One 、 Demand analysis

Recently, the computer needs to be connected WiFi, But found WiFi I forgot the password . And there's something saved in the phone WiFi password , But I can't see it in the setting interface of the mobile phone .

Although there are already some to see WiFi Cryptographically app, But the main concern is that the password will be destroyed by those app Send it backstage . It's better to write one by yourself . Also used app Just one click to see , It's more convenient than directly looking up the file in the system where the password is stored .

Two 、 Main function realization

2.1 Read system files

Android The system saved it WiFi The password file is saved in /data/misc/wifi/wpa_supplicant.conf in [1], By running a command line program in code ‘cat’ To read the file [3][4].

String commandResult=commandForResult("cat /data/misc/wifi/wpa_supplicant.conf");
public String commandForResult(String command) { try {
Process process = Runtime.getRuntime().exec("su");
DataOutputStream outputStream = null;
outputStream = new DataOutputStream(process.getOutputStream());
outputStream.flush(); BufferedReader in = new BufferedReader(new InputStreamReader(process.getInputStream()));
StringBuilder total = new StringBuilder();
String line;
while ((line = in.readLine()) != null) {
return total.toString();
} catch (IOException e) {
// TODO Auto-generated catch block
return "error";

2.2 Yes WiFi Information according to priority Sort from big to small

wpa_supplicant.conf In the file Wifi The information is mainly in the following format , Each network information is represented by network start .key_mgmt=NONE The network does not need a password . When key_mgmt=WPA-PSK when , Will pass psk Field to identify the password information .

In the cell phones we've seen so far wpa_supplicant.conf There are no different networks in the file according to priority Sort by . And the networks that you use often priority Relatively high , It was put at the back of the file , Therefore, we should consider the network information according to priority Sort from big to small .

 String sortByPriority(String input){
String [] stringPerLine=input.split("\n");
ArrayList<NetworkPara> list=new ArrayList<MainActivity.NetworkPara>();
int start=0,end=0;
NetworkPara networkPara = null;
for (int i = 0; i < stringPerLine.length; i++) {
if (stringPerLine[i].contains("network={")) {
networkPara=new NetworkPara();
if (start==1) {
if (networkPara!=null) {
if (stringPerLine[i].contains("priority")) {
String []prioSplit=stringPerLine[i].split("=");
if (stringPerLine[i].contains("}")) {
if (end==1) {
Collections.sort(list, new Comparator() {
public int compare(Object o1, Object o2) {
return ((Comparable) ((NetworkPara) (o2)).priority)
.compareTo(((NetworkPara) (o1)).priority);
}); String result="";
for (int i = 0; i < list.size(); i++) {
return result;

2.3 Support search by string

The entry selection of string search is adopted in actionar Add a search button on the , Line by line matching based on the input string . When there are multiple matching results , The forward and backward buttons are displayed in the interface , To support the selection of before and after content .

2.3.1 Actionbar Show search button in

First, in the menu item Add search button when generating , Then master activity implements OnQueryTextListener And implement onQueryTextChange and onQueryTextSubmit Method [2].

 public boolean onCreateOptionsMenu(Menu menu) {
// Inflate the menu; this adds items to the action bar if it is present.
getMenuInflater().inflate(, menu); searchView = (SearchView) MenuItemCompat.getActionView(menu.findItem(;
return true;
<menu xmlns:android=""
tools:context="com.zhigao.all_connect.MainActivity" > <item android:id="@+id/menu_search"

2.3.2 String matching and result saving

After the user enters the characters to be searched, click search , perform onQueryTextSubmit function . use stringSplit[i].toLowerCase().contains(arg0.toLowerCase()) Do case insensitive matching . Use scrollTo Function scrollview The jump [5].

 public boolean onQueryTextSubmit(String arg0) {
// TODO Auto-generated method stub
Log.v(TAG, "querysubmit"+arg0);
String []stringSplit=sortedResult.split("\n");
for (int i = 0; i < stringSplit.length; i++) {
//case insensitive match
if (stringSplit[i].toLowerCase().contains(arg0.toLowerCase())) {
} if (matchedLine.size()==0) {
Toast.makeText(getApplicationContext(), "no match!", Toast.LENGTH_SHORT).show();
return false;
}else if (matchedLine.size()==1) { }
else {
} Runnable() {
public void run() {
int y = textView.getLayout().getLineTop(matchedLine.get(0));
scrollView.scrollTo(0, y);
return false;

2.3.3 When there are multiple strings to match, the result shows

be based on relativelayout Construct out button Floating in textview Effect on , When the user slides down scrollview when ,button Can always stay in the lower right position [6]. Users click the button to search forward or backward . Click on textview Then cancel the button .

<RelativeLayout xmlns:android=""
</ScrollView> <Button

2.4 Generate a signature apk The problems encountered in the process and the current solutions

2.4.1 Duplicate id @+id/image problem [7]

Generate signature apk function lint When checking , Prompt by Duplicate id @+id/image problem . Even if it's going to be android support library Update to 23.0.1 And then there's still . For now, we will abc_activity_chooser_view.xml Second of @+id/image It is amended as follows @+id/image2.

2.4.2 This class should be public ( problem

modify lint, Let's take this problem from error Judgment for warning.window->preferences -> Android Lint Preferences, Search for Instantiatable. Set it to warning.

2.4.3 "abc_action_bar_home_description_format" is not translated in "mk-rMK" problem

Because we don't consider supporting too many languages at present , and android This package may be updated later . So for the moment, we will consider lint Of missing chanslation Set to warning.

3、 ... and 、 Complete source code sharing

Four 、apk download

5、 ... and 、 Reference material

[1] How Android phones view WIFI password _ Experience in baidu


[3]java - Android Reading from an Input stream efficiently - Stack Overflow

[4]java - execute shell command from android - Stack Overflow

[5]java - How to scroll to a given line number, TextView inside ScrollView - Stack Overflow

[6]How to add a floating button on scrolling in android? - Stack Overflow

[7]Issue 73197 - android - abc_activity_chooser_view_include.xml uses android:id="@+id/image" twice - Android Open Source Project - Issue Tracker - Google Project Hosting

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