最近從新溫習AIDL，發現技術這玩意就跟女人一樣，你過久沒去了解就會對它陌生卻又充滿新鮮感，然後查看網上的多半是胡扯，粘貼，我這裏整合下，裏面如果有錯誤望大家及時指出。廢話不多說，進入主題
首先來了解幾點常識：
1，一個Android應用程序對應一個進程；
2，Android應用程序進程間需要藉助IPC輕量級通訊協議；
3，切勿把線程和進程的概念搞混亂。一個進程可以包含多個線程，但是一個線程只會附屬於一個進程，可以理解成1對多的關係；
4，我們常見的Handler它是運行在UI主線程的，它負責的是異步處理數據，執行也是父線程和子線程；所以別把它和進程的概念混在一起。
進入主題，Android進程間的通訊：AIDL
這裏我以爲大家比較熟悉的C/S模式來講解整個通訊過程；但是我並沒有去新建立兩個項目了，就一個項目中，模擬進程通訊。不多說，先上項目圖
第一步，首先建立兩個aidl文件，forActivity.adil,forService.aidl 先來看看它們內部實現
package com.aidl;
interface forActivity{
void perAction();
void showString(int count);
}package com.aidl;
import com.aidl.forActivity;
interface forService{
void registerTestCall(forActivity fa);
void callBack();
}一看，哎喲，這裏面的編碼規則和java文件一樣，但是這個時候，我其他地方要調用怎麼辦？彆着急編譯器會默認在gen文件中生成對應.java文件
打開其中一個文件查看下其中源碼，先不詳細分析，慢慢來，就好比追女生一樣，要慢慢來，急不得
/*
* This file is auto-generated. DO NOT MODIFY.
* Original file: F:\\workspace\\AndroidAIDL\\src\\com\\example\\androidaidl\\aidl\\forActivity.aidl
*/
package com.example.androidaidl.aidl;
public interface forActivity extends android.os.IInterface
{
/** Local-side IPC implementation stub class. */
public static abstract class Stub extends android.os.Binder implements com.example.androidaidl.aidl.forActivity
{
private static final java.lang.String DESCRIPTOR = "com.example.androidaidl.aidl.forActivity";
/** Construct the stub at attach it to the interface. */
public Stub()
{
this.attachInterface(this, DESCRIPTOR);
}
/**
* Cast an IBinder object into an com.example.androidaidl.aidl.forActivity interface,
* generating a proxy if needed.
*/
public static com.example.androidaidl.aidl.forActivity asInterface(android.os.IBinder obj)
{
if ((obj==null)) {
return null;
}
android.os.IInterface iin = obj.queryLocalInterface(DESCRIPTOR);
if (((iin!=null)&&(iin instanceof com.example.androidaidl.aidl.forActivity))) {
return ((com.example.androidaidl.aidl.forActivity)iin);
}
return new com.example.androidaidl.aidl.forActivity.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_performAction:
{
data.enforceInterface(DESCRIPTOR);
this.performAction();
reply.writeNoException();
return true;
}
}
return super.onTransact(code, data, reply, flags);
}
private static class Proxy implements com.example.androidaidl.aidl.forActivity
{
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 void performAction() throws android.os.RemoteException
{
android.os.Parcel _data = android.os.Parcel.obtain();
android.os.Parcel _reply = android.os.Parcel.obtain();
try {
_data.writeInterfaceToken(DESCRIPTOR);
mRemote.transact(Stub.TRANSACTION_performAction, _data, _reply, 0);
_reply.readException();
}
finally {
_reply.recycle();
_data.recycle();
}
}
}
static final int TRANSACTION_performAction = (android.os.IBinder.FIRST_CALL_TRANSACTION + 0);
}
public void performAction() throws android.os.RemoteException;
}
第二步,新建mAIDLActivity.java文件，它模擬Client ， 新建mAIDLService.java文件,它模擬Server;
先看看mAIDLActivity.java文件;
public class mAIDLActivity extends Activity {
private static final String TAG = "AIDLActivity";
private Button btnOk;
private Button btnCancel;
private Button btnCallBack;
private void Log(String str) {
android.util.Log.d(TAG, "------ " + str + "------");
}
@Override
protected void onCreate(Bundle savedInstanceState) {
// TODO Auto-generated method stub
super.onCreate(savedInstanceState);
setContentView(R.layout.main);
btnOk = (Button) findViewById(R.id.btn_ok);
btnCancel = (Button) findViewById(R.id.btn_cancel);
btnCallBack = (Button) findViewById(R.id.btn_callback);
btnOk.setOnClickListener(new OnClickListener() {
public void onClick(View v) { //綁定服務
Intent intent = new Intent(mAIDLActivity.this,mAIDLService.class);
bindService(intent, mcConnection, Context.BIND_AUTO_CREATE);
//startService(intent);
}
});
btnCancel.setOnClickListener(new OnClickListener() {
public void onClick(View v) { //取消綁定
unbindService(mcConnection);
/*unbindService(mConnection);
// stopService(intent);
*/ }
});
btnCallBack.setOnClickListener(new OnClickListener() {
@Override
public void onClick(View v) {
try { //進程數據交互通訊
mService.callBack();
} catch (RemoteException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
}
});
}
forService mService;
forActivity mActivity = new forActivity.Stub() {
@Override
public void perAction() throws RemoteException {
Log("執行了啦");
}
@Override
public void showString(int count) throws RemoteException {
Log(count+"");
}
};
ServiceConnection mcConnection = new ServiceConnection() {
@Override
public void onServiceDisconnected(ComponentName name) {
}
@Override
public void onServiceConnected(ComponentName name, IBinder service) {
mService = forService.Stub.asInterface(service);
try {
mService.registerTestCall(mActivity);
} catch (RemoteException e) {
}
}
};
}
先分析下上述文件
ServiceConnection mcConnection = new ServiceConnection() {
@Override
public void onServiceDisconnected(ComponentName name) {
}
@Override
public void onServiceConnected(ComponentName name, IBinder service) {
mService = forService.Stub.asInterface(service);
try {
mService.registerTestCall(mActivity);
} catch (RemoteException e) {
}
}
};看這句代碼
mService = forService.Stub.asInterface(service);public interface forService extends android.os.IInterface
{
/** Local-side IPC implementation stub class. */
public static abstract class Stub extends android.os.Binder implements com.aidl.forService
{
private static final java.lang.String DESCRIPTOR = "com.aidl.forService";
/** Construct the stub at attach it to the interface. */
public Stub()
{
this.attachInterface(this, DESCRIPTOR);
}
/**
* Cast an IBinder object into an com.aidl.forService interface,
* generating a proxy if needed.
*/
public static com.aidl.forService asInterface(android.os.IBinder obj)
{
if ((obj==null)) {
return null;
}
android.os.IInterface iin = obj.queryLocalInterface(DESCRIPTOR);
if (((iin!=null)&&(iin instanceof com.aidl.forService))) {
return ((com.aidl.forService)iin);
}
return new com.aidl.forService.Stub.Proxy(obj);
}這裏我們發現,Stub是forService的內部靜態抽象類,並且是繼承Binder和實例化了接口forService. 查看方法adInterface中的實現,它分三步來判斷
1,如果是空,直接給你空,讓你一邊玩去
2,如果傳入的Ibinder對象就是com.aidl.forService，因爲forService的繼承的IInterface,看IInterface的介紹Base class for Binder interfaces. When
defining a new interface, you must derive it from IInterface.那得列直接強轉成forService對象返回去，萬事大吉；
3.如果爲空,那就new一個新的,對象嘛.程序猿從來不缺.
下面繼續分析mAIDLService文件.不多說,先看源碼
public class mAIDLService extends Service {
@Override
public IBinder onBind(Intent intent) {
return mIBinder;
}
forActivity mActivity;
int count=0;
forService.Stub mIBinder = new forService.Stub() {
@Override
public void registerTestCall(forActivity fa) throws RemoteException {
mActivity = fa;
}
@Override
public void callBack() throws RemoteException {
mActivity.perAction();
mActivity.showString(++count);
}
};
}它這裏相對就簡單了,基本不用多說了吧,這裏要注意的就是
public IBinder onBind(Intent intent) {
return mIBinder;
}那這裏就慢慢明朗了,整個相互間的通訊也就清楚了,當按下btnCallBack按鈕的時候,首先會調用forService中的callBack方法,而callBack方法的實現中又調用了forActivity的perAction.通過forActivity和forService的這次握手，就達到了mAIDLActivity和mAIDLService一直及時通訊
說到這裏有朋友跟我說ContentProvider就可以直接實現兩個應用間的數據傳遞了啊，爲什麼還要用AIDL，我轉頭一聲呵呵，我列出下面幾個區分點估計大家就明白了
1.ContentProvider是單向性的，不及時的，而AIDL是雙向性，及時的。就這麼來說吧。ContentProvider就好比你看到一個漂亮的妹子，你一直看着她，但是她卻對你無視，你看不清楚她身體的變化；AIDL就是你看到那個漂亮的妹子，她也看着，你下面的異樣，立即反饋給了她，而你也看到了她嘴邊的異樣，這比喻好理解嗎？哈哈哈
好了中間有些地方如果有錯或者大家要補充的直接留言吧，然後懇請轉載的指明地址，不然又是一堆廢文到處跑。
下篇博文準備分析下IBinder和Binder！
參考網友論文
http://blog.csdn.net/saintswordsman/article/details/5130947
源碼下載