用 Java 检测 USB 设备的插入和拔出（一种监听）？不只是笔式驱动器

Question

如何使用 Java 检测 USB 设备的插入和拔出（类似监听）？
不只是笔式驱动器，它也可以是扫描仪或打印机。

试过jUSB，没用
USB Java 库会更多，因为我只需要使用它的一部分。

我需要在我的代码中包含这些行，以便可以通知正在插入和拔出的设备。

Answer 1

Java 中的 USB 支持仅限于第三方库。我没有用过这些，但你可以试试 JUSB

如果您无法通过 USB 库找到解决方案，您总是可以做一些简单的工作并循环遍历所有可能的驱动器号，为每个驱动器号创建一个 File 对象并测试是否可以从中读取。如果插入 USB 存储设备，之前失败的驱动器盘符现在将通过，因此您会知道您有一个新设备。当然，您不知道它是什么类型的设备（即它可能是 CD/DVD）。但正如我所说，这不是一个理想的解决方案。

这里有一个实用工具来证明这一点

import java.io.*;

/**
* Waits for USB devices to be plugged in/unplugged and outputs a message
*/
public class FindDrive
{
/**
* Application Entry Point
*/
public static void main(String[] args)
{
String[] letters = new String[]{ "A", "B", "C", "D", "E", "F", "G", "H", "I"};
File[] drives = new File[letters.length];
boolean[] isDrive = new boolean[letters.length];

// init the file objects and the initial drive state
for ( int i = 0; i < letters.length; ++i )
    {
    drives[i] = new File(letters[i]+":/");

    isDrive[i] = drives[i].canRead();
    }

 System.out.println("FindDrive: waiting for devices...");

 // loop indefinitely
 while(true)
    {
    // check each drive 
    for ( int i = 0; i < letters.length; ++i )
        {
        boolean pluggedIn = drives[i].canRead();

        // if the state has changed output a message
        if ( pluggedIn != isDrive[i] )
            {
            if ( pluggedIn )
                System.out.println("Drive "+letters[i]+" has been plugged in");
            else
                System.out.println("Drive "+letters[i]+" has been unplugged");

            isDrive[i] = pluggedIn;
            }
        }

    // wait before looping
    try { Thread.sleep(100); }
    catch (InterruptedException e) { /* do nothing */ }

    }
 }
}

Answer 2

我在下面写了检测USB

import java.io.File;

public class UsbDetection {


    public static void main(String[] args) {

        //here the usb drive names are named as E,F,G,H in the system
        String[] drive_name = new String[]{"E", "F", "G", "H", "I", "J", "K", "L", "M", "N"};
        //here we initialize an array for the usb that is to be inserted
        File[] usb = new File[drive_name.length];
        //if the usb is detected then it is assigned True else False
        boolean[] usb_detected = new boolean[drive_name.length];

        // in below loop we append :/ to the drive names because E:/ D:/
        //and then the corresponding drive is searched with the help of canRead() method

        for (int i = 0; i < drive_name.length; ++i) {
            usb[i] = new File(drive_name[i] + ":/");
            //This method determines whether the program can read the file denoted by the mentioned path name
            usb_detected[i] = usb[i].canRead();
        }

        System.out.println("Insert USB");

        detect(usb, drive_name, usb_detected);


    }


    public static void detect(File[] usb, String[] drive_name, boolean[] usb_detected) {
        while (true) {
            //the following loop is iterated to find the usb inserted
            for (int i = 0; i < drive_name.length; ++i) {
                boolean if_detected;
                if_detected = usb[i].canRead();

                if (if_detected != usb_detected[i]) {
                    if (if_detected){
                        System.out.println("USB " + drive_name[i] + " detected ");
                    }else {
                        System.out.println("USB " + drive_name[i] + " removed ");
                    }
                    usb_detected[i] = if_detected;
                }

            }

        }
    }
}