Android开发——WiFi信号检测

1.首先在androidmanifest.xml文件中添加如下代码以开启权限：

 1 <!-- 获取wifi状态的权限 -->
 2 <uses-permission android:name="android.permission.access_wifi_state"/>
 3 <!-- 改变wifi状态的权限 -->
 4 <uses-permission android:name="android.permission.change_wifi_state"/>
 5 <!-- 获取网络的权限 -->
 6 <uses-permission android:name="android.permission.internet"/>
 7 <!-- 获取网络状态的权限 -->
 8 <uses-permission android:name="android.permission.access_network_state"/>
 9 <!-- 改变网络状态的权限 -->
10 <uses-permission android:name="android.permission.change_network_state"/>
11 
12 <!-- 往sdcard写入数据权限 -->
13 <uses-permission android:name="android.permission.write_external_storage"/>
14 <!-- 从sdcard读取数据权限 -->
15 <uses-permission android:name="android.permission.read_external_storage"/>
16 <!-- 在sdcard中创建与删除文件权限 -->
17 <uses-permission android:name="android.permission.mount_unmount_filesystems"/>

2.三个与wifi相关的类：wifimanager，wifiinfo，scanresult

• wifimanager

 1 // 获取系统wifi服务
 2 wifimanage wm = (wifimanager) getapplicationcontext().getsystemservice(wifi_service);
 3 
 4 // 获取当前所连接wifi的信息
 5 wifiinfo wi = wm.getconnectioninfo();
 6  
 7 // 获取扫描到的所有wifi信息
 8 list<scanresult> scanresults = wm.getscanresults();
 9 
10 // 将rssi分为numlevels个等级，返回rssi处在哪一个等级
11 int level = wm.calculatesignallevel (int rssi,int numlevels); 
12 
13 // 获取当前手机wifi网卡状态
14 int state = wm.getwifistate(); 
15 返回值为以下宏定义
16 wifimanager.wifi_state_enabled    wifi网卡可用
17 wifimanager.wifi_state_disabled    wifi网卡不可用
18 wifimanager.wifi_state_disabling    wifi网卡正关闭
19 wifimanager.wifi_state_enabling    wifi网卡正打开
20 wifimanager.wifi_state_unknown    状态未知
21 
22 // 判断wifi是否打开
23 boolean flag = iswifienabled();
24 // 打开wifi
25 boolean flag = setwifienabled(true);
26 // 关闭wifi
27 boolean flag = setwifienabled(false);

注：api文档中提到使用list<scanresult> getscanresults()时，最好额外添加两个权限（保护等级：危险），详见链接

an app must hold access_coarse_location or access_fine_location permission in order to get valid results
access_coarse_location：allows an app to access approximate location.
access_fine_location：allows an app to access precise location.

• wifiinfo

1 wifiinfo wifiinfo = wifi_service.getconnectioninfo();    // 获取当前所连接wifi的信息
2 wi.getssid();        // 获取当前连接wifi的名字
3 wi.getbssid();       // 获取当前所连wifi设备的mac地址，string类型
4 wi.getmacaddress();  // 获取本机mac地址
5 wi.getrssi();        // 获取当前连接wifi的信号强度，返回一个0~-100之间的int型数据
6 wi.getlinkspeed();   // 获取连接速度
7 wifiinfo.link_speed_units; // 定义为连接速度单位的字符串常量"mbps"

• scanresult

scanresult.ssid();
scanresult.bssid();
scanresult.level();    // 信号强度(原始数据)

3.代码

• activity_main.xml资源文件

 1 <?xml version="1.0" encoding="utf-8"?>
 2 <relativelayout
 3     xmlns:android="http://schemas.android.com/apk/res/android"
 4     xmlns:tools="http://schemas.android.com/tools"
 5     tools:context=".mainactivity"
 6     android:layout_width="match_parent"
 7     android:layout_height="match_parent"
 8     android:orientation="vertical">
 9 
10     <button
11         android:id="@+id/start_btn"
12         android:layout_width="wrap_content"
13         android:layout_height="wrap_content"
14         android:layout_marginstart="45dp"
15         android:text="@string/start_scan"
16         android:onclick="doclick"/>
17 
18     <button
19         android:id="@+id/stop_btn"
20         android:layout_width="wrap_content"
21         android:layout_height="wrap_content"
22         android:layout_marginstart="10dp"
23         android:layout_toendof="@+id/start_btn"
24         android:text="@string/stop_scan"
25         android:onclick="doclick"/>
26 
27     <button
28         android:id="@+id/save_btn"
29         android:layout_width="wrap_content"
30         android:layout_height="wrap_content"
31         android:layout_marginstart="10dp"
32         android:layout_toendof="@+id/stop_btn"
33         android:text="@string/save_data"
34         android:onclick="doclick"/>
35 
36     <linearlayout
37         android:layout_width="match_parent"
38         android:layout_height="wrap_content"
39         android:layout_below="@+id/start_btn"
40         android:layout_margintop="10dp"
41         android:orientation="vertical">
42 
43         <textview
44             android:id="@+id/connected_wifi_tv"
45             android:layout_width="match_parent"
46             android:layout_height="wrap_content"
47             android:text="@string/connected_wifi" />
48 
49         <textview
50             android:id="@+id/connected_wifi_info_tv"
51             android:layout_width="match_parent"
52             android:layout_height="wrap_content"
53             android:layout_margintop="10dp"
54             android:text=""/>
55 
56         <textview
57             android:layout_width="match_parent"
58             android:layout_height="2dp"
59             android:layout_margintop="5dp"/>
60 
61         <textview
62             android:id="@+id/scan_results_tv"
63             android:layout_width="match_parent"
64             android:layout_height="wrap_content"
65             android:layout_margintop="5dp"
66             android:text="@string/scan_results" />
67 
68         <scrollview
69             android:layout_width="match_parent"
70             android:layout_height="wrap_content"
71             android:layout_margintop="10dp"
72             android:fadingedge="vertical"
73             android:scrollbars="vertical">
74 
75             <textview
76                 android:id="@+id/scan_results_info_tv"
77                 android:layout_width="match_parent"
78                 android:layout_height="wrap_content"
79                 android:text=""/>
80         </scrollview>
81     </linearlayout>
82 </relativelayout>

 

• mainactivity.java主程序

  1 package com.lee.rss_sampler;
  2 
  3 import android.app.activity;
  4 import android.net.wifi.scanresult;
  5 import android.net.wifi.wifiinfo;
  6 import android.net.wifi.wifimanager;
  7 import android.os.environment;
  8 import android.os.bundle;
  9 import android.view.view;
 10 import android.widget.textview;
 11 import android.widget.toast;
 12 
 13 import java.io.fileoutputstream;
 14 import java.util.list;
 15 
 16 public class mainactivity extends activity {
 17 
 18     public boolean mflag = true;    // 控制线程终止
 19     private stringbuilder mlistinfo;// 保存扫描的wifi列表信息
 20     private textview mtextviewcurrwifiinfo; // 显示当前所连wifi信息的组件
 21     private textview mtextviewscanwifiinfo; // 显示扫描到的wifi信息的组件
 22 
 23     @override
 24     protected void oncreate(bundle savedinstancestate) {
 25         super.oncreate(savedinstancestate);
 26         setcontentview(r.layout.activity_main);
 27         mtextviewcurrwifiinfo = findviewbyid(r.id.connected_wifi_info_tv);
 28         mtextviewscanwifiinfo = findviewbyid(r.id.scan_results_info_tv);
 29     }
 30 
 31     public void doclick(view view){
 32         switch (view.getid()){
 33             case r.id.start_btn:
 34                 mflag = true;   // 标志位置为true，允许线程运行
 35                 // 启动wifi扫描的线程
 36                 scanthread scanthread = new scanthread();
 37                 scanthread.start();
 38                 break;
 39             case r.id.stop_btn:
 40                 mflag = false;  // 标志位置为false，终止线程
 41                 break;
 42             case r.id.save_btn:
 43                 string filename = "wifi_data.txt";
 44                 string filecontent = mlistinfo.tostring();
 45                 try{
 46                     savefiletosd(filename,filecontent);
 47                     toast.maketext(getapplicationcontext(), "数据写入成功", toast.length_short).show();
 48                 }catch (exception e){
 49                     e.printstacktrace();
 50                     toast.maketext(getapplicationcontext(), "数据写入失败", toast.length_short).show();
 51                 }
 52                 break;
 53         }
 54     }
 55 
 56     private class scanthread extends thread {
 57         @override
 58         public void run() {
 59             while (mflag) {
 60                 // 在ui线程中获取wifi信息，并更新ui
 61                 runonuithread(new runnable() {
 62                     @override
 63                     public void run() {
 64                         obtainlistinfo();
 65                     }
 66                 });
 67                 // 采样频率500ms
 68                 try {
 69                     thread.sleep(500);
 70                 } catch (interruptedexception e) {
 71                     e.printstacktrace();
 72                 }
 73             }
 74         }
 75     }
 76 
 77     private void obtainlistinfo(){
 78         // 获取wifi管理器
 79         wifimanager wifimanager = (wifimanager) getapplicationcontext().getsystemservice(wifi_service);
 80 
 81         // 如果wifi未打开，先打开wifi
 82         /*if (wifimanager.getwifistate() != wifimanager.wifi_state_enabled) {
 83             wifimanager.setwifienabled(true);
 84         }*/
 85         if(!wifimanager.iswifienabled()){
 86             wifimanager.setwifienabled(true);
 87         }
 88 
 89         // 获取并保存当前所连wifi信息
 90         wifiinfo wifiinfo = wifimanager.getconnectioninfo();
 91         string mcurrentconnect = "ssid: " + wifiinfo.getssid() +
 92                 "\nmac address: " + wifiinfo.getbssid() +
 93                 "\nsignal strength(dbm): " + wifiinfo.getrssi() +
 94                 "\nspeed: " + wifiinfo.getlinkspeed() + " " + wifiinfo.link_speed_units;
 95 
 96         // 获取并保存扫描的wifi列表信息
 97         mlistinfo = new stringbuilder();
 98         list<scanresult> scanresults = wifimanager.getscanresults();
 99         for (scanresult sr:scanresults){
100             mlistinfo.append("ssid: ");
101             mlistinfo.append(sr.ssid);
102             mlistinfo.append("\nmac address: ");
103             mlistinfo.append(sr.bssid);
104             mlistinfo.append("\nsignal strength(dbm): ");
105             mlistinfo.append(sr.level);
106             mlistinfo.append("\n\n");
107         }
108 
109         // 更新ui上显示的wifi信息
110         mtextviewcurrwifiinfo.settext(mcurrentconnect);
111         mtextviewscanwifiinfo.settext(mlistinfo.tostring());
112     }
113 
114     //往sd卡写入文件的方法
115     public void savefiletosd(string filename, string filecontent) throws exception {
116         // 先判断是否有sd卡以及是否有读取sd卡的权限
117         if (environment.getexternalstoragestate().equals(environment.media_mounted)) {
118             // 设置文件路径
119             string filepath = environment.getexternalstoragedirectory().getcanonicalpath() + "/" + filename;
120             // new一个文件输出流对象
121             fileoutputstream output = new fileoutputstream(filepath);
122             //将string字符串以字节流的形式写入到输出流中
123             output.write(filecontent.getbytes());
124             output.close();     //关闭输出流
125         } else {
126             toast.maketext(mainactivity.this, "sd卡不存在或者不可读写", toast.length_short).show();
127         }
128     }
129 
130     // 从sd卡中读取文件的方法
131     public string readfilefromsd(string filename){
132         // todo
133         return null;
134     }
135 }