我正在编写一个简单的应用程序来扫描和记录WiFi接入点，有三种选择;一次扫描，10次扫描或扫描一段时间。
当我进入我的nWiFiScans活动时，它会执行扫描，记录文件并重新开始活动！
为什么要这样做？
public class nWiFiScans extends Activity
{
//declarations
public static String pntNameStr;
public static int numScans;
public static int scansMin;
LinearLayout layout1;
ScrollView scrollLayout;
TextView label1;
EditText n1Text;
EditText n2Text;
LayoutParams params_layout1;
WifiManager mainWifi = null;
WifiReceiver receiverWifi;
List<ScanResult> wifiList;
StringBuilder sb = new StringBuilder();
Intent intent;
SimpleDateFormat time;
protected void onCreate(Bundle savedInstanceState)
{
super.onCreate(savedInstanceState);
scrollLayout = new ScrollView(this);
scrollLayout.setBackgroundColor(Color.BLUE);
//Create new layout in "this" activity
params_layout1 = new LayoutParams(LayoutParams.MATCH_PARENT,LayoutParams.MATCH_PARENT, 1);
layout1 = new LinearLayout(this);
layout1.setBackgroundColor(Color.RED);
layout1.setLayoutParams(params_layout1);
//Create TextView in "this" activity
label1 = new TextView(this);
label1.setBackgroundColor(Color.YELLOW);
//Put some text in the TextView
// Get the message from the intent
intent = getIntent();
pntNameStr = intent.getStringExtra(MainActivity.EXTRA_pntNameStr);
numScans = intent.getIntExtra(MainActivity.EXTRA_numScans, 1);
label1.setText(pntNameStr);
//Place the TextView inside the Layout
layout1.addView(label1);
layout1.setOrientation(LinearLayout.VERTICAL);
//scrollLayout.addView(label1);
//layout1.addView(n1Text);
//layout1.addView(n2Text);
//By default the layout is set to HOR, so we change it to VERT orientation:
// Display layout1 when the activity is created:
setContentView(layout1);
mainWifi = (WifiManager) getSystemService(Context.WIFI_SERVICE);
checkIfWifiIsOn(mainWifi);
receiverWifi = new WifiReceiver();
registerReceiver(receiverWifi, new IntentFilter(WifiManager.SCAN_RESULTS_AVAILABLE_ACTION));
mainWifi.startScan();
label1.setText("Starting Scan..."+String.valueOf(numScans));
}
public void checkIfWifiIsOn(WifiManager mainWifi)
{
if (mainWifi.isWifiEnabled() == false)
{
// If wifi disabled then enable it
Toast.makeText(getApplicationContext(), "wifi is disabled..making it enabled",
Toast.LENGTH_LONG).show();
mainWifi.setWifiEnabled(true);
}
else {Toast.makeText(getApplicationContext(), "wifi is enabled... thats good...",
Toast.LENGTH_SHORT).show();}
}
public void generateNoteOnSD(String sFileName, String sBody)
{
File root = null;
try
{
root = new File(Environment.getExternalStoragePublicDirectory("SurveyAppData"), "ScanResults");
if (!root.exists())
{
root.mkdirs();
}
File gpxfile = new File(root, sFileName);
FileWriter writer = new FileWriter(gpxfile);
writer.append(sBody);
writer.flush();
writer.close();
Toast.makeText(this, "Saved" + "/n" +root.toURI(), Toast.LENGTH_LONG).show();
Toast.makeText(getApplicationContext(), "IM MOTHERFUCKING DONE" ,
Toast.LENGTH_SHORT).show();
//Log.d("Scan Results",sb.toString());
Intent i=new Intent(nWiFiScans.this, MainActivity.class);
i.setFlags(Intent.FLAG_ACTIVITY_CLEAR_TOP);
startActivity(i);
finish();
}
catch(IOException e)
{
e.printStackTrace();
Toast.makeText(this, "!!! - Could NOT Saved" + "/n" +root.toURI(), Toast.LENGTH_LONG).show();
}
}
public class WifiReceiver extends BroadcastReceiver
{
// This method call when number of wifi connections changed
long fisrtScanTS;
private String FILENAME = pntNameStr;
public FileOutputStream outputStream;
@SuppressLint("NewApi")
public void onReceive(Context c, Intent intent)
{
time = new SimpleDateFormat("ddMMyyyyhhmmss");
int ScanTime = numScans;
if(ScanTime==1 | ScanTime==10)
{
for (int scanNum = 1; scanNum<ScanTime+1; scanNum++)
{
wifiList = mainWifi.getScanResults();
for(int i = 0; i < wifiList.size(); i++)
{
sb.append(((wifiList.get(i)).BSSID + " " + (wifiList.get(i)).level + " " + (wifiList.get(i)).frequency + " "+ (wifiList.get(i)).timestamp + " "+ (wifiList.get(i)).SSID +" "+ time.format(new Date()) + "\n" ) );
fisrtScanTS = (wifiList.get(1)).timestamp;
}
do
{
mainWifi.startScan();
wifiList = mainWifi.getScanResults();
try{Thread.currentThread().sleep(200);}
catch(InterruptedException ie){
//If this thread was intrrupted by nother thread
}
} while(fisrtScanTS == (wifiList.get(1)).timestamp);
Toast.makeText(getApplicationContext(), "Scan number " + scanNum ,
Toast.LENGTH_SHORT).show();
}
}else if (ScanTime!=0)
{
Calendar timeNow = Calendar.getInstance();
Calendar timeEnd = Calendar.getInstance();
timeEnd.set(timeNow.YEAR, timeNow.MONTH, timeNow.DAY_OF_MONTH, timeNow.HOUR, timeNow.MINUTE+numScans, timeNow.SECOND);
while(!(timeNow.after(timeEnd))){
wifiList = mainWifi.getScanResults();
for(int i = 0; i < wifiList.size(); i++){
sb.append(((wifiList.get(i)).BSSID + " " + (wifiList.get(i)).level + " " + (wifiList.get(i)).frequency + " "+ (wifiList.get(i)).timestamp + " "+ (wifiList.get(i)).SSID +" "+ time.format(new Date()) + "\n" ) );
fisrtScanTS = (wifiList.get(1)).timestamp;
}
do {
mainWifi.startScan();
wifiList = mainWifi.getScanResults();
try{Thread.currentThread().sleep(200);}
catch(InterruptedException ie){
//If this thread was intrrupted by nother thread
}} while(fisrtScanTS == (wifiList.get(1)).timestamp);
timeNow = Calendar.getInstance();
Toast.makeText(getApplicationContext(), timeNow.getTime().toString() + " :: " + timeEnd.getTime().toString() ,
Toast.LENGTH_SHORT).show();
}
}
generateNoteOnSD(FILENAME, sb.toString());
FILENAME="x";
ScanTime=0;
}
}
}
public class MainActivity extends Activity
{
LinearLayout mainLayout,leftLayout,rightLayout;
EditText pointName;
EditText scanTime;
Button scan10, scan1, timedScan;
TextView msg;
LayoutParams paramsL,paramsR;
static final String EXTRA_pntNameStr = "com.example.surveyappv2.pntNameStr";
static final String EXTRA_scanTimeMin = "com.example.surveyappv2.scanTimeMin";
static final String EXTRA_numScans = "com.example.surveyappv2.numScans";
@Override
protected void onCreate(Bundle savedInstanceState)
{
super.onCreate(savedInstanceState);
mainLayout = new LinearLayout(this);
mainLayout.setOrientation(LinearLayout.HORIZONTAL);
paramsL = new LayoutParams(500,LayoutParams.MATCH_PARENT, 1);
paramsR = new LayoutParams(500,LayoutParams.MATCH_PARENT, 1);
leftLayout = new LinearLayout(this);
leftLayout.setOrientation(LinearLayout.VERTICAL);
leftLayout.setLayoutParams(paramsL);
leftLayout.setGravity(Gravity.CENTER_HORIZONTAL);
leftLayout.setBackgroundColor(Color.YELLOW);
rightLayout = new LinearLayout(this);
rightLayout.setOrientation(LinearLayout.VERTICAL);
rightLayout.setLayoutParams(paramsR);
rightLayout.setGravity(Gravity.CENTER_HORIZONTAL);
rightLayout.setBackgroundColor(Color.BLUE);
scanTime = new EditText(this);
scanTime.setHint("Scan Duration (min)");
scanTime.setInputType(InputType.TYPE_CLASS_NUMBER);
pointName = new EditText(this);
pointName.setHint("Enter Point Name");
scan10 = new Button(this);
scan1 = new Button(this);
timedScan = new Button(this);
msg = new TextView(this);
scan10.setText("Do 10 Scans");
scan1.setText("Do a Single Scan");
timedScan.setText("Timed Scan");
msg.setText("Alec Sucks");
leftLayout.addView(pointName);
leftLayout.addView(scanTime);
rightLayout.addView(msg);
rightLayout.addView(scan10);
rightLayout.addView(scan1);
rightLayout.addView(timedScan);
mainLayout.addView(leftLayout);
mainLayout.addView(rightLayout);
mainLayout.setBackgroundColor(Color.RED);
setContentView(mainLayout);
setButtonClickListener();
}
private void setButtonClickListener()
{
scan10.setOnClickListener(new View.OnClickListener()
{
public void onClick(View v)
{
String message2 = "Button: \n" + scan10.getText();
msg.setText(message2);
startScan(mainLayout,10);
}
});
scan1.setOnClickListener(new View.OnClickListener()
{
public void onClick(View v)
{
String message2 = "Button: \n" + scan1.toString();
msg.setText(message2);
startScan(mainLayout,1);
}
});
timedScan.setOnClickListener(new View.OnClickListener()
{
public void onClick(View v)
{
String message2 = "Button: \n" + timedScan.toString();
msg.setText(message2);
startScan(mainLayout,Integer.parseInt(scanTime.getText().toString()));
}
});
}
@Override
public boolean onCreateOptionsMenu(Menu menu) {
// Inflate the menu; this adds items to the action bar if it is present.
getMenuInflater().inflate(R.menu.main, menu);
return true;
}
public void startScan(View view, int numScans)
{
Intent intent = new Intent(this, nWiFiScans.class);
String pntNameStr = pointName.getText().toString();
intent.putExtra(EXTRA_pntNameStr, pntNameStr);
intent.putExtra(EXTRA_numScans, numScans);
startActivity(intent);
}
}
答案 0 :(得分：2)
我运行它，删除了文件创建和Intent（你只需要调用finish（）;）然后它就可以了。你有没有检查过它是否真的为你创建了文件？因为我的卡住了然后它跳出了尝试所以它无法到达终点（）;电话，我也在unregisterReceiver(receiverWifi);
finish();
编辑，文件创建：
File sdCard = Environment.getExternalStorageDirectory(); //returns sdcard directory
File dir = new File (sdCard.getAbsolutePath() + "/mydirectory");
dir.mkdirs();
File file = new File(dir, "filename");