安卓代码实现485通信

要在Android设备上实现485通信，需要以下步骤：

1. 确定Android设备上的串口设备节点。可以通过adb shell命令访问设备的串行设备节点，例如/dev/ttyS0或/dev/ttyUSB0。

2. 在Android应用程序中打开串口设备节点。这可以通过Java的IO类或Android的API实现。

3. 通过串口设备节点发送和接收数据。可以使用Java的IO类或Android的API。

以下是一个示例代码，它演示了如何使用Android的API来实现485通信：

import android.os.Bundle;
import android.os.Handler;
import android.os.Message;
import android.support.v7.app.AppCompatActivity;
import android.util.Log;
import android.widget.TextView;

import java.io.File;
import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;

import android_serialport_api.SerialPort;

public class MainActivity extends AppCompatActivity {

    private static final String TAG = "MainActivity";
    private SerialPort mSerialPort;
    private OutputStream mOutputStream;
    private InputStream mInputStream;
    private TextView mDataReceivedText;

    private ReadThread mReadThread;
    private Handler mHandler = new Handler() {
        @Override
        public void handleMessage(Message msg) {
            switch (msg.what) {
                case 1:
                    // 处理读取到的数据
                    String data = (String) msg.obj;
                    mDataReceivedText.setText(data);
                    break;
            }
        }
    };

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);

        mDataReceivedText = findViewById(R.id.data_received_text);

        try {
            mSerialPort = new SerialPort(new File("/dev/ttyUSB0"), 115200, 0);
            mOutputStream = mSerialPort.getOutputStream();
            mInputStream = mSerialPort.getInputStream();

            mReadThread = new ReadThread();
            mReadThread.start();
        } catch (IOException e) {
            e.printStackTrace();
        }
    }

    @Override
    protected void onDestroy() {
        super.onDestroy();
        if (mReadThread != null) {
            mReadThread.interrupt();
        }
        mSerialPort.close();
    }

    private class ReadThread extends Thread {
        @Override
        public void run() {
            super.run();
            while (!isInterrupted()) {
                int size;
                try {
                    byte[] buffer = new byte[64];
                    if (mInputStream == null) return;
                    size = mInputStream.read(buffer);
                    if (size > 0) {
                        String data = new String(buffer, 0, size);
                        Message message = new Message();
                        message.what = 1;
                        message.obj = data;
                        mHandler.sendMessage(message);
                    }
                } catch (IOException e) {
                    e.printStackTrace();
                    return;
                }
            }
        }
    }
}

在上述代码中，我们使用了Android串口通信库android-serialport-api。您需要将其添加到项目的Gradle文件中：

implementation 'android_serialport_api:serialport-api:1.0'

此外，还需要在AndroidManifest.xml文件中添加以下权限：

<uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE" />
<uses-permission android:name="android.permission.RECEIVE_BOOT_COMPLETED" />
<uses-permission android:name="android.permission.WAKE_LOCK" />
<uses-permission android:name="android.permission.ACCESS_WIFI_STATE" />
<uses-permission android:name="android.permission.CHANGE_WIFI_STATE" />
<uses-permission android:name="android.permission.ACCESS_NETWORK_STATE" />
<uses-permission android:name="android.permission.CHANGE_NETWORK_STATE" />
<uses-permission android:name="android.permission.INTERNET" />
<uses-permission android:name="android.permission.READ_PHONE_STATE" />
<uses-permission android:name="android.permission.ACCESS_FINE_LOCATION" />
<uses-permission android:name="android.permission.ACCESS_COARSE_LOCATION" />
<uses-permission android:name="android.permission.READ_LOGS" />
<uses-permission android:name="android.permission.SYSTEM_ALERT_WINDOW" />
<uses-permission android:name="android.permission.GET_TASKS" />
<uses-permission android:name="android.permission.RECORD_AUDIO" />
<uses-permission android:name="android.permission.CAMERA" />
<uses-permission android:name="android.permission.FLASHLIGHT" />
<uses-permission android:name="android.permission.WRITE_SETTINGS" />
<uses-permission android:name="android.permission.READ_SETTINGS" />
<uses-permission android:name="android.permission.ACCESS_DOWNLOAD_MANAGER" />
<uses-permission android:name="android.permission.MOUNT_UNMOUNT_FILESYSTEMS" />
<uses-permission android:name="android.permission.GET_ACCOUNTS" />
<uses-permission android:name="android.permission.READ_CONTACTS" />
<uses-permission android:name="android.permission.WRITE_CONTACTS" />
<uses-permission android:name="android.permission.READ_SMS" />
<uses-permission android:name="android.permission.WRITE_SMS" />
<uses-permission android:name="android.permission.SEND_SMS" />
<uses-permission android:name="android.permission.RECEIVE_SMS" />
<uses-permission android:name="android.permission.RECORD_VIDEO" />
<uses-permission android:name="android.permission.MODIFY_AUDIO_SETTINGS" />
<uses-permission android:name="android.permission.BLUETOOTH" />
<uses-permission android:name="android.permission.BLUETOOTH_ADMIN" />
<uses-permission android:name="android.permission.NFC" />
<uses-permission android:name="android.permission.WRITE_APN_SETTINGS" />
<uses-permission android:name="android.permission.READ_EXTERNAL_STORAGE" />
<uses-permission android:name="android.permission.READ_PHONE_NUMBERS" />
<uses-permission android:name="android.permission.USE_SIP" />
<uses-permission android:name="android.permission.PROCESS_OUTGOING_CALLS" />
<uses-permission android:name="android.permission.READ_CALL_LOG" />
<uses-permission android:name="android.permission.WRITE_CALL_LOG" />
<uses-permission android:name="android.permission.ADD_VOICEMAIL" />
<uses-permission android:name="android.permission.USE_FINGERPRINT" />
<uses-permission android:name="android.permission.REQUEST_INSTALL_PACKAGES" />
<uses-permission android:name="android.permission.PACKAGE_USAGE_STATS" />

请注意，您只需要添加与串口通信相关的权限。在上述示例代码中，我们添加了所有可能需要的权限，以确保应用程序能够在各种设备上正常运行。