Android 简明教程

Android - Bluetooth

在多种方式中，蓝牙是用于在两部不同设备之间发送或接收数据的一种方式。Android 平台包括对蓝牙框架的支持，该框架允许设备通过无线方式与其他蓝牙设备交换数据。

Among many ways, Bluetooth is a way to send or receive data between two different devices. Android platform includes support for the Bluetooth framework that allows a device to wirelessly exchange data with other Bluetooth devices.

Android 提供蓝牙 API 来执行这些不同操作。

Android provides Bluetooth API to perform these different operations.

Scan for other Bluetooth devices
Get a list of paired devices
Connect to other devices through service discovery

Android 提供了 BluetoothAdapter 类来与蓝牙进行通信。通过调用静态方法 getDefaultAdapter() 来创建此调用的对象。其语法如下所示。

Android provides BluetoothAdapter class to communicate with Bluetooth. Create an object of this calling by calling the static method getDefaultAdapter(). Its syntax is given below.

private BluetoothAdapter BA;
BA = BluetoothAdapter.getDefaultAdapter();

为了启用设备的蓝牙功能，请调用带有以下蓝牙常量 ACTION_REQUEST_ENABLE 的 intent。其语法如下。

In order to enable the Bluetooth of your device, call the intent with the following Bluetooth constant ACTION_REQUEST_ENABLE. Its syntax is.

Intent turnOn = new Intent(BluetoothAdapter.ACTION_REQUEST_ENABLE);
startActivityForResult(turnOn, 0);

除了这个常量外，API 还提供了用于支持不同任务的其他常量。它们列在下面。

Apart from this constant, there are other constants provided the API , that supports different tasks. They are listed below.

Sr.No

Constant & description

ACTION_REQUEST_DISCOVERABLE This constant is used for turn on discovering of bluetooth

ACTION_STATE_CHANGED This constant will notify that Bluetooth state has been changed

ACTION_FOUND This constant is used for receiving information about each device that is discovered

在启用蓝牙后，你可以通过调用 getBondedDevices() 方法获取配对设备的列表。它会返回一组蓝牙设备。它的语法为：

Once you enable the Bluetooth , you can get a list of paired devices by calling getBondedDevices() method. It returns a set of bluetooth devices. Its syntax is.

private Set<BluetoothDevice>pairedDevices;
pairedDevices = BA.getBondedDevices();

除了配对设备外，API 中还有其他方法可提供对蓝牙的更多控制。它们列在下面。

Apart form the parried Devices , there are other methods in the API that gives more control over Blueetooth. They are listed below.

Sr.No	Method & description
1	enable() This method enables the adapter if not enabled
2	isEnabled() This method returns true if adapter is enabled
3	disable() This method disables the adapter
4	getName() This method returns the name of the Bluetooth adapter
5	setName(String name) This method changes the Bluetooth name
6	getState() This method returns the current state of the Bluetooth Adapter.
7	startDiscovery() This method starts the discovery process of the Bluetooth for 120 seconds.

Example

此示例提供 BluetoothAdapter 类演示，以控制蓝牙并显示蓝牙的配对设备列表。

This example provides demonstration of BluetoothAdapter class to manipulate Bluetooth and show list of paired devices by the Bluetooth.

要尝试此示例，您需要在实际设备上运行此示例。

To experiment with this example , you need to run this on an actual device.

Steps	Description
1	You will use Android studio to create an Android application a package com.example.sairamkrishna.myapplication.
2	Modify src/MainActivity.java file to add the code
3	Modify layout XML file res/layout/activity_main.xml add any GUI component if required.
4	Modify AndroidManifest.xml to add necessary permissions.
5	Run the application and choose a running android device and install the application on it and verify the results.

以下是 src/MainActivity.java 的内容

Here is the content of src/MainActivity.java

package com.example.sairamkrishna.myapplication;

import android.app.Activity;
import android.bluetooth.BluetoothAdapter;
import android.bluetooth.BluetoothDevice;

import android.content.Intent;
import android.os.Bundle;
import android.view.View;

import android.widget.ArrayAdapter;
import android.widget.Button;
import android.widget.ListView;

import android.widget.Toast;
import java.util.ArrayList;
import java.util.Set;

public class MainActivity extends Activity  {
   Button b1,b2,b3,b4;
   private BluetoothAdapter BA;
   private Set<BluetoothDevice>pairedDevices;
   ListView lv;

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

      b1 = (Button) findViewById(R.id.button);
      b2=(Button)findViewById(R.id.button2);
      b3=(Button)findViewById(R.id.button3);
      b4=(Button)findViewById(R.id.button4);

      BA = BluetoothAdapter.getDefaultAdapter();
      lv = (ListView)findViewById(R.id.listView);
   }

   public void on(View v){
      if (!BA.isEnabled()) {
         Intent turnOn = new Intent(BluetoothAdapter.ACTION_REQUEST_ENABLE);
         startActivityForResult(turnOn, 0);
         Toast.makeText(getApplicationContext(), "Turned on",Toast.LENGTH_LONG).show();
      } else {
         Toast.makeText(getApplicationContext(), "Already on", Toast.LENGTH_LONG).show();
      }
   }

   public void off(View v){
      BA.disable();
      Toast.makeText(getApplicationContext(), "Turned off" ,Toast.LENGTH_LONG).show();
   }


   public  void visible(View v){
      Intent getVisible = new Intent(BluetoothAdapter.ACTION_REQUEST_DISCOVERABLE);
      startActivityForResult(getVisible, 0);
   }


   public void list(View v){
      pairedDevices = BA.getBondedDevices();

      ArrayList list = new ArrayList();

      for(BluetoothDevice bt : pairedDevices) list.add(bt.getName());
      Toast.makeText(getApplicationContext(), "Showing Paired Devices",Toast.LENGTH_SHORT).show();

      final ArrayAdapter adapter = new  ArrayAdapter(this,android.R.layout.simple_list_item_1, list);

      lv.setAdapter(adapter);
   }
}

以下是 activity_main.xml 的内容。

Here is the content of activity_main.xml

<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout
xmlns:android="http://schemas.android.com/apk/res/android"
   xmlns:tools="http://schemas.android.com/tools"
   android:layout_width="match_parent"
   android:layout_height="match_parent"
   android:paddingLeft="@dimen/activity_horizontal_margin"
   android:paddingRight="@dimen/activity_horizontal_margin"
   android:paddingTop="@dimen/activity_vertical_margin"
   android:paddingBottom="@dimen/activity_vertical_margin"
   tools:context=".MainActivity"
   android:transitionGroup="true">

   <TextView android:text="Bluetooth Example"
      android:layout_width="wrap_content"
      android:layout_height="wrap_content"
      android:id="@+id/textview"
      android:textSize="35dp"
      android:layout_alignParentTop="true"
      android:layout_centerHorizontal="true" />

   <TextView
      android:layout_width="wrap_content"
      android:layout_height="wrap_content"
      android:text="Tutorials point"
      android:id="@+id/textView"
      android:layout_below="@+id/textview"
      android:layout_centerHorizontal="true"
      android:textColor="#ff7aff24"
      android:textSize="35dp" />

   <ImageView
      android:layout_width="wrap_content"
      android:layout_height="wrap_content"
      android:id="@+id/imageView"
      android:src="@drawable/abc"
      android:layout_below="@+id/textView"
      android:layout_centerHorizontal="true"
      android:theme="@style/Base.TextAppearance.AppCompat" />

   <Button
      android:layout_width="wrap_content"
      android:layout_height="wrap_content"
      android:text="Turn On"
      android:id="@+id/button"
      android:layout_below="@+id/imageView"
      android:layout_toStartOf="@+id/imageView"
      android:layout_toLeftOf="@+id/imageView"
      android:clickable="true"
      android:onClick="on" />

   <Button
      android:layout_width="wrap_content"
      android:layout_height="wrap_content"
      android:text="Get visible"
      android:onClick="visible"
      android:id="@+id/button2"
      android:layout_alignBottom="@+id/button"
      android:layout_centerHorizontal="true" />

   <Button
      android:layout_width="wrap_content"
      android:layout_height="wrap_content"
      android:text="List devices"
      android:onClick="list"
      android:id="@+id/button3"
      android:layout_below="@+id/imageView"
      android:layout_toRightOf="@+id/imageView"
      android:layout_toEndOf="@+id/imageView" />

   <Button
      android:layout_width="wrap_content"
      android:layout_height="wrap_content"
      android:text="turn off"
      android:onClick="off"
      android:id="@+id/button4"
      android:layout_below="@+id/button"
      android:layout_alignParentLeft="true"
      android:layout_alignParentStart="true" />

   <ListView
      android:layout_width="wrap_content"
      android:layout_height="wrap_content"
      android:id="@+id/listView"
      android:layout_alignParentBottom="true"
      android:layout_alignLeft="@+id/button"
      android:layout_alignStart="@+id/button"
      android:layout_below="@+id/textView2" />

   <TextView
      android:layout_width="wrap_content"
      android:layout_height="wrap_content"
      android:text="Paired devices:"
      android:id="@+id/textView2"
      android:textColor="#ff34ff06"
      android:textSize="25dp"
      android:layout_below="@+id/button4"
      android:layout_alignLeft="@+id/listView"
      android:layout_alignStart="@+id/listView" />

</RelativeLayout>

以下是 Strings.xml 的内容

Here is the content of Strings.xml

<resources>
   <string name="app_name">My Application</string>
</resources>

以下是 AndroidManifest.xml 的内容

Here is the content of AndroidManifest.xml

<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
   package="com.example.sairamkrishna.myapplication" >
   <uses-permission android:name="android.permission.BLUETOOTH"/>
   <uses-permission android:name="android.permission.BLUETOOTH_ADMIN"/>

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

      <activity
         android:name=".MainActivity"
         android:label="@string/app_name" >

         <intent-filter>
            <action android:name="android.intent.action.MAIN" />
            <category android:name="android.intent.category.LAUNCHER" />
         </intent-filter>

      </activity>

   </application>
</manifest>

我们尝试运行你的应用程序。我假设你已将真实的 Android 手机连接到你的计算机。要从 Android Studio 运行该应用，请打开项目中的一个活动文件，然后从工具栏中单击运行图标。如果你的蓝牙未打开，它将要求你允许启用蓝牙。

Let’s try to run your application. I assume you have connected your actual Android Mobile device with your computer. To run the app from Android studio, open one of your project’s activity files and click Run icon from the tool bar.If your Bluetooth will not be turned on then, it will ask your permission to enable the Bluetooth.

现在，只需选择“获得可见性”按钮即可打开你的可见性。会出现以下屏幕，要求你允许打开发现 120 秒。

Now just select the Get Visible button to turn on your visibility. The following screen would appear asking your permission to turn on discovery for 120 seconds.

现在，只需选择“列出设备”选项。它将在列表视图中列出配对的设备。在我的情况下，我只有一台配对设备。如下所示。

Now just select the List Devices option. It will list down the paired devices in the list view. In my case , I have only one paired device. It is shown below.

现在只需选择关闭按钮即可关闭蓝牙。关闭蓝牙后，将出现以下消息，指示蓝牙已成功关闭。

Now just select the Turn off button to switch off the Bluetooth. Following message would appear when you switch off the bluetooth indicating the successful switching off of Bluetooth.