2、安卓获取ble蓝牙信号强度rssi

毕业设计需要，需要用到蓝牙，检测蓝牙强度，当蓝牙强度减弱到一定的程度时，将停止扫描，调用其它函数
下面将实现这样的功能。
环境：Android Studio
官方指南：Ble|Android Developer

1、添加需要的权限
AndroidManifest.xml

    <uses-permission android:name="android.permission.BLUETOOTH" />
    <uses-permission android:name="android.permission.BLUETOOTH_ADMIN" />
    <uses-permission android:name="android.permission.ACCESS_FINE_LOCATION" />
    <uses-permission android:name="android.permission.ACCESS_COARSE_LOCATION" />
    <uses-feature android:name="android.hardware.bluetooth_le" android:required="true"/>

2、将minSdkVersion api改为18
build.gradle

android {
  ...
  minSdkVersion 18
  ...
}

3、在onCreate()中添加蓝牙初始化等操作
MainActivity.java

        final BluetoothManager bluetoothManager = (BluetoothManager) getSystemService(Context.BLUETOOTH_SERVICE);
        //查看是否支持ble
        if (!getPackageManager().hasSystemFeature(PackageManager.FEATURE_BLUETOOTH_LE)) {
            Toast.makeText(this, R.string.ble_not_supported, Toast.LENGTH_SHORT).show();
            finish();
        }
        bluetoothAdapter = bluetoothManager.getAdapter();
        //查看是否支持蓝牙
        if (bluetoothAdapter == null ){
            Toast.makeText(this, R.string.ble_not_supported, Toast.LENGTH_SHORT).show();
            finish();
        }
        //如果蓝牙没有打开，打开蓝牙
        if(!bluetoothAdapter.isEnabled()){
            bluetoothAdapter.enable();
            Toast.makeText(this, R.string.turn_on_ble, Toast.LENGTH_SHORT).show();
        }

        //实例化扫描类
        DeviceScanActivity ScanActivity = new DeviceScanActivity();
        ScanActivity.bluetoothAdapter = bluetoothAdapter;
        //实例化Ble类
        ScanActivity.makeBleInstance();
        //启动扫描
        ScanActivity.scanLeDevice(true);

创建新的java文件DeviceScanActivity.java
DeviceScanActivity.java

package com.zenos.bluetoothtest;

import android.app.ListActivity;
import android.bluetooth.BluetoothAdapter;
import android.bluetooth.BluetoothDevice;
import android.os.Handler;

import java.util.ArrayList;
import java.util.List;

public class DeviceScanActivity extends ListActivity {
    public BluetoothAdapter bluetoothAdapter;
    protected boolean mScanning;
    private Handler handler;

    protected int rsiAverage;

    protected boolean block =false;
    // Stops scanning after 10 seconds.
    private static final long SCAN_PERIOD = 5000;

    private List<Integer> rsiList = new ArrayList<>();

    //private BluetoothDevice mBluetoothDevice;

    private Ble mBle;
    public void scanLeDevice(final boolean enable) {
        block = false;
        rsiList.clear();
        if (enable) {
            // Stops scanning after a pre-defined scan period.
            handler = new Handler();
            handler.postDelayed(new Runnable() {
                @Override
                public void run() {
                    mScanning = false;
                    bluetoothAdapter.stopLeScan(leScanCallback);
                    rsiAverage = getRsiAverage();
                    if(rsiAverage < -70){
                        //信号弱于-70db时，启动block，触发回调函数，启动摄像头拍照。
                        mBle.doBlock();
                    }else if(rsiAverage == 0){
                        System.out.println("=====There is no ble device,please check=====");
                    }else{
                        System.out.println("=====scanLeDevice()=====");
                        scanLeDevice(true);
                    }
                }
            }, SCAN_PERIOD);
            mScanning = true;
            bluetoothAdapter.startLeScan(leScanCallback);
        } else {
            mScanning = false;
            bluetoothAdapter.stopLeScan(leScanCallback);
        }
    }


    private BluetoothAdapter.LeScanCallback leScanCallback =
            new BluetoothAdapter.LeScanCallback() {
                @Override
                public void onLeScan(final BluetoothDevice device, final int rssi,
                                     byte[] scanRecord) {
                    runOnUiThread(new Runnable() {
                        @Override
                        public void run() {
                            if (device.getAddress().equals("40:06:A0:9C:71:4A")) {
                                System.out.println("device name: " + device.getName() + ",   device address: " + device.getAddress() + ", rssi: " + rssi);
                                rsiList.add(rssi);
                            }
                        }
                    });
                }
            };

    public int getRsiAverage() {
        int sum = 0;
        int num = 1;
        int avrage = 0;
        for (int j = 0; j < rsiList.size(); j++) {
            sum = sum + rsiList.get(j);
        }
        num = rsiList.size();
        if(rsiList.size() == 0){
            num = 1;
            bluetoothAdapter.stopLeScan(leScanCallback);
        }
        avrage = sum/num;
        System.out.println("=====getRsiAverage=====");
        System.out.println("avrage: " + avrage);
        return avrage;
    }
    public void makeBleInstance(){
        mBle = new Ble();
        mBle.setBleListener(new BleListener(){
            @Override
            public void block() {
                System.out.println("a car is in the Parking space!");
                System.out.println("Now turn on the camera to shoot!");
            }
        });
    }
    //回调函数接口
    public interface BleListener{
        public void block();
    }

    public static class Ble{
        private BleListener mBleListener;

        public void setBleListener(BleListener mBleListener){
            this.mBleListener = mBleListener;
        }

        public void doBlock(){
            mBleListener.block();
        }
    }
}

在rssi小于-70时，将启动启动其它函数

控制台执行结果

这里就已经完成rssi的获取