为什么我使用Java在局域网上唤醒后才能在android 7.0上运行，而在8.0及更高版本上却不能运行？

Question

我写了一个Android应用程序，它使我可以通过局域网内的wifi启动和关闭车库中的服务器。

局域网唤醒功能与运行Android 7.0（牛轧糖）的旧三星Galaxy A5完美配合，现在，运行Android 8.0（奥利奥）的Samsung Galaxy A6 +不再运行。

我已经用运行Android 9.0（Pie）的Samsung Galaxy S9对它进行了不成功的测试。

尽管使用JSch的shutdown now仍然运行良好。

我从http://www.jibble.org/wake-on-lan/那里获得了Java Wake on Lan的代码

OLD Wakeup.java：

package ch.serversquare.archcontrolmobile.archcontrolmobile;

import java.net.DatagramPacket;
import java.net.DatagramSocket;
import java.net.InetAddress;

public class Wakeup {
private String MAC;
private String IPBroad;

public Wakeup() {

}

public String getMAC() {
    return MAC;
}

public String getIPBorad() {
    return IPBroad;
}

public static final int PORT = 9;

public void wakeup(String MAC, String IPBroad) {
    this.IPBroad = IPBroad;
    this.MAC = MAC;

    try {
        byte[] macBytes = getMacBytes(MAC);
        byte[] bytes = new byte[6 + 16 * macBytes.length];
        for(int i = 0; i < 6; i++) {
            bytes[i] = (byte) 0xff;
        }
        for(int i = 6; i < bytes.length; i+= macBytes.length) {
            System.arraycopy(macBytes, 0, bytes, i, macBytes.length);
        }
        InetAddress address = InetAddress.getByName(IPBroad);
        DatagramPacket packet = new DatagramPacket(bytes, bytes.length, address, PORT);
        DatagramSocket socket = new DatagramSocket();
        socket.send(packet);
        socket.close();
    } catch (Exception e) {
        e.printStackTrace();
    }

}

private static byte[] getMacBytes(String macStr) throws IllegalArgumentException {
    byte[] bytes = new byte[6];
    String[] hex = macStr.split("(\\:|\\-)");
    if(hex.length != 6) {
        throw new IllegalArgumentException("Invalid MAC address.");
    }
    try {
        for(int i = 0; i<6;i++) {
            bytes[i] = (byte) Integer.parseInt(hex[i], 16);
        }
    } catch (NumberFormatException e) {
        throw new IllegalArgumentException("Invalid hex digit in MAC address.");
    }
        return bytes;
    }
}

在我的MainActivity内看起来像这样：

package ch.serversquare.archcontrolmobile.archcontrolmobile;

public class MainActivity extends AppCompatActivity {

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    if(isWiifConnected(MainActivity.this) == true) {
        setContentView(R.layout.activity_main);
        final Button btnWakeup = (findViewById(R.id.btnWakeup));
        final Button btnShutdown = (findViewById(R.id.btnShutdown));
        final TextView count = (findViewById(R.id.count));
        final TextView status = (findViewById(R.id.status));

        checkConnToServer(status, btnWakeup, btnShutdown);

        btnWakeup.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                if(v == btnWakeup) {
                    Wakeup wol = new Wakeup();
                    wol.wakeup("00:0b:0e:0f:00:ed", "192.168.200.255");
                    btnWakeup.setEnabled(false);
                    new Handler().postDelayed(new Runnable() {
                        @Override
                        public void run() {
                            btnShutdown.setEnabled(true);
                            checkConnToServer(status, btnWakeup, btnShutdown);
                        }
                    }, 60000);
                    new CountDownTimer(60000, 1000) {
                        public void onTick(long millisUntilFinished) {
                            count.setText("Shutdown available in: " + millisUntilFinished / 1000);
                        }
                        public void onFinish() {
                            count.setText("");
                        }
                    }.start();
                }
            }
        });

（这不是整个MainActivity。它只是从顶部到唤醒按钮。）

您可能会问是否有任何错误。 简单的问题，简单的答案：不，没有。

如果有错误，我会在这里寻找答案，而不是在这里问：D

您中的某些人可能会对我的AndroidManifest中的内容感兴趣。

<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
package="uk.co.serversquare.archcontrolmobile.archcontrolmobile">

<uses-permission android:name="android.permission.INTERNET"/>
<uses-permission android:name="android.permission.ACCESS_NETWORK_STATE"></uses-permission>
<uses-permission android:name="android.permission.ACCESS_WIFI_STATE"></uses-permission>
<uses-permission android:name="android.permission.CHANGE_WIFI_STATE"></uses-permission>
<application
    android:allowBackup="true"
    android:icon="@mipmap/ic_launcher"
    android:label="@string/app_name"
    android:roundIcon="@mipmap/ic_launcher"
    android:supportsRtl="true"
    android:theme="@style/AppTheme">
    <activity android:name=".MainActivity" android:configChanges="orientation" android:screenOrientation="portrait">
        <intent-filter>
            <action android:name="android.intent.action.MAIN" />

            <category android:name="android.intent.category.LAUNCHER" />
        </intent-filter>
    </activity>
    <activity android:name=".About" android:configChanges="orientation" android:screenOrientation="portrait"></activity>
</application>

（只需稍微清理一下，ACCESS_NETWORK_STATE，ACCESS_WIFI_STATE，CHANGE_WIFI_STATE在这里检查是否启用并连接了wifi，如果没有启用，则会弹出一个对话框，说您应该激活wifi。但这对这个问题并不重要。）

我希望有人可以帮助我解决这个问题。 （对不起，我的英语知识很差：D）

如果缺少任何重要信息，请回答此主题，我将使用所需信息编辑该主题。

编辑：

编辑过的Wakeup.java

package uk.co.serversquare.archcontrolmobile.archcontrolmobile;

import java.net.DatagramPacket;
import java.net.DatagramSocket;
import java.net.InetAddress;
import android.os.Handler;

public class Wakeup {
private String MAC;
private String IPBroad;

public Wakeup() {

}

public String getMAC() {
    return MAC;
}

public String getIPBorad() {
    return IPBroad;
}

public static final int PORT = 9;

public void wakeup(String MAC, String IPBroad) {
    this.IPBroad = IPBroad;
    this.MAC = MAC;

    try {
        byte[] macBytes = getMacBytes(MAC);
        byte[] bytes = new byte[6 + 16 * macBytes.length];
        for(int i = 0; i < 6; i++) {
            bytes[i] = (byte) 0xff;
        }
        for(int i = 6; i < bytes.length; i+= macBytes.length) {
            System.arraycopy(macBytes, 0, bytes, i, macBytes.length);
        }
        InetAddress address = InetAddress.getByName(IPBroad);
        final DatagramPacket packet = new DatagramPacket(bytes, bytes.length, address, PORT);
        final DatagramSocket socket = new DatagramSocket();
        for(int i = 0; i<3;i++) {
            new Handler().postDelayed(new Runnable() {
                @Override
                public void run() {
                    try {
                        socket.send(packet);
                    } catch (Exception e) {
                        e.printStackTrace();
                    }
                }
            }, 300);
        }
        socket.close();
    } catch (Exception e) {
        e.printStackTrace();
    }

}

private static byte[] getMacBytes(String macStr) throws IllegalArgumentException {
    byte[] bytes = new byte[6];
    String[] hex = macStr.split("(\\:|\\-)");
    if(hex.length != 6) {
        throw new IllegalArgumentException("Invalid MAC address.");
    }
    try {
        for(int i = 0; i<6;i++) {
            bytes[i] = (byte) Integer.parseInt(hex[i], 16);
        }
    } catch (NumberFormatException e) {
        throw new IllegalArgumentException("Invalid hex digit in MAC address.");
        }
    return bytes;
    }
}

编辑，共1/3/19

再次

编辑Wakeup.java

package uk.co.serversquare.archcontrolmobile.archcontrolmobile;

import java.net.DatagramPacket;
import java.net.DatagramSocket;
import java.net.InetAddress;
import android.os.Handler;

public class Wakeup {
private String MAC;
private String IPBroad;

public Wakeup() {

}

public String getMAC() {
    return MAC;
}

public String getIPBorad() {
    return IPBroad;
}

public static final int PORT = 9;

public void wakeup(String MAC, String IPBroad) {
    this.IPBroad = IPBroad;
    this.MAC = MAC;

    try {
        byte[] macBytes = getMacBytes(MAC);
        byte[] bytes = new byte[6 + 16 * macBytes.length];
        for(int i = 0; i < 6; i++) {
            bytes[i] = (byte) 0xff;
        }
        for(int i = 6; i < bytes.length; i+= macBytes.length) {
            System.arraycopy(macBytes, 0, bytes, i, macBytes.length);
        }
        InetAddress address = InetAddress.getByName(IPBroad);
        final DatagramPacket packet = new DatagramPacket(bytes, bytes.length, address, PORT);
        final DatagramSocket socket = new DatagramSocket();
        socket.send(packet); //directly
        for(int i = 0; i<2;i++) {
            new Handler().postDelayed(new Runnable() {
                @Override
                public void run() {
                    try {
                        socket.send(packet); //after 300 & 600 ms
                    } catch (Exception e) {
                        e.printStackTrace();
                    }
                }
            }, 300);
        }
        new Handler().postDelayed(new Runnable() {
            @Override
            public void run() {
                try {
                    socket.send(packet); //afer 1000ms (1s)
                } catch (Exception e) {
                    e.printStackTrace();
                }
            }
        }, 1000);
        socket.close();
    } catch (Exception e) {
        e.printStackTrace();
    }

}

private static byte[] getMacBytes(String macStr) throws IllegalArgumentException {
    byte[] bytes = new byte[6];
    String[] hex = macStr.split("(\\:|\\-)");
    if(hex.length != 6) {
        throw new IllegalArgumentException("Invalid MAC address.");
    }
    try {
        for(int i = 0; i<6;i++) {
            bytes[i] = (byte) Integer.parseInt(hex[i], 16);
        }
    } catch (NumberFormatException e) {
        throw new IllegalArgumentException("Invalid hex digit in MAC address.");
    }
    return bytes;
}

}