先上实例代码：
service:
public class AidlService extends Service{ @Override public IBinder onBind(Intent arg0) { /*return new AIDLTest.Stub() { @Override public String hello(String name) throws RemoteException { // TODO Auto-generated method stub return "hello"+name; } };*/ return mBinder; } //一个类，继承了Binder，那么它的对象就可以被远程的进程使用了(前提是远程进程获取了这个类的对象【对象的引用】 private final AIDLTest.Stub mBinder = new AIDLTest.Stub() { @Override public String hello(String name) throws RemoteException { // TODO Auto-generated method stub return "hello"+name; } };
client:
Intent intent = new Intent();
intent.setPackage("包名");
context.bindService(intent, serviceConnection,Context.BIND_AUTO_CREATE);
private ServiceConnection serviceConnection = new ServiceConnection() {
@Override
public void onServiceConnected(ComponentName name, IBinder service) {
Log.d(TAG, "++++++ onServiceConnected: success ++++++");
AIDLTest vasInterface = AIDLTest.Stub.asInterface(service);
}
@Override
public void onServiceDisconnected(ComponentName name) {
vasInterface = null;
}
};
vasInterface.hello("aaaaaaaa");
解析：
最主要的部分是AS自动生成的AIDLTest文件：
/* * This file is auto-generated. DO NOT MODIFY. * Original file: F:\\Project\\Practice\\FrameworkDemo\\app\\src\\main\\aidl\\com\\example\\admin\\frameworkdemo\\AIDLTest.aidl */ package com.example.admin.frameworkdemo; public interface AIDLTest extends android.os.IInterface { /** * Local-side IPC implementation stub class. */ public static abstract class Stub extends android.os.Binder implements com.example.admin.frameworkdemo.AIDLTest { private static final java.lang.String DESCRIPTOR = "com.example.admin.frameworkdemo.AIDLTest"; /** * Construct the stub at attach it to the interface. */ public Stub() { this.attachInterface(this, DESCRIPTOR); } /** * Cast an IBinder object into an com.example.admin.frameworkdemo.AIDLTest interface, * generating a proxy if needed. */ public static com.example.admin.frameworkdemo.AIDLTest asInterface(android.os.IBinder obj) { if ((obj == null)) { return null; } android.os.IInterface iin = obj.queryLocalInterface(DESCRIPTOR); if (((iin != null) && (iin instanceof com.example.admin.frameworkdemo.AIDLTest))) { return ((com.example.admin.frameworkdemo.AIDLTest) iin); } return new com.example.admin.frameworkdemo.AIDLTest.Stub.Proxy(obj); } @Override public android.os.IBinder asBinder() { return this; } @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_hello: { data.enforceInterface(DESCRIPTOR); java.lang.String _arg0; _arg0 = data.readString(); java.lang.String _result = this.hello(_arg0); reply.writeNoException(); reply.writeString(_result); return true; } } return super.onTransact(code, data, reply, flags); } private static class Proxy implements com.example.admin.frameworkdemo.AIDLTest { 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; } @Override public java.lang.String hello(java.lang.String name) throws android.os.RemoteException { android.os.Parcel _data = android.os.Parcel.obtain(); android.os.Parcel _reply = android.os.Parcel.obtain(); java.lang.String _result; try { _data.writeInterfaceToken(DESCRIPTOR); _data.writeString(name); mRemote.transact(Stub.TRANSACTION_hello, _data, _reply, 0); _reply.readException(); _result = _reply.readString(); } finally { _reply.recycle(); _data.recycle(); } return _result; } } static final int TRANSACTION_hello = (android.os.IBinder.FIRST_CALL_TRANSACTION + 0); } public java.lang.String hello(java.lang.String name) throws android.os.RemoteException; }
步骤：
如以下代码，在服务端，AidlService在被client端的bindservice启动之后，会执行onBind，返回一个继承于IBinder的类mBinder，
IBinder是底层的一个借口，实现该接口的类也具有了远程调用的能力，并重写了方法hello,这个后面再说。
private final AIDLTest.Stub mBinder = new AIDLTest.Stub() { @Override public String hello(String name) throws RemoteException { // TODO Auto-generated method stub return "hello"+name; } };
client端绑定成功之后，得到IBinder的继承类，其实就是service端的mBinder
private ServiceConnection serviceConnection = new ServiceConnection() { @Override public void onServiceConnected(ComponentName name, IBinder service) { Log.d(TAG, "++++++ onServiceConnected: success ++++++"); vasInterface = AIDLTest.Stub.asInterface(service); } @Override public void onServiceDisconnected(ComponentName name) { vasInterface = null; } };
client端紧接着执行
AIDLTest.Stub.asInterface(service);
进入asInterface：
public static com.example.admin.frameworkdemo.AIDLTest asInterface(android.os.IBinder obj) { if ((obj == null)) { return null; } android.os.IInterface iin = obj.queryLocalInterface(DESCRIPTOR); if (((iin != null) && (iin instanceof com.example.admin.frameworkdemo.AIDLTest))) { return ((com.example.admin.frameworkdemo.AIDLTest) iin); } return new com.example.admin.frameworkdemo.AIDLTest.Stub.Proxy(obj); }
这里queryLocalInterface判断是跨进程调用，如果是跨进程调用，执行
return new com.example.admin.frameworkdemo.AIDLTest.Stub.Proxy(obj);
此时得到了一个Proxy类，传进去的obj是远程服务端的mBinder
此时回到client调用接口：
vasInterface.hello("aaaaaaaa");
此时我们知道vasInterface是一个AIDLTest.Stub.Proxy，执行里面的方法hello，
@Override public java.lang.String hello(java.lang.String name) throws android.os.RemoteException { android.os.Parcel _data = android.os.Parcel.obtain(); android.os.Parcel _reply = android.os.Parcel.obtain(); java.lang.String _result; try { _data.writeInterfaceToken(DESCRIPTOR); _data.writeString(name); mRemote.transact(Stub.TRANSACTION_hello, _data, _reply, 0); _reply.readException(); _result = _reply.readString(); } finally { _reply.recycle(); _data.recycle(); } return _result; }
可以看到hello里面执行了可以看到里面执行了mRemote.transact(Stub.TRANSACTION_hello, _data, _reply, 0);
data代表了客户端传进去的数据，reply代表了服务端将要返回来的数据。
根据上面的分析我们知道，mRemote其实就是服务端的mBinder，
点击进入mRemote.transact(Stub.TRANSACTION_hello, _data, _reply, 0);
发现是IBinder里面的一个接口，
public boolean transact(int code, @NonNull Parcel data, @Nullable Parcel reply, int flags)
throws RemoteException;
经过前面我们知道此时执行的应该是mBinder的transact，mBinder继承stub，stub继承android.os.Binder，Binder继承Ibinder，
所以此时进入的应该是Binder的transact函数：
/** * Default implementation rewinds the parcels and calls onTransact. On * the remote side, transact calls into the binder to do the IPC. */ public final boolean transact(int code, @NonNull Parcel data, @Nullable Parcel reply, int flags) throws RemoteException { if (false) Log.v("Binder", "Transact: " + code + " to " + this); if (data != null) { data.setDataPosition(0); } boolean r = onTransact(code, data, reply, flags); if (reply != null) { reply.setDataPosition(0); } return r; }
该函数里面调用了onTransact，根据前面的继承关系，mBinder继承stub，stub继承android.os.Binder，Binder继承Ibinder，
此时调用的应该是Stub这个类的复写了onTransact的函数：
@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_hello: { data.enforceInterface(DESCRIPTOR); java.lang.String _arg0; _arg0 = data.readString(); java.lang.String _result = this.hello(_arg0); reply.writeNoException(); reply.writeString(_result); return true; } } return super.onTransact(code, data, reply, flags); }
这里面执行了：this.hello(_arg0)，而这个函数执行的应该就是子类mBinder在应用层定义的匿名类的里面的方法：
rivate final AIDLTest.Stub mBinder = new AIDLTest.Stub() { @Override public String hello(String name) throws RemoteException { // TODO Auto-generated method stub return "hello"+name; } };
然后通过reply.writeString(_result);将执行结果写到replay里面。
原文：https://www.cnblogs.com/wnpp/p/13135501.html