AIDL --- Android中的远程接口(1)

更好的设计Android软件应该熟悉掌握AIDL IPC机制，可以让你编写的组件类似Windows ActiveX COM一样更好的复用，提供类似像Symbian那样的服务器机制。服务可以很好的解决在后台运行无UI的窗口。我们创建一个aidl文件名为android123.aidl下面是示例代码，修改于Android SDK文档。

一、创建AIDL文件

package cn.com.android123;

// 引入声明

import cn.com.android123.IAtmService;

// 声明一个接口，这里演示的是银行ATM程序
interface IBankAccountService {

int getAccountBalance(); //返回整数，无参数
void setOwnerNames(in List<String> names); //不返回，包含一个传入List参数
BankAccount createAccount(in String name, int startingDeposit, in IAtmService atmService); //返回一个自定义类型
int getCustomerList(in String branch, out String[] customerList); //返回整形，输入一个分支，输出一个客户列表
}

二、实现一个接口

显示的提供一个导出接口，为客户端提供绑定。

public class RemoteService extends Service {    @Override    public IBinder onBind(Intent intent) {        if (IRemoteService.class.getName().equals(intent.getAction())) {            return mBinder;        }        if (ISecondary.class.getName().equals(intent.getAction())) {            return mSecondaryBinder;        }        return null;    }

 //第一个接口    private final IRemoteService.Stub mBinder = new IRemoteService.Stub() {        public void registerCallback(IRemoteServiceCallback cb) {            if (cb != null) mCallbacks.register(cb);        }        public void unregisterCallback(IRemoteServiceCallback cb) {            if (cb != null) mCallbacks.unregister(cb);        }    };

//第二个接口    private final ISecondary.Stub mSecondaryBinder = new ISecondary.Stub() {        public int getPid() {            return Process.myPid();        }        public void basicTypes(int anInt, long aLong, boolean aBoolean,                float aFloat, double aDouble, String aString) {        }    };}

三、客户端交互

通过Android.os提供的Parcelable类型来传递数据，通常我们使用Eclipse+ADT插件来完成，在Eclipse中在Package Explorer view视图上单击鼠标右键，选择Create Aidl preprocess file for Parcelable classes(创建aidl预编译文件)，最终我们创建一个名为android123.aidl文件

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) { //当前数据写入到Parcel中
out.writeInt(left);
out.writeInt(top);
out.writeInt(right);
out.writeInt(bottom);
}

public void readFromParcel(Parcel in) { //从Parcel中读取数据
left = in.readInt();
top = in.readInt();
right = in.readInt();
bottom = in.readInt();
}
}

IPC调用方式

public class RemoteServiceBinding 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(RemoteServiceBinding.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(RemoteServiceBinding.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(RemoteServiceBinding.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);      }    }

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