Android多程式系列
分析系統生成的Binder類
package com.xxq2dream.aidl;
public interface IBookManager extends android.os.IInterface {
/**
* Local-side IPC implementation stub class.
*/
public static abstract class Stub extends android.os.Binder implements com.xxq2dream.aidl.IBookManager {
private static final java.lang.String DESCRIPTOR = "com.xxq2dream.aidl.IBookManager";
/**
* Construct the stub at attach it to the interface.
*/
public Stub() {
this.attachInterface(this, DESCRIPTOR);
}
/**
* 用於將服務端的Binder物件轉換成客戶端所需要的AIDL介面型別的物件
*/
public static com.xxq2dream.aidl.IBookManager asInterface(android.os.IBinder obj) {
if ((obj == null)) {
return null;
}
android.os.IInterface iin = obj.queryLocalInterface(DESCRIPTOR);
//這裡通過instanceof方法判斷是否是跨程式，如果客戶端和服務端位於同一程式，則返回的是服務端的Stub物件本身，不會呼叫跨程式的transact方法
if (((iin != null) && (iin instanceof com.xxq2dream.aidl.IBookManager))) {
return ((com.xxq2dream.aidl.IBookManager) iin);
}
//如果客戶端和服務端不在同一個程式中，那麼返回的是系統封裝好的Stub.Proxy代理物件，客戶端呼叫會走transact方法發起跨程式請求
return new com.xxq2dream.aidl.IBookManager.Stub.Proxy(obj);
}
//返回當前Binder物件
@Override
public android.os.IBinder asBinder() {
return this;
}
/**
* 執行在服務端的Binder執行緒池中
*
* @param code 要執行的方法標識
* @param data 客戶端傳遞過來的引數
* @param reply 回傳給客戶端的資料
* @param flags
* @return true 表示執行成功；false，執行失敗，客戶端的請求失敗
* @throws RemoteException
*/
@Override
public boolean onTransact(int code, android.os.Parcel data, android.os.Parcel reply, int flags) throws android.os.RemoteException {
switch (code) {
case INTERFACE_TRANSACTION: {
reply.writeString(DESCRIPTOR);
return true;
}
case TRANSACTION_getBookList: {
data.enforceInterface(DESCRIPTOR);
java.util.List<com.xxq2dream.aidl.Book> _result = this.getBookList();
reply.writeNoException();
//將結果寫入reply返回
reply.writeTypedList(_result);
return true;
}
case TRANSACTION_addBook: {
data.enforceInterface(DESCRIPTOR);
com.xxq2dream.aidl.Book _arg0;
if ((0 != data.readInt())) {
_arg0 = com.xxq2dream.aidl.Book.CREATOR.createFromParcel(data);
} else {
_arg0 = null;
}
this.addBook(_arg0);
reply.writeNoException();
return true;
}
}
return super.onTransact(code, data, reply, flags);
}
private static class Proxy implements com.xxq2dream.aidl.IBookManager {
private android.os.IBinder mRemote;
Proxy(android.os.IBinder remote) {
mRemote = remote;
}
@Override
public android.os.IBinder asBinder() {
return mRemote;
}
public java.lang.String getInterfaceDescriptor() {
return DESCRIPTOR;
}
/**
* 執行在客戶端的Binder執行緒池中
* 當客戶端和服務端不在同一個程式中時，通過上面的asInterface方法返回的就是這個Proxy物件
* 呼叫服務端的方法就是呼叫這裡對應的方法，最終走的是transact方法發起遠端過程呼叫
*
* @return
* @throws RemoteException
*/
@Override
public java.util.List<com.xxq2dream.aidl.Book> getBookList() throws android.os.RemoteException {
//用於向服務端傳遞引數
android.os.Parcel _data = android.os.Parcel.obtain();
//用於接收服務端傳回來的結果
android.os.Parcel _reply = android.os.Parcel.obtain();
java.util.List<com.xxq2dream.aidl.Book> _result;
try {
_data.writeInterfaceToken(DESCRIPTOR);
//發起遠端過程呼叫請求，同時當前執行緒掛起，服務端的onTransact方法會被呼叫
mRemote.transact(Stub.TRANSACTION_getBookList, _data, _reply, 0);
//上述呼叫過程返回後，當前執行緒繼續執行，從reply中取出結果返回
_reply.readException();
_result = _reply.createTypedArrayList(com.xxq2dream.aidl.Book.CREATOR);
} finally {
_reply.recycle();
_data.recycle();
}
return _result;
}
@Override
public void addBook(com.xxq2dream.aidl.Book book) throws android.os.RemoteException {
android.os.Parcel _data = android.os.Parcel.obtain();
android.os.Parcel _reply = android.os.Parcel.obtain();
try {
_data.writeInterfaceToken(DESCRIPTOR);
if ((book != null)) {
_data.writeInt(1);
book.writeToParcel(_data, 0);
} else {
_data.writeInt(0);
}
mRemote.transact(Stub.TRANSACTION_addBook, _data, _reply, 0);
_reply.readException();
} finally {
_reply.recycle();
_data.recycle();
}
}
}
//介面的標識
static final int TRANSACTION_getBookList = (android.os.IBinder.FIRST_CALL_TRANSACTION + 0);
static final int TRANSACTION_addBook = (android.os.IBinder.FIRST_CALL_TRANSACTION + 1);
}
//提供的介面
public java.util.List<com.xxq2dream.aidl.Book> getBookList() throws android.os.RemoteException;
public void addBook(com.xxq2dream.aidl.Book book) throws android.os.RemoteException;
}
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動手編寫Binder類
- 從上面的分析可以看出Binder類主要可以分為2個部分，一個是Stub類，也就是真正的Binder類；另一個就是AIDL介面
抽取出AIDL介面
public interface IBookManager extends IInterface {
static final String DESCRIPTOR = "com.xxq2dream.manualbinder.IBookManager";
static final int TRANSACTION_getBookList = IBinder.FIRST_CALL_TRANSACTION + 0;
static final int TRANSACTION_addBook = IBinder.FIRST_CALL_TRANSACTION + 1;
<!--註釋1-->
<!--static final int TRANSACTION_registerListener= IBinder.FIRST_CALL_TRANSACTION + 2;-->
<!--static final int TRANSACTION_unRegisterListener= IBinder.FIRST_CALL_TRANSACTION + 3;-->
public List<Book> getBookList() throws RemoteException;
public void addBook(Book book) throws RemoteException;
<!--註釋2-->
<!--void registerListener(IOnNewBookArrivedListener listener) throws RemoteException;-->
<!--void unRegisterListener(IOnNewBookArrivedListener listener) throws RemoteException;-->
}
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實現Stub類和Stub類的代理類
public class BookManagerImpl extends Binder implements IBookManager {
private static final String TAG = "BookManagerImpl";
public BookManagerImpl() {
Log.e(TAG, "attachInterface-->"+ System.currentTimeMillis());
this.attachInterface(this,DESCRIPTOR);
}
/**
* Cast an IBinder object into an com.xxq2dream.IBookManager interface,
* generating a proxy if needed.
*/
public static IBookManager asInterface(IBinder obj) {
if ((obj == null)) {
return null;
}
android.os.IInterface iin = obj.queryLocalInterface(DESCRIPTOR);
if (((iin != null) && (iin instanceof IBookManager))) {
Log.e(TAG, "asInterface");
return ((IBookManager) iin);
}
Log.e(TAG, "asInterface Proxy-->"+ System.currentTimeMillis());
return new BookManagerImpl.Proxy(obj);
}
/**
* 執行在服務端的Binder執行緒池中
*
* @param code 要執行的方法標識
* @param data 客戶端傳遞過來的引數
* @param reply 回傳給客戶端的資料
* @param flags
* @return true 表示執行成功；false，執行失敗，客戶端的請求失敗
* @throws RemoteException
*/
@Override
public boolean onTransact(int code, Parcel data, Parcel reply, int flags) throws RemoteException {
Log.e(TAG, "onTransact-->"+System.currentTimeMillis());
switch (code) {
case INTERFACE_TRANSACTION: {
Log.e(TAG, "INTERFACE_TRANSACTION-->"+ System.currentTimeMillis());
reply.writeString(DESCRIPTOR);
return true;
}
case TRANSACTION_getBookList: {
Log.e(TAG, "TRANSACTION_getBookList-->"+ System.currentTimeMillis());
data.enforceInterface(DESCRIPTOR);
List<Book> result = this.getBookList();
reply.writeNoException();
reply.writeTypedList(result);
return true;
}
case TRANSACTION_addBook: {
Log.e(TAG, "TRANSACTION_addBook-->"+ System.currentTimeMillis());
data.enforceInterface(DESCRIPTOR);
Book arg0;
if (0 != data.readInt()) {
arg0 = Book.CREATOR.createFromParcel(data);
}else {
arg0 = null;
}
this.addBook(arg0);
reply.writeNoException();
return true;
}
<!--註釋6-->
<!--case TRANSACTION_registerListener: {-->
<!-- Log.e(TAG, "TRANSACTION_registerListener-->" +System.currentTimeMillis());-->
<!-- data.enforceInterface(DESCRIPTOR);-->
<!-- IOnNewBookArrivedListener arg0;-->
<!-- arg0 = OnNewBookArrivedListenerImpl.asInterface(data.readStrongBinder());-->
<!-- this.registerListener(arg0);-->
<!-- reply.writeNoException();-->
<!-- return true;-->
<!--}-->
<!--case TRANSACTION_unRegisterListener: {-->
<!-- Log.e(TAG, "TRANSACTION_unRegisterListener-->" +System.currentTimeMillis());-->
<!-- data.enforceInterface(DESCRIPTOR);-->
<!-- IOnNewBookArrivedListener arg0;-->
<!-- arg0 = OnNewBookArrivedListenerImpl.asInterface(data.readStrongBinder());-->
<!-- this.unRegisterListener(arg0);-->
<!-- reply.writeNoException();-->
<!-- return true;-->
<!--}-->
}
return super.onTransact(code, data, reply, flags);
}
@Override
public List<Book> getBookList() throws RemoteException {
return null;
}
@Override
public void addBook(Book book) throws RemoteException {
}
<!--註釋5-->
<!--@Override-->
<!--public void registerListener(IOnNewBookArrivedListener listener) {-->
<!--}-->
<!--@Override-->
<!--public void unRegisterListener(IOnNewBookArrivedListener listener) {-->
<!--}-->
/**
* Retrieve the Binder object associated with this interface.
* You must use this instead of a plain cast, so that proxy objects
* can return the correct result.
*/
@Override
public IBinder asBinder() {
Log.e(TAG, "asBinder-->"+ System.currentTimeMillis());
return this;
}
private static class Proxy implements IBookManager {
private IBinder mRemote;
Proxy(IBinder remote) {
mRemote = remote;
}
public String getInterfaceDescriptor() {
return DESCRIPTOR;
}
/**
* 執行在客戶端的Binder執行緒池中
*
* @return
* @throws RemoteException
*/
@Override
public List<Book> getBookList() throws RemoteException {
Log.e(TAG, "Proxy-->getBookList-->"+ System.currentTimeMillis());
//用於向服務端傳遞引數
Parcel data = Parcel.obtain();
//用於接收服務端傳回來的結果
Parcel reply = Parcel.obtain();
List<Book> result;
try {
data.writeInterfaceToken(DESCRIPTOR);
//發起遠端過程呼叫請求，同時當前執行緒掛起，服務端的onTransact方法會被呼叫
mRemote.transact(TRANSACTION_getBookList, data, reply, 0);
//上述呼叫過程返回後，當前執行緒繼續執行，從reply中取出結果返回
reply.readException();
result = reply.createTypedArrayList(Book.CREATOR);
} finally {
reply.recycle();
data.recycle();
}
return result;
}
@Override
public void addBook(Book book) throws RemoteException {
Log.e(TAG, "Proxy-->addBook-->"+ System.currentTimeMillis());
//用於向服務端傳遞引數
Parcel data = Parcel.obtain();
//用於接收服務端傳回來的結果
Parcel reply = Parcel.obtain();
try {
data.writeInterfaceToken(DESCRIPTOR);
if (book != null) {
data.writeInt(1);
book.writeToParcel(data,0);
}else {
data.writeInt(0);
}
mRemote.transact(TRANSACTION_addBook, data, reply, 0);
reply.readException();
}finally {
reply.recycle();
data.recycle();
}
}
<!--註釋3-->
<!--@Override-->
<!--public void registerListener(IOnNewBookArrivedListener listener) throws RemoteException{-->
<!-- Log.e(TAG, "Proxy-->registerListener-->"+ System.currentTimeMillis());-->
<!-- //用於向服務端傳遞引數-->
<!-- Parcel data = Parcel.obtain();-->
<!-- //用於接收服務端傳回來的結果-->
<!-- Parcel reply = Parcel.obtain();-->
<!-- try {-->
<!-- data.writeInterfaceToken(DESCRIPTOR);-->
<!-- data.writeStrongBinder((listener != null)?(listener.asBinder()) : (null));-->
<!-- mRemote.transact(TRANSACTION_registerListener, data, reply, 0);-->
<!-- reply.readException();-->
<!-- }finally {-->
<!-- reply.recycle();-->
<!-- data.recycle();-->
<!-- }-->
<!--}-->
<!--註釋4-->
<!--@Override-->
<!--public void unRegisterListener(IOnNewBookArrivedListener listener) throws RemoteException{-->
<!-- Log.e(TAG, "Proxy-->unRegisterListener-->"+ System.currentTimeMillis());-->
<!-- //用於向服務端傳遞引數-->
<!-- Parcel data = Parcel.obtain();-->
<!-- //用於接收服務端傳回來的結果-->
<!-- Parcel reply = Parcel.obtain();-->
<!-- try {-->
<!-- data.writeInterfaceToken(DESCRIPTOR);-->
<!-- data.writeStrongBinder((listener != null)?(listener.asBinder()) : (null));-->
<!-- mRemote.transact(TRANSACTION_unRegisterListener, data, reply, 0);-->
<!-- reply.readException();-->
<!-- }finally {-->
<!-- reply.recycle();-->
<!-- data.recycle();-->
<!-- }-->
<!--}-->
/**
* Retrieve the Binder object associated with this interface.
* You must use this instead of a plain cast, so that proxy objects
* can return the correct result.
*/
@Override
public IBinder asBinder() {
Log.e(TAG, "Proxy-->asBinder-->"+ System.currentTimeMillis());
return mRemote;
}
}
}
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- 以上就是我們自己動手寫的Binder類，沒有使用系統的方法，也不用編寫AIDL檔案
擴充套件我們的Binder類
- 比如我們要實現當服務端有新書時就通知客戶端，也就是觀察者模式。我們需要在客戶端繫結服務端後繫結監聽的介面，還要提供解綁的介面，上面的程式碼中標記的註釋1-6就是擴充套件Binder類的步驟
- 當然，由於AIDL中不支援普通的介面，只支援AIDL介面，我們要增加服務端的AIDL介面服務，像上面的程式碼裡那樣傳遞的介面肯定就是AIDL實現的介面，也就是
- 所以我們還得增加AIDL介面，同樣的我們可以通過編寫AIDL檔案然後由系統自動生成，也可以手動編寫。這裡我們還是以手動的方式編寫
- AIDL介面IOnNewBookArrivedListener
public interface IOnNewBookArrivedListener extends IInterface {
static final String DESCRIPTOR = "com.xxq2dream.aidl.IOnNewBookArrivedListener";
static final int TRANSACTION_onNewBookArrived = IBinder.FIRST_CALL_TRANSACTION + 0;
void onNewBookArrived(Book book) throws RemoteException;
}
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public class OnNewBookArrivedListenerImpl extends Binder implements IOnNewBookArrivedListener {
private static final String TAG = "NewBookArrivedListener";
public OnNewBookArrivedListenerImpl() {
Log.e(TAG, "attachInterface-->"+ System.currentTimeMillis());
this.attachInterface(this,DESCRIPTOR);
}
public static IOnNewBookArrivedListener asInterface (IBinder obj) {
if ((obj == null)) {
return null;
}
android.os.IInterface iin = obj.queryLocalInterface(DESCRIPTOR);
if (((iin != null) && (iin instanceof IOnNewBookArrivedListener))) {
Log.e(TAG, "asInterface");
return ((IOnNewBookArrivedListener) iin);
}
Log.e(TAG, "asInterface Proxy-->"+ System.currentTimeMillis());
return new OnNewBookArrivedListenerImpl.Proxy(obj);
}
/**
* 執行在服務端的Binder執行緒池中
*
* @param code 要執行的方法標識
* @param data 客戶端傳遞過來的引數
* @param reply 回傳給客戶端的資料
* @param flags
* @return true 表示執行成功；false，執行失敗，客戶端的請求失敗
* @throws RemoteException
*/
@Override
public boolean onTransact(int code, Parcel data, Parcel reply, int flags) throws RemoteException {
Log.e(TAG, "onTransact-->"+System.currentTimeMillis());
switch (code) {
case INTERFACE_TRANSACTION: {
Log.e(TAG, "INTERFACE_TRANSACTION-->"+ System.currentTimeMillis());
reply.writeString(DESCRIPTOR);
return true;
}
case TRANSACTION_onNewBookArrived: {
Log.e(TAG, "TRANSACTION_onNewBookArrived-->"+ System.currentTimeMillis());
data.enforceInterface(DESCRIPTOR);
Book _arg0;
if ((0 != data.readInt())) {
_arg0 = Book.CREATOR.createFromParcel(data);
} else {
_arg0 = null;
}
this.onNewBookArrived(_arg0);
reply.writeNoException();
return true;
}
}
return super.onTransact(code, data, reply, flags);
}
@Override
public void onNewBookArrived(Book book) {
}
/**
* Retrieve the Binder object associated with this interface.
* You must use this instead of a plain cast, so that proxy objects
* can return the correct result.
*/
@Override
public IBinder asBinder() {
return this;
}
private static class Proxy implements IOnNewBookArrivedListener {
private IBinder mRemote;
Proxy(IBinder remote) {
mRemote = remote;
}
public String getInterfaceDescriptor() {
return DESCRIPTOR;
}
/**
* Retrieve the Binder object associated with this interface.
* You must use this instead of a plain cast, so that proxy objects
* can return the correct result.
*/
@Override
public IBinder asBinder() {
Log.e(TAG, "Proxy-->asBinder-->"+ System.currentTimeMillis());
return mRemote;
}
@Override
public void onNewBookArrived(Book newBook) throws RemoteException{
Log.e(TAG, "onNewBookArrived-->" + System.currentTimeMillis());
android.os.Parcel _data = android.os.Parcel.obtain();
android.os.Parcel _reply = android.os.Parcel.obtain();
try {
_data.writeInterfaceToken(DESCRIPTOR);
if ((newBook != null)) {
_data.writeInt(1);
newBook.writeToParcel(_data, 0);
} else {
_data.writeInt(0);
}
mRemote.transact(TRANSACTION_onNewBookArrived, _data, _reply, 0);
_reply.readException();
} finally {
_reply.recycle();
_data.recycle();
}
}
}
}
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Binder傳遞AIDL介面
- 通過上面的程式碼我們可以看到，和傳遞普通的Parcelable序列化物件不同的是，在Proxy類中要通過writeStrongBinder方法將AIDL介面加入到引數中去
- 在服務端的onTransact方法中要通過對應的Binder類的asInterface方法獲得傳遞過來的介面引數
IOnNewBookArrivedListener arg0;
arg0 = OnNewBookArrivedListenerImpl.asInterface(data.readStrongBinder());
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結語
- 通過手動編寫Binder類，可以讓我們更好地理解Binder的工作機制
- 擴充套件了Binder類以後，下一步我們還需要相應的改造客戶端和服務端，以便增加註冊監聽的功能
歡迎關注我的微信公眾號，和我一起學習一起成長！
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