windows – 在不知道VID和PID的情况下读取USB HID条形码扫描器输

一年多以前,我在更恶劣的环境下实施了条形码阅读器支持.这是一个报告应用程序,与纯Java(跨平台富客户端,主要是Windows)中的逻辑数据相关联.
我发现你对键盘驱动程序的看法是一样的,这可以防止在用户模式下区分实际的USB设备,至少乍一看.有更昂贵的设备具有自己的驱动程序和高级功能,这将允许某种区别.
我在该环境中遇到的所有条形码阅读器都显示为键盘,用于简单填写SAP表单字段并点击回车键,这是一种常见情况.可以使用“魔术条形码”或其他制造商特定方法来配置终止.

因此,该决定针对任何基于JNI的平台特定实施.
相反,我通过使用以下标准评估某些Swing / AWT表单中的通用keyoard输入,实现了类似拦截的方法(你的扩展版本)：

>前两个字符确定的击键频率(最初/超时后)
>抖动(频率/速率变化)
>一组有效的字符
>终止换行符.

输入被缓冲区消耗,直到不满足机器生成的输入的条件,或者已经通过验证,其中将通知条形码监听器.在任何一种情况下,都可以转发输入,就像没有其他事情一样.

这被证明是非常准确的,因为对于人来说,几乎不可能以条形码阅读器的速率输入有效序列(几乎)零抖动.

编辑：

刚挖出Java源代码;我可以为您提供上述实施的早期修订代码示例(无保修,也考虑实施CR)：

import java.awt.event.KeyEvent;
import java.awt.event.KeyListener;
import java.util.regex.Matcher;
import java.util.regex.Pattern;

/**
 * A {@link KeyListener} implementation for barcode readers. This implementation
 * checks for input rate and jitter to distinguish human and scanner
 * input sequences by 'precision'. A barcode input sequence from a scanner is
 * typically terminated with a line break.
 * 
 * @author Me
 */
public abstract class AbstractBarcodeInputListener implements KeyListener {
    public static final int DEFAULT_MIN_PAUSE = 300;// [ms]
    public static final int DEFAULT_MAX_TIME_DELTA = 200;// [ms]
    public static final int DEFAULT_MAX_TIME_JITTER = 50;// [ms]

    public static Integer parseInt(Pattern pattern,int group,String line) {
        final Matcher matcher = pattern.matcher(line);
        if (matcher.matches())
            return Integer.parseInt(matcher.group(group));
        return null;
    }

    private String input;

    private final long minPause;
    private long maxTimeDelta;
    private final long maxTimeJitter;

    private long firstTime;
    private long firstTimeDelta;
    private long lastTimeDelta;
    private long lastTime;

    public AbstractBarcodeInputListener(long maxTimeDelta,long maxTimeJitter) {
        this.input = new String();

        this.minPause = AbstractBarcodeInputListener.DEFAULT_MIN_PAUSE;
        this.maxTimeDelta = maxTimeDelta;
        this.maxTimeJitter = maxTimeJitter;

        this.firstTime = 0;
        this.firstTimeDelta = 0;
        this.lastTimeDelta = 0;
        this.lastTime = 0;
    }

    public AbstractBarcodeInputListener() {
        this(AbstractBarcodeInputListener.DEFAULT_MAX_TIME_DELTA,AbstractBarcodeInputListener.DEFAULT_MAX_TIME_JITTER);
    }

    private boolean checkTiming(KeyEvent e) {
        final int inputLength = this.input.length();
        final long time = e.getWhen();
        long timeDelta = time - this.lastTime;
        long absJitter = 0;
        long relJitter = 0;

        boolean inputOK = true;

        switch (inputLength) {
        case 0: // pause check
            inputOK &= (timeDelta > this.minPause);
            this.firstTime = time;
            this.firstTimeDelta = timeDelta = 0;
            break;
        case 1: // delta check
            this.firstTimeDelta = timeDelta;
            inputOK &= (timeDelta < this.maxTimeDelta);
            break;
        default:// jitter check & delta check
            absJitter = Math.abs(timeDelta - this.firstTimeDelta);
            relJitter = Math.abs(timeDelta - this.lastTimeDelta);
            inputOK &= (absJitter < this.maxTimeJitter);
            inputOK &= (relJitter < this.maxTimeJitter);
            inputOK &= (timeDelta < this.maxTimeDelta);
            break;
        }

        this.lastTime = time;
        this.lastTimeDelta = timeDelta;

        return inputOK;
    }

    @Override
    public void keyPressed(KeyEvent e) {
    }

    private void clearInput() {
        this.input = new String();
    }

    private void commitInput(KeyEvent e) {
        final String code = this.input;
        if (!code.isEmpty()) {
            final long avgIntervalTime = e.getWhen() - this.firstTime;
            this.maxTimeDelta = (avgIntervalTime * 15) / 10;
            this.clearInput();
            this.codeRead(code);
        }
    }

    @Override
    public void keyReleased(KeyEvent e) {
    }

    @Override
    public void keyTyped(KeyEvent e) {
        if (this.checkTiming(e)) {
            final char c = e.getKeyChar();
            switch (c) {
            case 'b':
                this.clearInput();
                break;
            case 'n':
                this.commitInput(e);
                break;
            default:
                this.input += c;
                break;
            }
        } else {
            this.clearInput();
        }
    }

    public abstract void codeRead(String line);
}