Android的跨进程通信介绍----------------aidl,传递复杂对象以及Server和Clicent之间的回调
Android的跨进程通信———aidl
做android也有一段时间了,一直没有在博客中去做过这样的总结,刚好这段时间学习开始总结点东西,想着一些简单的问题就不在上面总结了,而之前一些写的都是关于C一方面的总结,几乎看不到Android相关的,今天在这也就给大家分享一下,一个简单的跨进程通信的案例,aidl
其实Android的IPC机制最初应该是引用自Linux中的Ipc概念吧。做过Linux开发的人可能对这个IPC相对来说更加的清晰,什么是FIFO,PIPO管道啊,操作共享内存区域啊等等,都是源自Linux的
最近刚好在做一个跨进程通信用aidl进行重构优化的项目,所以对这一块可能比之前对aidl的了解又更深一步了吧。以前只是单纯的绑定,基本上没有用到server和Client之间的回调,以及也没有用到过于复杂对象的序列化。
首先我们来讲一下整体流程:
1:Client去绑定Server端
2:Server端在绑定过后,返回aidl的接口对象
3:Client将参数(json字符串)传递给Server端,在Server端去做处理
4:Server端然后再将处理的结果回调给Client
注意:Json字符串本来就是可以序列化的,所以这个时候我们可以剖除掉复杂的序列化的过程
带着问题讨论下:
1:aidl的传递复杂对象的时候是需要进行序列化的,也就是Parcelable接口,但是会有一个问题,如果这个对象过于复杂,在对象里面不断的包含另外一个对象,或者Map和List进行多层嵌套的时候,可能序列化就会出现问题
2:关于CallBack的回调,也就是Server回调给Client,它是一个类似aidl文件的接口。
这是我写的一个很简单的关于aidl整个流程的一个Demo,也是我在项目中用到的大概的整个流程吧:
IServer.aidl文件
package com.example.aidl;import com.example.aidl.IServerCallback;interface IServer{ void setAddNum(int num1,int num2); void registerServerCallBack(IServerCallback callback); void unregisterServerCallBack(IServerCallback callback); void setString(String jsonString);}
IServerCallback.aidl文件:
package com.example.aidl;interface IServerCallback{ void setResult(int result); void setTransferString(String jsonString);}
Server端代码:
MyCustomServer.java文件
package com.example.aidl2;import android.app.Service;import android.content.Intent;import android.os.IBinder;import android.os.RemoteCallbackList;import android.os.RemoteException;import android.util.Log;import com.example.aidl.IServer;import com.example.aidl.IServerCallback;public class MyCustomServer extends Service{ int Result = 0; IServerCallback cback; private final RemoteCallbackList mCallbacks = new RemoteCallbackList(); @Override public void onCreate() { // TODO Auto-generated method stub Log.i("123", "oncreate"); super.onCreate(); } @Override public IBinder onBind(Intent arg0) { Log.i("123", "onBind"); return new MyCustomImpl(); } @Override public boolean onUnbind(Intent intent) { // TODO Auto-generated method stub return super.onUnbind(intent); } Plus plus; private class MyCustomImpl extends IServer.Stub{ @Override public void setAddNum(int num1, int num2) throws RemoteException { // TODO Auto-generated method stub Result = num1 + num2; Log.i("123", "RESULT:"+Result); plus = new Plus(cback); plus.add(num1, num2);// if(cback != null){// cback .setResult(plus.add(num1, num2));// } } @Override public void registerServerCallBack(IServerCallback callback) throws RemoteException { // TODO Auto-generated method stub Log.i("123","register callback"); if(callback != null){ mCallbacks.register(callback); cback = callback; } } @Override public void unregisterServerCallBack(IServerCallback callback) throws RemoteException { // TODO Auto-generated method stub Log.i("123","unregister callback"); if(callback!=null){ mCallbacks.unregister(callback); cback = null; } } @Override public void setString(String jsonString) throws RemoteException { // TODO Auto-generated method stub if(plus == null){ plus = new Plus(cback); } plus.getResult(jsonString); } } @Override public void onDestroy() { // TODO Auto-generated method stub super.onDestroy(); } }
Plus.java
package com.example.aidl2;import android.os.RemoteException;import com.example.aidl.IServerCallback;import com.google.gson.Gson;public class Plus { IServerCallback cback; public Plus(IServerCallback cback){ this.cback = cback; } public void add(int num1,int num2){ try { cback.setResult(num1+num2); } catch (RemoteException e) { // TODO Auto-generated catch block e.printStackTrace(); } } private int num1; private int num2; public int getNum1() { return num1; } public void setNum1(int num1) { this.num1 = num1; } public int getNum2() { return num2; } public void setNum2(int num2) { this.num2 = num2; } public Plus(int num1, int num2) { super(); this.num1 = num1; this.num2 = num2; } public void getResult(String jsonString){ Plus plus = new Gson().fromJson(jsonString, Plus.class); try { cback.setTransferString(plus.num1 +"+"+plus.num2 + "="+plus.getNum1()+plus.getNum2()); } catch (RemoteException e) { // TODO Auto-generated catch block e.printStackTrace(); } }}
Client端的代码如下:
package com.example.aidl1;import com.example.aidl.IServer;import com.example.aidl.IServerCallback;import com.google.gson.Gson;import android.app.Activity;import android.content.ComponentName;import android.content.Context;import android.content.Intent;import android.content.ServiceConnection;import android.os.Bundle;import android.os.IBinder;import android.os.RemoteException;import android.util.Log;import android.view.Menu;import android.view.View;import android.view.View.OnClickListener;import android.widget.Button;import android.widget.TextView;public class MainActivity extends Activity { Button btnBind; TextView tvResult; Intent server; IServer mServer = null; Button btnTransfer ; Button btnTransfeString; iServerCallImpl callback = new iServerCallImpl(); private ServiceConnection conn = new ServiceConnection(){ @Override public void onServiceConnected(ComponentName arg0, IBinder arg1) { // TODO Auto-generated method stub Log.i("123", "onServerConnected"); mServer = IServer.Stub.asInterface(arg1); registerCallBack(); } @Override public void onServiceDisconnected(ComponentName arg0) { // TODO Auto-generated method stub ungisterCallBack(); } }; @Override protected void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.activity_main); btnBind = (Button) findViewById(R.id.btn_bind); tvResult = (TextView) findViewById(R.id.tv_result); btnTransfer = (Button) findViewById(R.id.btn_transfer); btnTransfeString = (Button) findViewById(R.id.btn_transferstring); btnBind.setOnClickListener(new OnClickListener() { @Override public void onClick(View arg0) { // TODO Auto-generated method stub server = new Intent("com.example.server"); bindService(server, conn, Context.BIND_AUTO_CREATE); } }); btnTransfer.setOnClickListener(new OnClickListener() { @Override public void onClick(View arg0) { // TODO Auto-generated method stub if(mServer!=null){ try { mServer.setAddNum(10, 22); } catch (RemoteException e) { // TODO Auto-generated catch block e.printStackTrace(); } } } }); btnTransfeString.setOnClickListener(new OnClickListener() { @Override public void onClick(View arg0) { // TODO Auto-generated method stub Plus plsPlus = new Plus(30, 50); String json = new Gson().toJson(plsPlus); try { mServer.setString(json); } catch (RemoteException e) { // TODO Auto-generated catch block e.printStackTrace(); } } }); } private class iServerCallImpl extends IServerCallback.Stub{ @Override public void setResult(int result) throws RemoteException { // TODO Auto-generated method stub if(tvResult != null){ tvResult.setText(""+result); } } @Override public void setTransferString(String jsonString) throws RemoteException { // TODO Auto-generated method stub if(tvResult != null){ tvResult.setText(""+jsonString); } } } private void registerCallBack(){ if(mServer == null){ return; } try { mServer.registerServerCallBack(callback); } catch (RemoteException e) { // TODO Auto-generated catch block e.printStackTrace(); } } private void ungisterCallBack(){ if(mServer == null){ return; } try { mServer.unregisterServerCallBack(callback); } catch (RemoteException e) { // TODO Auto-generated catch block e.printStackTrace(); } } @Override public boolean onCreateOptionsMenu(Menu menu) { // Inflate the menu; this adds items to the action bar if it is present. getMenuInflater().inflate(R.menu.main, menu); return true; } }
Plus.java
package com.example.aidl1;import android.os.RemoteException;import com.example.aidl.IServerCallback;import com.google.gson.Gson;public class Plus { private int num1; private int num2; public int getNum1() { return num1; } public void setNum1(int num1) { this.num1 = num1; } public int getNum2() { return num2; } public void setNum2(int num2) { this.num2 = num2; } public Plus(int num1, int num2) { super(); this.num1 = num1; this.num2 = num2; } IServerCallback cback; public Plus(IServerCallback cback){ this.cback = cback; } public void add(int num1,int num2){ try { cback.setResult(num1+num2); } catch (RemoteException e) { // TODO Auto-generated catch block e.printStackTrace(); } } public void getResult(String jsonString){ Plus plus = new Gson().fromJson(jsonString, Plus.class); try { cback.setTransferString(plus.num1 +"+"+plus.num2 + "="+plus.getNum1()+plus.getNum2()); } catch (RemoteException e) { // TODO Auto-generated catch block e.printStackTrace(); } }}
从以上我们可以看到:
使用json字符串取代了复杂的对象的序列化
使用CallBack回调将server处理的数值来进行回调给Client
注意:因为我这个是一个Client对应的一个Server端,但是在实际操作中,很多时候我们往往遇到多个Client绑定一个Server端,那么这个时候我们就会遇到多个CallBack,这个时候,可能我们的,每个CallBack需要回调不同的结果再调用给Client端。那么我就需要用到RemoteCallBack的广播机制,去轮询所有的CallBack,然后才能通知不同的Client
如:
final int N = mCallbacks.beginBroadcast(); for (int i=0; itry { mCallbacks.getBroadcastItem(i).(方法); } catch (RemoteException e) { // The RemoteCallbackList will take care of removing // the dead object for us. } } mCallbacks.finishBroadcast();
类似以上伪代码,这样就可以整体的向所有的Client进行回调了
注意:使用Json可以取代复杂的序列化过程
源码下载地址:源码地址
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