Java(树莓派)线程

Question

我是一名正在学习java的学生。(特别是Raspberry pi)我有一个关于多线程的问题。是可以编译的。但它在我的套件中不起作用。如果你们不介意的话，可以检查一下我的代码并帮助我吗？谢谢...

import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;
import java.net.Socket;
import java.net.SocketAddress;
import java.util.logging.Level;
import java.util.logging.Logger;
import java.io.File;
import java.io.FileWriter;

public class RcvThread2 implements Runnable{
    private static final int sizeBuf = 50;
    private Socket clientSocket;
    private Logger logger;
    private SocketAddress clientAddress;

public RcvThread2(Socket clntSock, SocketAddress clientAddress, Logger logger) {
    this.clientSocket = clntSock;
    this.logger = logger;
    this.clientAddress = clientAddress;
    }

static class CloseExtends extends Thread {
    static final String GPIO_OUT = "out";
    static final String GPIO_ON = "1";
    static final String GPIO_OFF = "0";
    static final String[] GpioChannels = {"18"};

public static void main(String[] args) {
    FileWriter[] commandChannels;

    try {
        FileWriter unexportFile = new FileWriter("sys/class/gpio/unexport");
    FileWriter exportFile = new FileWriter("sys/class/gpio/gpio/export");

for(String gpioChannel : GpioChannels) {
    System.out.println(gpioChannel);

    File exportFileCheck =
        new File("sys/class/gpio/gpio" +gpioChannel);
        if(exportFileCheck.exists()) {
            unexportFile.write(gpioChannel);
            exportFile.flush();
        }
        exportFile.write(gpioChannel);
        exportFile.flush();

        FileWriter directionFile = new FileWriter("/sys/class/gpio/gpio" + gpioChannel + "/direction");

        directionFile.write(GPIO_OUT);
        directionFile.flush();
    }
    FileWriter commandChannel = new FileWriter("sys/class/gpio/gpio" + GpioChannels[0] + "/value");

    int period = 20;
    int repeatLoop = 25;
    int counter;

    while(true) {
        for(counter = 0; counter < repeatLoop; counter++) {
            commandChannel.write(GPIO_ON);
            commandChannel.flush();
            java.lang.Thread.sleep(2, 20000);

            commandChannel.write(GPIO_OFF);
            commandChannel.flush();
            java.lang.Thread.sleep(period);
        }
        break;
    }
} catch(Exception exception) {
    exception.printStackTrace();
    }
}
}

public void main(){
try {
    InputStream ins = clientSocket.getInputStream();
    OutputStream outs = clientSocket.getOutputStream();

    int rcvBufSize;
    byte[] rcvBuf = new byte[sizeBuf];
    while ((rcvBufSize = ins.read(rcvBuf)) != -1) {

    String rcvData = new String(rcvBuf, 0, rcvBufSize, "UTF-8");

    if(rcvData.compareTo("MotorLock") == 0) {
        CloseExtends te = new CloseExtends();
        te.start();
    }

    if(rcvData.compareTo("MotorOpen") == 0) {
    }

    logger.info("Received data :" + rcvData + " (" + clientAddress + ")");
    outs.write(rcvBuf, 0, rcvBufSize);
    }

    logger.info(clientSocket.getRemoteSocketAddress() + "Closed");
    } catch (IOException ex) {
        logger.log(Level.WARNING, "Exception in RcvThread", ex);
    }finally {
        try{
            clientSocket.close();
                System.out.println("Disconnected! Client IP :" + clientAddress);
                } catch (IOException e) {}
            }
        }
    }

Answer 1

下面的 main 方法永远不会被调用。如果运行程序，它将执行 public static void main(String[] args) { 方法。

我认为这是您想要在第二个线程中运行的方法？!

如果您使用

声明并运行新线程

CloseExtends te = new CloseExtends();
te.start();它将运行线程 public void run() { 方法。

因此，如果我正确理解您的意图，您应该将 CloseExtends 类中的 main 方法的名称更改为线程 run 方法，并将较低的 main 方法的签名更改为 java 程序的 main 方法 public static void main (字符串[]参数){。

如果任何其他方法不是真正的主方法，我不会将其命名为“main”。

您可以在此处查看使用 Runnable 接口(interface)创建新线程的示例:https://docs.oracle.com/javase/tutorial/essential/concurrency/runthread.html