Jetpack

Jetpack 是一個(gè)由多個(gè)庫(kù)組成的套件，可幫助開發(fā)者遵循最佳做法屠橄，減少樣板代碼并編寫可在各種 Android 版本和設(shè)備中一致運(yùn)行的代碼梁厉，讓開發(fā)者精力集中編寫重要的代碼。

Android Architecture Component (AAC)刽射。

官方推薦架構(gòu)

73bd0ed878dd68c2ee1511da5862d662.png

請(qǐng)注意听隐，每個(gè)組件僅依賴于其下一級(jí)的組件补鼻。例如，Activity 和 Fragment 僅依賴于視圖模型。存儲(chǔ)區(qū)是唯一依賴于其他多個(gè)類的類风范；在本例中咨跌，存儲(chǔ)區(qū)依賴于持久性數(shù)據(jù)模型和遠(yuǎn)程后端數(shù)據(jù)源。

MVVM

MVVM即Model - View - ViewModel的縮寫硼婿，它的出現(xiàn)是為了將圖形界面與業(yè)務(wù)邏輯锌半，數(shù)據(jù)模型進(jìn)行解耦。

MVVM也是Google推崇的一種Android項(xiàng)目架構(gòu)模型寇漫。

之前學(xué)習(xí)的Jetpack組建刊殉，大部分都是為了能夠更好地架構(gòu)MVVM應(yīng)用程序而設(shè)計(jì)的。

API接口

接口：https://api.github.com/users/yaoxin521123

工程結(jié)構(gòu)

bean：實(shí)體類州胳。
api：網(wǎng)絡(luò)請(qǐng)求接口记焊。
repository：倉(cāng)儲(chǔ)層。用于存放Room數(shù)據(jù)栓撞，網(wǎng)絡(luò)數(shù)據(jù)遍膜，本地?cái)?shù)據(jù)等。
viewmodel：從倉(cāng)儲(chǔ)層獲取數(shù)據(jù)瓤湘，不需要關(guān)心數(shù)據(jù)來(lái)源瓢颅。
view：Activity，F(xiàn)ragment和布局文件弛说，用會(huì)用到DataBinding組件
dao：Room數(shù)據(jù)庫(kù)操作
application：實(shí)例化全局文件和獲取全局上下文惜索。
bindingAdapter：放一些

添加依賴

implementation 'androidx.swiperefreshlayout:swiperefreshlayout:1.1.0'
implementation 'de.hdodenhof:circleimageview:3.0.1'

搭建項(xiàng)目

通過(guò)獲取GitHub API獲取個(gè)人信息進(jìn)行展示。

1. 定義User實(shí)體類

@Entity(tableName = "user")
data class User(
    @PrimaryKey @ColumnInfo(name = "id", typeAffinity = ColumnInfo.INTEGER) var id: Int,
    @ColumnInfo(name = "login", typeAffinity = ColumnInfo.TEXT) var login: String,
    @ColumnInfo(name = "name", typeAffinity = ColumnInfo.TEXT) var name: String?,
    @ColumnInfo(name = "avatar_url", typeAffinity = ColumnInfo.TEXT) @SerializedName("avatar_url")var avatar: String?,
    @ColumnInfo(name = "blog", typeAffinity = ColumnInfo.TEXT) var blog: String,
    @ColumnInfo(name = "company", typeAffinity = ColumnInfo.TEXT) var company: String?,
    @ColumnInfo(name = "bio", typeAffinity = ColumnInfo.TEXT) var bio: String?,
    @ColumnInfo(name = "location", typeAffinity = ColumnInfo.TEXT) var location: String?,
    @ColumnInfo(name = "htmlUrl", typeAffinity = ColumnInfo.TEXT) @SerializedName("html_url") var htmlUrl: String?
)

2. 定義Dao類

@Dao
interface UserDao {
    @Insert(onConflict = OnConflictStrategy.REPLACE)
    fun insertUser(user: User)

    @Delete
    fun deleteUser(user: User)

    @Query("select * from user where login =:name")
    fun getUserByName(name: String): LiveData<User>
}

3. 定義DataBase類

@Database(entities = [User::class], version =7)
abstract class AppDatabase : RoomDatabase() {
    abstract fun userDao(): UserDao

    companion object {
        private var instance: AppDatabase? = null

        @Synchronized
        fun getDatabase(context: Context): AppDatabase {
            instance?.let {
                return it
            }
            return Room.databaseBuilder(
                context.applicationContext,
                AppDatabase::class.java,
                "user_db"
            ).fallbackToDestructiveMigration().build().apply {
                instance = this
            }
        }
    }
}

4. 定義API接口

interface Api {
    @GET("users/{userName}")
    fun getUser(@Path("userName") userName: String): Call<User>
}

5. 定義Retrofit訪問(wèn)網(wǎng)絡(luò)

object RetrofitClient {
    private const val BASE_URL = "https://api.github.com/"
    var retrofit: Retrofit

    init {
        retrofit =
            Retrofit.Builder().baseUrl(BASE_URL).addConverterFactory(GsonConverterFactory.create())
                .build()
    }

    fun getApi(): Api? {
        return retrofit.create(Api::class.java)
    }
}

6. 定義Application類

class MyApplication : Application() {
    companion object {
        lateinit var context: Context
    }

    override fun onCreate() {
        super.onCreate()
        context = applicationContext
    }
}

7. 定義Repository

object UserRepository {
    var userDao: UserDao = AppDatabase.getDatabase(MyApplication.context).userDao()

    fun getUser(name: String): LiveData<User> {
        refresh(name)
        return userDao.getUserByName(name)
    }

    fun refresh(name: String) {
        RetrofitClient.getApi()?.getUser(name)?.enqueue(object : Callback<User> {
            override fun onResponse(call: Call<User>, response: Response<User>) {
                if (response.body() != null) {
                    insertUser(response.body()!!)
                }
            }

            override fun onFailure(call: Call<User>, t: Throwable) {
                Log.d("UserRepository", "onFailure$t")
            }

        })
    }

    fun insertUser(user: User) {
        thread {
            userDao.insertUser(user)
        }
    }
}

8. 定義ViewModel

class MvvmViewModel : ViewModel() {
    val userName = "yaoxin521123"
    fun getUser() = UserRepository.getUser(userName)
    fun refresh() = UserRepository.refresh(userName)
}

9. 繪制xml

<?xml version="1.0" encoding="utf-8"?>
<layout xmlns:app="http://schemas.android.com/apk/res-auto">

    <data>

        <variable
            name="user"
            type="com.yx.androidseniorpreparetest.eighth.bean.User" />
    </data>

    <androidx.swiperefreshlayout.widget.SwipeRefreshLayout xmlns:android="http://schemas.android.com/apk/res/android"
        xmlns:tools="http://schemas.android.com/tools"
        android:id="@+id/srl_SwipeRefreshLayout"
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        tools:context=".eighth.MvvmActivity">

        <LinearLayout
            android:layout_width="match_parent"
            android:layout_height="match_parent"
            android:orientation="vertical">

            <de.hdodenhof.circleimageview.CircleImageView
                android:layout_width="95dp"
                android:layout_height="95dp"
                android:layout_gravity="center"
                android:layout_marginTop="20dp"
                app:image="@{user.avatar}" />

            <TextView
                android:layout_width="wrap_content"
                android:layout_height="wrap_content"
                android:layout_gravity="center"
                android:layout_marginTop="20dp"
                android:text="@{user.name}"
                android:textColor="#000000"
                android:textSize="20sp" />

            <TextView
                android:layout_width="wrap_content"
                android:layout_height="wrap_content"
                android:layout_gravity="center"
                android:layout_marginTop="20dp"
                android:text="@{user.login}"
                android:textColor="#000000"
                android:textSize="20sp" />

            <TextView
                android:layout_width="wrap_content"
                android:layout_height="wrap_content"
                android:layout_gravity="center"
                android:layout_marginTop="20dp"
                android:text="@{user.blog}"
                android:textColor="#000000"
                android:textSize="20sp" />

            <TextView
                android:layout_width="wrap_content"
                android:layout_height="wrap_content"
                android:layout_gravity="center"
                android:layout_marginTop="20dp"
                android:text="@{user.company}"
                android:textColor="#000000"
                android:textSize="20sp" />

            <TextView
                android:layout_width="wrap_content"
                android:layout_height="wrap_content"
                android:layout_gravity="center"
                android:layout_marginTop="20dp"
                android:text="@{user.bio}"
                android:textColor="#000000"
                android:textSize="20sp" />

            <TextView
                android:layout_width="wrap_content"
                android:layout_height="wrap_content"
                android:layout_gravity="center"
                android:layout_marginTop="20dp"
                android:text="@{user.location}"
                android:textColor="#000000"
                android:textSize="20sp" />

            <TextView
                android:layout_width="wrap_content"
                android:layout_height="wrap_content"
                android:layout_gravity="center"
                android:layout_marginTop="20dp"
                android:text="@{user.htmlUrl}"
                android:textColor="#000000"
                android:textSize="20sp" />
        </LinearLayout>
    </androidx.swiperefreshlayout.widget.SwipeRefreshLayout
</layout>

10. 在Activity觸發(fā)事件

class MvvmActivity : AppCompatActivity() {
    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)

        val binding =
            DataBindingUtil.setContentView<ActivityMvvmBinding>(this, R.layout.activity_mvvm)
        val viewModel = ViewModelProviders.of(this).get(MvvmViewModel::class.java)
        viewModel.getUser().observe(this, {
            if (it != null) {
                binding.user = it
            }
        })
        binding.srlSwipeRefreshLayout.setOnRefreshListener {
            viewModel.refresh()
            binding.srlSwipeRefreshLayout.isRefreshing = false
        }

    }
}

11. 定義BindingAapter

class BindingAdapter {
    companion object {
        @JvmStatic
        @BindingAdapter(value = ["image", "defaultImageResource"], requireAll = false)
        fun setImage(imageView: ImageView, imageUrl: String?, imageResource: Int) {
            if (!TextUtils.isEmpty(imageUrl)) {
                Picasso.get()
                    .load(imageUrl)
                    .placeholder(R.drawable.ic_launcher_background)
                    .error(R.drawable.ic_launcher_background)
                    .into(imageView)
            } else {
                imageView.setImageResource(imageResource)
            }
        }
    }
}

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相關(guān)視頻
【Android進(jìn)階】jetpack教程