Android點將臺：外交官[-Intent-]

摘要： 至美不過回首，往事重重，顧來時，荊棘漫漫，血浸途中。 今銅衣鐵靴，再行來路，任荊棘漫漫，唯落綠葉殘枝。 ----張風捷特烈 複製程式碼 零、前言 在此之前希望你已經閱讀了： Android點將臺：顏值擔當[-Activity...

至美不過回首，往事重重，顧來時，荊棘漫漫，血浸途中。
今銅衣鐵靴，再行來路，任荊棘漫漫，唯落綠葉殘枝。
----張風捷特烈 
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零、前言

在此之前希望你已經閱讀了： Android點將臺：顏值擔當[-Activity-]

1.本文的知識點

2.Intent總覽

類名:Intent父類:Object
實現的介面:[Parcelable, Cloneable]
包名:android.content'依賴類個數:52
內部類/介面個數：3
原始碼行數：10086原始碼行數(除註釋):3407
屬性個數：24方法個數:164
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一、Intent類簡單認識

1.Intent建構函式

原始碼上來看一共有8個建構函式，上面兩個是空參和隱藏的，不用管

左邊兩個通過拷貝來生成Intent物件，兩參的拷貝是似有的

右邊兩個通過 設定匹配資訊 方法來生成Intent物件(隱式)

下面兩個加入了 ComponentName 來生成Intent物件 (顯式)

2.Intent中的常用成員變數

component(元件)：目的元件(應用包名+元件全類名)
action（動作）：意圖的行為action
category（類別）：行為action的類別
data（資料）：表示與動作要操縱的資料
type（資料型別）：對於data範例的描寫
extras（擴充套件資訊）：擴充套件資訊
Flags（標誌位）：期望這個意圖的執行模式
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二、Intent的隱式使用

即不指定元件名，通過 action,category,data,type 等資訊開啟元件

系統中內建了很多應用，我們可以通過這些資訊來匹配開啟需要的應用

1.僅匹配Action

1.1：新建一個Activity: ActivityJustAction

class ActivityJustAction : AppCompatActivity() {

override fun onCreate(savedInstanceState: Bundle?) {
super.onCreate(savedInstanceState)
setContentView(LinearLayout(this))
title = "ActivityJustAction"
}
}

---->[AndroidManifest.xml配置]------------
<activity android:name=".activity.ActivityJustAction">
<intent-filter>
<action android:name="www.toly1994.com.ActivityJustAction"></action>
<category android:name="android.intent.category.DEFAULT"></category>
</intent-filter>
</activity>
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1.2：intent開啟指定Action：

就像一個人在喊，我要找 旺財 ,然後 旺財 就來了

---->[IntentActivity]--------------
id_btn_just_action.setOnClickListener { v ->
val intent = Intent("www.toly1994.com.ActivityJustAction")
startActivity(intent)
}
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1.3:兩個都叫 旺財 怎麼辦?

新建一個ActivityJustAction2，intent-filter設定的一樣

既然兩個都叫 旺財 ，就把兩個都帶來，讓你選一個唄(你應該經常遇到)

class ActivityJustAction2 : AppCompatActivity() {
override fun onCreate(savedInstanceState: Bundle?) {
super.onCreate(savedInstanceState)
setContentView(LinearLayout(this))
title = "ActivityJustAction2"
}
}

<activity android:name=".activity.ActivityJustAction2">
<intent-filter>
<action android:name="www.toly1994.com.ActivityJustAction2"></action>
<category android:name="android.intent.category.DEFAULT"></category>
</intent-filter>
</activity>
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2.匹配 action+category

名字加類別,一個 intent-filter 可以加多個類別，就像一件事物可以劃分在多個領域

如人、程式設計師、中國公民可以指同一人，新增category之後，相當於你喊了句：

我要找一個叫旺財的程式設計師 ，這樣就能更精確匹配，縮小撞名的可能，方便管理

---->[AndroidManifest.xml配置]------------
<activity android:name=".activity.ActivityJustAction">
<intent-filter>
<action android:name="www.toly1994.com.ActivityJustAction"></action>
<category android:name="android.intent.category.DEFAULT"></category>
<category android:name="www.toly1994.com.people"></category>
<category android:name="www.toly1994.com.coder"></category>
</intent-filter>
</activity>

<activity android:name=".activity.ActivityJustAction2">
<intent-filter>
<action android:name="www.toly1994.com.ActivityJustAction"></action>
<category android:name="android.intent.category.DEFAULT"></category>
<category android:name="www.toly1994.com.dog"></category>
<category android:name="www.toly1994.com.erha"></category>
</intent-filter>
</activity>

---->[IntentActivity]--------------
id_btn_just_action.setOnClickListener { v ->
val intent = Intent("www.toly1994.com.ActivityJustAction")
//intent.addCategory("www.toly1994.com.coder")//開1
//intent.addCategory("www.toly1994.com.people")//開1
//intent.addCategory("www.toly1994.com.dog")//開2
intent.addCategory("www.toly1994.com.erha")//開2
startActivity(intent)
}
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3.行為+新增資源定位識別符號： action + data

說起Uri(Uniform Resource Identifier)，統一資源識別符號

形式為： <scheme>://<authority><path>?<query>

3.1：開啟網頁

id_btn_open_web.setOnClickListener { v ->
val intent = Intent(Intent.ACTION_VIEW)
intent.data = Uri.parse("https://juejin.im/user/5b42c0656fb9a04fe727eb37")
startActivity(intent)
}
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3.2：開啟簡訊

/**
 * 傳送簡訊
 * @param number 號碼
 * @param body 內容
 */
private fun sendMsg(number: String, body: String) {
val intent = Intent(Intent.ACTION_SENDTO, Uri.parse("smsto:$number"))
intent.putExtra("sms_body", body)
startActivity(intent)
}
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4.Intent開啟相簿Activity( action+type )

根據action打一個應用，附加 MIME型別

/**
 * 開啟相簿
 */
private fun openGallery() {
val intent = Intent(Intent.ACTION_PICK)
intent.type = "image/*";
startActivity(intent)
}
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看一下相簿的原始碼是如何配置

5.Intent開啟檔案 action+type+data

5.1:適配

Android API 24 及以上對file的Uri做了限制，需要適配一下

/**
 * 作者：張風捷特烈<br/>
 * 時間：2018/10/30 0030:18:38<br/>
 * 郵箱：[email protected]<br/>
 * 說明：適配類
 */
public class Compat {
public static void fileUri(Context context, Intent intent, File file, String type) {
//判斷是否是AndroidN以及更高的版本
if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.N) {
intent.setFlags(Intent.FLAG_GRANT_READ_URI_PERMISSION);
Uri contentUri = FileProvider.getUriForFile(context, BuildConfig.APPLICATION_ID + ".fileProvider", file);
intent.setDataAndType(contentUri, type);
} else {
intent.setDataAndType(Uri.fromFile(file), type);
intent.setFlags(Intent.FLAG_ACTIVITY_NEW_TASK);
}
}
}

---->[AndroidManifest.xml配置provider]------
<!--android:authorities="本應用包名.fileProvider"-->
<provider android:name="android.support.v4.content.FileProvider"
android:authorities="com.toly1994.tolyservice.fileProvider"
android:grantUriPermissions="true"
android:exported="false">
<meta-data
android:name="android.support.FILE_PROVIDER_PATHS"
android:resource="@xml/file_paths" />
</provider>

---->[xml/file_paths.xml]-----------
<?xml version="1.0" encoding="utf-8"?>
<paths>
<!--Android/data/本應用包名/-->
<external-path path="Android/data/com.toly1994.tolyservice/" name="files_root" />
<external-path path="." name="external_storage_root" />
</paths>
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5.2:使用

需要加檔案讀許可權 <uses-permission android:name="android.permission.READ_EXTERNAL_STORAGE"/>

id_btn_music.setOnClickListener { v ->//音訊
val intent = Intent(Intent.ACTION_VIEW)
val file = File("/sdcard/toly/勇氣-梁靜茹-1772728608-1.mp3")
Compat.fileUri(this, intent, file, "audio/mp3")
startActivity(intent)
}
id_btn_video.setOnClickListener { v ->//視訊
val intent = Intent(Intent.ACTION_VIEW)
val file = File("/sdcard/toly/cy3d.mp4")
Compat.fileUri(this, intent, file, "video/mp4")
startActivity(intent)
}
id_btn_txt.setOnClickListener { v ->//文字
val intent = Intent(Intent.ACTION_VIEW)
val file = File("/sdcard/toly/應龍.txt")
Compat.fileUri(this, intent, file, "text/*")
startActivity(intent)
}
id_btn_pic.setOnClickListener { v ->//圖片
val intent = Intent(Intent.ACTION_VIEW)
val file = File("/sdcard/toly/touch.jpg.png")
Compat.fileUri(this, intent, file, "image/*")
startActivity(intent)
}
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相簿原始碼中對於開啟一張圖片的配置：

隱式的intent抓住 action、category、data、type 四個要點就行了

三、Intent顯式呼叫

即已經明確需要開啟的元件

1.開啟元件 本元件上下文+目標元件位元組碼

這個是我們最常用的，開啟 Activity,Service,BroadcastReceiver

private fun openComponent() {
val intent = Intent(this, MainActivity::class.java)
startActivity(intent)
}
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2.ComponentName的簡介

一直用Intent開啟Activity，貌似沒有分析過，現在進原始碼裡看看吧

---->[Intent#Intent(Context, Class<?>)]-------
public Intent(Context packageContext, Class<?> cls) {
mComponent = new ComponentName(packageContext, cls);
}

可見該方法核心是ComponentName，顧名思義"元件名稱" 
原始碼首行註釋說：特定應用程式元件的識別符號
---->[ComponentName#ComponentName(Context, lang.Class<?>)]--------
public ComponentName(@NonNull Context pkg, @NonNull Class<?> cls) {
mPackage = pkg.getPackageName();
mClass = cls.getName();
}

-------------------------------------------------------------------
ComponentName是一個比較簡單的類,核心是兩個成員變數mPackage和mClass
這個兩參構造中，mPackage是傳入的context的包名，mClass是目標元件的類名

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看一下兩個String的ComponentName構造，更能表達出它們的作用

也能夠實現開啟元件的功能，所以知道專案的包名，和元件的全類名，就能開啟元件

val intent = Intent()
val compName = ComponentName(
"com.toly1994.tolyservice",//專案的包名
"com.toly1994.tolyservice.activity.MainActivity")//要開啟的元件全類名
intent.component = compName
startActivity(intent)
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3.開啟微信： 元件包名+目標元件全類名+flag

private fun openComponent() {
val intent = Intent()
intent.flags=Intent.FLAG_ACTIVITY_NEW_TASK
val compName = ComponentName(
"com.tencent.mm",//本元件的包名
"com.tencent.mm.ui.LauncherUI")//要開啟的元件全類名
intent.component = compName
startActivity(intent)
}
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4.拷貝構造原始碼

---->[Intent拷貝構造]---------
public Intent(Intent o) {
this(o, COPY_MODE_ALL);
}
//|--使用兩參的[COPY_MODE_ALL]模式

---->[Intent兩參拷貝]---------
private Intent(Intent o, @CopyMode int copyMode) {
this.mAction = o.mAction;
this.mData = o.mData;
this.mType = o.mType;
this.mPackage = o.mPackage;
this.mComponent = o.mComponent;
if (o.mCategories != null) {
this.mCategories = new ArraySet<>(o.mCategories);
}
 //|--至此把category,action,data, type,component,package 的欄位拷貝了
 //|--COPY_MODE_ALL顧名思義，把所有的內容都拷貝
if (copyMode != COPY_MODE_FILTER) {
this.mFlags = o.mFlags;
this.mContentUserHint = o.mContentUserHint;
this.mLaunchToken = o.mLaunchToken;
if (o.mSourceBounds != null) {
this.mSourceBounds = new Rect(o.mSourceBounds);
}
if (o.mSelector != null) {
this.mSelector = new Intent(o.mSelector);
}
if (copyMode != COPY_MODE_HISTORY) {
if (o.mExtras != null) {
this.mExtras = new Bundle(o.mExtras);
}
if (o.mClipData != null) {
this.mClipData = new ClipData(o.mClipData);
}
} else {
if (o.mExtras != null && !o.mExtras.maybeIsEmpty()) {
this.mExtras = Bundle.STRIPPED;
}
// Also set "stripped" clip data when we ever log mClipData in the (broadcast)
// history.
}
}
}

---->[還有個clone方法]------------------
@Override
public Object clone() {
return new Intent(this);
}
|----根據呼叫的intent物件，直接返回了一個新的例項，本質上合拷貝構造並無區別
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四、系列化與反序列化

序列化有什麼用?

1.永久的儲存物件資料(儲存在檔案當中,或者是磁碟中)，需要時反序列化生成物件
2.將物件資料轉換成位元組流進行網路傳輸
3.使用Intent時傳遞序列化物件
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1.物件的序列化 Serializable

//類的可序列化，只要實現Serializable即可，非常簡單
class Person(var name: String?, var age: Int) : Serializable {
override fun toString(): String {
return "Person{" +
"name='" + name + '\''.toString() +
", age=" + age +
'}'.toString()
}
}
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2.1： Serializable 序列化儲存到磁碟

val toly = Person("toly", 24)
val file = File(cacheDir, "toly.obj")
val oos = ObjectOutputStream(FileOutputStream(file))
oos.writeObject(toly)
oos.close()
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2.2：反序列化從磁碟例項化物件

val ois = ObjectInputStream(FileInputStream(file))
val toly = ois.readObject() as Person
ois.close()
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2.3：限制欄位的序列化方式

當某些欄位不需要序列化時，可使用 @Transient(kotlin) 或 transient(Java)關鍵字
比如我不想讓name欄位序列化。(因為欄位越多，消耗的資源越多)

class Person(@Transient var name: String?, var age: Int) : Serializable {

override fun toString(): String {
return "Person{" +
"name='" + name + '\''.toString() +
", age=" + age +
'}'.toString()
}
}
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2.4：關於 serialVersionUID

看一下Android原始碼，實現Serializable的類都有一個`serialVersionUID`的常量
Java的序列化機制是通過判斷類的serialVersionUID來驗證版本一致性的。
在進行反序列化時，JVM會把傳來的位元組流和當前類中的serialVersionUID進行對比，
是一致的則進行反序列化，否則拋序列化版本不一致的異常(InvalidCastException)
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3. Parcelable 實現物件的序列化(Java版)

當一個實現Parcelable介面時必須實現 describeContents和writeToParcel 方法

感覺怪麻煩的，還好AndroidStudio有快捷生成方式

/**
 * 作者：張風捷特烈<br/>
 * 時間：2019/1/21/021:22:30<br/>
 * 郵箱：[email protected]<br/>
 * 說明：Parcelable序列化
 */
public class Book implements Parcelable {

private String name;
private int price;

public Book(String name, int price) {
this.name = name;
this.price = price;
}

@Override
public int describeContents() {
return 0;
}

@Override
public void writeToParcel(Parcel dest, int flags) {
dest.writeString(this.name);
dest.writeInt(this.price);
}

protected Book(Parcel in) {
this.name = in.readString();
this.price = in.readInt();
}

public static final Parcelable.Creator<Book> CREATOR = new Parcelable.Creator<Book>() {
@Override
public Book createFromParcel(Parcel source) {
return new Book(source);
}

@Override
public Book[] newArray(int size) {
return new Book[size];
}
};

@Override
public String toString() {
return "Book{" +
"name='" + name + '\'' +
", price=" + price +
'}';
}
}
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3. Parcelable 與 Serializable 的比較

此小點參考文章，講得挺好

Parcelable所屬包android.os
Serializable所屬包java.io
|---所屬包說明了Parcelable只能在Android中使用

P以Ibinder作為資訊載體的，在記憶體上的開銷比較小,P在效能方面要強於S
S在序列化操作的時候會產生大量的臨時變數,(反射機制)從而導致GC的頻繁呼叫
|---Parcelable的效能要強於Serializable

在讀寫資料的時候,Parcelable是在記憶體中直接進行讀寫
而Serializable是通過使用IO流的形式將資料讀寫入在硬碟上

Parcelable無法將資料進行持久化(磁碟儲存)，Serializable可以
(在不同的Android版本當中,Parcelable可能會不)

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五、Intent的資料傳遞

Intent 除來一大堆對屬性的set之外，還有一大堆的putExtra來盛放資料

Intent不僅傳遞"命令"還能攜帶資料傳達，put資料的方法躲到令人髮指

可以說應有盡有，有put，當然對應有get,下面僅列舉出put資料的方法

1.常見資料型別的傳輸

由於常見型別很多，這裡選三個代表，其他的用法類似，怎麼放怎麼取

---->[FromActivity點選時]--------
val intent = Intent(this, ToActivity::class.java)
//String型別資料
intent.putExtra("stringData", "張風捷特烈")
//int型別資料
intent.putExtra("intData", 100)
//容器型別資料
val arr = arrayListOf(1, 2, 3, 4, 5)
intent.putExtra("arrData", arr)
startActivity(intent)

---->[ToActivity#onCreate]--------
var result = ""
val stringData = intent.getStringExtra("stringData")
val intData = intent.getIntExtra("intData", 10)
val arrData = intent.getIntegerArrayListExtra("arrData")
result+=intData.toString()+"\n"
if (stringData != null) {
result+=stringData+"\n"
}
if (arrData != null) {
result+=arrData.toString()+"\n"
}
id_tv_result.append(result)
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2.Intent傳遞Bundle物件

簡單來看就是鍵值對,並沒有什麼非常神奇的。也有一堆的put,get

其中最重要的是有put序列化物件( Parcelable/Serializable )的方法

A mapping from String keys to various {@link Parcelable} values.
字串型的鍵到不同值得對映(link 到 Parcelable)
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---->[FromActivity點選時]--------
val intent = Intent(this, ToActivity::class.java)
val bundle = Bundle()
//存放Serializable序列化物件
val toly = Person("toly", 24)
bundle.putSerializable("person", toly)
//存放Parcelable序列化物件
val book = Book("《幻將錄》", 10000)
bundle.putParcelable("book", book)
intent.putExtra("bean", bundle)
startActivity(intent)

---->[ToActivity#onCreate]--------
val bundle = intent.getBundleExtra("bean")
if (bundle != null) {
val personBean = bundle.get("person") as Person
val bookBean = bundle.get("book") as Book
}
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六：Android原始碼 intent-filter 的解析流程

1.解析流程

PackageManagerService在啟動後會掃描系統和第三方的app資訊,
在scanPackageLI方法中例項化PackageParser物件pp，使用pp對包進行解析
PackageParser的parseBaseApk在呼叫之後解析AndroidManifest.xml,返回一個Package物件
將手機中所有的app的AndroidManifest.xml解析完畢，構建出一個手機中所有app的資訊樹
從這顆棵樹上


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---->[PackageParser#parseMonolithicPackage]------------
@Deprecated
public Package parseMonolithicPackage(File apkFile, int flags) throws PackageParserException {
//略...
final AssetManager assets = new AssetManager();
try {
final Package pkg = parseBaseApk(apkFile, assets, flags);
pkg.codePath = apkFile.getAbsolutePath();
return pkg;
} finally {
IoUtils.closeQuietly(assets);
}
}

private static final String ANDROID_MANIFEST_FILENAME = "AndroidManifest.xml";

---->[PackageParser#parseBaseApk 3參]------------
private Package parseBaseApk(File apkFile, AssetManager assets, int flags)
throws PackageParserException {
final String apkPath = apkFile.getAbsolutePath();
//略...
Resources res = null;
XmlResourceParser parser = null;//構建Xml的解析器
try {
res = new Resources(assets, mMetrics, null);
assets.setConfiguration(0, 0, null, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
Build.VERSION.RESOURCES_SDK_INT);
parser = assets.openXmlResourceParser(cookie, ANDROID_MANIFEST_FILENAME);//開啟`AndroidManifest.xml`檔案

final String[] outError = new String[1];
final Package pkg = parseBaseApk(res, parser, flags, outError);
if (pkg == null) {
throw new PackageParserException(mParseError,
apkPath + " (at " + parser.getPositionDescription() + "): " + outError[0]);
}

pkg.volumeUuid = volumeUuid;
pkg.applicationInfo.volumeUuid = volumeUuid;
pkg.baseCodePath = apkPath;
pkg.mSignatures = null;
return pkg;
//略...
}

---->[PackageParser#parseBaseApk 4參]------------
|--------核心的解析xml邏輯全在這個方法裡，非常長，----------
----------這裡從application的解析開始看------------------
private Package parseBaseApk(Resources res, XmlResourceParser parser, int flags,
String[] outError) throws XmlPullParserException, IOException {
//略...
String tagName = parser.getName();
if (tagName.equals("application")) {//下面開始解析application
//略...
//這裡呼叫了parseBaseApplication方法，activity的解析就在其中
if (!parseBaseApplication(pkg, res, parser, attrs, flags, outError)) {
return null;
}

---->[PackageParser#parseBaseApplication]------------
private boolean parseBaseApplication(Package owner, Resources res,
XmlPullParser parser, AttributeSet attrs, int flags, String[] outError)
//略...
while ((type = parser.next()) != XmlPullParser.END_DOCUMENT
&& (type != XmlPullParser.END_TAG || parser.getDepth() > innerDepth)) {
if (type == XmlPullParser.END_TAG || type == XmlPullParser.TEXT) {
continue;
}

String tagName = parser.getName();
if (tagName.equals("activity")) {//這裡開始解析activity
Activity a = parseActivity(owner, res, parser, attrs, flags, outError, false,
owner.baseHardwareAccelerated);
if (a == null) {
mParseError = PackageManager.INSTALL_PARSE_FAILED_MANIFEST_MALFORMED;
return false;
}
owner.activities.add(a);
} else if (tagName.equals("receiver")) {//這裡開始解析receiver
Activity a = parseActivity(owner, res, parser, attrs, flags, outError, true, false);
if (a == null) {
mParseError = PackageManager.INSTALL_PARSE_FAILED_MANIFEST_MALFORMED;
return false;
}
owner.receivers.add(a);

} else if (tagName.equals("service")) {//這裡開始解析service
Service s = parseService(owner, res, parser, attrs, flags, outError);
if (s == null) {
mParseError = PackageManager.INSTALL_PARSE_FAILED_MANIFEST_MALFORMED;
return false;
}

owner.services.add(s);

} else if (tagName.equals("provider")) {//這裡開始解析provider
Provider p = parseProvider(owner, res, parser, attrs, flags, outError);
if (p == null) {
mParseError = PackageManager.INSTALL_PARSE_FAILED_MANIFEST_MALFORMED;
return false;
}
owner.providers.add(p);
//略...還有很多解析的東西
return true;
}

---->[PackageParser#parseActivity]------------
private Activity parseActivity(Package owner, Resources res,
XmlPullParser parser, AttributeSet attrs, int flags, String[] outError,
boolean receiver, boolean hardwareAccelerated)
throws XmlPullParserException, IOException {
TypedArray sa = res.obtainAttributes(attrs, R.styleable.AndroidManifestActivity);
//略...
//下面開始解析：intent-filter
if (parser.getName().equals("intent-filter")) {
//建立ActivityIntentInfo
ActivityIntentInfo intent = new ActivityIntentInfo(a);
//呼叫parseIntent方法
if (!parseIntent(res, parser, attrs, true, true, intent, outError)) {
return null;
}
if (intent.countActions() == 0) {
} else {
a.intents.add(intent);
//略...
return a;
}

---->[PackageParser#parseIntent]------------

private boolean parseIntent(Resources res, XmlPullParser parser, AttributeSet attrs,
boolean allowGlobs, boolean allowAutoVerify, IntentInfo outInfo, String[] outError)
throws XmlPullParserException, IOException {

TypedArray sa = res.obtainAttributes(attrs,
com.android.internal.R.styleable.AndroidManifestIntentFilter);
//略...
int outerDepth = parser.getDepth();
int type;
while ((type = parser.next()) != XmlPullParser.END_DOCUMENT
&& (type != XmlPullParser.END_TAG || parser.getDepth() > outerDepth)) {
if (type == XmlPullParser.END_TAG || type == XmlPullParser.TEXT) {
continue;
}
String nodeName = parser.getName();
if (nodeName.equals("action")) {//解析action
String value = attrs.getAttributeValue(
ANDROID_RESOURCES, "name");
if (value == null || value == "") {
outError[0] = "No value supplied for <android:name>";
return false;
}
XmlUtils.skipCurrentTag(parser);

outInfo.addAction(value);
} else if (nodeName.equals("category")) {//解析category
String value = attrs.getAttributeValue(
ANDROID_RESOURCES, "name");
if (value == null || value == "") {
outError[0] = "No value supplied for <android:name>";
return false;
}
XmlUtils.skipCurrentTag(parser);
outInfo.addCategory(value);
} else if (nodeName.equals("data")) {//解析data
sa = res.obtainAttributes(attrs,
com.android.internal.R.styleable.AndroidManifestData);
String str = sa.getNonConfigurationString( com.android.internal.R.styleable.AndroidManifestData_mimeType, 0);
if (str != null) {
try {
outInfo.addDataType(str);
} catch (IntentFilter.MalformedMimeTypeException e) {
outError[0] = e.toString();
sa.recycle();
return false;
}
}
return true;
}

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2. startActivity(intent) 做了什麼?

startActivity一連串的呼叫之後，最終核心是下面的方法

前一篇已經涉及過Instrumentation類，它真可謂Activity的忠實僕人

------>[Activity#startActivityForResult]----------------------
public void startActivityForResult(@RequiresPermission Intent intent, int requestCode,
@Nullable Bundle options) {
if (mParent == null) {
options = transferSpringboardActivityOptions(options);
Instrumentation.ActivityResult ar =
mInstrumentation.execStartActivity(
this, mMainThread.getApplicationThread(), mToken, this,
intent, requestCode, options);
//略...
}
}

------>[Instrumentation#execStartActivity]----------------------
public ActivityResult execStartActivity(
Context who, IBinder contextThread, IBinder token, String target,
Intent intent, int requestCode, Bundle options) {
IApplicationThread whoThread = (IApplicationThread) contextThread;
if (mActivityMonitors != null) {
synchronized (mSync) {
final int N = mActivityMonitors.size();
for (int i=0; i<N; i++) {
final ActivityMonitor am = mActivityMonitors.get(i);
if (am.match(who, null, intent)) {
am.mHits++;
if (am.isBlocking()) {
return requestCode >= 0 ? am.getResult() : null;
}
break;
}
}
}
}
try {
intent.migrateExtraStreamToClipData();
intent.prepareToLeaveProcess(who);
int result = ActivityManagerNative.getDefault()
.startActivity(whoThread, who.getBasePackageName(), intent,
intent.resolveTypeIfNeeded(who.getContentResolver()),
token, target, requestCode, 0, null, options);
checkStartActivityResult(result, intent);
} catch (RemoteException e) {
throw new RuntimeException("Failure from system", e);
}
return null;
}

------>[ActivityManagerNative#getDefault]----------------------
static public IActivityManager getDefault() {
return gDefault.get();
}

------>[ActivityManagerNative#Singleton]----------------------
private static final Singleton<IActivityManager> gDefault = new Singleton<IActivityManager>() {
protected IActivityManager create() {
IBinder b = ServiceManager.getService("activity");
if (false) {
Log.v("ActivityManager", "default service binder = " + b);
}
IActivityManager am = asInterface(b);//IActivityManager的建立
if (false) {
Log.v("ActivityManager", "default service = " + am);
}
return am;
}
};

------>[ActivityManagerNative#asInterface]----------------------
|--------這裡可以看出get的IActivityManager物件是一個ActivityManagerProxy物件
static public IActivityManager asInterface(IBinder obj) {
if (obj == null) {
return null;
}
IActivityManager in =
(IActivityManager)obj.queryLocalInterface(descriptor);
if (in != null) {
return in;
}
return new ActivityManagerProxy(obj);
}

>現在焦點在ActivityManagerProxy的身上
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3.ActivityManagerProxy是何許人也?

先看IActivityManager，他是一個介面定義了很多關於Activity管理的方法

ActivityManagerProxy作為它的實現類，當然也就實現了這些方法

---->[ActivityStackSupervisor#startActivity]--------
 @Override
public final int startActivity(IApplicationThread caller, String callingPackage,
Intent intent, String resolvedType, IBinder resultTo, String resultWho, int requestCode,
int startFlags, ProfilerInfo profilerInfo, Bundle options) {
return startActivityAsUser(caller, callingPackage, intent, resolvedType, resultTo,

---->[ActivityStackSupervisor#startActivityAsUser]--------
 @Override
public final int startActivityAsUser(IApplicationThread caller, String callingPackage,
Intent intent, String resolvedType, IBinder resultTo, String resultWho, int requestCode,
int startFlags, ProfilerInfo profilerInfo, Bundle options, int userId) {
enforceNotIsolatedCaller("startActivity");
userId = handleIncomingUser(Binder.getCallingPid(), Binder.getCallingUid(), userId,
false, ALLOW_FULL_ONLY, "startActivity", null);
// TODO: Switch to user app stacks here.
return mStackSupervisor.startActivityMayWait(caller, -1, callingPackage, intent,
resolvedType, null, null, resultTo, resultWho, requestCode, startFlags,
profilerInfo, null, null, options, false, userId, null, null);

---->[ActivityStackSupervisor#resolveActivity]--------
 ActivityInfo resolveActivity(Intent intent, String resolvedType, int startFlags,
ProfilerInfo profilerInfo, int userId) {
// Collect information about the target of the Intent.
ActivityInfo aInfo;
try {
ResolveInfo rInfo =
//這裡通過AppGlobals獲取了getPackageManager，也就是包管理器
AppGlobals.getPackageManager().resolveIntent(
intent, resolvedType,
PackageManager.MATCH_DEFAULT_ONLY
| ActivityManagerService.STOCK_PM_FLAGS, userId);
aInfo = rInfo != null ? rInfo.activityInfo : null;

---->[ActivityStackSupervisor#resolveActivity]--------
public static IPackageManager getPackageManager() {
//通過ActivityThread獲取PackageManager
return ActivityThread.getPackageManager();
}

---->[ActivityThread#getPackageManager]--------
public static IPackageManager getPackageManager() {
if (sPackageManager != null) {
//Slog.v("PackageManager", "returning cur default = " + sPackageManager);
return sPackageManager;
}
//通過ServiceManager獲取包管理器的IBinder
IBinder b = ServiceManager.getService("package");
//Slog.v("PackageManager", "default service binder = " + b);
//生成的IPackageManager物件
sPackageManager = IPackageManager.Stub.asInterface(b);
//Slog.v("PackageManager", "default service = " + sPackageManager);
return sPackageManager;
}

//接下來的焦點集中到了PackageManager和IPackageManager身上
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IPackageManager.aidl 的描述中有這個方法

PackageManagerService作為IPackageManager.Stub的實現類

肯定也實現了queryIntentActivities方法,就是他檢視intent是否匹配

其中aidl的相關知識，會寫一篇進行詳述

---->[PackageManagerService#queryIntentActivities]------------
@Override
public List<ResolveInfo> queryIntentActivities(Intent intent,
String resolvedType, int flags, int userId) {
//略...
synchronized (mPackages) {//有包名
final String pkgName = intent.getPackage();
if (pkgName == null) {
//略...
//ActivityIntentResolver#queryIntent進行查詢
List<ResolveInfo> result = mActivities.queryIntent(
intent, resolvedType, flags, userId);
//略... 
}
return result;
}
final PackageParser.Package pkg = mPackages.get(pkgName);
if (pkg != null) {
return filterIfNotPrimaryUser(
mActivities.queryIntentForPackage(
intent, resolvedType, flags, pkg.activities, userId),
userId);
}
return new ArrayList<ResolveInfo>();
}
}

---->[PackageManagerService$ActivityIntentResolver#queryIntent]------------
final class ActivityIntentResolver
extends IntentResolver<PackageParser.ActivityIntentInfo, ResolveInfo> {
public List<ResolveInfo> queryIntent(Intent intent, String resolvedType,
boolean defaultOnly, int userId) {
if (!sUserManager.exists(userId)) return null;
mFlags = defaultOnly ? PackageManager.MATCH_DEFAULT_ONLY : 0;
//這裡呼叫了父類的queryIntent方法
return super.queryIntent(intent, resolvedType, defaultOnly, userId);
}

---->[IntentResolver#queryIntent]------------
public List<R> queryIntent(Intent intent, String resolvedType, boolean defaultOnly,int userId) {
String scheme = intent.getScheme();

ArrayList<R> finalList = new ArrayList<R>();

final boolean debug = localLOGV ||
((intent.getFlags() & Intent.FLAG_DEBUG_LOG_RESOLUTION) != 0);

if (debug) Slog.v(
TAG, "Resolving type=" + resolvedType + " scheme=" + scheme
+ " defaultOnly=" + defaultOnly + " userId=" + userId + " of " + intent);

F[] firstTypeCut = null;
F[] secondTypeCut = null;
F[] thirdTypeCut = null;
F[] schemeCut = null;

// If the intent includes a MIME type, then we want to collect all of
// the filters that match that MIME type.
if (resolvedType != null) {
int slashpos = resolvedType.indexOf('/');
if (slashpos > 0) {
final String baseType = resolvedType.substring(0, slashpos);
if (!baseType.equals("*")) {
if (resolvedType.length() != slashpos+2
|| resolvedType.charAt(slashpos+1) != '*') {
// Not a wild card, so we can just look for all filters that
// completely match or wildcards whose base type matches.
firstTypeCut = mTypeToFilter.get(resolvedType);
if (debug) Slog.v(TAG, "First type cut: " + Arrays.toString(firstTyp
secondTypeCut = mWildTypeToFilter.get(baseType);
if (debug) Slog.v(TAG, "Second type cut: "
+ Arrays.toString(secondTypeCut));
} else {
// We can match anything with our base type.
firstTypeCut = mBaseTypeToFilter.get(baseType);
if (debug) Slog.v(TAG, "First type cut: " + Arrays.toString(firstTyp
secondTypeCut = mWildTypeToFilter.get(baseType);
if (debug) Slog.v(TAG, "Second type cut: "
+ Arrays.toString(secondTypeCut));
}
// Any */* types always apply, but we only need to do this
// if the intent type was not already */*.
thirdTypeCut = mWildTypeToFilter.get("*");
if (debug) Slog.v(TAG, "Third type cut: " + Arrays.toString(thirdTypeCut
} else if (intent.getAction() != null) {
// The intent specified any type ({@literal *}/*).This
// can be a whole heck of a lot of things, so as a first
// cut let's use the action instead.
firstTypeCut = mTypedActionToFilter.get(intent.getAction());
if (debug) Slog.v(TAG, "Typed Action list: " + Arrays.toString(firstType
}
}
}

// If the intent includes a data URI, then we want to collect all of
// the filters that match its scheme (we will further refine matches
// on the authority and path by directly matching each resulting filter).
if (scheme != null) {
schemeCut = mSchemeToFilter.get(scheme);
if (debug) Slog.v(TAG, "Scheme list: " + Arrays.toString(schemeCut));
}

// If the intent does not specify any data -- either a MIME type or
// a URI -- then we will only be looking for matches against empty
// data.
if (resolvedType == null && scheme == null && intent.getAction() != null) {
firstTypeCut = mActionToFilter.get(intent.getAction());
if (debug) Slog.v(TAG, "Action list: " + Arrays.toString(firstTypeCut));
}

FastImmutableArraySet<String> categories = getFastIntentCategories(intent);
if (firstTypeCut != null) {
buildResolveList(intent, categories, debug, defaultOnly,
resolvedType, scheme, firstTypeCut, finalList, userId);
}
if (secondTypeCut != null) {
buildResolveList(intent, categories, debug, defaultOnly,
resolvedType, scheme, secondTypeCut, finalList, userId);
}
if (thirdTypeCut != null) {
buildResolveList(intent, categories, debug, defaultOnly,
resolvedType, scheme, thirdTypeCut, finalList, userId);
}
if (schemeCut != null) {
buildResolveList(intent, categories, debug, defaultOnly,
resolvedType, scheme, schemeCut, finalList, userId);
}
sortResults(finalList);

if (debug) {
Slog.v(TAG, "Final result list:");
for (int i=0; i<finalList.size(); i++) {
Slog.v(TAG, "" + finalList.get(i));
}
}
return finalList;
}
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後記：捷文規範

1.本文成長記錄及勘誤表

專案原始碼	日期	備註
V0.1--無	2018-1-22	Android點將臺：外交官[-Intent-]

2.更多關於我

筆名	QQ	微信	愛好
張風捷特烈	1981462002	zdl1994328	語言
我的github	我的簡書	我的CSDN	個人網站

3.宣告

1----本文由張風捷特烈原創,轉載請註明

2----歡迎廣大程式設計愛好者共同交流

3----個人能力有限，如有不正之處歡迎大家批評指證，必定虛心改正

4----看到這裡，我在此感謝你的喜歡與支援