首页 > 代码库 > 自顶向下分析Binder【1】—— Binder实例篇

自顶向下分析Binder【1】—— Binder实例篇

2024-07-09 07:47:46   223人阅读

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


一个Binder实例

我们Binder的学习将从下面的一个实例开始。根据Android文档中的描述，创建一个Binder服务主要包括如下3步：



下面具体看一下在eclipse中是如何开发一个Binder应用的。

第一步：在工程目录下定义aidl文件。

1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
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在工程目录的gen目录下会自动生成对应的接口，下面是有aidl自动生成的Java代码：

1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
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 = http://www.mamicode.com/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 = http://www.mamicode.com/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 = http://www.mamicode.com/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 = http://www.mamicode.com/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 = http://www.mamicode.com/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：

1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
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：实现客户端代码：

1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
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，下面是工程目录的截图：



完整代码可以查看后面的附件。下面来介绍一下这个实例中涉及到的一些知识点。

AIDL

除了eclipse，也可以使用Android开发包中提供的aidl命令工具来生成，如下是adil命令：



关于adil的详细介绍可以查看Android官方文档，地址为：http://developer.android.com/intl/zh-cn/guide/components/aidl.html

想要了解aidl处理过程的朋友也可以自己查看aidl的源代码，位于@/frameworks/base/tools/adil。

AIDL编译产生的类

下面我们来分析一下aidl编译产生的ITestManager类。

从ITestManager中可以看出，ITestManager实现了IInterface接口。在ITestManager类中共包含了三部分内容，分别是：

  • 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，来提供具体的处理逻辑。

  • Proxy类：客户端代理，通过mRemote成员变量访问远程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。

客户端和服务端的通信主要通过onTransact方法实现，客户端和服务端的数据传递通过Parcel类完成。这里需要注意一个问题：就是在客户端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。

虽然在上面的实现中，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，使用者完全可以自己定义。


联系
我们