[Android笔记] IPC系列之AIDL

出于玉刚的《Android开发艺术探索》2.3.3-Binder

Demo源码

• Book.java文件

  // 实体类
  package com.chen.interview.aidl;
  
  import android.os.Parcel;
  import android.os.Parcelable;
  
  public class Book implements Parcelable {
  
      private int id;
      private String name;
  
      public Book(int id, String name) {
          this.id = id;
          this.name = name;
      }
  
      public int getId() {
          return id;
      }
  
      public void setId(int id) {
          this.id = id;
      }
  
      public String getName() {
          return name;
      }
  
      public void setName(String name) {
          this.name = name;
      }
  
      @Override
      public int describeContents() {
          return 0;
      }
  
      @Override
      public void writeToParcel(Parcel dest, int flags) {
          dest.writeInt(this.id);
          dest.writeString(this.name);
      }
  
      protected Book(Parcel in) {
          this.id = in.readInt();
          this.name = in.readString();
      }
  
      public static final Parcelable.Creator<Book> CREATOR = new Parcelable.Creator<Book>() {
          @Override
          public Book createFromParcel(Parcel source) {
              return new Book(source);
          }
  
          @Override
          public Book[] newArray(int size) {
              return new Book[size];
          }
      };
  
      @Override
      public String toString() {
          return "Book{" +
                  "id=" + id +
                  ", name='" + name + '\'' +
                  '}';
      }
  }
  
  

• Book.aidl文件

  package com.chen.interview.aidl;
  parcelable Book;
  

• IBookManager.aidl文件

  // IMyService.aidl
  package com.chen.interview.aidl;
  import com.chen.interview.aidl.Book; // 注意：就算在同一个包名下也需手动导入
  
  // Declare any non-default types here with import statements
  
  interface IBookManager {
      List<Book> getBookList();
      void addBook(in Book book);
  }
  
  

• AS自动生成的IBookManager.java文件

  /*
   * This file is auto-generated.  DO NOT MODIFY.
   * Original file: /Users/zehua_chen/Android/work/wrokspace/android/work_as/Interview/app/src/main/aidl/com/chen/interview/aidl/IBookManager.aidl
   */
  package com.chen.interview.aidl;
  // Declare any non-default types here with import statements
  
  public interface IBookManager extends android.os.IInterface {
      /**
       * Local-side IPC implementation stub class.
       */
      public static abstract class Stub extends android.os.Binder implements com.chen.interview.aidl.IBookManager {
          // 唯一标识，一般用当前类名全称表示
          private static final java.lang.String DESCRIPTOR = "com.chen.interview.aidl.IBookManager";
  
          /**
           * Construct the stub at attach it to the interface.
           */
          public Stub() {
              this.attachInterface(this, DESCRIPTOR);
          }
  
          /**
           * 用户将服务端的Binder对象转换成客户端所需的AIDL接口类型额对象
           * 区分进程，如果服务端和客户端处于同一进程则返回服务端对象本身，否则返回Stub.Proxy对象
           *
           * Cast an IBinder object into an com.chen.interview.aidl.IBookManager interface,
           * generating a proxy if needed.
           */
          public static com.chen.interview.aidl.IBookManager asInterface(android.os.IBinder obj) {
              if ((obj == null)) {
                  return null;
              }
              android.os.IInterface iin = obj.queryLocalInterface(DESCRIPTOR);
              if (((iin != null) && (iin instanceof com.chen.interview.aidl.IBookManager))) {
                  // 同一进程
                  return ((com.chen.interview.aidl.IBookManager) iin);
              }
              // 不同进程
              return new com.chen.interview.aidl.IBookManager.Stub.Proxy(obj);
          }
  
          /**
           * 用于返回当前Binder对象
           *
           * @return Binder
           */
          @Override
          public android.os.IBinder asBinder() {
              return this;
          }
  
          /**
           * 该方法运行与服务端的Binder线程池中，客户端发起请求时，远程请求会通过系统底层封装后交给此方法处理
           * @param code 确定客户端请求的目标方法
           * @param data 可从data获取目标方法所需的参数
           * @param reply 方法执行完会向reply写入返回值（如果有返回值）
           * @param flags 一些额外的标识，0表示正常的PRC，如果为
           * {@link android.os.Binder#FLAG_ONEWAY}即为1，表示单向的RPC
           * @return 返回false则表示客户端请求失败
           * @throws android.os.RemoteException
           */
          @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<com.chen.interview.aidl.Book> _result = this.getBookList();
                      reply.writeNoException();
                      reply.writeTypedList(_result);
                      return true;
                  }
                  case TRANSACTION_addBook: {
                      data.enforceInterface(DESCRIPTOR);
                      com.chen.interview.aidl.Book _arg0;
                      if ((0 != data.readInt())) {
                          _arg0 = com.chen.interview.aidl.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 com.chen.interview.aidl.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;
              }
  
              /**
               * 运行在客户端
               * @return
               * @throws android.os.RemoteException
               */
              @Override
              public java.util.List<com.chen.interview.aidl.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<com.chen.interview.aidl.Book> _result;
                  try {
                      _data.writeInterfaceToken(DESCRIPTOR);
                      // transact发起RPC，当前线程挂起，然后服务端的onTransact方法会被调用
                      mRemote.transact(Stub.TRANSACTION_getBookList, _data, _reply, 0);
                      // 直到PRC过程返回后，当前线程继续执行，若远程方式是耗时的，勿在主线程发起RPC请求
                      _reply.readException();
                      // 从_reply获取返回的数据
                      _result = _reply.createTypedArrayList(com.chen.interview.aidl.Book.CREATOR);
                  } finally {
                      _reply.recycle();
                      _data.recycle();
                  }
                  return _result;
              }
  
              @Override
              public void addBook(com.chen.interview.aidl.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<com.chen.interview.aidl.Book> getBookList() throws android.os.RemoteException;
  
      public void addBook(com.chen.interview.aidl.Book book) throws android.os.RemoteException;
  }
  
  

IPC通信

• 服务端角色BookManagerService.java

  public class BookManagerService extends Service {
  
      private static final String TAG = "BMS";
  
      private CopyOnWriteArrayList<Book> mBookList = new CopyOnWriteArrayList<>();
  
      private Binder mBinder = new IBookManager.Stub() {
          @Override
          public List<Book> getBookList() throws RemoteException {
              return mBookList;
          }
  
          @Override
          public void addBook(Book book) throws RemoteException {
              mBookList.add(book);
          }
      };
  
      @Nullable
      @Override
      public IBinder onBind(Intent intent) {
          return mBinder;
      }
  
      @Override
      public void onCreate() {
          super.onCreate();
          mBookList.add(new Book(1, "java"));
          mBookList.add(new Book(2, "C++"));
          mBookList.add(new Book(3, "python"));
      }
  }
  

• 客户端角色MainActivity.java

  public class MainActivity extends Activity {
  
      private static final String TAG = "MainActivity";
  
      private ServiceConnection mConnection = new ServiceConnection() {
          @Override
          public void onServiceConnected(ComponentName name, IBinder service) {
              IBookManager bookManager = IBookManager.Stub.asInterface(service);
              try {
                  bookManager.addBook(new Book(4, "算法"));
                  List<Book> bookList = bookManager.getBookList();
                  Log.i(TAG, "list type: " + bookList.getClass().getCanonicalName());
                  Log.i(TAG, "list: " + bookList);
  
              } catch (RemoteException e) {
                  e.printStackTrace();
              }
  
          }
  
          @Override
          public void onServiceDisconnected(ComponentName name) {
  
          }
      };
  
      @Override
      protected void onCreate(Bundle savedInstanceState) {
          super.onCreate(savedInstanceState);
          setContentView(R.layout.activity_main);
  
          Intent intent = new Intent(this, BookManagerService.class);
          bindService(intent, mConnection, Context.BIND_AUTO_CREATE);
  
          findViewById(R.id.btn1).setOnClickListener(new View.OnClickListener() {
              @Override
              public void onClick(View v) {
                  startActivity(new Intent(MainActivity.this, ProviderActivity.class));
              }
          });
      }
  
      @Override
      protected void onDestroy() {
          unbindService(mConnection);
          super.onDestroy();
      }