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  • 自顶向下分析Binder【1】—— Binder实例篇

    欢迎转载，转载请注明：http://blog.csdn.net/zhgxhuaa


    一个Binder实例

    我们Binder的学习将从以下的一个实例開始。依据Android文档中的描写叙述，创建一个Binder服务主要包含例如以下3步：



    以下详细看一下在eclipse中是怎样开发一个Binder应用的。

    第一步：在project文件夹下定义aidl文件。

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    package com.zxh.ipc;
     
    import com.zxh.ipc.PermissionInfo;
     
    interface ITestManager{
        int checkPermission(String permName, String pkgName);
         
        int checkUidPermission(String permName, int uid);
         
        boolean addPermission(in PermissionInfo info);
         
        void removePermission(String name);
     
        boolean isProtectedBroadcast(String actionName);
    }

    第二步：在定义aidl后，eclipse在project文件夹的gen文件夹下会自己主动生成相应的接口，以下是有aidl自己主动生成的Java代码：

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    package com.zxh.ipc;
      
    public interface ITestManager extends android.os.IInterface
    {
        /** Local-side IPC implementation stub class. */
        public static abstract class Stub extends android.os.Binder implements com.zxh.ipc.ITestManager
        {
            private static final java.lang.String DESCRIPTOR = "com.zxh.ipc.ITestManager";
      
            /** Construct the stub at attach it to the interface. */
            public Stub()
            {
                this.attachInterface(this, DESCRIPTOR);
            }
      
            /**
             * Cast an IBinder object into an com.zxh.ipc.ITestManager interface, generating a proxy if needed.
             */
            public static com.zxh.ipc.ITestManager asInterface(android.os.IBinder obj)
            {
                if ((obj == null)) {
                    return null;
                }
                android.os.IInterface iin = obj.queryLocalInterface(DESCRIPTOR);
                if (((iin != null) && (iin instanceof com.zxh.ipc.ITestManager))) {
                    return ((com.zxh.ipc.ITestManager) iin);
                }
                return new com.zxh.ipc.ITestManager.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_checkPermission: {
                        data.enforceInterface(DESCRIPTOR);
                        java.lang.String _arg0;
                        _arg0 = data.readString();
                        java.lang.String _arg1;
                        _arg1 = data.readString();
                        int _result = this.checkPermission(_arg0, _arg1);
                        reply.writeNoException();
                        reply.writeInt(_result);
                        return true;
                    }
                    case TRANSACTION_checkUidPermission: {
                        data.enforceInterface(DESCRIPTOR);
                        java.lang.String _arg0;
                        _arg0 = data.readString();
                        int _arg1;
                        _arg1 = data.readInt();
                        int _result = this.checkUidPermission(_arg0, _arg1);
                        reply.writeNoException();
                        reply.writeInt(_result);
                        return true;
                    }
                    case TRANSACTION_addPermission: {
                        data.enforceInterface(DESCRIPTOR);
                        com.zxh.ipc.PermissionInfo _arg0;
                        if ((0 != data.readInt())) {
                            _arg0 = com.zxh.ipc.PermissionInfo.CREATOR.createFromParcel(data);
                        }
                        else {
                            _arg0 = null;
                        }
                        boolean _result = this.addPermission(_arg0);
                        reply.writeNoException();
                        reply.writeInt(((_result) ? (1) : (0)));
                        return true;
                    }
                    case TRANSACTION_removePermission: {
                        data.enforceInterface(DESCRIPTOR);
                        java.lang.String _arg0;
                        _arg0 = data.readString();
                        this.removePermission(_arg0);
                        reply.writeNoException();
                        return true;
                    }
                    case TRANSACTION_isProtectedBroadcast: {
                        data.enforceInterface(DESCRIPTOR);
                        java.lang.String _arg0;
                        _arg0 = data.readString();
                        boolean _result = this.isProtectedBroadcast(_arg0);
                        reply.writeNoException();
                        reply.writeInt(((_result) ? (1) : (0)));
                        return true;
                    }
                }
                return super.onTransact(code, data, reply, flags);
            }
      
            private static class Proxy implements com.zxh.ipc.ITestManager
            {
                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;
                }
      
                @Override
                public int checkPermission(java.lang.String permName, java.lang.String pkgName)
                        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.writeString(permName);
                        _data.writeString(pkgName);
                        mRemote.transact(Stub.TRANSACTION_checkPermission, _data, _reply, 0);
                        _reply.readException();
                        _result = _reply.readInt();
                    } finally {
                        _reply.recycle();
                        _data.recycle();
                    }
                    return _result;
                }
      
                @Override
                public int checkUidPermission(java.lang.String permName, int uid) 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.writeString(permName);
                        _data.writeInt(uid);
                        mRemote.transact(Stub.TRANSACTION_checkUidPermission, _data, _reply, 0);
                        _reply.readException();
                        _result = _reply.readInt();
                    } finally {
                        _reply.recycle();
                        _data.recycle();
                    }
                    return _result;
                }
      
                @Override
                public boolean addPermission(com.zxh.ipc.PermissionInfo info) throws android.os.RemoteException
                {
                    android.os.Parcel _data = android.os.Parcel.obtain();
                    android.os.Parcel _reply = android.os.Parcel.obtain();
                    boolean _result;
                    try {
                        _data.writeInterfaceToken(DESCRIPTOR);
                        if ((info != null)) {
                            _data.writeInt(1);
                            info.writeToParcel(_data, 0);
                        }
                        else {
                            _data.writeInt(0);
                        }
                        mRemote.transact(Stub.TRANSACTION_addPermission, _data, _reply, 0);
                        _reply.readException();
                        _result = (0 != _reply.readInt());
                    } finally {
                        _reply.recycle();
                        _data.recycle();
                    }
                    return _result;
                }
      
                @Override
                public void removePermission(java.lang.String name) throws android.os.RemoteException
                {
                    android.os.Parcel _data = android.os.Parcel.obtain();
                    android.os.Parcel _reply = android.os.Parcel.obtain();
                    try {
                        _data.writeInterfaceToken(DESCRIPTOR);
                        _data.writeString(name);
                        mRemote.transact(Stub.TRANSACTION_removePermission, _data, _reply, 0);
                        _reply.readException();
                    } finally {
                        _reply.recycle();
                        _data.recycle();
                    }
                }
      
                @Override
                public boolean isProtectedBroadcast(java.lang.String actionName) throws android.os.RemoteException
                {
                    android.os.Parcel _data = android.os.Parcel.obtain();
                    android.os.Parcel _reply = android.os.Parcel.obtain();
                    boolean _result;
                    try {
                        _data.writeInterfaceToken(DESCRIPTOR);
                        _data.writeString(actionName);
                        mRemote.transact(Stub.TRANSACTION_isProtectedBroadcast, _data, _reply, 0);
                        _reply.readException();
                        _result = (0 != _reply.readInt());
                    } finally {
                        _reply.recycle();
                        _data.recycle();
                    }
                    return _result;
                }
            }
      
            static final int TRANSACTION_checkPermission = (android.os.IBinder.FIRST_CALL_TRANSACTION + 0);
            static final int TRANSACTION_checkUidPermission = (android.os.IBinder.FIRST_CALL_TRANSACTION + 1);
            static final int TRANSACTION_addPermission = (android.os.IBinder.FIRST_CALL_TRANSACTION + 2);
            static final int TRANSACTION_removePermission = (android.os.IBinder.FIRST_CALL_TRANSACTION + 3);
            static final int TRANSACTION_isProtectedBroadcast = (android.os.IBinder.FIRST_CALL_TRANSACTION + 4);
        }
      
        public int checkPermission(java.lang.String permName, java.lang.String pkgName) throws android.os.RemoteException;
      
        public int checkUidPermission(java.lang.String permName, int uid) throws android.os.RemoteException;
      
        public boolean addPermission(com.zxh.ipc.PermissionInfo info) throws android.os.RemoteException;
      
        public void removePermission(java.lang.String name) throws android.os.RemoteException;
      
        public boolean isProtectedBroadcast(java.lang.String actionName) throws android.os.RemoteException;
    }

    第三步：继承上一步生成的接口，实现自己的Service类：

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    package com.zxh.server;
     
    import android.app.Service;
    import android.content.Intent;
    import android.content.ServiceConnection;
    import android.os.IBinder;
    import android.os.RemoteException;
    import android.util.Log;
    import com.zxh.ipc.ITestManager;
     
    import com.zxh.ipc.PermissionInfo;
    public class TestService extends Service{
        private final static String TAG = "zxh";
     
        class TestManagerService extends ITestManager.Stub{
             
            @Override
            public int checkPermission(String permName, String pkgName)
                    throws RemoteException {
                Log.i(TAG, "checkPermission server");
                return 0;
            }
     
            @Override
            public int checkUidPermission(String permName, int uid)
                    throws RemoteException {
                Log.i(TAG, "checkUidPermission server");
                return 0;
            }
     
            @Override
            public boolean addPermission(PermissionInfo info) throws RemoteException {
                Log.i(TAG, "addPermission server");
                return false;
            }
     
            @Override
            public void removePermission(String name) throws RemoteException {
                Log.i(TAG, "removePermission server");
            }
     
     
            @Override
            public boolean isProtectedBroadcast(String actionName)
                    throws RemoteException {
                Log.i(TAG, "isProtectedBroadcast server");
                return false;
            }
        }
         
         
        private TestManagerService mService = new TestManagerService();
         
        @Override
        public IBinder onBind(Intent intent) {
            Log.i("zxh", "unbindService");
            return mService;
        }
         
        @Override
        public void unbindService(ServiceConnection conn) {
            super.unbindService(conn);
            Log.i("zxh", "unbindService");
        }
    }

    第四步：实现client代码：

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    package com.zxh.server;
     
    import android.app.Activity;
    import android.app.Service;
    import android.content.ComponentName;
    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.View;
    import android.view.View.OnClickListener;
     
    import com.zxh.ipc.ITestManager;
     
    public class MainActivity extends Activity {
     
        private ITestManager manager = null;
         
        ServiceConnection connection = new ServiceConnection() {
            @Override
            public void onServiceDisconnected(ComponentName name) {
                Log.i("binder", "onServiceDisconnected");
            }
             
            @Override
            public void onServiceConnected(ComponentName name, IBinder service) {
                manager = ITestManager.Stub.asInterface(service);
            }
        };
         
        @Override
        protected void onCreate(Bundle savedInstanceState) {
            super.onCreate(savedInstanceState);
            setContentView(R.layout.activity_main);
            findViewById(R.id.startServer).setOnClickListener(new OnClickListener() {
                @Override
                public void onClick(View v) {
                    bindService(new Intent(MainActivity.this, TestService.class), connection, Service.BIND_AUTO_CREATE);
                }
            });
             
            findViewById(R.id.stop).setOnClickListener(new OnClickListener() {
                @Override
                public void onClick(View v) {
                    unbindService(connection);
                }
            });
             
            findViewById(R.id.check).setOnClickListener(new OnClickListener() {
                @Override
                public void onClick(View v) {
                    try {
                        manager.checkPermission("permName", "pkgName");
                    } catch (RemoteException e) {
                        e.printStackTrace();
                    }
                }
            });
        }
    }

    到这里我们就实现了一个完整的Binder实例，以下是project文件夹的截图：



    完整代码能够查看后面的附件。以下来介绍一下这个实例中涉及到的一些知识点。

    AIDL

    除了eclipse，也能够使用Android开发包中提供的aidl命令工具来生成，例如以下是adil命令：



    关于adil的具体介绍能够查看Android官方文档，地址为：http://developer.android.com/intl/zh-cn/guide/components/aidl.html

    想要了解aidl处理过程的朋友也能够自己查看aidl的源码，位于@/frameworks/base/tools/adil。

    AIDL编译产生的类

    以下我们来分析一下aidl编译产生的ITestManager类。

    从ITestManager中能够看出，ITestManager实现了IInterface接口。在ITestManager类中共包括了三部分内容，各自是：

    • 我们在ITestManager.adil中定义的接口。

    • Stub类：主要由Server端实现，Server端通过继承本类，来提供详细的处理逻辑。

    • Proxy类：client代理，通过mRemote成员变量訪问远程Binder服务。

    为了实现我们在ITestManager自定义接口的跨进程通信，Stub类和Proxy都实现了ITestManager接口。Stub自己继承了Binder类来实现Binder机制，Proxy则以引用的方式实现Binder机制。

    client和服务端的通信主要通过onTransact方法实现，client和服务端的数据传递通过Parcel类完毕。这里须要注意一个问题：就是在client写入数据的顺序与在服务端读取数据的顺序必须是一致的。

    尽管在上面的实现中，我们定义了一个Service类TestService，但这里要说明的是Service甚至adil都不是必须的，使用者全然能够自定义。
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  • 原文地址：https://www.cnblogs.com/hrhguanli/p/4002381.html
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