如果不需要进行不同应用程序间的并发通信(IPC)，you should create your interface by implementing a Binder；或者你想进行IPC，但不需要处理多线程的，则implement your interface using a Messenger。无论如何，在使用AIDL前，必须要理解如何绑定service——bindService。
Calls made from the local process are executed in the same thread that is making the call. If this is your main UI thread, that thread continues to execute in the AIDL interface. If it is another thread, that is the one that executes your code in the service. Thus, if only local threads are accessing the service, you can completely control which threads are executing in it (but if that is the case, then you shouldn't be using AIDL at all, but should instead create the interface by implementing a Binder).
Calls from a remote process are dispatched from a thread pool the platform maintains inside of your own process. You must be prepared for incoming calls from unknown threads, with multiple calls happening at the same time. In other words, an implementation of an AIDL interface must be completely thread-safe.
The
oneway
keyword modifies the behavior of remote calls. When used, a remote call does not block; it simply sends the transaction data and immediately returns. The implementation of the interface eventually receives this as a regular call from the
Binder
thread pool as a normal remote call. If
oneway
is used with a local call, there is no impact and the call is still synchronous.
private ServiceConnection mRemoteConnection = new ServiceConnection() {
public void onServiceConnected(ComponentName className, IBinder service) {
mRemoteService = IMyService.Stub.asInterface(service);
}
public void onServiceDisconnected(ComponentName className) {
mRemoteService = null;
}
};
在生成的IMyService.java里面会找到这样的代码：
/**
* Cast an IBinder object into an com.demo.IMyService interface,
* generating a proxy if needed.
*/
public static com.demo.IMyService asInterface(android.os.IBinder obj) {...}
而service的绑定没有什么不同：
if (mIsRemoteBound) {
unbindService(mRemoteConnection);
}else{
bindService(new Intent("com.demo.IMyService"),
mRemoteConnection, Context.BIND_AUTO_CREATE);
}
mIsRemoteBound = !mIsRemoteBound;
通过IPC调用/传递数据
客户端绑定service后就能通过IPC来调用/传递数据了，直接调用service对象的接口方法：
addPersonButton.setOnClickListener(
new View.OnClickListener(){
private int index = 0;
@Override
public void onClick(View view) {
Person person = new Person();
index = index + 1;
person.setName("Person" + index);
person.setAge(20);
person.setTelNumber("123456");
try {
mRemoteService.savePersonInfo(person);
} catch (RemoteException e) {
e.printStackTrace();
}
}
});
listPersonButton.setOnClickListener(
new View.OnClickListener(){
@Override
public void onClick(View view) {
List<Person> list = null;
if (list != null){
StringBuilder text = new StringBuilder();
for(Person person : list){
text.append("
Person name:");
text.append(person.getName());
text.append("
age :");
text.append(person.getAge());
text.append("
tel number:");
text.append(person.getTelNumber());
}
android:process
The name of the process where the service is to run. Normally, all components of an application run in the default process created for the application. It has the same name as the application package. The <application> element's process attribute can set a different default for all components. But component can override the default with its own process attribute, allowing you to spread your application across multiple processes.
If the name assigned to this attribute begins with a colon (':'), a new process, private to the application, is created when it's needed and the service runs in that process. If the process name begins with a lowercase character, the service will run in a global process of that name, provided that it has permission to do so. This allows components in different applications to share a process, reducing resource usage. 也就是说android:process=":remote"，代表在应用程序里，当需要该service时，会自动创建新的进程。而如果是android:process="remote"，没有“:”分号的，则创建全局进程，不同的应用程序共享该进程。
Java技术网站 → 『 Java开发技术 』 → 『 Android技术专题 』 → Android Service学习之AIDL, Parcelable和远程服务-学习Android
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