Hilt 初探

Posted 2023-02-13 Vincent（朱志强）

Hilt 初探
Hilt就是android团队联系了Dagger2团队，一起开发出来的一个专门面向Android的依赖注入框架。
相比于Dagger2，Hilt最明显的特征就是：1. 简单。2. 提供了Android专属的API。

Hilt 做的优化包括
无需编写大量的Component代码
Scope也会与Component自动绑定
预定义绑定，例如 Application与Activity
预定义的限定符，例如@ApplicationContext与@ActivityContext
Hilt 组件介绍

Hilt 组件生命周期

Hilt 组件作用域

Hilt 集成
1、在项目结构的 build.gradle里面添加以下代码
classpath ‘com.google.dagger:hilt-android-gradle-plugin:2.28-alpha’
2、在App结构的 build.gradle里面添加
apply plugin: ‘dagger.hilt.android.plugin’
1
compileOptions //支持 java8
sourceCompatibility JavaVersion.VERSION_1_8
targetCompatibility JavaVersion.VERSION_1_8

implementation “com.google.dagger:hilt-android:2.28-alpha”
annotationProcessor “com.google.dagger:hilt-android-compiler:2.28-alpha”
3、App完整gradle代码
apply plugin: ‘com.android.application’
apply plugin: ‘dagger.hilt.android.plugin’

android
compileSdkVersion 30
buildToolsVersion “30.0.3”

defaultConfig 
    applicationId "com.hqk.hiltdemo"
    minSdkVersion 21
    targetSdkVersion 30
    versionCode 1
    versionName "1.0"

    testInstrumentationRunner "androidx.test.runner.AndroidJUnitRunner"


buildTypes 
    release 
        minifyEnabled false
        proguardFiles getDefaultProguardFile('proguard-android-optimize.txt'), 'proguard-rules.pro'
    

compileOptions 
    sourceCompatibility JavaVersion.VERSION_1_8
    targetCompatibility JavaVersion.VERSION_1_8

dependencies
implementation ‘androidx.appcompat:appcompat:1.3.0’
implementation ‘com.google.android.material:material:1.4.0’
implementation ‘androidx.constraintlayout:constraintlayout:2.0.4’
testImplementation ‘junit:junit:4.+’
androidTestImplementation ‘androidx.test.ext:junit:1.1.3’
androidTestImplementation ‘androidx.test.espresso:espresso-core:3.4.0’
implementation “com.google.dagger:hilt-android:2.28-alpha”
annotationProcessor “com.google.dagger:hilt-android-compiler:2.28-alpha”

Hilt 对象的使用
1、提供一个对象 HttpObject
public class HttpObject

2、编写对应Module
//详见上面的 hilt 对应组件
@InstallIn(ApplicationComponent.class)
@Module
public class HttpModule

@Singleton
@Provides 
public HttpObject getHttpObject()
    return new HttpObject();

3、注入到Activity
@AndroidEntryPoint
public class MainActivity extends AppCompatActivity

@Inject
HttpObject httpObject;

@Inject
HttpObject httpObject2;

@Override
protected void onCreate(Bundle savedInstanceState) 
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);
    Log.i("hqk_MainActivity",httpObject.hashCode()+"");
    Log.i("hqk_MainActivity",httpObject2.hashCode()+"");

4、在Application中注册
@HiltAndroidApp
public class MyApplication extends Application

5、项目运行打印
2021-07-12 16:03:31.319 3509-3509/com.hqk.hiltdemo I/hqk_MainActivity: 59372848
2021-07-12 16:03:31.319 3509-3509/com.hqk.hiltdemo I/hqk_MainActivity: 59372848

Hilt 接口的使用
1、提供一个待实现的接口
public interface TestInterface

void method();

2、提供一个实现接口的对象
import android.util.Log;

import javax.inject.Inject;

public class TestClass implements TestInterface

@Inject
TestClass() 


@Override
public void method() 
    Log.i("TestClass", "TestClass注入成功！");

3、编写对应Module
import dagger.Binds;
import dagger.Module;
import dagger.hilt.InstallIn;
import dagger.hilt.android.components.ActivityComponent;

@Module
@InstallIn(ActivityComponent.class)
public abstract class TestInterfaceModule

// @Binds
// public abstract TestInterface bindTestClass(TestClassTwo testClass //实现不同的 功能);

@Binds
public abstract TestInterface bindTestClass(TestClass testClass);

4、最终使用
@AndroidEntryPoint
public class MainActivity extends AppCompatActivity
@Inject
HttpObject httpObject;

@Inject
HttpObject httpObject2;
@Inject
public TestInterface testInterface;

@Override
protected void onCreate(Bundle savedInstanceState) 
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);
    Log.i("hqk_MainActivity",httpObject.hashCode()+"");
    Log.i("hqk_MainActivity",httpObject2.hashCode()+"");
    testInterface.method();