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Today, I would like to talk to you about how to analyze the Android sensor system, many people may not know much about it. In order to make you understand better, the editor has summarized the following for you. I hope you can get something according to this article.

Android is a flexible and attractive platform. The Android field of Google is growing rapidly and becoming more and more powerful. The following article provides a comprehensive introduction to the application architecture related to Android sensors and reporting systems.

After the application (activity) is paused, the listener needs to be unregistered so that no more sensor updates will be received later. This is achieved through the unregisterListener method of SensorManager. The only parameter is an instance of SensorListener. In registerListener and unregisterListener method calls, the application uses the keyword this. Note the implements keyword in the class definition.

It is declared that this class implements the SensorListener interface. That's why you want to pass it to registerListener and unregisterListener. SensorListener must implement two methods, onSensorChange and onAccuracyChanged. The sample application does not care about the accuracy of the sensor.

But pay attention to the current X, Y, and Z values of the sensor. The onAccuracyChanged method does essentially nothing; it only adds a log entry with each call. It seems that you often need to call the onSensorChanged method because the accelerometer and the direction sensor are sending data quickly. Check the * parameters to determine which sensor is sending data.

After confirming the sensor that sent the data, the corresponding UI element is updated with the data contained in the floating-point array passed by the second parameter of the method. This example only shows these values, but in more advanced applications, you can also analyze these values, compare the original values, or set up some pattern recognition algorithm to determine the behavior of the user (or external environment).

Now that you know about the sensor subsystem, the next section reviews a sample code for recording audio on an Android sensor. The sample runs on a DEV1 development device. The android.media package contains classes that interact with the media subsystem. Use the android.media.MediaRecorder class for media sampling, including audio and video. MediaRecorder runs as a state machine.

You need to set different parameters, such as the source device and format. Once set, recording can be performed for any length of time until the user stops. Listing 2 contains the code to record audio on an Android device. The code displayed does not include the UI element of the application (see download for the complete source code). In the startRecording method, instantiate and initialize an instance of MediaRecorder:

The input source is set to a MIC. The output format is set to 3GPP (* .3gp file), which is a media format specific to mobile devices. The encoder is set to AMR_NB, which is an audio format with a sampling rate of 8 KHz. NB stands for narrow band. The SDK documentation explains different data formats and available encoders.

Audio files are stored in a storage card rather than in memory. External.getExternalStorageDirectory () returns the name of the storage card location in which a temporary file name is created. Then, associate the file to the MediaRecorder instance by calling the setOutputFile method. The audio data is stored in the file. Call the prepare method to complete the initialization of the MediaRecorder.

The start method is called when you are ready to start the recording process. The file on the memory card is recorded before the stop method is called. The release method releases the resources allocated to the MediaRecorder instance. In this code sample, the processaudiofile method adds audio to the library. Use Intent to notify the media application on the device that new content is available.

One thing to note about this code snippet is that if you try it, it won't record audio at first. You will see the file you created, but without any audio. You need to add permissions to the AndroidManifest.xml file. Now you've learned a little bit about Android sensors and recording audio. The next section provides a more comprehensive description of the application architecture related to data acquisition and reporting systems.

The architecture is flexible; the application logic can be divided into local Android devices and server-side resources (for larger database and computing capabilities). For example, tracks recorded on a local Android device can be POST to a Web server, where the data is compared against the audio mode database. Obviously, this is just the tip of the iceberg. I hope you can do more in-depth research to make the Android platform beyond the scope of mobile phones.

The architecture is flexible; the application logic can be divided into local Android devices and server-side resources (for larger database and computing capabilities). For example, tracks recorded on a local Android device can be POST to a Web server, where the data is compared against the audio mode database. Obviously, this is just the tip of the iceberg. I hope you can do more in-depth research to make the Android sensor beyond the scope of mobile phones.

After reading the above, do you have any further understanding of how to analyze the Android sensor system? If you want to know more knowledge or related content, please follow the industry information channel, thank you for your support.

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