Wi-fi扫描广播接收器不工作

Question

我目前正在开发一个简单的Wi-fi扫描仪android应用程序API最低26级，目标API 28级。

我想实时更新扫描结果，所以我已经创建了一个广播接收器，但它没有按预期工作。

注意：我已经试过了Wifi扫描结果广播接收器不工作，广播接收器与Wifi扫描不工作

请注意，我想要明确的广播接收器，而不是通过清单文件

我会感谢你的。

下面是我的java代码：

package com.example.quickshare;
import androidx.appcompat.app.AppCompatActivity;
import android.content.BroadcastReceiver;
import android.content.Context;
import android.content.Intent;
import android.content.IntentFilter;
import android.net.wifi.ScanResult;
import android.net.wifi.WifiManager;
import android.os.Bundle;
import android.view.View;
import android.widget.AdapterView;
import android.widget.ListView;
import android.widget.TextView;
import android.widget.Toast;
import java.util.List;
public class ActivitySend extends AppCompatActivity {
WifiManager wifiManager;
ListView ScanList;
List<ScanResult> results;
ListAdapter listAdapter;
WifiReceiver wifiReceiver;
IntentFilter intentFilter;
TextView msg;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_send);
wifiManager = (WifiManager)getApplicationContext().getSystemService(Context.WIFI_SERVICE);
CheckWifiStatus();
msg = findViewById(R.id.wifiStatus);
intentFilter = new IntentFilter();
intentFilter.addAction(WifiManager.SCAN_RESULTS_AVAILABLE_ACTION);
intentFilter.addAction(WifiManager.EXTRA_RESULTS_UPDATED);
try {
getApplicationContext().registerReceiver(wifiReceiver, intentFilter);
}
catch(Exception e){
System.out.println(e);
}
boolean success = wifiManager.startScan();
if(success)
Toast.makeText(ActivitySend.this, "Scanning", Toast.LENGTH_SHORT).show();
}
@Override
protected void onResume() {
super.onResume();
CheckWifiStatus();
registerReceiver(wifiReceiver, intentFilter);
wifiManager.startScan();
results = wifiManager.getScanResults();
if (results.size() > 0)
Toast.makeText(ActivitySend.this, "Scan Successful", Toast.LENGTH_LONG).show();
else
Toast.makeText(ActivitySend.this, "No Device Available", Toast.LENGTH_LONG).show();
ScanList = findViewById(R.id.ScanList);
listAdapter = new ListAdapter(getApplicationContext(), results);
ScanList.setAdapter(listAdapter);
ScanList.setOnItemClickListener(new AdapterView.OnItemClickListener() {
@Override
public void onItemClick(AdapterView<?> parent, View view, int position, long id) {
Toast.makeText(ActivitySend.this, "Selected" + results.get(position).SSID, Toast.LENGTH_LONG).show();
//TODO: Establish Connection with selected SSID
}
});
}
class WifiReceiver extends BroadcastReceiver{
@Override
public void onReceive(Context context, Intent intent) {
Toast.makeText(ActivitySend.this,"Available Device list changed",Toast.LENGTH_LONG).show();
//TODO: Append SSID of new Available APs in ListView and arrange a callback to onResume().
}
}
public void CheckWifiStatus(){
if (!wifiManager.isWifiEnabled()){
wifiManager.setWifiEnabled(true);
Toast.makeText(ActivitySend.this, "Wifi turned 'On' Successfully", Toast.LENGTH_SHORT).show();
msg.setText("Wifi Status : ON");
}
}
@Override
protected void onPause() {
unregisterReceiver(wifiReceiver);
super.onPause();
}
}

使用Above java代码，如果在启动活动之前可用，我可以扫描可用的AP。启动此活动后，扫描结果没有任何变化，即使我关闭了AP，它也会继续显示以前获取的结果。

Answer 1

为了检测AP断开连接，intentFilter缺少ConnectivityManager.CONNECTIVITY_ACTION。

你可以听通过以下行对这些操作：

intentFilter.addAction(ConnectivityManager.CONNECTIVITY_ACTION);

此外，您需要将括号添加到其他代码块，即

if {
// ...
} else {
Toast.makeText(ActivitySend.this, "No Device Available", Toast.LENGTH_LONG).show();
ScanList = findViewById(R.id.ScanList);
// ...
}