由于自己搭建了博客最近都没有在csdn发过博客了，现在发一篇自己的学习笔记，具体内容参照：

Android的IPC机制

Inter-Process Communication => 进程间通信

app多进程的开启

在定义四大组件时添加如下属性：

android:process=":remote"android:process="io.github.grooters.remote"

:remote指当前app的包名.remote，为私有进程

由于开启多进程后，处于不同进程的组件会导致数据无法通信问题，故需要通过以下方式实现IPC

Serializable

实现Serializable接口的类可通过Intent和Binder进行传递

private static final long serialVersionUID = 42L;

该长整形静态常量用于辅助序列化与反序列化操作，通过识别该id可判断对象是否发生改变

eg:

public class Serializabler implement Serializable{  private static final long serialVersionUID = 42L;  private int id;  private String name;  public String getName() {    return name;  }  public void setName(String name) {      this.name = name;  }  public int getId() {      return id;  }  public void setId(int id) {      this.id = id;  }}

传递对象：

bundle.putSerializable("key",serializabler);intent.putExtra("key",bundle);

写出/读入对象：

try {    ObjectOutputStream outputStream = new ObjectOutputStream(new FileOutputStream(new File(Environment.getExternalStorageDirectory().getAbsolutePath()+"/test.text")));    outputStream.writeObject(serializabler);}catch (IOException e){    e.printStackTrace();}

Parceleable

需要重写四个方法：

public int describeContents()

内容描述，无描述返回0，有描述返回CONTENTS_FILE_DESCRIPTOR（1）

public abstract void writeToParcel（Parcel dest，int flags）

序列化方法

[Parcelable.Creator](https://developer.android.google.cn/reference/android/os/Parcelable.Creator)

需要实现的接口，包括以下方法：

public abstract T createFromParcel（Parcel source）

反序列化

public abstract T [] newArray（int size）

创建一个Parceleable类型的新数组

eg:

package io.github.grooters.practicer;import android.os.Parcel;import android.os.Parcelable;/** * Create by 李林浪 in 2018/10/24 * Elegant Code... */public class Parceleabler implements Parcelable {    private String name;    private int id;    private int sex;    public String getName() {        return name;    }    public void setName(String name) {        this.name = name;    }    public int getId() {        return id;    }    public void setId(int id) {        this.id = id;    }    public int getSex() {        return sex;    }    public void setSex(int sex) {        this.sex = sex;    }    public static final Parcelable.Creator<Parceleabler> CREATOR=new Parcelable.Creator<Parceleabler>(){        @Override        public Parceleabler createFromParcel(Parcel source) {            Parceleabler parceleabler=new Parceleabler();            //顺序要和序列化的write操作一样            parceleabler.setId(source.readInt());            parceleabler.setName(source.readString());            parceleabler.setSex(source.readInt());            return parceleabler;        }        @Override        public Parceleabler[] newArray(int size) {            return new Parceleabler[size];        }    };    @Override    public int describeContents() {        return 0;    }    @Override    public void writeToParcel(Parcel dest, int flags) {        dest.writeInt(id);        dest.writeString(name);        dest.writeInt(sex);    }}

传递和写出读入方法和Serializable方法相同

Binder

Android 接口定义语言 (AIDL)

新建一个AIDL文件系统会自动生成对应的java文件，eg：

IBookManager.aidl：

// IBookManager.aidlpackage io.github.grooters.practicer.BindeRer;import io.github.grooters.practicer.BindeRer.Book;// Declare any non-default types here with import statementsinterface IBookManager {    /**     * Demonstrates some basic types that you can use as parameters     * and return values in AIDL.     */     List<Book> getBookList();     void addBook(in Book book);}

IBookManager.java：

/* * This file is auto-generated.  DO NOT MODIFY. * Original file: D:\\Android\\Source\\Practicer\\app\\src\\main\\aidl\\io\\github\\grooters\\practicer\\BindeRer\\IBookManager.aidl */package io.github.grooters.practicer.BindeRer;// Declare any non-default types here with import statementspublic interface IBookManager extends android.os.IInterface {/** Local-side IPC implementation stub class. */    public static abstract class Stub extends android.os.Binder implements io.github.grooters.practicer.BindeRer.IBookManager {        private static final java.lang.String DESCRIPTOR = "io.github.grooters.practicer.BindeRer.IBookManager";        /** Construct the stub at attach it to the interface. */        public Stub(){          this.attachInterface(this, DESCRIPTOR);        }        /**         * Cast an IBinder object into an io.github.grooters.practicer.BindeRer.IBookManager interface,         * generating a proxy if needed.         */        public static io.github.grooters.practicer.BindeRer.IBookManager asInterface(android.os.IBinder obj) {            if ((obj==null)) {                return null;            }            android.os.IInterface iin = obj.queryLocalInterface(DESCRIPTOR);            if (((iin!=null)&&(iin instanceof io.github.grooters.practicer.BindeRer.IBookManager))) {                return ((io.github.grooters.practicer.BindeRer.IBookManager)iin);            }            return new io.github.grooters.practicer.BindeRer.IBookManager.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_getBookList: {                    data.enforceInterface(DESCRIPTOR);                    java.util.List<io.github.grooters.practicer.BindeRer.Book> _result = this.getBookList();                    reply.writeNoException();                    reply.writeTypedList(_result);                    return true;                }                case TRANSACTION_addBook: {                    data.enforceInterface(DESCRIPTOR);                    io.github.grooters.practicer.BindeRer.Book _arg0;                    if ((0!=data.readInt())) {                        _arg0 = io.github.grooters.practicer.BindeRer.Book.CREATOR.createFromParcel(data);                    }                    else {                        _arg0 = null;                    }                    this.addBook(_arg0);                    reply.writeNoException();                    return true;                }            }            return super.onTransact(code, data, reply, flags);        }        private static class Proxy implements io.github.grooters.practicer.BindeRer.IBookManager {            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;            }            /**             * Demonstrates some basic types that you can use as parameters             * and return values in AIDL.             */            @Override            public java.util.List<io.github.grooters.practicer.BindeRer.Book> getBookList() throws android.os.RemoteException {                android.os.Parcel _data = android.os.Parcel.obtain();                android.os.Parcel _reply = android.os.Parcel.obtain();                java.util.List<io.github.grooters.practicer.BindeRer.Book> _result;                try {                    _data.writeInterfaceToken(DESCRIPTOR);                    mRemote.transact(Stub.TRANSACTION_getBookList, _data, _reply, 0);                    _reply.readException();                    _result = _reply.createTypedArrayList(io.github.grooters.practicer.BindeRer.Book.CREATOR);                }                finally {                    _reply.recycle();                    _data.recycle();                }                return _result;            }            @Override            public void addBook(io.github.grooters.practicer.BindeRer.Book book) throws android.os.RemoteException            {                android.os.Parcel _data = android.os.Parcel.obtain();                android.os.Parcel _reply = android.os.Parcel.obtain();                try {                    _data.writeInterfaceToken(DESCRIPTOR);                    if ((book!=null)) {                        _data.writeInt(1);                        book.writeToParcel(_data, 0);                    }                    else {                        _data.writeInt(0);                    }                    mRemote.transact(Stub.TRANSACTION_addBook, _data, _reply, 0);                    _reply.readException();                }                finally {                    _reply.recycle();                    _data.recycle();                }            }        }        static final int TRANSACTION_getBookList = (android.os.IBinder.FIRST_CALL_TRANSACTION + 0);        static final int TRANSACTION_addBook = (android.os.IBinder.FIRST_CALL_TRANSACTION + 1);    }  public java.util.List<io.github.grooters.practicer.BindeRer.Book> getBookList() throws android.os.RemoteException;      public void addBook(io.github.grooters.practicer.BindeRer.Book book) throws android.os.RemoteException;}

asInterface (android.os.IBinder obj)

将服务端Binder对象转换成客户端所需的AIDL接口类型的对象，若客户端和服务端在不同进程，则返回的是Stub.Proxy ：

android.os.IInterface iin = obj.queryLocalInterface(DESCRIPTOR);if (((iin!=null)&&(iin instanceof io.github.grooters.practicer.BindeRer.IBookManager))) {    return ((io.github.grooters.practicer.BindeRer.IBookManager)iin);}return new io.github.grooters.practicer.BindeRer.IBookManager.Stub.Proxy(obj);

android.os.IBinder asBinder()

返回当前的Binder对象（实现了IBinder接口）

onTransact(int code, android.os.Parcel data, android.os.Parcel reply, int flags)

运行在服务端的Binder线程池中，当跨进程访问时会通过code判断出使用哪个方法，当方法执行后，会将_result结果写入到reply中：

java.util.List<io.github.grooters.practicer.BindeRer.Book> _result = this.getBookList();reply.writeNoException();reply.writeTypedList(_result);return true;

当返回false时表示请求失败

客户端定义的方法（getBookList，addBook）

方法中含有输入Paecel对象_data，输出Parcel对象_reply和返回值对象，其中方法参数会写入_data对象，然后调用transact方法发起RPC(远程过程调用)请求，此时该线程会挂起，直到onTransact中对应的方法执行并返回reply才会重写激活线程，此时可从_reply中获取对应的结果

Binder工作机制：

跨进程方式

Messenger

客户端：

Intent intent=new Intent(this,Servicer.class);bindService(intent,serviceConnection, Context.BIND_AUTO_CREATE);ServiceConnection serviceConnection=new ServiceConnection() {    @Override    public void onServiceConnected(ComponentName name, IBinder service) {        Messenger reply=new Messenger(new MessengerHandler());        Messenger messenger=new Messenger(service);        Message msg=Message.obtain();        msg.replyTo=reply;        try {            messenger.send(msg);        } catch (RemoteException e) {            e.printStackTrace();        }    }    @Override    public void onServiceDisconnected(ComponentName name) {}};private static class MessengerHandler extends Handler{    @Override    public void handleMessage(Message msg) {        super.handleMessage(msg);        Log.i(TAG,"handleMessage");    }}

创建一个绑定了Binder的Messenger对象用于发送消息，再创建一个绑定了MessengerHandler的Messenger对象并作为replyTo传过给服务端。

服务端：

public class Servicer extends Service {    @Override    public int onStartCommand(Intent intent, int flags, int startId) {        return super.onStartCommand(intent, flags, startId);    }    private static class MessagerHandler extends Handler{        @Override        public void handleMessage(Message msg) {            super.handleMessage(msg);            Messenger client=msg.replyTo;            Message message=Message.obtain();            try {                client.send(message);            } catch (RemoteException e) {                e.printStackTrace();            }        }    }    Messenger messenger=new Messenger(new MessagerHandler());    @Nullable    @Override    public IBinder onBind(Intent intent) {        return messenger.getBinder();    }    @Override    public boolean onUnbind(Intent intent) {        return super.onUnbind(intent);    }}

服务端收到消息后从Message中取出客户端存入的replyTo即绑定了客户端Handler的Messenger对象，通过该对象服务端可以向客户端发送消息。

AIDL

服务端：

public class Servicer extends Service {  IBinder iBookManager=new IBookManager.Stub() {      @Override      public List<Book> getBookList() throws RemoteException {          Log.i(TAG,"getBookList()");          return null;      }      @Override      public void addBook(Book book) throws RemoteException {          Log.i(TAG,"book.id："+book.getId());      }      @Override      public IBinder asBinder() {          return this;      }  };}

实例化通过AIDL定义自动生成的Java类中的内部类IBookManager.Stub，实现提供给客户端调用的方法

客户端：

Intent intent=new Intent(this,Servicer.class);ServiceConnection serviceConnection=new ServiceConnection() {    @Override    public void onServiceConnected(ComponentName name, IBinder service) {        Log.i(TAG,"onServiceConnected");        IBookManager bookManager=IBookManager.Stub.asInterface(service);        try {            final Book book=new Book();            book.setId(5);            bookManager.addBook(book);        } catch (RemoteException e) {            e.printStackTrace();        }    }    @Override    public void onServiceDisconnected(ComponentName name) {}};

通过调用IBookManager.Stub类中的asInterface方法传入服务端返回的IBinder对象获得IBookManager对象，通过该对象便可调用服务端方法

RemoteCallbackList

由于跨进程通讯，从客户端传到服务端的对象会被重建（序列化和反序列化），所以无法通过简单的对象判断来识别是否是同一个对象，针对某种情况需要注销对某个listener的监听(如监听者模式)，该类就提供了解决方案

private RemoteCallbackList<BookArrivedListener> bookArrivedListeners=new RemoteCallbackList<>();@Overridepublic void registerListener(BookArrivedListener listener) throws RemoteException {    bookArrivedListeners.register(listener);}@Overridepublic void unRegisterListener(BookArrivedListener listener) throws RemoteException {    bookArrivedListeners.unregister(listener);}

该类为map结构实现对listnner的存储，通过IBinder作为key值，通过Callback保存listnner后作为value：

IBinder key=listner.asBinder()Callback value=new Callback(listener,cookies)

权限验证

在onBinder中验证

服务端：

<permission android:name="io.github.grooters.practicer.BindeRer.ACCESS_BOOK"    android:protectionLevel="normal"/>

@Nullable@Overridepublic IBinder onBind(Intent intent) {    Log.i(TAG,"onBind");    int check=checkCallingOrSelfPermission("io.github.grooters.practicer.BindeRer.ACCESS_BOOK");    if(check==PackageManager.PERMISSION_DENIED){        Log.i(TAG,"check==PackageManager.PERMISSION_DENIED");        return null;    }    return iBookManager;}

checkCallingOrSelfPermission判断是否具有某项权限，有返回0，没有返回1

PackageManager.PERMISSION_DENIED指不具备该权限

PackageManager.PERMISSION_GRANTED指具备该权限

客户端：

<uses-permission android:name="io.github.grooters.practicer.BindeRer.ACCESS_BOOK"/>

在onBinder中验证

服务端：

@Overridepublic boolean onTransact(int code, Parcel data, Parcel reply, int flags) throws RemoteException {    int check = checkCallingPermission("io.github.grooters.practicer.BindeRer.ACCESS_BOOK");    if(check == PackageManager.PERMISSION_DENIED){        return false;    }    return super.onTransact(code, data, reply, flags);}

深入了解Binder可参看这篇文章：

Android跨进程通信：图文详解 Binder机制原理

ContentProvider

具体参考内容提供器的使用

Android的IPC机制