Android之Intents 和Intent Filters
1. Intents 和Intent Filters
- to start an Activity
startActivity or startActivityForResults - to start a service
startService or bindService - to deliever a broadcast
sendBroadcast, sendOrderedBroadcast or sendStickyBroadcast
1.1 Intent Types
- Explicit intents
指定请求组件的全限定名，就包名+类名。 - Implicit intents
申明通用的动作去执行，允许其他App处理该动作。
1.2 Building Intent
- Component name
是决定该Intent是否为Explicit Intent，可通过set Component(), setClass(), setClassName(), 或者是作为Intent()的构造器的参数。若没指定该参数，则系统使用一下item进行匹配。其中Service必须指定Component Name。 - Action
是一个String字符串，指定通用动作去执行，如View or Pick。该字段通常能够决定Intent的其他字段如何构造，尤其是在data域和extras域。可自定义Action，但更推荐使用系统提供的。以下为常用的Action， ACTION_VIEW(使用地图显示地址或使用相册显示图片)，ACTION_SEND(使用其他App共享数据，诸如电子邮件或者社交网络共享).
可以通过setAction(),或者Intent的构造器进行指定。定义自己的ACTION，请加上包名，如下static final String ACTION_TIMETRAVEL = "com.example.action.TIMETRAVEL"; - Data
使用URI指定MIME类型的数据，通常需要指定数据类型。但是使用content: URI的URI数据，可不指定类型，因为系统可识别出该数据位于设备上，并且受到ContentProvider控制，因此MIME类型就变为可见。
指定方式为setData(), setType() or setDataAndType(),其中setData和setType不可同时使用，若需要，请使用setDataAndType()。 - Category
一个String，包含可处理该Intent的组件种类。每个Intent可包含任意数量的Category，但大部分的Intent都不需要，通常设置为android.intent.category.DEFAULT。常见的Category：CATEGORY_BROWSABLE和CATEGORY_LAUNCHER。前者表示该数据可为浏览器打开，后者表示该Activity是一个任务的初始Activity,并且将会被显示在Launcher里。可用'addCategory()'来指定该项。
>Tip 以上介绍的component name, action, data, 和category限定了一个intent的特性，Android系统可知道如何决定一个组件来处理或启动。 - Extras
携带键值对信息，KV来完成特定的Action。可通过putExtras（K, V），或者创建一个Bundle携带所有的KVP，然后putExtras到Intent。指定自己的Extras Key，务必加上包名，如static final String EXTRA_GIGAWATTS = "com.example.EXTRA_GIGAWATTS"; - FLAG
定义Intent的元素据metadata，可指导Android系统如何启动一个Activity（task所属），或者启动后如何对待（是否属于其他已经启动的Activity）
1.2 Examples
- Explicit Intent
// Executed in an Activity, so 'this' is the Context// The fileUrl is a string URL, such as "http://www.example.com/image.png"Intent downloadIntent = new Intent(this, DownloadService.class);downloadIntent.setData(Uri.parse(fileUrl));startService(downloadIntent);- Implicit Intent
模糊的Intent，可能会没有App响应，导致App Crash。因此可通过resolveActitvity()来验证是否有Activity响应，然后再决定是否启动Activity。
// Create the text message with a stringIntent sendIntent = new Intent();sendIntent.setAction(Intent.ACTION_SEND);sendIntent.putExtra(Intent.EXTRA_TEXT, textMessage);sendIntent.setType(HTTP.PLAIN_TEXT_TYPE); // "text/plain" MIME type// Verify that the intent will resolve to an activityif (sendIntent.resolveActivity(getPackageManager()) != null) { startActivity(sendIntent);}若有多个App响应，则显示列表对话框以供用户选择，如果只有一个App响应，则直接启动。
- 强制出现App选择器
如分享文件或者数据到各种App，ACTION_SEND。可使用Intent的creatChooser来操作，如下：
Intent intent = new Intent(Intent.ACTION_SEND);...// Always use string resources for UI text.// This says something like "Share this photo with"String title = getResources().getString(R.string.chooser_title);// Create intent to show chooserIntent chooser = Intent.createChooser(intent, title);// Verify the intent will resolve to at least one activityif (sendIntent.resolveActivity(getPackageManager()) != null) { startActivity(sendIntent);}1.3 Receiving an Implicit Intent
在Manifest文件中申明< intent-filters >标签，通过action, data, and category等字段制定Intent可接受的类型。
一个Explicit Intent无视组件所申明的接受Intent类型，直接传递过去。
不同job应申明不同的< intent-filters >,可包括action, data, and category3个字段。
-action， 指定可接受的intetn action。
-data，可接受的数据类型，URI (scheme, host, port, path, etc.) and MIME type。
-category,必须是一个Action的string值。
Tip: 为了收到Implicit Intents，必须设定
CATEGORY_DEFAULT。这样， startActivity() and startActivityForResult() 才可调用，否则没有任何Implicit可启动该Activity。
举例：
只有三个item都通过验证，Android才会传递Intent给该Activity。对于Broadcast Receiver，可通过registerReceiver() or unregisterReceiver()动态绑定。
- Example Filters
1.4 Using a Pending Intent
它是对Intent的包装器，主要用途是给予其他App权限获取本进程的数据。主要用途如下：
- Notification Manager
- AppWidget
- AlarmManager
由于每个Intent都是为特定的组件设计的，因此PendingIntent也同样。
- PendingIntent.getActivity()，启动Activtiy
- PendingIntent.getService()，启动Service
- PendingIntent.getBroadcast(), 启动BroadcastReceiver（）。
1.5 Intent Resolution
Android 系统匹配最优的组件的算法，基于以下三方面的匹配测试：
- The intent action
- The intent data (both URI and data type)
- The intent category
其中data的URI 结构和MIME 类型。
URI：:// : /
ex：content://com.example.project:200/folder/subfolder/etc
这4个元素是线性依赖的：
>If a scheme is not specified, the host is ignored.
If a host is not specified, the port is ignored.
If both the scheme and host are not specified, the path is ignored.
PackageManager 可以调用以下几个方法列出可接受该Intent的组件
- queryIntentActivities(), 返回所有相似的Activity
- queryIntentServices()，返回相似的所有Service
- queryIntentBroadcastReceivers(), 返回所有
1.6 Common Intents
1 AlarmClock
Action: ACTION_SET_ALARM
Extras:....
ex:
public void createAlarm(String message, int hour, int minutes) { Intent intent = new Intent(AlarmClock.ACTION_SET_ALARM) .putExtra(AlarmClock.EXTRA_MESSAGE, message) .putExtra(AlarmClock.EXTRA_HOUR, hour) .putExtra(AlarmClock.EXTRA_MINUTES, minutes); if (intent.resolveActivity(getPackageManager()) != null) { startActivity(intent); }}并其需要使用权限：
相应的Intent-Filter
2 Timer
Action：ACTION_SET_TIMER
Extras：。。。
e.g.
public void startTimer(String message, int seconds) { Intent intent = new Intent(AlarmClock.ACTION_SET_TIMER) .putExtra(AlarmClock.EXTRA_MESSAGE, message) .putExtra(AlarmClock.EXTRA_LENGTH, seconds) .putExtra(AlarmClock.EXTRA_SKIP_UI, true); if (intent.resolveActivity(getPackageManager()) != null) { startActivity(intent); }}Permission:
Intent-Filter:
3 显示所有Alarms
Action：ACTION_SHOW_ALARMS
4 添加Calendar Event
Action：ACTION_INSERT
Data URI：Events.CONTENT_URI
MIME Type： "vnd.android.cursor.dir/event"
Extras： 。。。
4 拍摄照片或摄制录像
Action：ACTION_IMAGE_CAPTURE or ACTION_VIDEO_CAPTURE
Extras：EXTRA_OUTPUT
使用onActivityResult()接收返回数据：
static final int REQUEST_IMAGE_CAPTURE = 1;static final Uri mLocationForPhotos;public void capturePhoto(String targetFilename) { Intent intent = new Intent(MediaStore.ACTION_IMAGE_CAPTURE); intent.putExtra(MediaStore.EXTRA_OUTPUT, Uri.withAppendedPath(mLocationForPhotos, targetFilename); if (intent.resolveActivity(getPackageManager()) != null) { startActivityForResult(intent, REQUEST_IMAGE_CAPTURE); }}@Overrideprotected void onActivityResult(int requestCode, int resultCode, Intent data) { if (requestCode == REQUEST_IMAGE_CAPTURE && resultCode == RESULT_OK) { Bitmap thumbnail = data.getParcelable("data"); // Do other work with full size photo saved in mLocationForPhotos ... }}相应的Intent-Filter
5 Start a camera app in still image mode
Action: INTENT_ACTION_STILL_IMAGE_CAMERA
6 Start a camera app in video mode
Action: INTENT_ACTION_VIDEO_CAMERA
7 选择一个联系人
Action：ACTION_PICK
MIME Type：Contacts.CONTENT_TYPE
e.g.:
static final int REQUEST_SELECT_CONTACT = 1;public void selectContact() { Intent intent = new Intent(Intent.ACTION_PICK); intent.setType(ContactsContract.Contacts.CONTENT_TYPE); if (intent.resolveActivity(getPackageManager()) != null) { startActivityForResult(intent, REQUEST_SELECT_CONTACT); }}@Overrideprotected void onActivityResult(int requestCode, int resultCode, Intent data) { if (requestCode == REQUEST_SELECT_CONTACT && resultCode == RESULT_OK) { Uri contactUri = data.getData(); // Do something with the selected contact at contactUri ... }}8 选择特定的联系人
Action： ACTION_PICK
MIME Type：
CommonDataKinds.Phone.CONTENT_TYPE。Pick from contacts with a phone number.
CommonDataKinds.Email.CONTENT_TYPE，Pick from contacts with an email address.
CommonDataKinds.StructuredPostal.CONTENT_TYPE，Pick from contacts with a postal address.
static final int REQUEST_SELECT_PHONE_NUMBER = 1;public void selectContact() { // Start an activity for the user to pick a phone number from contacts Intent intent = new Intent(Intent.ACTION_PICK); intent.setType(CommonDataKinds.Phone.CONTENT_TYPE); if (intent.resolveActivity(getPackageManager()) != null) { startActivityForResult(intent, REQUEST_SELECT_PHONE_NUMBER); }}@Overrideprotected void onActivityResult(int requestCode, int resultCode, Intent data) { if (requestCode == REQUEST_SELECT_PHONE_NUMBER && resultCode == RESULT_OK) { // Get the URI and query the content provider for the phone number Uri contactUri = data.getData(); String[] projection = new String[]{CommonDataKinds.Phone.NUMBER}; Cursor cursor = getContentResolver().query(contactUri, projection, null, null, null); // If the cursor returned is valid, get the phone number if (cursor != null && cursor.moveToFirst()) { int numberIndex = cursor.getColumnIndex(CommonDataKinds.Phone.NUMBER); String number = cursor.getString(numberIndex); // Do something with the phone number ... } }}9 显示一个联系人
- ACTION_PICK返回的contactURI，然后使用ACTION_VIEW查看。
- 直接访问联系人列表，需要READ_CONTACTS权限
public void viewContact(Uri contactUri) { Intent intent = new Intent(Intent.ACTION_VIEW, contactUri); if (intent.resolveActivity(getPackageManager()) != null) { startActivity(intent); }} 10 编辑一个联系人
Action：ACTION_EDIT
URI： 之前ACTION_PICK返回的contactURI。
Extras：ContactsContract.Intents.Insert中定义的条目都可编辑
public void editContact(Uri contactUri, String email) { Intent intent = new Intent(Intent.ACTION_EDIT); intent.setData(contactUri); intent.putExtra(Intents.Insert.EMAIL, email); if (intent.resolveActivity(getPackageManager()) != null) { startActivity(intent); }}11 插入一个联系人
Action：ACTION_INSERT
MIME Type：Contacts.CONTENT_TYPE
Extras：One or more of the extras defined in ContactsContract.Intents.Insert.
e.g.:
public void insertContact(String name, String email) { Intent intent = new Intent(Intent.ACTION_INSERT); intent.setType(Contacts.CONTENT_TYPE); intent.putExtra(Intents.Insert.NAME, name); intent.putExtra(Intents.Insert.EMAIL, email); if (intent.resolveActivity(getPackageManager()) != null) { startActivity(intent); }}12 Email
13 File Storage
14 Fitness
15 Local Actions
16 Maps, show a location on a map
Action: ACTION_VIEW
URI: geo:latitude,longtitude
e.g.:
public void showMap(Uri geoLocation) { Intent intent = new Intent(Intent.ACTION_VIEW); intent.setData(geoLocation); if (intent.resolveActivity(getPackageManager()) != null) { startActivity(intent); }}intent filter:
17 MUSIC or VIDEO
Action: ACTION_VIEW
Data URI Scheme:
- file:
- content:
- http:
MIME Type:
- "audio/*"
- "application/ogg"
- "application/x-ogg"
- "application/itunes" Or any other that your app may require.
example intent filter:
18 Phone
Action: ACTION_DIAL , ACTION_CALL
其中ACTION_DIAL，需要传输一个号码，然后跳转到拨打界面，需要点击拨打按钮。
而ACTION_CALL，需要传输一个号码，然后直接开始拨打，但是需要权限
Data URI Scheme：'tel:< phone-number>，voicemail:< phone-number>'
e.g.:
public void dialPhoneNumber(String phoneNumber) { Intent intent = new Intent(Intent.ACTION_DIAL); intent.setData(Uri.parse("tel:" + phoneNumber)); if (intent.resolveActivity(getPackageManager()) != null) { startActivity(intent); }}19 Settings
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
20 Text Messaging
Action: ACTION_SENDTO, ACTION_SEND, ACTION_SEND_MULTIPLE
Data URI Scheme:
sms:smsto:mms:mmsto: MIME Type:
PLAIN_TEXT_TYPE ("text/plain")
"image/"
"video/"
Extras:
"subject",'sms_body','EXTRA_STREAM'
e.g.:
public void composeMmsMessage(String message, Uri attachment) { Intent intent = new Intent(Intent.ACTION_SENDTO); intent.setType(HTTP.PLAIN_TEXT_TYPE); intent.putExtra("sms_body", message); intent.putExtra(Intent.EXTRA_STREAM, attachment); if (intent.resolveActivity(getPackageManager()) != null) { startActivity(intent); }}若想要确保intent被短信应用处理，使用 ACTION_SENDTO，并且设置data schmem为‘smsto:’.
相应的Intent-filter
21. WebBrowser
加载网址
- Action: ACTION_VIEW
- Data URI Scheme:
http:< URL>
https:< URL>
- MIME Type:
PLAIN_TEXT_TYPE ("text/plain")
"text/html"
"application/xhtml+xml"
"application/vnd.wap.xhtml+xml"
Web查询
Action： ACTION_WEB_SEARCH
Extras：SearchManager.QUERY The search string.
public void searchWeb(String query) { Intent intent = new Intent(Intent.ACTION_SEARCH); intent.putExtra(SearchManager.QUERY, query); if (intent.resolveActivity(getPackageManager()) != null) { startActivity(intent); }}22 Verify Intents with the Android Debug Bridge
- Set up an Android device for development, or use a virtual device.
- Install a version of your app that handles the intents you want to support.
- Fire an intent using adb:
adb shell am start -a -t-d \ -e -n
For example:adb shell am start -a android.intent.action.DIAL \ -d tel:555-5555 -n org.example.MyApp/.MyActivity
If you defined the required intent filters, your app should handle the intent.
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