Intent 可以啟動activity，service，broadcast receiver，intent 可以指定action跟data，action是指要做什麼樣的事，例如打電話或編輯文章，data則是指此action boundle在一起的資料內容，以URI格式表示。
Intent分成兩種，implicit intent與explicit intent，明確的intent表示指定要啟動的activity，而implicit intent，則是透過設定intent-filter讓系統有能力解析最適合的activity或service等，intent要由哪個應用程式接收，有三種比對的filter，分別是<action>,<category>,<data>。，而implicit intent自動加入CATEGORY_DEFAULT，如果intent-filter中沒有android.intent.category
.DEFAULT，則match就會失敗，所以要讓activity或service接收implicit intent就必須要加入android.intent.category.DEFAULT。
intent-filter 可以被包在 activity,service,receiver中
<intent-filter android:icon="drawable resource"
android:label="string resource"
android:priority="integer">
<action android:name="string" />
//可以有很多action，只要其中一項符合即可，如果intent filter
//沒有指定action，這此AP永不被執行，若intent沒有指定action
//，則任何app的action filter皆符合此intent
<category android:name="string" />
//若intent有設定Category，必須intent的每項category都通過filter設定
//的Category，若intent沒有設定Category，則都符合此intent
<data android:name="string" />
//1.當filter內沒有設定任何data tag,而intent內也沒有設定URI與data type,
//那這test就通過
//2.當filter有設定URI,沒有設定data type,而intent object也是只有URI沒有
//data type,這時候通過，這通常只會發生在mailto: 與tel: 時
//3.當filter內只有設定data type 沒有設定URI,而intent object有設定相同
//的data type無URI則通過
//4.當filter內設定的data type與URI都與intent Object內設定的對應即通過
//若filter內只有設定data type而URI不設定,只有在intent Object內的
//data type有對應，而URI為content: 或file:才會通過
</intent-filter>
intent機制的好處是，要擴充功能只要發出intent，android就會去找最適合的應用程式，不需要在自己的應用程式裡加code。網路上收集的intent範例(轉自http://ysl-paradise.blogspot.com/2008/12/intent.html)
顯示網頁
Uri uri = Uri.parse("http://google.com");
Intent it = new Intent(Intent.ACTION_VIEW, uri);
startActivity(it);
顯示地圖
Uri uri = Uri.parse("geo:38.899533,-77.036476");
Intent it = new Intent(Intent.ACTION_VIEW, uri);
startActivity(it);
//其他 geo URI 範例
//geo:latitude,longitude
//geo:latitude,longitude?z=zoom
//geo:0,0?q=my+street+address
//geo:0,0?q=business+near+city
//google.streetview:cbll=lat,lng&cbp=1,yaw,,pitch,zoom&mz=mapZoom
路徑規劃
Uri uri = Uri.parse("http://maps.google.com/maps?f=d&saddr=startLat%20startLng&daddr=endLat%20endLng&hl=en");
Intent it = new Intent(Intent.ACTION_VIEW, uri);
startActivity(it);
//where startLat, startLng, endLat, endLng are a long with 6 decimals like: 50.123456
撥打電話
//叫出撥號程式
Uri uri = Uri.parse("tel:0800000123");
Intent it = new Intent(Intent.ACTION_DIAL, uri);
startActivity(it);
//直接打電話出去
Uri uri = Uri.parse("tel:0800000123");
Intent it = new Intent(Intent.ACTION_CALL, uri);
startActivity(it);
//用這個，要在 AndroidManifest.xml 中，加上
//
傳送 SMS/MMS
//叫起簡訊程式
Intent it = new Intent(Intent.ACTION_VIEW);
it.putExtra("sms_body", "The SMS text");
it.setType("vnd.android-dir/mms-sms");
startActivity(it);
//傳送簡訊
Uri uri = Uri.parse("smsto:0800000123");
Intent it = new Intent(Intent.ACTION_SENDTO, uri);
it.putExtra("sms_body", "The SMS text");
startActivity(it);
//傳送 MMS
Uri uri = Uri.parse("content://media/external/images/media/23");
Intent it = new Intent(Intent.ACTION_SEND);
it.putExtra("sms_body", "some text");
it.putExtra(Intent.EXTRA_STREAM, uri);
it.setType("image/png");
startActivity(it);
//如果是 HTC Sense 手機，你要用
Intent sendIntent = new Intent("android.intent.action.SEND_MSG");
sendIntent.putExtra("address", toText);
sendIntent.putExtra(Intent.EXTRA_SUBJECT, "subject");
sendIntent.putExtra("sms_body", textMessage);
sendIntent.putExtra(Intent.EXTRA_STREAM, Uri.parse(url));
sendIntent.setType("image/jpeg");
startActivity(sendIntent);
//底下這段更好，可在所有手機上用
//refer to http://stackoverflow.com/questions/2165516/sending-mms-into-different-android-devices
Intent intent = new Intent(Intent.ACTION_SENDTO, Uri.parse("mmsto:");
intent.putExtra("address", );
intent.putExtra("subject", );
startActivity(intent);
傳送 Email
Uri uri = Uri.parse("mailto:xxx@abc.com");
Intent it = new Intent(Intent.ACTION_SENDTO, uri);
startActivity(it);
Intent it = new Intent(Intent.ACTION_SEND);
it.putExtra(Intent.EXTRA_EMAIL, "me@abc.com");
it.putExtra(Intent.EXTRA_TEXT, "The email body text");
it.setType("text/plain");
startActivity(Intent.createChooser(it, "Choose Email Client"));
Intent it=new Intent(Intent.ACTION_SEND);
String[] tos={"me@abc.com"};
String[] ccs={"you@abc.com"};
it.putExtra(Intent.EXTRA_EMAIL, tos);
it.putExtra(Intent.EXTRA_CC, ccs);
it.putExtra(Intent.EXTRA_TEXT, "The email body text");
it.putExtra(Intent.EXTRA_SUBJECT, "The email subject text");
it.setType("message/rfc822");
startActivity(Intent.createChooser(it, "Choose Email Client"));
//傳送影音附件檔
Intent it = new Intent(Intent.ACTION_SEND);
it.putExtra(Intent.EXTRA_SUBJECT, "The email subject text");
it.putExtra(Intent.EXTRA_STREAM, Uri.parse("file:///sdcard/mysong.mp3"));
it.setType("audio/mp3");
startActivity(Intent.createChooser(it, "Choose Email Client"));
//傳送圖片附件檔
Intent it = new Intent(Intent.ACTION_SEND);
it.putExtra(Intent.EXTRA_SUBJECT, "The email subject text");
it.putExtra(Intent.EXTRA_STREAM, Uri.parse("file:///sdcard/mypic.jpg"));
it.setType("image/jpeg");
startActivity(Intent.createChooser(it, "Choose Email Client"));
顯示聯絡人清單
Intent it = new Intent(Intent.ACTION_VIEW, People.CONTENT_URI); startActivity(it);顯示某個朋友的詳細資料
Uri uriPerson = ContentUris.withAppendedId(People.CONTENT_URI, 5); //5 是朋友的 ID Intent it = new Intent(Intent.ACTION_VIEW, uriPerson); startActivity(it);播放多媒體
Intent it = new Intent(Intent.ACTION_VIEW);
Uri uri = Uri.parse("file:///sdcard/song.mp3");
it.setDataAndType(uri, "audio/mp3");
startActivity(it);
Uri uri = Uri.withAppendedPath(MediaStore.Audio.Media.INTERNAL_CONTENT_URI, "1");
Intent it = new Intent(Intent.ACTION_VIEW, uri);
startActivity(it);
從圖庫中回傳選到的圖片
Intent it = new Intent(Intent.ACTION_GET_CONTENT);
it.addCategory(Intent.CATEGORY_OPENABLE);
it.setType("image/*");
startActivityForResult(it, 0);
//回傳的圖片可透過 it.getData() 取得圖片之 Uri
啟動照相機，並將相片存在指定的檔案中
Intent it = new Intent(MediaStore.ACTION_IMAGE_CAPTURE); //假設你要將相片存在 /sdcard/xxx.jpg 中 File f = new File(Environment.getExternalStorageDirectory().getAbsolutePath() + "/xxx.jpg"); it.putExtra(MediaStore.EXTRA_OUTPUT, Uri.fromFile(f)); startActivity(it, 0);Market 相關
//尋找某個應用程式
Uri uri = Uri.parse("market://search?q=pname:pkg_name");
Intent it = new Intent(Intent.ACTION_VIEW, uri);
startActivity(it);
//where pkg_name is the full package path for an application
//顯示某應用程式詳細畫面
Uri uri = Uri.parse("market://details?id=pkg_name_or_app_id");
Intent it = new Intent(Intent.ACTION_VIEW, uri);
startActivity(it);
//where app_id is the application ID, find the ID
//by clicking on your application on Market home
//page, and notice the ID from the address bar
Uninstall 應用程式
Uri uri = Uri.fromParts("package", strPackageName, null);
Intent it = new Intent(Intent.ACTION_DELETE, uri);
startActivity(it);
安裝 APK 檔
Uri uri = Uri.parse("url_of_apk_file");
Intent it = new Intent(Intent.ACTION_VIEW, uri);
it.setData(uri);
it.addFlags(Intent.FLAG_GRANT_READ_URI_PERMISSION);
it.setClassName("com.android.packageinstaller",
"com.android.packageinstaller.PackageInstallerActivity");
startActivity(it);
//make sure the url_of_apk_file is readable for all users
