AIDL使用1 – 简单通信

AIDL使用1 – 简单通信

终于又有活儿干了。
监控网速。可以提供给其他app。涉及到IPC，bound service不再适用。这里就用上了AIDL。
AIDL简介详见官方文档：http://developer.android.com/intl/zh-cn/guide/components/aidl.html
这里主要简单介绍一下基本用法（复杂的用法留到下篇再讲）：

---

服务端创建AIDL：

package com.meizu.flyme.tv.bandwithmonitor;

// Declare any non-default types here with import statements

// 有参数的情况会略有不同，这个下篇再讲
interface IMonitorService {
    long getBandwidth();   // 返回带宽。单位KB/s。下同
    long getRealTimeSpeed();  // 返回实时网速
}

可以看到，AS为我们自动生成了一些类：

生成的类中，最重要的是IMonitorService.Stub。在服务端，我们要重载这个类，需要重载的方法和对应aidl文件中声明的方法一样，如下：

private IMonitorService.Stub mStub = new IMonitorService.Stub() {
        @Override
        public long getBandwidth() throws RemoteException {
            return 0;
        }

        @Override
        public long getRealTimeSpeed() throws RemoteException {
            return 0;
        }
    };

都对应Stub中重载的方法完全和aidl中声明的一样。这样，我们便能控制返回给客户端的结果。

---

下面看看客户端需要做些什么：
1.将服务端中的aidl文件拷贝到客户端的工程中。对于这个例子，则是把PROJECT_PATH/app/src/main/aidl/com/robert/bandwidthmonitor中的com/robert/bandwidthmonitor/IMonitorService.aidl拷贝了到CLIENT_ROOT_PATH/app/src/main/aidl下。
2.和通常的绑定服务一样，不过在SerivceConnection.onServiceConnected中调用IMonitorService.Stub.asInterface(Binder)得到Service。如下：

    private IMonitorService mService;
    private ServiceConnection mConnection = new ServiceConnection() {
        @Override
        public void onServiceConnected(ComponentName componentName, IBinder iBinder) {
            KLog.e();
            mService =  IMonitorService.Stub.asInterface(iBinder);

            setupTimer();
        }

        @Override
        public void onServiceDisconnected(ComponentName componentName) {
        }
    };

---

下面是具体代码：

服务端

下面看一下服务端（接受请求的一端）是怎么实现逻辑的（忽略监听网络的逻辑）：

package com.robert.bandwidthmonitor.service;

public class MonitorService extends Service {
    private static final int SAMPLE_PERIOD_TIME = 1000;
    private static final int DOWNLOAD_TEST_TIME = 15000; // 15s

    private long mBandwidth = 0;
    private long mCurrentSpeed = 0;

    private Timer mTimer;
    private long mLastRecv = 0;

    // 最重要的是这个Stub
    private IMonitorService.Stub mStub = new IMonitorService.Stub() {
        @Override
        public long getBandwidth() throws RemoteException {
            return mBandwidth;
        }

        @Override
        public long getRealTimeSpeed() throws RemoteException {
            return mCurrentSpeed;
        }
    };

    public static Intent newIntent(Context context) {
        return new Intent(context, MonitorService.class);
    }

    @Override
    public IBinder onBind(Intent intent) {
        KLog.e();
        return mStub;
    }

    @Override
    public void onCreate() {
        super.onCreate();
        KLog.e();

        mTimer = new Timer("MonitorTimer");
        mTimer.schedule(new TimerTask() {
            @Override
            public void run() {
                calculateRealTimeSpeed();
            }
        }, 1000, SAMPLE_PERIOD_TIME);     // sample frequency: 1s

        initBandwidth();
    }

    @Override
    public int onStartCommand(Intent intent, int flags, int startId) {
        return START_STICKY;
    }

    @Override
    public void onDestroy() {
        KLog.d();
        if (mTimer != null) {
            mTimer.cancel();
        }
    }

    private void initBandwidth() {
        startTestTask();
    }



    private void startTestTask() {
        KLog.e();
        new StatCollectTask().execute("https://qd.myapp.com/myapp/qqteam/AndroidQQ/mobileqq_android.apk");  // 下载qq apk
    }

    private void calculateRealTimeSpeed() {
        long cur = TrafficStats.getTotalRxBytes();
        mCurrentSpeed = (cur - mLastRecv) / SAMPLE_PERIOD_TIME;
        mLastRecv = cur;
    }


    private class StatCollectTask extends AsyncTask<String, Void, Long> {
        private String urlString;

        @Override
        protected Long doInBackground(String... strings) {
            urlString = strings[0];

            Timer timer = new Timer("FinishTaskTimer");
            timer.schedule(new TimerTask() {
                @Override
                public void run() {
                    StatCollectTask.this.cancel(true);
                }
            }, DOWNLOAD_TEST_TIME);

            try {
                URL url = new URL(urlString);
                long start = System.currentTimeMillis();
                int tot = 0;
                while (isCancelled() == false) {
                    tot += readBytes(url);
                }
                long end = System.currentTimeMillis();
                KLog.d("read bytes: " + tot / 1024);
                return tot / ((end - start) / 1000);
            } catch (MalformedURLException e) {
                KLog.e();
            } catch (IOException e) {
                e.printStackTrace();
            } finally {
                timer.cancel();
            }
            return null;
        }

        @Override
        protected void onCancelled(Long aLong) {
            processResult(aLong);
        }

        @Override
        protected void onPostExecute(Long aLong) {
            processResult(aLong);
        }

        // on ui thread
        private void processResult(Long aLong) {
            if (aLong != null) {
                mBandwidth = aLong / 1024;
                KLog.e("finish download test. result: " + mBandwidth + " KB/s");
            }
        }

        private int readBytes(URL url) throws IOException {
            KLog.e("execute downloading: " + url);
            URLConnection conn = url.openConnection();
            conn.setUseCaches(false);
            InputStream in = conn.getInputStream();
            int cnt = 0;
            try {
                int bytesRead = 0;
                byte[] buffer = new byte[1024 * 1024];     // 1MB
                while ((bytesRead = in.read(buffer)) != -1) {
                    cnt += bytesRead;
                    if (isCancelled()) {
                        break;
                    }
                }
            } finally {
                in.close();
            }
            return cnt;
        }
    }
}

AndroidManifest.xml

<manifest package="com.robert.bandwidthmonitor"
          xmlns:android="http://schemas.android.com/apk/res/android">

    <uses-permission android:name="android.permission.INTERNET"/>
    <uses-permission android:name="android.permission.RECEIVE_BOOT_COMPLETED"/>
    <uses-permission android:name="android.permission.ACCESS_NETWORK_STATE"/>

    <application
        android:allowBackup="true"
        android:icon="@mipmap/ic_launcher"
        android:label="@string/app_name"
        android:supportsRtl="true"
        android:theme="@style/AppTheme">



        <service
            android:name=".service.MonitorService"
            android:enabled="true"
            android:exported="true"
            android:process=":remote">
            <intent-filter>
                <action android:name="com.robert.bandwidthmonitor.service.IMonitorService"/>
            intent-filter>
        service>

    application>

manifest>

注意service的android:process属性。(:remote为BandwidthMonitor创建了一个私有进程，如果没有冒号，则代表创建一个全局的进程，名字就是remote。名字应该避免冲突。)

---

客户端代码：

public class AIDLActivity extends AppCompatActivity {
    private TextView mBandwidth;
    private TextView mSpeed;
    private Timer mTimer;
    private IMonitorService mService;
    private ServiceConnection mConnection = new ServiceConnection() {
        @Override
        public void onServiceConnected(ComponentName componentName, IBinder iBinder) {
            KLog.e();
            mService =  IMonitorService.Stub.asInterface(iBinder);

            setupTimer();
        }

        @Override
        public void onServiceDisconnected(ComponentName componentName) {
        }
    };

    private void setupTimer() {
        mTimer = new Timer("speed");
        mTimer.schedule(new TimerTask() {
            @Override
            public void run() {
                try {
                    final long speed = mService.getRealTimeSpeed();
                    final long max = mService.getBandwidth();
                    runOnUiThread(new Runnable() {
                        @Override
                        public void run() {
                            mSpeed.setText("speed: " + speed + "KB/s");
                            mBandwidth.setText("bandwidth: " + max + "KB/s");
                        }
                    });
                } catch (DeadObjectException e) {
                  e.printStackTrace();
                } catch (RemoteException e) {
                    e.printStackTrace();
                }
            }
        }, 1000, 1000);
    }

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_aidl);

        KLog.e();

        mBandwidth = (TextView) findViewById(R.id.bandwidth);
        mSpeed = (TextView) findViewById(R.id.speed);


//        Intent intent = new Intent(this, MonitorService.class);
        Intent intent = new Intent("com.meizu.flyme.tv.bandwidth.service.IMonitorService");
        intent.setPackage("com.robert.bandwithmonitor");  // 必须设置
        bindService(intent, mConnection, Context.BIND_AUTO_CREATE);
    }

    @Override
    protected void onDestroy() {
        super.onDestroy();
        KLog.e();

        if (mTimer != null) {
            mTimer.cancel();
        }
        unbindService(mConnection);
    }
}

intent必须设置package，intent必须为显示的（explicit），否则会报错。（在官方看到过，不过找不到了。）