Android多进程系列
分析系统生成的Binder类
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);
}
/**
* 用于将服务端的Binder对象转换成客户端所需要的AIDL接口类型的对象
*/
public static com.xxq2dream.aidl.IBookManager asInterface(android.os.IBinder obj) {
if ((obj == null)) {
return null;
}
android.os.IInterface iin = obj.queryLocalInterface(DESCRIPTOR);
//这里通过instanceof方法判断是否是跨进程，如果客户端和服务端位于同一进程，则返回的是服务端的Stub对象本身，不会调用跨进程的transact方法
if (((iin != null) && (iin instanceof com.xxq2dream.aidl.IBookManager))) {
return ((com.xxq2dream.aidl.IBookManager) iin);
}
//如果客户端和服务端不在同一个进程中，那么返回的是系统封装好的Stub.Proxy代理对象，客户端调用会走transact方法发起跨进程请求
return new com.xxq2dream.aidl.IBookManager.Stub.Proxy(obj);
}
//返回当前Binder对象
@Override
public android.os.IBinder asBinder() {
return this;
}
/**
* 运行在服务端的Binder线程池中
*
* @param code 要运行的方法标识
* @param data 客户端传递过来的参数
* @param reply 回传给客户端的数据
* @param flags
* @return true 表示执行成功；false，执行失败，客户端的请求失败
* @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();
//将结果写入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;
}
/**
* 运行在客户端的Binder线程池中
* 当客户端和服务端不在同一个进程中时，通过上面的asInterface方法返回的就是这个Proxy对象
* 调用服务端的方法就是调用这里对应的方法，最终走的是transact方法发起远程过程调用
*
* @return
* @throws RemoteException
*/
@Override
public java.util.List<com.xxq2dream.aidl.Book> getBookList() throws android.os.RemoteException {
//用于向服务端传递参数
android.os.Parcel _data = android.os.Parcel.obtain();
//用于接收服务端传回来的结果
android.os.Parcel _reply = android.os.Parcel.obtain();
java.util.List<com.xxq2dream.aidl.Book> _result;
try {
_data.writeInterfaceToken(DESCRIPTOR);
//发起远程过程调用请求，同时当前线程挂起，服务端的onTransact方法会被调用
mRemote.transact(Stub.TRANSACTION_getBookList, _data, _reply, 0);
//上述调用过程返回后，当前线程继续执行，从reply中取出结果返回
_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();
}
}
}
//接口的标识
static final int TRANSACTION_getBookList = (android.os.IBinder.FIRST_CALL_TRANSACTION + 0);
static final int TRANSACTION_addBook = (android.os.IBinder.FIRST_CALL_TRANSACTION + 1);
}
//提供的接口
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;
}
动手编写Binder类
- 从上面的分析可以看出Binder类主要可以分为2个部分，一个是Stub类，也就是真正的Binder类；另一个就是AIDL接口
抽取出AIDL接口
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;
<!--注释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;
<!--注释2-->
<!--void registerListener(IOnNewBookArrivedListener listener) throws RemoteException;-->
<!--void unRegisterListener(IOnNewBookArrivedListener listener) throws RemoteException;-->
}实现Stub类和Stub类的代理类
- 这个和上面自动生成的代码大部分都是一样的
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);
}
/**
* 运行在服务端的Binder线程池中
*
* @param code 要运行的方法标识
* @param data 客户端传递过来的参数
* @param reply 回传给客户端的数据
* @param flags
* @return true 表示执行成功；false，执行失败，客户端的请求失败
* @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;
}
<!--注释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 {
}
<!--注释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;
}
/**
* 运行在客户端的Binder线程池中
*
* @return
* @throws RemoteException
*/
@Override
public List<Book> getBookList() throws RemoteException {
Log.e(TAG, "Proxy-->getBookList-->"+ System.currentTimeMillis());
//用于向服务端传递参数
Parcel data = Parcel.obtain();
//用于接收服务端传回来的结果
Parcel reply = Parcel.obtain();
List<Book> result;
try {
data.writeInterfaceToken(DESCRIPTOR);
//发起远程过程调用请求，同时当前线程挂起，服务端的onTransact方法会被调用
mRemote.transact(TRANSACTION_getBookList, data, reply, 0);
//上述调用过程返回后，当前线程继续执行，从reply中取出结果返回
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());
//用于向服务端传递参数
Parcel data = Parcel.obtain();
//用于接收服务端传回来的结果
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();
}
}
<!--注释3-->
<!--@Override-->
<!--public void registerListener(IOnNewBookArrivedListener listener) throws RemoteException{-->
<!-- Log.e(TAG, "Proxy-->registerListener-->"+ System.currentTimeMillis());-->
<!-- //用于向服务端传递参数-->
<!-- Parcel data = Parcel.obtain();-->
<!-- //用于接收服务端传回来的结果-->
<!-- 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();-->
<!-- }-->
<!--}-->
<!--注释4-->
<!--@Override-->
<!--public void unRegisterListener(IOnNewBookArrivedListener listener) throws RemoteException{-->
<!-- Log.e(TAG, "Proxy-->unRegisterListener-->"+ System.currentTimeMillis());-->
<!-- //用于向服务端传递参数-->
<!-- Parcel data = Parcel.obtain();-->
<!-- //用于接收服务端传回来的结果-->
<!-- 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;
}
}
}- 以上就是我们自己动手写的Binder类，没有使用系统的方法，也不用编写AIDL文件
扩展我们的Binder类
- 比如我们要实现当服务端有新书时就通知客户端，也就是观察者模式。我们需要在客户端绑定服务端后绑定监听的接口，还要提供解绑的接口，上面的代码中标记的注释1-6就是扩展Binder类的步骤
- 当然，由于AIDL中不支持普通的接口，只支持AIDL接口，我们要增加服务端的AIDL接口服务，像上面的代码里那样传递的接口肯定就是AIDL实现的接口，也就是
- 所以我们还得增加AIDL接口，同样的我们可以通过编写AIDL文件然后由系统自动生成，也可以手动编写。这里我们还是以手动的方式编写
- AIDL接口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;
}- 对应的Binder类
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);
}
/**
* 运行在服务端的Binder线程池中
*
* @param code 要运行的方法标识
* @param data 客户端传递过来的参数
* @param reply 回传给客户端的数据
* @param flags
* @return true 表示执行成功；false，执行失败，客户端的请求失败
* @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();
}
}
}
}Binder传递AIDL接口
- 通过上面的代码我们可以看到，和传递普通的Parcelable序列化对象不同的是，在Proxy类中要通过writeStrongBinder方法将AIDL接口加入到参数中去
- 在服务端的onTransact方法中要通过对应的Binder类的asInterface方法获得传递过来的接口参数
IOnNewBookArrivedListener arg0;
arg0 = OnNewBookArrivedListenerImpl.asInterface(data.readStrongBinder());结语
- 通过手动编写Binder类，可以让我们更好地理解Binder的工作机制
- 扩展了Binder类以后，下一步我们还需要相应的改造客户端和服务端，以便增加注册监听的功能
欢迎关注我的微信公众号，和我一起学习一起成长！