- Create .aidl文件
定义Service接口
Caution: AIDL 做的任何改变，都必须保持后向兼容
方法支持参数和返回值，参数和返回值可以是任意类型。
1. 所有Java原型都支持（int, long, float, char ,boolean等）
2. String
3. Charsequence
4. List,元素必须是支持的数据类型，也可是其他AIDL所申明的，或者是parcelables。同时也可使用泛型申明。实际使用ArrayList来存储元素。
5. Map，也list要求相同。但不可使用泛型，实际使用HashMap来存储。
如果要使用除以上数据的类型其他类型数据，则必须使用import进行申明。
此外，在定义接口时，还需注意的有：
1. 方法可为0个或多个参数，可返回值或者void
2. 所有非原型参数，需要方向标签，in,out,inout。
3. 所有代码注释都会被生成到java接口中，除了import和package申明之前的。
4. 只支持方法，不支持静态成员变量的申明。
案例
// IRemoteService.aidl
package com.example.android;
// Declare any non-default types here with import statements
/** Example service interface */
interface IRemoteService {
/** Request the process ID of this service, to do evil things with it. */
int getPid();
/** Demonstrates some basic types that you can use as parameters
* and return values in AIDL.
*/
void basicTypes(int anInt, long aLong, boolean aBoolean, float aFloat,
double aDouble, String aString);
}
- 实现一个接口
Android SDK tools会根据aidl文件自动生成一个java语言的编程接口，这个接口包含一个继承于Binder的抽象类和aidl中的接口方法实现。必须继承Stub然后实现方法。
保存到/src目录下，ADT tool 会在/gen目录下生成IBinder接口文件。注意包名。
生成的接口包含一个子类Stub, 是对接口的抽象实现。因此，需要继承该Stub，然后实现抽象方法。
其中Stub还有一个助手方法asInterface(),传递IBinder并返回stub接口实例。
实例代码如下：
private final IRemoteService.Stub mBinder = new IRemoteService.Stub() {
public int getPid(){
return Process.myPid();
}
public void basicTypes(int anInt, long aLong, boolean aBoolean,
float aFloat, double aDouble, String aString) {
// Does nothing
}
};
Caution: 注意多线程，要确保方法是线程安全的。RPC calls 通常是同步的，所以在client调用时，请使用子线程避免hand up the main thread and encounter ANR.此外，Server端不会返回Exception。
- Expose the interface to the clients
继承Service，重写onBind()，然后返回Stub 类的实现，即mBinder。
public class RemoteService extends Service {
@Override
public void onCreate() {
super.onCreate();
}
@Override
public IBinder onBind(Intent intent) {
// Return the interface
return mBinder;
}
}
Client调用，如果与Server不再同一个Application下，那么需要将aidl文件拷贝到Client，并且保持包名的一致。
Passing Objects over IPC
支持Parcelable，将允许Android系统decompose objects into primitives that can be marshalled over processes, 意思就是允许Android系统将objects 解耦成primitives，而这些primitives可在进程间传递。
Step:
1. 让需要传递的类实现Parcelable接口，
2. 实现writeToParcel()方法，它将把对象的当前状态写到一个Parcel
3. 添加静态字段CREATOR，它时实现Parcelable.Creator接口。
4. create a aidl, 然后申明这个Parcelable 类。
aidl 申明Rect类代码如下：
package android.graphics;
// Declare Rect so AIDL can find it and knows that it implements
// the parcelable protocol.
parcelable Rect;
接下来是Rect类实现Parcelable接口代码：
import android.os.Parcel;
import android.os.Parcelable;
public final class Rect implements Parcelable {
public int left;
public int top;
public int right;
public int bottom;
public static final Parcelable.Creator<Rect> CREATOR = new
Parcelable.Creator<Rect>() {
public Rect createFromParcel(Parcel in) {
return new Rect(in);
}
public Rect[] newArray(int size) {
return new Rect[size];
}
};
public Rect() {
}
private Rect(Parcel in) {
readFromParcel(in);
}
public void writeToParcel(Parcel out) {
out.writeInt(left);
out.writeInt(top);
out.writeInt(right);
out.writeInt(bottom);
}
public void readFromParcel(Parcel in) {
left = in.readInt();
top = in.readInt();
right = in.readInt();
bottom = in.readInt();
}
}
Calling an IPC Method
调用远程服务的实例，在之前的Service节中已经出现过了。这里不妨再赘上,有效长，:）
public static class Binding extends Activity {
/** The primary interface we will be calling on the service. */
IRemoteService mService = null;
/** Another interface we use on the service. */
ISecondary mSecondaryService = null;
Button mKillButton;
TextView mCallbackText;
private boolean mIsBound;
/**
* Standard initialization of this activity. Set up the UI, then wait
* for the user to poke it before doing anything.
*/
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.remote_service_binding);
// Watch for button clicks.
Button button = (Button)findViewById(R.id.bind);
button.setOnClickListener(mBindListener);
button = (Button)findViewById(R.id.unbind);
button.setOnClickListener(mUnbindListener);
mKillButton = (Button)findViewById(R.id.kill);
mKillButton.setOnClickListener(mKillListener);
mKillButton.setEnabled(false);
mCallbackText = (TextView)findViewById(R.id.callback);
mCallbackText.setText("Not attached.");
}
/**
* Class for interacting with the main interface of the service.
*/
private ServiceConnection mConnection = new ServiceConnection() {
public void onServiceConnected(ComponentName className,
IBinder service) {
// This is called when the connection with the service has been
// established, giving us the service object we can use to
// interact with the service. We are communicating with our
// service through an IDL interface, so get a client-side
// representation of that from the raw service object.
mService = IRemoteService.Stub.asInterface(service);
mKillButton.setEnabled(true);
mCallbackText.setText("Attached.");
// We want to monitor the service for as long as we are
// connected to it.
try {
mService.registerCallback(mCallback);
} catch (RemoteException e) {
// In this case the service has crashed before we could even
// do anything with it; we can count on soon being
// disconnected (and then reconnected if it can be restarted)
// so there is no need to do anything here.
}
// As part of the sample, tell the user what happened.
Toast.makeText(Binding.this, R.string.remote_service_connected,
Toast.LENGTH_SHORT).show();
}
public void onServiceDisconnected(ComponentName className) {
// This is called when the connection with the service has been
// unexpectedly disconnected -- that is, its process crashed.
mService = null;
mKillButton.setEnabled(false);
mCallbackText.setText("Disconnected.");
// As part of the sample, tell the user what happened.
Toast.makeText(Binding.this, R.string.remote_service_disconnected,
Toast.LENGTH_SHORT).show();
}
};
/**
* Class for interacting with the secondary interface of the service.
*/
private ServiceConnection mSecondaryConnection = new ServiceConnection() {
public void onServiceConnected(ComponentName className,
IBinder service) {
// Connecting to a secondary interface is the same as any
// other interface.
mSecondaryService = ISecondary.Stub.asInterface(service);
mKillButton.setEnabled(true);
}
public void onServiceDisconnected(ComponentName className) {
mSecondaryService = null;
mKillButton.setEnabled(false);
}
};
private OnClickListener mBindListener = new OnClickListener() {
public void onClick(View v) {
// Establish a couple connections with the service, binding
// by interface names. This allows other applications to be
// installed that replace the remote service by implementing
// the same interface.
bindService(new Intent(IRemoteService.class.getName()),
mConnection, Context.BIND_AUTO_CREATE);
bindService(new Intent(ISecondary.class.getName()),
mSecondaryConnection, Context.BIND_AUTO_CREATE);
mIsBound = true;
mCallbackText.setText("Binding.");
}
};
private OnClickListener mUnbindListener = new OnClickListener() {
public void onClick(View v) {
if (mIsBound) {
// If we have received the service, and hence registered with
// it, then now is the time to unregister.
if (mService != null) {
try {
mService.unregisterCallback(mCallback);
} catch (RemoteException e) {
// There is nothing special we need to do if the service
// has crashed.
}
}
// Detach our existing connection.
unbindService(mConnection);
unbindService(mSecondaryConnection);
mKillButton.setEnabled(false);
mIsBound = false;
mCallbackText.setText("Unbinding.");
}
}
};
private OnClickListener mKillListener = new OnClickListener() {
public void onClick(View v) {
// To kill the process hosting our service, we need to know its
// PID. Conveniently our service has a call that will return
// to us that information.
if (mSecondaryService != null) {
try {
int pid = mSecondaryService.getPid();
// Note that, though this API allows us to request to
// kill any process based on its PID, the kernel will
// still impose standard restrictions on which PIDs you
// are actually able to kill. Typically this means only
// the process running your application and any additional
// processes created by that app as shown here; packages
// sharing a common UID will also be able to kill each
// other's processes.
Process.killProcess(pid);
mCallbackText.setText("Killed service process.");
} catch (RemoteException ex) {
// Recover gracefully from the process hosting the
// server dying.
// Just for purposes of the sample, put up a notification.
Toast.makeText(Binding.this,
R.string.remote_call_failed,
Toast.LENGTH_SHORT).show();
}
}
}
};
// ----------------------------------------------------------------------
// Code showing how to deal with callbacks.
// ----------------------------------------------------------------------
/**
* This implementation is used to receive callbacks from the remote
* service.
*/
private IRemoteServiceCallback mCallback = new IRemoteServiceCallback.Stub() {
/**
* This is called by the remote service regularly to tell us about
* new values. Note that IPC calls are dispatched through a thread
* pool running in each process, so the code executing here will
* NOT be running in our main thread like most other things -- so,
* to update the UI, we need to use a Handler to hop over there.
*/
public void valueChanged(int value) {
mHandler.sendMessage(mHandler.obtainMessage(BUMP_MSG, value, 0));
}
};
private static final int BUMP_MSG = 1;
private Handler mHandler = new Handler() {
@Override public void handleMessage(Message msg) {
switch (msg.what) {
case BUMP_MSG:
mCallbackText.setText("Received from service: " + msg.arg1);
break;
default:
super.handleMessage(msg);
}
}
};
}
