本文主要是介绍android aidl进程间的通信，希望对大家解决编程问题提供一定的参考价值，需要的开发者们随着小编来一起学习吧！
1、IPC是Inter-Process Communication的缩写，含义就是进程间通信或者跨进程通信，是指两个进程之间进行数据交换的过程。进程在PC和移动设备上指的是一个程序或者一个应用。一个进程可以包含多个线程，因此进程和线程是包含被包含的关系。这里主要是实现activity通过aidl调用service方法和一个应用调用另一个应用方法的实现。
2、aidl在应用间的使用
首先可以先实现 .aidl文件，.aidl文件可以直接新建，跟java同级
// IMyAidlInterface.aidl
package com.example.apple.myfragment;// Declare any non-default types here with import statementsinterface IMyAidlInterface {/*** Demonstrates some basic types that you can use as parameters* and return values in AIDL.*/int add(int a, int b);int reduce(int a,int b);
}
package com.example.apple.myfragment;import android.app.Service;
import android.content.Intent;
import android.os.IBinder;
import android.os.RemoteException;
import android.support.annotation.Nullable;
import android.util.Log;/*** Created by apple on 17/4/14.*/public class MyService extends Service {@Nullable@Overridepublic IBinder onBind(Intent intent) {return myAidlInterface;}private final IMyAidlInterface.Stub myAidlInterface = new IMyAidlInterface.Stub() {@Overridepublic int add(int a, int b) throws RemoteException {Log.e("nsc","a+b="+(a+b));return a+b;}@Overridepublic int reduce(int a, int b) throws RemoteException {Log.e("nsc","a-b="+(a-b));return rd(a,b);}};private int rd(int a ,int b){if (a>b){return a-b;}else {return b-a;}}
}
service和activity连接需要使用ServiceConnection，里面实现了两个方法，连接和断开连接。建立连接后就可以对service实例进行引用了，当建立连接需要调用aidlInterface = IMyAidlInterface.Stub.asInterface(service)；如下所示，使用完还要在onDestroy里调用unbindService(connection);
package com.example.apple.myfragment;import android.content.ComponentName;
import android.content.Context;
import android.content.Intent;
import android.content.ServiceConnection;
import android.os.IBinder;
import android.os.RemoteException;
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.view.View;
import android.widget.Button;
import android.widget.TextView;public class MainActivity extends AppCompatActivity {private Button btnAdd;private Button btnReduce;private TextView tvResult;private IMyAidlInterface aidlInterface;private ServiceConnection connection = new ServiceConnection() {@Overridepublic void onServiceConnected(ComponentName name, IBinder service) {aidlInterface = IMyAidlInterface.Stub.asInterface(service);}/*** 断开连接* @param name*/@Overridepublic void onServiceDisconnected(ComponentName name) {aidlInterface = null;}};@Overrideprotected void onCreate(Bundle savedInstanceState) {super.onCreate(savedInstanceState);setContentView(R.layout.activity_main);initView();bindAndStartService();}/*** 绑定服务*/private void bindAndStartService() {Intent intent = new Intent(this, MyService.class);intent.setAction("com.example.apple.myfragment");bindService(intent, connection, Context.BIND_AUTO_CREATE);startService(intent);}private void initView() {tvResult = (TextView)findViewById(R.id.tv_result);btnAdd = (Button)findViewById(R.id.btn_add);btnAdd.setOnClickListener(new View.OnClickListener() {@Overridepublic void onClick(View v) {try {if (aidlInterface!=null){tvResult.setText(aidlInterface.add(3,4)+"");}}catch (Exception e){e.printStackTrace();}}});btnReduce = (Button)findViewById(R.id.btn_reduce);btnReduce.setOnClickListener(new View.OnClickListener() {@Overridepublic void onClick(View v) {try {if (aidlInterface!=null){tvResult.setText(aidlInterface.reduce(5,3)+"");}}catch (Exception e){e.printStackTrace();}}});}@Overrideprotected void onDestroy() {unbindService(connection);super.onDestroy();}
}
<service android:name=".MyService"><intent-filter><action android:name="com.example.apple.myfragment"></action><category android:name="android.intent.category.DEFAULT"/></intent-filter></service>最后记得在build.gradl里面的android{}加入下面代码，以便实现对.aidl文件的调用。
sourceSets {main {java.srcDirs = ['src/main/java', 'src/main/aidl']}}实现效果
3、这里是activity调用service方法的实现。下面实现一下不同应用间的通信实现。上面的实现算是服务端，下面实现一下客户端代码
客户端的.aidl 文件直接拷贝服务端的就可以，保持好同样的路径，代码中实现需要注意的是在5.0以上的系统中启动服务需要用setPackage,否则报错，填写是服务端的包名，其他没什么注意的了。详细可以看下面代码：
/*** 绑定服务*/private void bindAndStartService() {Intent intent = new Intent();intent.setAction("com.example.apple.myfragment");intent.setPackage("com.example.apple.myfragment");bindService(intent, connection, Context.BIND_ABOVE_CLIENT);}
package com.example.apple.aidl;import android.content.ComponentName;
import android.content.Context;
import android.content.Intent;
import android.content.ServiceConnection;
import android.os.IBinder;
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.view.View;
import android.widget.Button;
import android.widget.TextView;import com.example.apple.aidlactivity.R;
import com.example.apple.myfragment.IMyAidlInterface;public class MainActivity extends AppCompatActivity {private Button btnAdd;private Button btnReduce;private TextView tvResult;private IMyAidlInterface aidlInterface;private ServiceConnection connection = new ServiceConnection() {@Overridepublic void onServiceConnected(ComponentName name, IBinder service) {aidlInterface = IMyAidlInterface.Stub.asInterface(service);}/*** 断开连接* @param name*/@Overridepublic void onServiceDisconnected(ComponentName name) {aidlInterface = null;}};@Overrideprotected void onCreate(Bundle savedInstanceState) {super.onCreate(savedInstanceState);setContentView(R.layout.activity_main);initView();bindAndStartService();}/*** 绑定服务*/private void bindAndStartService() {Intent intent = new Intent();intent.setAction("com.example.apple.myfragment");intent.setPackage("com.example.apple.myfragment");bindService(intent, connection, Context.BIND_ABOVE_CLIENT);}private void initView() {tvResult = (TextView)findViewById(R.id.tv_result);btnAdd = (Button)findViewById(R.id.btn_add);btnAdd.setOnClickListener(new View.OnClickListener() {@Overridepublic void onClick(View v) {// bindAndStartService();try {// if (aidlInterface!=null){tvResult.setText(aidlInterface.add(3,4)+"");// }}catch (Exception e){e.printStackTrace();}}});btnReduce = (Button)findViewById(R.id.btn_reduce);btnReduce.setOnClickListener(new View.OnClickListener() {@Overridepublic void onClick(View v) {try {if (aidlInterface!=null){tvResult.setText(aidlInterface.reduce(5,3)+"");}}catch (Exception e){e.printStackTrace();}}});}@Overrideprotected void onDestroy() {unbindService(connection);super.onDestroy();}
}
4、了解一下IMyAidlInterface里面的代码，就是服务端和客户端是如何建立关联的。服务端提供的服务是由IMyAidlInterface.Stub来执行，Stub这个类是Binder的子类，继承了binder的，而且mBinder实现了IMyAidlInterface接口的方法。
public interface IMyAidlInterface extends android.os.IInterface {/*** Local-side IPC implementation stub class.*/public static abstract class Stub extends android.os.Binder implements com.example.apple.myfragment.IMyAidlInterface {private static final java.lang.String DESCRIPTOR = "com.example.apple.myfragment.IMyAidlInterface";我们在.aidl文件里面添加的两个方法在这里都可以看到
@Overridepublic int add(int a, int b) throws android.os.RemoteException {android.os.Parcel _data = android.os.Parcel.obtain();android.os.Parcel _reply = android.os.Parcel.obtain();int _result;try {_data.writeInterfaceToken(DESCRIPTOR);_data.writeInt(a);_data.writeInt(b);mRemote.transact(Stub.TRANSACTION_add, _data, _reply, 0);_reply.readException();_result = _reply.readInt();} finally {_reply.recycle();_data.recycle();}return _result;}@Overridepublic int reduce(int a, int b) throws android.os.RemoteException {android.os.Parcel _data = android.os.Parcel.obtain();android.os.Parcel _reply = android.os.Parcel.obtain();int _result;try {_data.writeInterfaceToken(DESCRIPTOR);_data.writeInt(a);_data.writeInt(b);mRemote.transact(Stub.TRANSACTION_reduce, _data, _reply, 0);_reply.readException();_result = _reply.readInt();} finally {_reply.recycle();_data.recycle();}return _result;}}这个proxy实例传入了我们的binder驱动，并且封装了我们调用服务端的代码，客户端通过Binder驱动的transact（）方法调用服务端代码。
首先声明两个parce对象，一个用于传递数据，一个用于接收返回的数据。与服务端的enforceInterfac对应。
_data.writeInterfaceToken(DESCRIPTOR);_data.writeInt(a);_data.writeInt(b);mRemote.transact(Stub.TRANSACTION_reduce, _data, _reply, 0);最后读出我们服务端返回的数据，然后return。可以看到和服务端的onTransact基本是一行一行对应的。
/** This file is auto-generated. DO NOT MODIFY.* Original file: /Users/apple/Desktop/MyFragment/app/src/main/aidl/com/example/apple/myfragment/IMyAidlInterface.aidl*/
package com.example.apple.myfragment;
// Declare any non-default types here with import statementspublic interface IMyAidlInterface extends android.os.IInterface {/*** Local-side IPC implementation stub class.*/public static abstract class Stub extends android.os.Binder implements com.example.apple.myfragment.IMyAidlInterface {private static final java.lang.String DESCRIPTOR = "com.example.apple.myfragment.IMyAidlInterface";/*** Construct the stub at attach it to the interface.*/public Stub() {this.attachInterface(this, DESCRIPTOR);}/*** Cast an IBinder object into an com.example.apple.myfragment.IMyAidlInterface interface,* generating a proxy if needed.*/public static com.example.apple.myfragment.IMyAidlInterface asInterface(android.os.IBinder obj) {if ((obj == null)) {return null;}android.os.IInterface iin = obj.queryLocalInterface(DESCRIPTOR);if (((iin != null) && (iin instanceof com.example.apple.myfragment.IMyAidlInterface))) {return ((com.example.apple.myfragment.IMyAidlInterface) iin);}return new com.example.apple.myfragment.IMyAidlInterface.Stub.Proxy(obj);}@Overridepublic android.os.IBinder asBinder() {return this;}@Overridepublic 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_add: {data.enforceInterface(DESCRIPTOR);int _arg0;_arg0 = data.readInt();int _arg1;_arg1 = data.readInt();int _result = this.add(_arg0, _arg1);reply.writeNoException();reply.writeInt(_result);return true;}case TRANSACTION_reduce: {data.enforceInterface(DESCRIPTOR);int _arg0;_arg0 = data.readInt();int _arg1;_arg1 = data.readInt();int _result = this.reduce(_arg0, _arg1);reply.writeNoException();reply.writeInt(_result);return true;}}return super.onTransact(code, data, reply, flags);}private static class Proxy implements com.example.apple.myfragment.IMyAidlInterface {private android.os.IBinder mRemote;Proxy(android.os.IBinder remote) {mRemote = remote;}@Overridepublic android.os.IBinder asBinder() {return mRemote;}public java.lang.String getInterfaceDescriptor() {return DESCRIPTOR;}@Overridepublic int add(int a, int b) throws android.os.RemoteException {android.os.Parcel _data = android.os.Parcel.obtain();android.os.Parcel _reply = android.os.Parcel.obtain();int _result;try {_data.writeInterfaceToken(DESCRIPTOR);_data.writeInt(a);_data.writeInt(b);mRemote.transact(Stub.TRANSACTION_add, _data, _reply, 0);_reply.readException();_result = _reply.readInt();} finally {_reply.recycle();_data.recycle();}return _result;}@Overridepublic int reduce(int a, int b) throws android.os.RemoteException {android.os.Parcel _data = android.os.Parcel.obtain();android.os.Parcel _reply = android.os.Parcel.obtain();int _result;try {_data.writeInterfaceToken(DESCRIPTOR);_data.writeInt(a);_data.writeInt(b);mRemote.transact(Stub.TRANSACTION_reduce, _data, _reply, 0);_reply.readException();_result = _reply.readInt();} finally {_reply.recycle();_data.recycle();}return _result;}}static final int TRANSACTION_add = (android.os.IBinder.FIRST_CALL_TRANSACTION + 0);static final int TRANSACTION_reduce = (android.os.IBinder.FIRST_CALL_TRANSACTION + 1);}public int add(int a, int b) throws android.os.RemoteException;public int reduce(int a, int b) throws android.os.RemoteException;
}
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