Intents và Navigation

1. Giới thiệu

Intent là cơ chế messaging để yêu cầu hành động từ component khác.

2. Loại Intent

Explicit Intent

Chỉ định rõ component đích:

// Mở Activity cụ thể
val intent = Intent(this, DetailActivity::class.java)
startActivity(intent)

Implicit Intent

Khai báo action chung, hệ thống chọn component phù hợp:

// Mở URL
val intent = Intent(Intent.ACTION_VIEW, Uri.parse("https://google.com"))
startActivity(intent)

3. Truyền dữ liệu

Primitives

val intent = Intent(this, DetailActivity::class.java).apply {
    putExtra("id", 123)
    putExtra("name", "Alice")
    putExtra("active", true)
}
startActivity(intent)

Nhận dữ liệu

class DetailActivity : ComponentActivity() {
    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)

        val id = intent.getIntExtra("id", 0)
        val name = intent.getStringExtra("name") ?: ""
        val active = intent.getBooleanExtra("active", false)
    }
}

Parcelable Objects

@Parcelize
data class User(
    val id: Int,
    val name: String,
    val email: String
) : Parcelable

// Gửi
intent.putExtra("user", user)

// Nhận
val user = intent.getParcelableExtra<User>("user")

4. Implicit Intents phổ biến

Mở trình duyệt

val intent = Intent(Intent.ACTION_VIEW, Uri.parse("https://example.com"))
startActivity(intent)

Gửi email

val intent = Intent(Intent.ACTION_SENDTO).apply {
    data = Uri.parse("mailto:")
    putExtra(Intent.EXTRA_EMAIL, arrayOf("recipient@example.com"))
    putExtra(Intent.EXTRA_SUBJECT, "Subject")
    putExtra(Intent.EXTRA_TEXT, "Email body")
}
if (intent.resolveActivity(packageManager) != null) {
    startActivity(intent)
}

Gọi điện

val intent = Intent(Intent.ACTION_DIAL).apply {
    data = Uri.parse("tel:0123456789")
}
startActivity(intent)

Chia sẻ

val intent = Intent(Intent.ACTION_SEND).apply {
    type = "text/plain"
    putExtra(Intent.EXTRA_TEXT, "Check this out!")
}
startActivity(Intent.createChooser(intent, "Share via"))

Chụp ảnh

val intent = Intent(MediaStore.ACTION_IMAGE_CAPTURE)
if (intent.resolveActivity(packageManager) != null) {
    startActivityForResult(intent, REQUEST_IMAGE_CAPTURE)
}

5. Activity Result API (Modern)

class MainActivity : ComponentActivity() {

    private val getContent = registerForActivityResult(
        ActivityResultContracts.GetContent()
    ) { uri: Uri? ->
        // Handle selected image URI
    }

    private val takePicture = registerForActivityResult(
        ActivityResultContracts.TakePicturePreview()
    ) { bitmap: Bitmap? ->
        // Handle captured image
    }

    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)
        setContent {
            Column {
                Button(onClick = { getContent.launch("image/*") }) {
                    Text("Pick Image")
                }
                Button(onClick = { takePicture.launch(null) }) {
                    Text("Take Photo")
                }
            }
        }
    }
}

6. Custom Activity Result

// Activity A
private val detailLauncher = registerForActivityResult(
    ActivityResultContracts.StartActivityForResult()
) { result ->
    if (result.resultCode == Activity.RESULT_OK) {
        val data = result.data?.getStringExtra("result")
        // Handle result
    }
}

// Launch
detailLauncher.launch(Intent(this, DetailActivity::class.java))

// Activity B (DetailActivity)
setResult(Activity.RESULT_OK, Intent().apply {
    putExtra("result", "Success")
})
finish()

7. Navigation với Compose

Setup Navigation

@Composable
fun NavGraph() {
    val navController = rememberNavController()

    NavHost(navController, startDestination = "home") {
        composable("home") {
            HomeScreen(
                onNavigateToDetail = { id ->
                    navController.navigate("detail/$id")
                }
            )
        }
        composable(
            "detail/{id}",
            arguments = listOf(navArgument("id") { type = NavType.IntType })
        ) { backStackEntry ->
            val id = backStackEntry.arguments?.getInt("id") ?: 0
            DetailScreen(id)
        }
    }
}

Navigate với arguments

// Navigate
navController.navigate("detail/123")

// Navigate và pop current
navController.navigate("home") {
    popUpTo("home") { inclusive = true }
}

// Go back
navController.popBackStack()

8. Deep Links

Khai báo trong Manifest

<activity android:name=".MainActivity">
    <intent-filter>
        <action android:name="android.intent.action.VIEW" />
        <category android:name="android.intent.category.DEFAULT" />
        <category android:name="android.intent.category.BROWSABLE" />
        <data android:scheme="myapp"
              android:host="product" />
    </intent-filter>
</activity>

Trong Compose Navigation

composable(
    "detail/{id}",
    deepLinks = listOf(navDeepLink {
        uriPattern = "myapp://product/{id}"
    })
) { backStackEntry ->
    DetailScreen(backStackEntry.arguments?.getInt("id") ?: 0)
}

---

📝 Tóm tắt

Loại	Mục đích
Explicit Intent	Mở component cụ thể
Implicit Intent	Yêu cầu action chung
putExtra/getExtra	Truyền dữ liệu
ActivityResultAPI	Nhận kết quả từ Activity
NavHost	Navigation trong Compose
Deep Links	Mở app từ URL