概述

Intent是用于和其他应用组件通信的消息对象，

通常有三种用途：启动Activity、启动Service、发送Broadcast

Intent类型

• 显式Intent
• 隐式Intent

创建Intent

• Component name

  • setComponent()
  • setClass()
  • setClassName()

• Action

  • ACTION_VIEW
  • ACTION_SEND

• Data

  Uri对象、指定数据的MIME类型

  • setDataAndType()

• Category

  • CATEGORY_BROWSABLE
  • CATEGORY_LAUNCHER

• Extras

  Bundle键值对

• Flags

  指示如何启动Activity，以及启动后它所属的任务栈

示例: App选择器

val sendIntent = Intent(Intent.ACTION_SEND)
...

// Always use string resources for UI text.
// This says something like "Share this photo with"
val title: String = resources.getString(R.string.chooser_title)
// Create intent to show the chooser dialog
val chooser: Intent = Intent.createChooser(sendIntent, title)

// Verify the original intent will resolve to at least one activity
if (sendIntent.resolveActivity(packageManager) != null) {
    startActivity(chooser)
}

接收隐式Intent

清单文件中定义<intent-filter>

- <action>
- <data>
- <category>

<activity android:name="MainActivity">
    <!-- This activity is the main entry, should appear in app launcher -->
    <intent-filter>
        <action android:name="android.intent.action.MAIN" />
        <category android:name="android.intent.category.LAUNCHER" />
    </intent-filter>
</activity>

<activity android:name="ShareActivity">
    <!-- This activity handles "SEND" actions with text data -->
    <intent-filter>
        <action android:name="android.intent.action.SEND"/>
        <category android:name="android.intent.category.DEFAULT"/>
        <data android:mimeType="text/plain"/>
    </intent-filter>
    <!-- This activity also handles "SEND" and "SEND_MULTIPLE" with media data -->
    <intent-filter>
        <action android:name="android.intent.action.SEND"/>
        <action android:name="android.intent.action.SEND_MULTIPLE"/>
        <category android:name="android.intent.category.DEFAULT"/>
        <data android:mimeType="application/vnd.google.panorama360+jpg"/>
        <data android:mimeType="image/*"/>
        <data android:mimeType="video/*"/>
    </intent-filter>
</activity>

PendingIntent

使用场景：

- Notification
- App Widget
- AlarmManager

创建：

- PendingIntent.getActivity()
- PendingIntent.getService()
- PendingIntent.getBroadcast()

<font color="red">解析Intent</font>

• action

  Intent中指定的action必须与intent-filter中列出的action一项匹配。

  若intent-filter中不包含action，匹配永远不会成功。

  若Intent中未指定action，而只要intent-filter至少包含一个action就会默认匹配成功。

• category

  Intent中的每个category都必须与intent-filter中列出的category匹配。

  即Intent中指定的category必须是intent-filter中category的子集。

  若Intent不包含category，则匹配成功。

• data

  1. 仅当过滤器未指定任何 URI 或 MIME 类型时，不含 URI 和 MIME 类型的 Intent 才会通过测试。
  2. 对于包含 URI 但不含 MIME 类型（既未显式声明，也无法通过 URI 推断得出）的 Intent，仅当其 URI 与过滤器的 URI 格式匹配、且过滤器同样未指定 MIME 类型时，才会通过测试。
  3. 仅当过滤器列出相同的 MIME 类型且未指定 URI 格式时，包含 MIME 类型但不含 URI 的 Intent 才会通过测试。
  4. 如果过滤器只是列出 MIME 类型，则假定组件支持 content: 和 file: 数据。

Intent匹配

PackageManager 提供一整套 query...() 方法来返回所有能够接受特定 Intent 的组件。

此外，还会提供一系列类似的 resolve...() 方法来确定响应 Intent 的最佳组件。

常见Intent

闹钟

• Action：ACTION_SET_ALARM
• Extras
  • EXTRA_HOUR
  • EXTRA_MINUTES
  • EXTRA_MESSAGE
  • EXTRA_DAYS
  • EXTRA_RINGTONE
  • EXTRA_VIBRATE
  • EXTRA_SKIP_UI

//SET_ALARM permission 
fun createAlarm(message: String, hour: Int, minutes: Int) {
    val intent = Intent(AlarmClock.ACTION_SET_ALARM).apply {
        putExtra(AlarmClock.EXTRA_MESSAGE, message)
        putExtra(AlarmClock.EXTRA_HOUR, hour)
        putExtra(AlarmClock.EXTRA_MINUTES, minutes)
    }
    if (intent.resolveActivity(packageManager) != null) {
        startActivity(intent)
    }
}

定时器

• Action：ACTION_SET_TIMER
• Extras：
  • EXTRA_LENGTH
  • EXTRA_MESSAGE
  • EXTRA_SKIP_UI

//SET_ALARM permission
fun startTimer(message: String, seconds: Int) {
    val intent = Intent(AlarmClock.ACTION_SET_TIMER).apply {
        putExtra(AlarmClock.EXTRA_MESSAGE, message)
        putExtra(AlarmClock.EXTRA_LENGTH, seconds)
        putExtra(AlarmClock.EXTRA_SKIP_UI, true)
    }
    if (intent.resolveActivity(packageManager) != null) {
        startActivity(intent)
    }
}

显示所有闹钟

• Action：ACTION_SHOW_ALARMS

日历

• Action：ACTION_INSERT
• Data URI：Events.CONTENT_URI
• MIME Type：“vnd.android.cursor.dir/event”
• Extra：
  • EXTRA_EVENT_ALL_DAY
  • EXTRA_EVENT_BEGIN_TIME
  • EXTRA_EVENT_END_TIME
  • TITLE
  • DESCRIPTION
  • EVENT_LOCATION
  • EXTRA_EMAIL

fun addEvent(title: String, location: String, begin: Long, end: Long) {
    val intent = Intent(Intent.ACTION_INSERT).apply {
        data = Events.CONTENT_URI
        putExtra(Events.TITLE, title)
        putExtra(Events.EVENT_LOCATION, location)
        putExtra(CalendarContract.EXTRA_EVENT_BEGIN_TIME, begin)
        putExtra(CalendarContract.EXTRA_EVENT_END_TIME, end)
    }
    if (intent.resolveActivity(packageManager) != null) {
        startActivity(intent)
    }
}

相机

拍摄照片或视频

相对于相机应用，此界面只要拍摄功能，无相册

• Action：ACTION_IMAGE_CAPTURE or ACTION_VIDEO_CAPTURE
• Extras：EXTRA_OUTPUT

const val REQUEST_IMAGE_CAPTURE = 1
val locationForPhotos: Uri = ...

fun capturePhoto(targetFilename: String) {
    val intent = Intent(MediaStore.ACTION_IMAGE_CAPTURE).apply {
        putExtra(MediaStore.EXTRA_OUTPUT, Uri.withAppendedPath(locationForPhotos, targetFilename))
    }
    if (intent.resolveActivity(packageManager) != null) {
        startActivityForResult(intent, REQUEST_IMAGE_CAPTURE)
    }
}

override fun onActivityResult(requestCode: Int, resultCode: Int, data: Intent) {
    if (requestCode == REQUEST_IMAGE_CAPTURE && resultCode == Activity.RESULT_OK) {
        val thumbnail: Bitmap = data.getParcelableExtra("data")
        // Do other work with full size photo saved in locationForPhotos
        ...
    }
}

For more information about how to use this intent to capture a photo, including how to create an appropriate Uri for the output location, read Taking Photos Simply or Taking Videos Simply.

启动相机应用

• INTENT_ACTION_STILL_IMAGE_CAMERA
• INTENT_ACTION_VIDEO_CAMERA

联系人

选择联系人

• Action：ACTION_PICK
• MIME Type：Contacts.CONTENT_TYPE

选择特定联系人数据

• Action：ACTION_PICK
• MIME Type：
  • CommonDataKinds.Phone.CONTNET_TYPE
  • CommonDataKinds.Email.CONTNET_TYPE

const val REQUEST_SELECT_PHONE_NUMBER = 1

fun selectContact() {
    // Start an activity for the user to pick a phone number from contacts
    val intent = Intent(Intent.ACTION_PICK).apply {
        type = CommonDataKinds.Phone.CONTENT_TYPE   
    }
    if (intent.resolveActivity(packageManager) != null) {
        startActivityForResult(intent, REQUEST_SELECT_PHONE_NUMBER)
    }
}

override fun onActivityResult(requestCode: Int, resultCode: Int, data: Intent) {
    if (requestCode == REQUEST_SELECT_PHONE_NUMBER && resultCode == Activity.RESULT_OK) {
        // Get the URI and query the content provider for the phone number
        val contactUri: Uri = data.data
        val projection: Array<String> = arrayOf(CommonDataKinds.Phone.NUMBER)
        contentResolver.query(contactUri, projection, null, null, null).use { cursor ->
            // If the cursor returned is valid, get the phone number
            if (cursor.moveToFirst()) {
                val numberIndex = cursor.getColumnIndex(CommonDataKinds.Phone.NUMBER)
                val number = cursor.getString(numberIndex)
                // Do something with the phone number
                ...
            }
        }
    }
}

查看联系人

• Action：ACTION_VIEW
• Data URI：content:<URI>

fun viewContact(contactUri: Uri) {
    val intent = Intent(Intent.ACTION_VIEW, contactUri)
    if (intent.resolveActivity(packageManager) != null) {
        startActivity(intent)
    }
}

编辑现有联系人

• Action：ACTION_EDIT
• Data URI：content:<URI>
• MIME Type：该类型是从联系人 URI 推断得出
• Extra：ContactsContract.Intents.Insert

fun editContact(contactUri: Uri, email: String) {
    val intent = Intent(Intent.ACTION_EDIT).apply {
        data = contactUri
        putExtra(ContactsContract.Intents.Insert.EMAIL, email)
    }
    if (intent.resolveActivity(packageManager) != null) {
        startActivity(intent)
    }
}

插入联系人

• Action：ACTION_INSERT
• MIME Type：Contacts.CONTENT_TYPE
• Extra：ContactsContract.Intents.Insert

fun insertContact(name: String, email: String) {
    val intent = Intent(Intent.ACTION_INSERT).apply {
        type = ContactsContract.Contacts.CONTENT_TYPE
        putExtra(ContactsContract.Intents.Insert.NAME, name)
        putExtra(ContactsContract.Intents.Insert.EMAIL, email)
    }
    if (intent.resolveActivity(packageManager) != null) {
        startActivity(intent)
    }
}

电子邮件

文件存储

检索特定类型的文件

• Action：ACTION_GET_CONTENT
• MIME Type：文件对应类型
• Extra：
  • EXTRA_ALLOW_MULTIPLE
  • EXTRA_LOCAL_ONLY
• Category（可选）：CATEGORY_OPENABLE

//获取照片
const val REQUEST_IMAGE_GET = 1

fun selectImage() {
    val intent = Intent(Intent.ACTION_GET_CONTENT).apply {
        type = "image/*"
    }
    if (intent.resolveActivity(packageManager) != null) {
        startActivityForResult(intent, REQUEST_IMAGE_GET)
    }
}

override fun onActivityResult(requestCode: Int, resultCode: Int, data: Intent) {
    if (requestCode == REQUEST_IMAGE_GET && resultCode == Activity.RESULT_OK) {
        val thumbnail: Bitmap = data.getParcelableExtra("data")
        val fullPhotoUri: Uri = data.data
        // Do work with photo saved at fullPhotoUri
        ...
    }
}

打开特定类型的文件

• Action：ACTION_OPEN_DOCUMENT or ACTION_CREATE_DOCUMENT

• MIME Type：文件对应类型

• Extra：

  • EXTRA_MIME_TYPES
  • EXTRA_ALLOW_MULTIPLE
  • EXTRA_TITLE
  • EXTRA_LOCAL_ONLY

• Category：CATEGORY_OPENABLE

//获取照片2
const val REQUEST_IMAGE_OPEN = 1

fun selectImage2() {
    val intent = Intent(Intent.ACTION_OPEN_DOCUMENT).apply {
        type = "image/*"
        addCategory(Intent.CATEGORY_OPENABLE)
    }
    // Only the system receives the ACTION_OPEN_DOCUMENT, so no need to test.
    startActivityForResult(intent, REQUEST_IMAGE_OPEN)
}

override fun onActivityResult(requestCode: Int, resultCode: Int, data: Intent) {
    if (requestCode == REQUEST_IMAGE_OPEN && resultCode == Activity.RESULT_OK) {
        val fullPhotoUri: Uri = data.data
        // Do work with full size photo saved at fullPhotoUri
        ...
    }
}

地图

• Action：ACTION_VIEW

• Data URI：

  • geo:latitude,longitude

    显示给定经纬度地图

  • geo:latitude,longitude?z=zoom

    按照特定缩放级别显示（1-23，1为全球地图，23为最高精度缩放）

  • geo:0,0?q=lat,lng(label)

    显示给定经纬度处带字符串标签的地图

  • geo:0,0?q=my+street+address

    显示“我的街道”位置

fun showMap(geoLocation: Uri) {
    val intent = Intent(Intent.ACTION_VIEW).apply {
        data = geoLocation
    }
    if (intent.resolveActivity(packageManager) != null) {
        startActivity(intent)
    }
}

音乐或视频

播放媒体文件

• Action：ACTION_VIEW
• Data URI：
  • file:<URI>
  • content:<URI>
  • http:<URI>
• MIME Type:
  • "audio/*"
  • "application/ogg"
  • "application/x-ogg"
  • "application/itunes"

fun playMedia(file: Uri) {
    val intent = Intent(Intent.ACTION_VIEW).apply {
        data = file
    }
    if (intent.resolveActivity(packageManager) != null) {
        startActivity(intent)
    }
}

基于搜索播放音乐

• Action：INTENT_ACTION_MEDIA_PLAY_FROM_SEARCH
• Extra：MediaStore.EXTRA_MEDIA_FOCUS

fun playSearchArtist(artist: String) {
    val intent = Intent(MediaStore.INTENT_ACTION_MEDIA_PLAY_FROM_SEARCH).apply {
        putExtra(MediaStore.EXTRA_MEDIA_FOCUS, MediaStore.Audio.Artists.ENTRY_CONTENT_TYPE)
        putExtra(MediaStore.EXTRA_MEDIA_ARTIST, artist)
        putExtra(SearchManager.QUERY, artist)
    }
    if (intent.resolveActivity(packageManager) != null) {
        startActivity(intent)
    }
}

新笔记

• Action：ACTION_CREATE_NOTE
• MIME Type：PLAIN_TEXT_TYPE
• Extra：
  • EXTRA_NAME
  • EXTRA_TEXT

fun createNote(subject: String, text: String) {
    val intent = Intent(NoteIntents.ACTION_CREATE_NOTE).apply {
        putExtra(NoteIntents.EXTRA_NAME, subject)
        putExtra(NoteIntents.EXTRA_TEXT, text)
    }
    if (intent.resolveActivity(packageManager) != null) {
        startActivity(intent)
    }
}

电话

• Action：
  • ACTION_DIAL 打开拨号界面
  • ACTION_CALL 拨打电话（需要CALL_PHONE权限）
• Data URI：
  • tel:<phone-number>
  • voicemail:<phone-number>

fun dialPhoneNumber(phoneNumber: String) {
    val intent = Intent(Intent.ACTION_DIAL).apply {
        data = Uri.parse("tel:$phoneNumber")
    }
    if (intent.resolveActivity(packageManager) != null) {
        startActivity(intent)
    }
}

网页搜索

• Action：ACTION_WEB_SEARCH
• Extra：SearchManager.QUERY 搜索字符串

fun searchWeb(query: String) {
    val intent = Intent(Intent.ACTION_WEB_SEARCH).apply {
        putExtra(SearchManager.QUERY, query)
    }
    if (intent.resolveActivity(packageManager) != null) {
        startActivity(intent)
    }
}

设置

• Action：
  • ACTION_SETTINGS
  • ACTION_WIRELESS_SETTINGS
  • ACTION_AIRPLANE_MODE_SETTINGS
  • ACTION_WIFI_SETTINGS
  • ACTION_APN_SETTINGS
  • ACTION_BLUETOOTH_SETTINGS
  • ACTION_DATE_SETTINGS
  • ACTION_LOCALE_SETTINGS
  • ACTION_INPUT_METHOD_SETTINGS
  • ACTION_DISPLAY_SETTINGS
  • ACTION_SECURITY_SETTINGS
  • ACTION_LOCATION_SOURCE_SETTINGS
  • ACTION_INTERNAL_STORAGE_SETTINGS
  • ACTION_MEMORY_CARD_SETTINGS

fun openWifiSettings() {
    val intent = Intent(Settings.ACTION_WIFI_SETTINGS)
    if (intent.resolveActivity(packageManager) != null) {
        startActivity(intent)
    }
}

发短信

• Action：
  • ACTION_SENDTO
  • ACTION_SEND
  • ACTION_SEND_MULTIPLE
• Data URI：
  • sms:<phone_number>
  • smsto:<phone_number>
  • mms:<phone_number>
  • mmsto:<phone_number>
• MIME Type:
  • "text/plain"
  • "image/*"
  • "video/*"
• Extra
  • "subject"
  • "sms_body"
  • EXTRA_STREAM

fun composeMmsMessage(message: String, attachment: Uri) {
    val intent = Intent(Intent.ACTION_SEND).apply {
        data = Uri.parse("smsto:")  // This ensures only SMS apps respond
        putExtra("sms_body", message)
        putExtra(Intent.EXTRA_STREAM, attachment)
    }
    if (intent.resolveActivity(packageManager) != null) {
        startActivity(intent)
    }
}

网页浏览器

• Action：ACTION_VIEW
• Data URI：
  • http:<URL>
  • https:<URL>
• MIME Type：
  • "text/plain"
  • "text/html"
  • "application/xhtml+xml"
  • "application/vnd.wap.xhtml+xml"

fun openWebPage(url: String) {
    val webpage: Uri = Uri.parse(url)
    val intent = Intent(Intent.ACTION_VIEW, webpage)
    if (intent.resolveActivity(packageManager) != null) {
        startActivity(intent)
    }
}

示例intent-filter

<activity ...>
    <intent-filter>
        <action android:name="android.intent.action.VIEW" />
        <!-- Include the host attribute if you want your app to respond
             only to URLs with your app's domain. -->
        <data android:scheme="http" android:host="www.example.com" />
        <category android:name="android.intent.category.DEFAULT" />
        <!-- The BROWSABLE category is required to get links from web pages. -->
        <category android:name="android.intent.category.BROWSABLE" />
    </intent-filter>
</activity>

使用adb调试Intent

adb shell am start -a <ACTION> -t <MIME_TYPE> -d <DATA> \
  -e <EXTRA_NAME> <EXTRA_VALUE> -n <ACTIVITY>

如：

adb shell am start -a android.intent.action.DIAL \
  -d tel:555-5555 -n org.example.MyApp/.MyActivity