AIDL实现进程间通讯（Android 同步调用）

服务端代码：

• AIDL接口：IAIDLConfigService.aidl

package com.android.aidl;

interface IAIDLConfigService {
    int setHomePage(String homepage);
}

• Android.mk中增加对AIDL文件编译的支持

LOCAL_SRC_FILES += \ $(call all-Iaidl-files-under, src)

LOCAL_AIDL_INCLUDES := $(LOCAL_PATH)/src/

• 模块编译过程中AIDL文件会生成IAIDLConfigService.java

• AIDLConfigService.java

package com.android.aidl;

import com.android.aidl.IAIDLConfigService;

import android.content.Context;
import android.content.Intent;
import android.app.Service;
import android.os.IBinder;
import android.os.RemoteException;
import android.util.Log;

import com.android.browser.BrowserSettings;
import com.android.browser.UrlUtils;

public class AIDLConfigService extends Service {

    static final String TAG = "AIDLConfigService";

    @Override
    public IBinder onBind(Intent intent) {
        Log.d(TAG, "====>onBind().");
        IBinder binder = new ImplAIDLConfigService();
        Log.d(TAG, "====>onBind().binder = " + binder);
        return binder;
    }

    public class ImplAIDLConfigService extends IAIDLConfigService.Stub{
        @Override
        public int setHomePage(String homepage) throws RemoteException {
            Log.d(TAG, "setHomePage(), homepage = " + homepage);
            if (homepage != null) {
                BrowserSettings.getInstance().setHomePage(UrlUtils.smartUrlFilter(homepage,false));
            }
            return 123;
        }
    }

}

• AndroidManifest.xml

<manifest xmlns:android="http://schemas.android.com/apk/res/android" package="com.android.browser">
......
        <service android:name="com.android.aidl.AIDLConfigService">
            <intent-filter>
                <action android:name="com.andorid.aidl.BrowserDataConfig" />
            </intent-filter>
        </service>

    </application>

</manifest>

客户端代码：

• AIDL接口：IAIDLConfigService.aidl

package com.android.aidl;

interface IAIDLConfigService {
    int setHomePage(String homepage);
}

Note:
客户端IAIDLConfigService.aidl跟服务端文件需要完全一样, 包括目录结构也需要一样,都在src\com\android\aidl\目录下

• Android.mk中增加对AIDL文件编译的支持

LOCAL_SRC_FILES += \ $(call all-Iaidl-files-under, src)

LOCAL_AIDL_INCLUDES := $(LOCAL_PATH)/src/

• 模块编译过程中AIDL文件会生成IAIDLConfigService.java

• 接口层AIDLBrowserImpl.java

import android.content.Context;

import android.app.Service;
import android.content.Intent;
import android.content.ComponentName;
import android.content.ServiceConnection;
import android.os.Bundle;
import android.os.IBinder;
import android.os.RemoteException;
import com.android.aidl.IAIDLConfigService;

import android.util.Log;

public class AIDLBrowserImpl {
    public final String TAG = "AIDLBrowserImpl";
    public final static String AIDL_BROWSER_ACTION = "com.andorid.aidl.BrowserDataConfig";

    private boolean mIsBound;
    private IAIDLConfigService mBoundService = null;

    private void bindService(Context context) {
        Log.e(TAG, "bindService(): enter");
        Intent i = new Intent();
        i.setAction(AIDL_BROWSER_ACTION);
        i.setPackage("com.android.browser");
        context.bindService(i, mConnection, Context.BIND_AUTO_CREATE);
        mIsBound = true;
    }

    private void unbindService(Context context) {
        if (mIsBound) {
            context.unbindService(mConnection);
            mIsBound = false;
        }
    }

    private ServiceConnection mConnection = new ServiceConnection() {

        @Override
        public void onServiceConnected(ComponentName className, IBinder service) {
            Log.d(TAG, "-->> onServiceConnected() enter.");
            mBoundService = IAIDLConfigService.Stub.asInterface(service);
            Log.d(TAG, "-->> onServiceConnected(),  boundService = " + mBoundService);
        }

        @Override
        public void onServiceDisconnected(ComponentName className) {
            mBoundService = null;
            Log.d(TAG, "-->> onServiceDisconnected()");
        }
    };

    public void init(Context context) {
        bindService(context);
    }

    public void free(Context context) {
        unbindService(context);
    }

    public boolean setHomePage(Context context, String link, String name){

        Log.d(TAG, "setHomePage(): enter, link = " + link + ", name = " + name);
        int result = -1;

        try {
                if(mBoundService == null) return false;
                result = mBoundService.setHomePage(link);
                Log.e(TAG,"mBoundService.setHomePage() result = " + result);
        } catch (RemoteException e) {
            e.printStackTrace();
            return false;
        } 

        if(result != 0) return false;

        return true;
    }

}

• MainActivity.java

package com.android.aidltest;

import android.os.Bundle;
import android.widget.Button;
import android.view.View;
import android.content.Context;
import android.widget.Toast;
import android.app.Activity;
import android.util.Log;

import com.sprd.aidl.adapter.porting.AIDLBrowserImpl;

public class MainActivity extends Activity {

    public static final String TAG = "AIDLTest";
    AIDLBrowserImpl mAIDLBrowserImpl;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);

        final Button btnTestBrowser = (Button) findViewById(R.id.btnTestBrowser);
        btnTestBrowser.setOnClickListener(new View.OnClickListener() {
            public void onClick(View v) {
                testBrowserDataConfig(true);
            }
        });

        mAIDLBrowserImpl = new AIDLBrowserImpl();
    }

    @Override
    protected void onStart() {
        super.onStart();
        Log.i(TAG, "onStart: this=" + this);
        if(mAIDLBrowserImpl != null) {
            mAIDLBrowserImpl.init(this);
        }
    }

    @Override
    protected void onStop() {
        Log.i(TAG, "onStop");
        mAIDLBrowserImpl.free(this);
        super.onStop();
    }

    private void testBrowserDataConfig(boolean isNormalTest) {

        Log.d(TAG, "Test aidl browser data config beging ... isNormalTest = " + isNormalTest);

        //Test homepage
        {
            String link = "cn.bing.com";
            String name = "BingBing";

            mAIDLBrowserImpl.setHomePage(this, link, name);
        }

        Toast.makeText(this, "Test aidl browser data config end", Toast.LENGTH_SHORT).show();

        return;
    }

}

小结

• 至此实现了一个应用程序进程（apk）对另一个应用程序进程（apk）的同步调用就完成了；
• 至于AIDL通讯原理，网上很多资料，这里都不多讲了；总结一下期间遇到的问题：
  1. 客户端bindService时Intent的setAction需要跟服务端AndroidManifest.xml中intent-filter/action一致：

           <intent-filter>
               <action android:name="com.andorid.aidl.BrowserDataConfig" />
           </intent-filter>
     

  2. 客户端bindService时Intent的setPackage设置的是服务端的包名
  3. 客户端bindService的过程是异步过程，并且onServiceConnected回调函数运行在主线程中，所以当我们的同步调用接口AIDLBrowserImpl.setHomePage也运行在主线程时；bindService如果在AIDLBrowserImpl.setHomePage接口内调用；onServiceConnected回调函数会一直等到AIDLBrowserImpl.setHomePage运行完成，才能得到调用；因为同一线程不可能前一个消息没处理完毕的情况下，就去处理后面的消息。所以，目前的解决方法就是，在客户端的onStart方法中先去bindService；然后客户端就可以直接同步调用AIDL实现的所有接口了；

     官方文档：Interface for monitoring the state of an application service. Like many callbacks from the system, the methods on this class are called from the main thread of your process.

  4. 客户端bindService的动作建议放在主线程中；
  5. 为什么同步调用接口AIDLBrowserImpl.setHomePage不放在其他线程中？因为这样就失去了同步的意义了。