wrap_content" android:layout_height="wrap_content" android:orientation="vertical" app:layout_constraintGuide_percent="0.5" /> <androidx.constraintlayout.widget.Guideline android:id="@+id/guideline2" android:layout_width="wrap_content" android:layout_height="wrap_content" android:orientation="horizontal" app:layout_constraintGuide_percent="0.5" /> <androidx.constraintlayout.widget.Guideline android:id="@+id/guideline3" android:layout_width="wrap_content" android:layout_height="wrap_content" android:orientation="horizontal" app:layout_constraintGuide_percent="0.15" /> <androidx.constraintlayout.widget.Guideline android:id="@+id/guideline9" android:layout_width="wrap_content" android:layout_height="wrap_content" android:orientation="horizontal" app:layout_constraintGuide_percent="0.9" /> <androidx.constraintlayout.widget.Guideline android:id="@+id/guideline10" android:layout_width="wrap_content" android:layout_height="wrap_content" android:orientation="vertical" app:layout_constraintGuide_percent="0.05" /> <androidx.constraintlayout.widget.Guideline android:id="@+id/guideline11" android:layout_width="wrap_content" android:layout_height="wrap_content" android:orientation="vertical" app:layout_constraintGuide_percent="0.95" /> <TextView android:id="@+id/textView" android:layout_width="wrap_content" android:layout_height="wrap_content" android:text="@string/textview1" android:textSize="@dimen/teamTextSize" app:layout_constraintBottom_toTopOf="@+id/guideline3" app:layout_constraintEnd_toStartOf="@+id/guideline" app:layout_constraintStart_toStartOf="parent" app:layout_constraintTop_toTopOf="@+id/guideline7" /> <TextView android:id="@+id/textView2" android:layout_width="wrap_content" android:layout_height="wrap_content" android:text="@string/textview2" android:textSize="@dimen/teamTextSize" app:layout_constraintBottom_toTopOf="@+id/guideline3" app:layout_constraintEnd_toStartOf="@+id/guideline11" app:layout_constraintStart_toStartOf="@+id/guideline" app:layout_constraintTop_toTopOf="@+id/guideline7" /> <TextView android:id="@+id/textView3" android:layout_width="wrap_content" android:layout_height="wrap_content" android:text="@{String.valueOf(data.getaTeamScore())}" android:textColor="@color/colorAccent" android:textSize="@dimen/scoreTextSize" app:layout_constraintBottom_toTopOf="@+id/guideline4" app:layout_constraintEnd_toStartOf="@+id/guideline" app:layout_constraintStart_toStartOf="parent" app:layout_constraintTop_toTopOf="@+id/guideline3" tools:text="120" /> <TextView android:id="@+id/textView4" android:layout_width="wrap_content" android:layout_height="wrap_content" android:text="@{String.valueOf(data.getbTeamScore())}" android:textColor="@color/colorPrimary" android:textSize="@dimen/scoreTextSize" app:layout_constraintBottom_toTopOf="@+id/guideline4" app:layout_constraintEnd_toEndOf="parent" app:layout_constraintStart_toStartOf="@+id/guideline" app:layout_constraintTop_toTopOf="@+id/guideline3" tools:text="50" /> <Button android:id="@+id/button" android:layout_width="0dp" android:layout_height="wrap_content" android:layout_marginStart="8dp" android:layout_marginTop="8dp" android:layout_marginEnd="8dp" android:layout_marginBottom="8dp" android:background="@color/colorAccent" android:text="@string/button1" android:textColor="@android:color/white" android:textSize="@dimen/buttonTextSize" android:onClick="@{()->data.aTeamAdd(1)}" app:layout_constraintBottom_toTopOf="@+id/guideline2" app:layout_constraintEnd_toStartOf="@+id/guideline" app:layout_constraintStart_toStartOf="@+id/guideline10" app:layout_constraintTop_toTopOf="@+id/guideline4" app:layout_constraintVertical_bias="0.58" /> <Button android:id="@+id/button2" android:layout_width="0dp" android:layout_height="wrap_content" android:layout_marginStart="8dp" android:layout_marginTop="8dp" android:layout_marginEnd="8dp" android:layout_marginBottom="8dp" android:background="@color/colorPrimary" android:text="@string/button1" android:textColor="@android:color/white" android:textSize="@dimen/buttonTextSize" android:onClick="@{()->data.bTeamAdd(1)}" app:layout_constraintBottom_toTopOf="@+id/guideline2" app:layout_constraintEnd_toStartOf="@+id/guideline11" app:layout_constraintStart_toStartOf="@+id/guideline" app:layout_constraintTop_toTopOf="@+id/guideline4" /> <Button android:id="@+id/button3" android:layout_width="0dp" android:layout_height="wrap_content" android:layout_marginStart="8dp" android:layout_marginTop="8dp" android:layout_marginEnd="8dp" android:layout_marginBottom="8dp" android:background="@color/colorAccent" android:text="@string/button2" android:textColor="@android:color/white" android:textSize="@dimen/buttonTextSize" android:onClick="@{()->data.aTeamAdd(2)}" app:layout_constraintBottom_toTopOf="@+id/guideline5" app:layout_constraintEnd_toStartOf="@+id/guideline" app:layout_constraintStart_toStartOf="@+id/guideline10" app:layout_constraintTop_toTopOf="@+id/guideline2" /> <Button android:id="@+id/button4" android:layout_width="0dp" android:layout_height="wrap_content" android:layout_marginStart="8dp" android:layout_marginTop="8dp" android:layout_marginEnd="8dp" android:layout_marginBottom="8dp" android:background="@color/colorPrimary" android:text="@string/button2" android:textColor="@android:color/white" android:textSize="@dimen/buttonTextSize" android:onClick="@{()->data.bTeamAdd(2)}" app:layout_constraintBottom_toTopOf="@+id/guideline5" app:layout_constraintEnd_toStartOf="@+id/guideline11" app:layout_constraintStart_toStartOf="@+id/guideline" app:layout_constraintTop_toTopOf="@+id/guideline2" /> <Button android:id="@+id/button5" android:layout_width="0dp" android:layout_height="wrap_content" android:layout_marginStart="8dp" android:layout_marginTop="8dp" android:layout_marginEnd="8dp" android:layout_marginBottom="8dp" android:background="@color/colorAccent" android:text="@string/button3" android:textColor="@android:color/white" android:textSize="@dimen/buttonTextSize" android:onClick="@{()->data.aTeamAdd(3)}" app:layout_constraintBottom_toTopOf="@+id/guideline6" app:layout_constraintEnd_toStartOf="@+id/guideline" app:layout_constraintStart_toStartOf="@+id/guideline10" app:layout_constraintTop_toTopOf="@+id/guideline5" /> <Button android:id="@+id/button6" android:layout_width="0dp" android:layout_height="wrap_content" android:layout_marginStart="8dp" android:layout_marginTop="8dp" android:layout_marginEnd="8dp" android:layout_marginBottom="8dp" android:background="@color/colorPrimary" android:text="@string/button3" android:textColor="@android:color/white" android:textSize="@dimen/buttonTextSize" android:onClick="@{()->data.bTeamAdd(3)}" app:layout_constraintBottom_toTopOf="@+id/guideline6" app:layout_constraintEnd_toStartOf="@+id/guideline11" app:layout_constraintStart_toStartOf="@+id/guideline" app:layout_constraintTop_toTopOf="@+id/guideline5" /> <ImageButton android:id="@+id/imageButton" 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/undoButton" android:onClick="@{()->data.undo()}" app:layout_constraintBottom_toTopOf="@+id/guideline9" app:layout_constraintEnd_toStartOf="@+id/guideline" app:layout_constraintHorizontal_bias="0.8" app:layout_constraintStart_toStartOf="@+id/guideline10" app:layout_constraintTop_toTopOf="@+id/guideline6" app:srcCompat="@drawable/ic_undo_black_24dp" /> <ImageButton android:id="@+id/imageButton2" 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/resetButton" android:onClick="@{()->data.reset()}" app:layout_constraintBottom_toTopOf="@+id/guideline9" app:layout_constraintEnd_toStartOf="@+id/guideline11" app:layout_constraintHorizontal_bias="0.20" app:layout_constraintStart_toStartOf="@+id/guideline" app:layout_constraintTop_toTopOf="@+id/guideline6" app:srcCompat="@drawable/ic_loop_black_24dp" /> </androidx.constraintlayout.widget.ConstraintLayout> </layout>
今天因身体不适便只学了这些内容，明天我会继续学习Android Jetpack的相关知识。
